import all

.github/workflows/check-prelude.yml

@@ -14,7 +14,6 @@ jobs:
           sparse-checkout: |
             src/Lean
             src/Std
-            src/lake/Lake
       - name: Check Prelude
         run: |
           failed_files=""
@@ -22,7 +21,7 @@ jobs:
             if ! grep -q "^prelude$" "$file"; then
               failed_files="$failed_files$file\n"
             fi
-          done < <(find src/Lean src/Std src/lake/Lake -name '*.lean' -print0)
+          done < <(find src/Lean src/Std -name '*.lean' -print0)
           if [ -n "$failed_files" ]; then
             echo -e "The following files should use 'prelude':\n$failed_files"
             exit 1

.github/workflows/pr-release.yml

@@ -34,7 +34,7 @@ jobs:
       - name: Download artifact from the previous workflow.
         if: ${{ steps.workflow-info.outputs.pullRequestNumber != '' }}
         id: download-artifact
-        uses: dawidd6/action-download-artifact@v7 # https://github.com/marketplace/actions/download-workflow-artifact
+        uses: dawidd6/action-download-artifact@v6 # https://github.com/marketplace/actions/download-workflow-artifact
         with:
           run_id: ${{ github.event.workflow_run.id }}
           path: artifacts
@@ -111,7 +111,7 @@ jobs:
 
       - name: 'Setup jq'
         if: ${{ steps.workflow-info.outputs.pullRequestNumber != '' }}
-        uses: dcarbone/install-jq-action@v3.0.1
+        uses: dcarbone/install-jq-action@v2.1.0
 
       # Check that the most recently nightly coincides with 'git merge-base HEAD master'
       - name: Check merge-base and nightly-testing-YYYY-MM-DD

CODEOWNERS

@@ -4,7 +4,7 @@
 # Listed persons will automatically be asked by GitHub to review a PR touching these paths.
 # If multiple names are listed, a review by any of them is considered sufficient by default.
 
-/.github/ @kim-em
+/.github/ @Kha @kim-em
 /RELEASES.md @kim-em
 /src/kernel/ @leodemoura
 /src/lake/ @tydeu
@@ -14,7 +14,9 @@
 /src/Lean/Elab/Tactic/ @kim-em
 /src/Lean/Language/ @Kha
 /src/Lean/Meta/Tactic/ @leodemoura
-/src/Lean/PrettyPrinter/ @kmill
+/src/Lean/Parser/ @Kha
+/src/Lean/PrettyPrinter/ @Kha
+/src/Lean/PrettyPrinter/Delaborator/ @kmill
 /src/Lean/Server/ @mhuisi
 /src/Lean/Widget/ @Vtec234
 /src/Init/Data/ @kim-em

RELEASES.md

@@ -8,299 +8,15 @@ This file contains work-in-progress notes for the upcoming release, as well as p
 Please check the [releases](https://github.com/leanprover/lean4/releases) page for the current status
 of each version.
 
-v4.16.0
+v4.15.0
 ----------
 
 Development in progress.
 
-v4.15.0
-----------
-
-Release candidate, release notes will be copied from the branch `releases/v4.15.0` once completed.
-
 v4.14.0
 ----------
 
-**Full Changelog**: https://github.com/leanprover/lean4/compare/v4.13.0...v4.14.0
-
-### Language features, tactics, and metaprograms
-
-* `structure` and `inductive` commands
-  * [#5517](https://github.com/leanprover/lean4/pull/5517) improves universe level inference for the resulting type of an `inductive` or `structure.` Recall that a `Prop`-valued inductive type is a syntactic subsingleton if it has at most one constructor and all the arguments to the constructor are in `Prop`. Such types have large elimination, so they could be defined in `Type` or `Prop` without any trouble. The way inference has changed is that if a type is a syntactic subsingleton with exactly one constructor, and the constructor has at least one parameter/field, then the `inductive`/`structure` command will prefer creating a `Prop` instead of a `Type`. The upshot is that the `: Prop` in `structure S : Prop` is often no longer needed. (With @arthur-adjedj).
-  * [#5842](https://github.com/leanprover/lean4/pull/5842) and [#5783](https://github.com/leanprover/lean4/pull/5783) implement a feature where the `structure` command can now define recursive inductive types:
-    ```lean
-    structure Tree where
-      n : Nat
-      children : Fin n → Tree
-
-    def Tree.size : Tree → Nat
-      | {n, children} => Id.run do
-        let mut s := 0
-        for h : i in [0 : n] do
-          s := s + (children ⟨i, h.2⟩).size
-        pure s
-    ```
-  * [#5814](https://github.com/leanprover/lean4/pull/5814) fixes a bug where Mathlib's `Type*` elaborator could lead to incorrect universe parameters with the `inductive` command.
-  * [#3152](https://github.com/leanprover/lean4/pull/3152) and [#5844](https://github.com/leanprover/lean4/pull/5844) fix bugs in default value processing for structure instance notation (with @arthur-adjedj).
-  * [#5399](https://github.com/leanprover/lean4/pull/5399) promotes instance synthesis order calculation failure from a soft error to a hard error.
-  * [#5542](https://github.com/leanprover/lean4/pull/5542) deprecates `:=` variants of `inductive` and `structure` (see breaking changes).
-
-* **Application elaboration improvements**
-  * [#5671](https://github.com/leanprover/lean4/pull/5671) makes `@[elab_as_elim]` require at least one discriminant, since otherwise there is no advantage to this alternative elaborator.
-  * [#5528](https://github.com/leanprover/lean4/pull/5528) enables field notation in explicit mode. The syntax `@x.f` elaborates as `@S.f` with `x` supplied to the appropriate parameter.
-  * [#5692](https://github.com/leanprover/lean4/pull/5692) modifies the dot notation resolution algorithm so that it can apply `CoeFun` instances. For example, Mathlib has `Multiset.card : Multiset α →+ Nat`, and now with `m : Multiset α`, the notation `m.card` resolves to `⇑Multiset.card m`.
-  * [#5658](https://github.com/leanprover/lean4/pull/5658) fixes a bug where 'don't know how to synthesize implicit argument' errors might have the incorrect local context when the eta arguments feature is activated.
-  * [#5933](https://github.com/leanprover/lean4/pull/5933) fixes a bug where `..` ellipses in patterns made use of optparams and autoparams.
-  * [#5770](https://github.com/leanprover/lean4/pull/5770) makes dot notation for structures resolve using *all* ancestors. Adds a *resolution order* for generalized field notation. This is the order of namespaces visited during resolution when trying to resolve names. The algorithm to compute a resolution order is the commonly used C3 linearization (used for example by Python), which when successful ensures that immediate parents' namespaces are considered before more distant ancestors' namespaces. By default we use a relaxed version of the algorithm that tolerates inconsistencies, but using `set_option structure.strictResolutionOrder true` makes inconsistent parent orderings into warnings.
-
-* **Recursion and induction principles**
-  * [#5619](https://github.com/leanprover/lean4/pull/5619) fixes functional induction principle generation to avoid over-eta-expanding in the preprocessing step.
-  * [#5766](https://github.com/leanprover/lean4/pull/5766) fixes structural nested recursion so that it is not confused when a nested type appears first.
-  * [#5803](https://github.com/leanprover/lean4/pull/5803) fixes a bug in functional induction principle generation when there are `let` bindings.
-  * [#5904](https://github.com/leanprover/lean4/pull/5904) improves functional induction principle generation to unfold aux definitions more carefully.
-  * [#5850](https://github.com/leanprover/lean4/pull/5850) refactors code for `Predefinition.Structural`.
-
-* **Error messages**
-  * [#5276](https://github.com/leanprover/lean4/pull/5276) fixes a bug in "type mismatch" errors that would structurally assign metavariables during the algorithm to expose differences.
-  * [#5919](https://github.com/leanprover/lean4/pull/5919) makes "type mismatch" errors add type ascriptions to expose differences for numeric literals.
-  * [#5922](https://github.com/leanprover/lean4/pull/5922) makes "type mismatch" errors expose differences in the bodies of functions and pi types.
-  * [#5888](https://github.com/leanprover/lean4/pull/5888) improves the error message for invalid induction alternative names in `match` expressions (@josojo).
-  * [#5719](https://github.com/leanprover/lean4/pull/5719) improves `calc` error messages.
-
-* [#5627](https://github.com/leanprover/lean4/pull/5627) and [#5663](https://github.com/leanprover/lean4/pull/5663) improve the **`#eval` command** and introduce some new features.
-  * Now results can be pretty printed if there is a `ToExpr` instance, which means **hoverable output**. If `ToExpr` fails, it then tries looking for a `Repr` or `ToString` instance like before. Setting `set_option eval.pp false` disables making use of `ToExpr` instances.
-  * There is now **auto-derivation** of `Repr` instances, enabled with the `pp.derive.repr` option (default to **true**). For example:
-    ```lean
-    inductive Baz
-    | a | b
-
-    #eval Baz.a
-    -- Baz.a
-    ```
-    It simply does `deriving instance Repr for Baz` when there's no way to represent `Baz`.
-  * The option `eval.type` controls whether or not to include the type in the output. For now the default is false.
-  * Now expressions such as `#eval do return 2`, where monad is unknown, work. It tries unifying the monad with `CommandElabM`, `TermElabM`, or `IO`.
-  * The classes `Lean.Eval` and `Lean.MetaEval` have been removed. These each used to be responsible for adapting monads and printing results. Now the `MonadEval` class is responsible for adapting monads for evaluation (it is similar to `MonadLift`, but instances are allowed to use default data when initializing state), and representing results is handled through a separate process.
-  * Error messages about failed instance synthesis are now more precise. Once it detects that a `MonadEval` class applies, then the error message will be specific about missing `ToExpr`/`Repr`/`ToString` instances.
-  * Fixes bugs where evaluating `MetaM` and `CoreM` wouldn't collect log messages.
-  * Fixes a bug where `let rec` could not be used in `#eval`.
-
-* `partial` definitions
-  * [#5780](https://github.com/leanprover/lean4/pull/5780) improves the error message when `partial` fails to prove a type is inhabited. Add delta deriving.
-  * [#5821](https://github.com/leanprover/lean4/pull/5821) gives `partial` inhabitation the ability to create local `Inhabited` instances from parameters.
-
-* **New tactic configuration syntax.** The configuration syntax for all core tactics has been given an upgrade. Rather than `simp (config := { contextual := true, maxSteps := 22})`, one can now write `simp +contextual (maxSteps := 22)`. Tactic authors can migrate by switching from `(config)?` to `optConfig` in tactic syntaxes and potentially deleting `mkOptionalNode` in elaborators. [#5883](https://github.com/leanprover/lean4/pull/5883), [#5898](https://github.com/leanprover/lean4/pull/5898),  [#5928](https://github.com/leanprover/lean4/pull/5928), and [#5932](https://github.com/leanprover/lean4/pull/5932). (Tactic authors, see breaking changes.)
-
-* `simp` tactic
-  * [#5632](https://github.com/leanprover/lean4/pull/5632) fixes the simpproc for `Fin` literals to reduce more consistently.
-  * [#5648](https://github.com/leanprover/lean4/pull/5648) fixes a bug in `simpa ... using t` where metavariables in `t` were not properly accounted for, and also improves the type mismatch error.
-  * [#5838](https://github.com/leanprover/lean4/pull/5838) fixes the docstring of `simp!` to actually talk about `simp!`.
-  * [#5870](https://github.com/leanprover/lean4/pull/5870) adds support for `attribute [simp ←]` (note the reverse direction). This adds the reverse of a theorem as a global simp theorem.
-
-* `decide` tactic
-  * [#5665](https://github.com/leanprover/lean4/pull/5665) adds `decide!` tactic for using kernel reduction (warning: this is renamed to `decide +kernel` in a future release).
-
-* `bv_decide` tactic
-  * [#5714](https://github.com/leanprover/lean4/pull/5714) adds inequality regression tests (@alexkeizer).
-  * [#5608](https://github.com/leanprover/lean4/pull/5608) adds `bv_toNat` tag for `toNat_ofInt` (@bollu).
-  * [#5618](https://github.com/leanprover/lean4/pull/5618) adds support for `at` in `ac_nf` and uses it in `bv_normalize` (@tobiasgrosser).
-  * [#5628](https://github.com/leanprover/lean4/pull/5628) adds udiv support.
-  * [#5635](https://github.com/leanprover/lean4/pull/5635) adds auxiliary bitblasters for negation and subtraction.
-  * [#5637](https://github.com/leanprover/lean4/pull/5637) adds more `getLsbD` bitblaster theory.
-  * [#5652](https://github.com/leanprover/lean4/pull/5652) adds umod support.
-  * [#5653](https://github.com/leanprover/lean4/pull/5653) adds performance benchmark for modulo.
-  * [#5655](https://github.com/leanprover/lean4/pull/5655) reduces error on `bv_check` to warning.
-  * [#5670](https://github.com/leanprover/lean4/pull/5670) adds `~~~(-x)` support.
-  * [#5673](https://github.com/leanprover/lean4/pull/5673) disables `ac_nf` by default.
-  * [#5675](https://github.com/leanprover/lean4/pull/5675) fixes context tracking in `bv_decide` counter example.
-  * [#5676](https://github.com/leanprover/lean4/pull/5676) adds an error when the LRAT proof is invalid.
-  * [#5781](https://github.com/leanprover/lean4/pull/5781) introduces uninterpreted symbols everywhere.
-  * [#5823](https://github.com/leanprover/lean4/pull/5823) adds `BitVec.sdiv` support.
-  * [#5852](https://github.com/leanprover/lean4/pull/5852) adds `BitVec.ofBool` support.
-  * [#5855](https://github.com/leanprover/lean4/pull/5855) adds `if` support.
-  * [#5869](https://github.com/leanprover/lean4/pull/5869) adds support for all the SMTLIB BitVec divison/remainder operations.
-  * [#5886](https://github.com/leanprover/lean4/pull/5886) adds embedded constraint substitution.
-  * [#5918](https://github.com/leanprover/lean4/pull/5918) fixes loose mvars bug in `bv_normalize`.
-  * Documentation:
-    * [#5636](https://github.com/leanprover/lean4/pull/5636) adds remarks about multiplication.
-
-* `conv` mode
-  * [#5861](https://github.com/leanprover/lean4/pull/5861) improves the `congr` conv tactic to handle "over-applied" functions.
-  * [#5894](https://github.com/leanprover/lean4/pull/5894) improves the `arg` conv tactic so that it can access more arguments and so that it can handle "over-applied" functions (it generates a specialized congruence lemma for the specific argument in question). Makes `arg 1` and `arg 2` apply to pi types in more situations. Adds negative indexing, for example `arg -2` is equivalent to the `lhs` tactic. Makes the `enter [...]` tactic show intermediate states like `rw`.
-
-* **Other tactics**
-  * [#4846](https://github.com/leanprover/lean4/pull/4846) fixes a bug where `generalize ... at *` would apply to implementation details (@ymherklotz).
-  * [#5730](https://github.com/leanprover/lean4/pull/5730) upstreams the `classical` tactic combinator.
-  * [#5815](https://github.com/leanprover/lean4/pull/5815) improves the error message when trying to unfold a local hypothesis that is not a local definition.
-  * [#5862](https://github.com/leanprover/lean4/pull/5862) and [#5863](https://github.com/leanprover/lean4/pull/5863) change how `apply` and `simp` elaborate, making them not disable error recovery. This improves hovers and completions when the term has elaboration errors.
-
-* `deriving` clauses
-  * [#5899](https://github.com/leanprover/lean4/pull/5899) adds declaration ranges for delta-derived instances.
-  * [#5265](https://github.com/leanprover/lean4/pull/5265) removes unused syntax in `deriving` clauses for providing arguments to deriving handlers (see breaking changes).
-
-* [#5065](https://github.com/leanprover/lean4/pull/5065) upstreams and updates `#where`, a command that reports the current scope information.
-
-* **Linters**
-  * [#5338](https://github.com/leanprover/lean4/pull/5338) makes the unused variables linter ignore variables defined in tactics by default now, avoiding performance bottlenecks.
-  * [#5644](https://github.com/leanprover/lean4/pull/5644) ensures that linters in general do not run on `#guard_msgs` itself.
-
-* **Metaprogramming interface**
-  * [#5720](https://github.com/leanprover/lean4/pull/5720) adds `pushGoal`/`pushGoals` and `popGoal` for manipulating the goal state. These are an alternative to `replaceMainGoal` and `getMainGoal`, and with them you don't need to worry about making sure nothing clears assigned metavariables from the goal list between assigning the main goal and using `replaceMainGoal`. Modifies `closeMainGoalUsing`, which is like a `TacticM` version of `liftMetaTactic`. Now the callback is run in a context where the main goal is removed from the goal list, and the callback is free to modify the goal list. Furthermore, the `checkUnassigned` argument has been replaced with `checkNewUnassigned`, which checks whether the value assigned to the goal has any *new* metavariables, relative to the start of execution of the callback. Modifies `withCollectingNewGoalsFrom` to take the `parentTag` argument explicitly rather than indirectly via `getMainTag`. Modifies `elabTermWithHoles` to optionally take `parentTag?`.
-  * [#5563](https://github.com/leanprover/lean4/pull/5563) fixes `getFunInfo` and `inferType` to use `withAtLeastTransparency` rather than `withTransparency`.
-  * [#5679](https://github.com/leanprover/lean4/pull/5679) fixes `RecursorVal.getInduct` to return the name of major argument’s type. This makes "structure eta" work for nested inductives.
-  * [#5681](https://github.com/leanprover/lean4/pull/5681) removes unused `mkRecursorInfoForKernelRec`.
-  * [#5686](https://github.com/leanprover/lean4/pull/5686) makes discrimination trees index the domains of foralls, for better performance of the simplify and type class search.
-  * [#5760](https://github.com/leanprover/lean4/pull/5760) adds `Lean.Expr.name?` recognizer for `Name` expressions.
-  * [#5800](https://github.com/leanprover/lean4/pull/5800) modifies `liftCommandElabM` to preserve more state, fixing an issue where using it would drop messages.
-  * [#5857](https://github.com/leanprover/lean4/pull/5857) makes it possible to use dot notation in `m!` strings, for example `m!"{.ofConstName n}"`.
-  * [#5841](https://github.com/leanprover/lean4/pull/5841) and [#5853](https://github.com/leanprover/lean4/pull/5853) record the complete list of `structure` parents in the `StructureInfo` environment extension.
-
-* **Other fixes or improvements**
-  * [#5566](https://github.com/leanprover/lean4/pull/5566) fixes a bug introduced in [#4781](https://github.com/leanprover/lean4/pull/4781) where heartbeat exceptions were no longer being handled properly. Now such exceptions are tagged with `runtime.maxHeartbeats` (@eric-wieser).
-  * [#5708](https://github.com/leanprover/lean4/pull/5708) modifies the proof objects produced by the proof-by-reflection tactics `ac_nf0` and `simp_arith` so that the kernel is less prone to reducing expensive atoms.
-  * [#5768](https://github.com/leanprover/lean4/pull/5768) adds a `#version` command that prints Lean's version information.
-  * [#5822](https://github.com/leanprover/lean4/pull/5822) fixes elaborator algorithms to match kernel algorithms for primitive projections (`Expr.proj`).
-  * [#5811](https://github.com/leanprover/lean4/pull/5811) improves the docstring for the `rwa` tactic.
-
-
-### Language server, widgets, and IDE extensions
-
-* [#5224](https://github.com/leanprover/lean4/pull/5224) fixes `WorkspaceClientCapabilities` to make `applyEdit` optional, in accordance with the LSP specification (@pzread).
-* [#5340](https://github.com/leanprover/lean4/pull/5340) fixes a server deadlock when shutting down the language server and a desync between client and language server after a file worker crash.
-* [#5560](https://github.com/leanprover/lean4/pull/5560) makes `initialize` and `builtin_initialize` participate in the call hierarchy and other requests.
-* [#5650](https://github.com/leanprover/lean4/pull/5650) makes references in attributes participate in the call hierarchy and other requests.
-* [#5666](https://github.com/leanprover/lean4/pull/5666) add auto-completion in tactic blocks without having to type the first character of the tactic, and adds tactic completion docs to tactic auto-completion items.
-* [#5677](https://github.com/leanprover/lean4/pull/5677) fixes several cases where goal states were not displayed in certain text cursor positions.
-* [#5707](https://github.com/leanprover/lean4/pull/5707) indicates deprecations in auto-completion items.
-* [#5736](https://github.com/leanprover/lean4/pull/5736), [#5752](https://github.com/leanprover/lean4/pull/5752), [#5763](https://github.com/leanprover/lean4/pull/5763), [#5802](https://github.com/leanprover/lean4/pull/5802), and [#5805](https://github.com/leanprover/lean4/pull/5805) fix various performance issues in the language server.
-* [#5801](https://github.com/leanprover/lean4/pull/5801) distinguishes theorem auto-completions from non-theorem auto-completions.
-
-### Pretty printing
-
-* [#5640](https://github.com/leanprover/lean4/pull/5640) fixes a bug where goal states in messages might print newlines as spaces.
-* [#5643](https://github.com/leanprover/lean4/pull/5643) adds option `pp.mvars.delayed` (default false), which when false causes delayed assignment metavariables to pretty print with what they are assigned to. Now `fun x : Nat => ?a` pretty prints as `fun x : Nat => ?a` rather than `fun x ↦ ?m.7 x`.
-* [#5711](https://github.com/leanprover/lean4/pull/5711) adds options `pp.mvars.anonymous` and `pp.mvars.levels`, which when false respectively cause expression metavariables and level metavariables to pretty print as `?_`.
-* [#5710](https://github.com/leanprover/lean4/pull/5710) adjusts the `⋯` elaboration warning to mention `pp.maxSteps`.
-
-* [#5759](https://github.com/leanprover/lean4/pull/5759) fixes the app unexpander for `sorryAx`.
-* [#5827](https://github.com/leanprover/lean4/pull/5827) improves accuracy of binder names in the signature pretty printer (like in output of `#check`). Also fixes the issue where consecutive hygienic names pretty print without a space separating them, so we now have `(x✝ y✝ : Nat)` rather than `(x✝y✝ : Nat)`.
-* [#5830](https://github.com/leanprover/lean4/pull/5830) makes sure all the core delaborators respond to `pp.explicit` when appropriate.
-* [#5639](https://github.com/leanprover/lean4/pull/5639) makes sure name literals use escaping when pretty printing.
-* [#5854](https://github.com/leanprover/lean4/pull/5854) adds delaborators for `<|>`, `<*>`, `>>`, `<*`, and `*>`.
-
-### Library
-
-* `Array`
-  * [#5687](https://github.com/leanprover/lean4/pull/5687) deprecates `Array.data`.
-  * [#5705](https://github.com/leanprover/lean4/pull/5705) uses a better default value for `Array.swapAt!`.
-  * [#5748](https://github.com/leanprover/lean4/pull/5748) moves `Array.mapIdx` lemmas to a new file.
-  * [#5749](https://github.com/leanprover/lean4/pull/5749) simplifies signature of `Array.mapIdx`.
-  * [#5758](https://github.com/leanprover/lean4/pull/5758) upstreams `Array.reduceOption`.
-  * [#5786](https://github.com/leanprover/lean4/pull/5786) adds simp lemmas for `Array.isEqv` and `BEq`.
-  * [#5796](https://github.com/leanprover/lean4/pull/5796) renames `Array.shrink` to `Array.take`, and relates it to `List.take`.
-  * [#5798](https://github.com/leanprover/lean4/pull/5798) upstreams `List.modify`, adds lemmas, relates to `Array.modify`.
-  * [#5799](https://github.com/leanprover/lean4/pull/5799) relates `Array.forIn` and `List.forIn`.
-  * [#5833](https://github.com/leanprover/lean4/pull/5833) adds `Array.forIn'`, and relates to `List`.
-  * [#5848](https://github.com/leanprover/lean4/pull/5848) fixes deprecations in `Init.Data.Array.Basic` to not recommend the deprecated constant.
-  * [#5895](https://github.com/leanprover/lean4/pull/5895) adds `LawfulBEq (Array α) ↔ LawfulBEq α`.
-  * [#5896](https://github.com/leanprover/lean4/pull/5896) moves `@[simp]` from `back_eq_back?` to `back_push`.
-  * [#5897](https://github.com/leanprover/lean4/pull/5897) renames `Array.back` to `back!`.
-
-* `List`
-  * [#5605](https://github.com/leanprover/lean4/pull/5605) removes `List.redLength`.
-  * [#5696](https://github.com/leanprover/lean4/pull/5696) upstreams `List.mapIdx` and adds lemmas.
-  * [#5697](https://github.com/leanprover/lean4/pull/5697) upstreams `List.foldxM_map`.
-  * [#5701](https://github.com/leanprover/lean4/pull/5701) renames `List.join` to `List.flatten`.
-  * [#5703](https://github.com/leanprover/lean4/pull/5703) upstreams `List.sum`.
-  * [#5706](https://github.com/leanprover/lean4/pull/5706) marks `prefix_append_right_inj` as a simp lemma.
-  * [#5716](https://github.com/leanprover/lean4/pull/5716) fixes `List.drop_drop` addition order.
-  * [#5731](https://github.com/leanprover/lean4/pull/5731) renames `List.bind` and `Array.concatMap` to `flatMap`.
-  * [#5732](https://github.com/leanprover/lean4/pull/5732) renames `List.pure` to `List.singleton`.
-  * [#5742](https://github.com/leanprover/lean4/pull/5742) upstreams `ne_of_mem_of_not_mem`.
-  * [#5743](https://github.com/leanprover/lean4/pull/5743) upstreams `ne_of_apply_ne`.
-  * [#5816](https://github.com/leanprover/lean4/pull/5816) adds more `List.modify` lemmas.
-  * [#5879](https://github.com/leanprover/lean4/pull/5879) renames `List.groupBy` to `splitBy`.
-  * [#5913](https://github.com/leanprover/lean4/pull/5913) relates `for` loops over `List` with `foldlM`.
-
-* `Nat`
-  * [#5694](https://github.com/leanprover/lean4/pull/5694) removes `instBEqNat`, which is redundant with `instBEqOfDecidableEq` but not defeq.
-  * [#5746](https://github.com/leanprover/lean4/pull/5746) deprecates `Nat.sum`.
-  * [#5785](https://github.com/leanprover/lean4/pull/5785) adds `Nat.forall_lt_succ` and variants.
-
-* Fixed width integers
-  * [#5323](https://github.com/leanprover/lean4/pull/5323) redefine unsigned fixed width integers in terms of `BitVec`.
-  * [#5735](https://github.com/leanprover/lean4/pull/5735) adds `UIntX.[val_ofNat, toBitVec_ofNat]`.
-  * [#5790](https://github.com/leanprover/lean4/pull/5790) defines `Int8`.
-  * [#5901](https://github.com/leanprover/lean4/pull/5901) removes native code for `UInt8.modn`.
-
-* `BitVec`
-  * [#5604](https://github.com/leanprover/lean4/pull/5604) completes `BitVec.[getMsbD|getLsbD|msb]` for shifts (@luisacicolini).
-  * [#5609](https://github.com/leanprover/lean4/pull/5609) adds lemmas for division when denominator is zero (@bollu).
-  * [#5620](https://github.com/leanprover/lean4/pull/5620) documents Bitblasting (@bollu)
-  * [#5623](https://github.com/leanprover/lean4/pull/5623) moves `BitVec.udiv/umod/sdiv/smod` after `add/sub/mul/lt` (@tobiasgrosser).
-  * [#5645](https://github.com/leanprover/lean4/pull/5645) defines `udiv` normal form to be `/`, resp. `umod` and `%` (@bollu).
-  * [#5646](https://github.com/leanprover/lean4/pull/5646) adds lemmas about arithmetic inequalities (@bollu).
-  * [#5680](https://github.com/leanprover/lean4/pull/5680) expands relationship with `toFin` (@tobiasgrosser).
-  * [#5691](https://github.com/leanprover/lean4/pull/5691) adds `BitVec.(getMSbD, msb)_(add, sub)` and `BitVec.getLsbD_sub` (@luisacicolini).
-  * [#5712](https://github.com/leanprover/lean4/pull/5712) adds `BitVec.[udiv|umod]_[zero|one|self]` (@tobiasgrosser).
-  * [#5718](https://github.com/leanprover/lean4/pull/5718) adds `BitVec.sdiv_[zero|one|self]` (@tobiasgrosser).
-  * [#5721](https://github.com/leanprover/lean4/pull/5721) adds `BitVec.(msb, getMsbD, getLsbD)_(neg, abs)` (@luisacicolini).
-  * [#5772](https://github.com/leanprover/lean4/pull/5772) adds `BitVec.toInt_sub`, simplifies `BitVec.toInt_neg` (@tobiasgrosser).
-  * [#5778](https://github.com/leanprover/lean4/pull/5778) prove that `intMin` the smallest signed bitvector (@alexkeizer).
-  * [#5851](https://github.com/leanprover/lean4/pull/5851) adds `(msb, getMsbD)_twoPow` (@luisacicolini).
-  * [#5858](https://github.com/leanprover/lean4/pull/5858) adds `BitVec.[zero_ushiftRight|zero_sshiftRight|zero_mul]` and cleans up BVDecide (@tobiasgrosser).
-  * [#5865](https://github.com/leanprover/lean4/pull/5865) adds `BitVec.(msb, getMsbD)_concat` (@luisacicolini).
-  * [#5881](https://github.com/leanprover/lean4/pull/5881) adds `Hashable (BitVec n)`
-
-* `String`/`Char`
-  * [#5728](https://github.com/leanprover/lean4/pull/5728) upstreams `String.dropPrefix?`.
-  * [#5745](https://github.com/leanprover/lean4/pull/5745) changes `String.dropPrefix?` signature.
-  * [#5747](https://github.com/leanprover/lean4/pull/5747) adds `Hashable Char` instance
-
-* `HashMap`
-  * [#5880](https://github.com/leanprover/lean4/pull/5880) adds interim implementation of `HashMap.modify`/`alter`
-
-* **Other**
-  * [#5704](https://github.com/leanprover/lean4/pull/5704) removes `@[simp]` from `Option.isSome_eq_isSome`.
-  * [#5739](https://github.com/leanprover/lean4/pull/5739) upstreams material on `Prod`.
-  * [#5740](https://github.com/leanprover/lean4/pull/5740) moves `Antisymm` to `Std.Antisymm`.
-  * [#5741](https://github.com/leanprover/lean4/pull/5741) upstreams basic material on `Sum`.
-  * [#5756](https://github.com/leanprover/lean4/pull/5756) adds `Nat.log2_two_pow` (@spinylobster).
-  * [#5892](https://github.com/leanprover/lean4/pull/5892) removes duplicated `ForIn` instances.
-  * [#5900](https://github.com/leanprover/lean4/pull/5900) removes `@[simp]` from `Sum.forall` and `Sum.exists`.
-  * [#5812](https://github.com/leanprover/lean4/pull/5812) removes redundant `Decidable` assumptions (@FR-vdash-bot).
-
-### Compiler, runtime, and FFI
-
-* [#5685](https://github.com/leanprover/lean4/pull/5685) fixes help message flags, removes the `-f` flag and adds the `-g` flag (@James-Oswald).
-* [#5930](https://github.com/leanprover/lean4/pull/5930) adds `--short-version` (`-V`) option to display short version (@juhp).
-* [#5144](https://github.com/leanprover/lean4/pull/5144) switches all 64-bit platforms over to consistently using GMP for bignum arithmetic.
-* [#5753](https://github.com/leanprover/lean4/pull/5753) raises the minimum supported Windows version to Windows 10 1903 (released May 2019).
-
-### Lake
-
-* [#5715](https://github.com/leanprover/lean4/pull/5715) changes `lake new math` to use `autoImplicit false` (@eric-wieser).
-* [#5688](https://github.com/leanprover/lean4/pull/5688) makes `Lake` not create core aliases in the `Lake` namespace.
-* [#5924](https://github.com/leanprover/lean4/pull/5924) adds a `text` option for `buildFile*` utilities.
-* [#5789](https://github.com/leanprover/lean4/pull/5789) makes `lake init` not `git init` when inside git work tree (@haoxins).
-* [#5684](https://github.com/leanprover/lean4/pull/5684) has Lake update a package's `lean-toolchain` file on `lake update` if it finds the package's direct dependencies use a newer compatible toolchain. To skip this step, use the `--keep-toolchain` CLI option. (See breaking changes.)
-* [#6218](https://github.com/leanprover/lean4/pull/6218) makes Lake no longer automatically fetch GitHub cloud releases if the package build directory is already present (mirroring the behavior of the Reservoir cache). This prevents the cache from clobbering existing prebuilt artifacts. Users can still manually fetch the cache and clobber the build directory by running `lake build <pkg>:release`.
-* [#6231](https://github.com/leanprover/lean4/pull/6231) improves the errors Lake produces when it fails to fetch a dependency from Reservoir. If the package is not indexed, it will produce a suggestion about how to require it from GitHub.
-
-### Documentation
-
-* [#5617](https://github.com/leanprover/lean4/pull/5617) fixes MSYS2 build instructions.
-* [#5725](https://github.com/leanprover/lean4/pull/5725) points out that `OfScientific` is called with raw literals (@eric-wieser).
-* [#5794](https://github.com/leanprover/lean4/pull/5794) adds a stub for application ellipsis notation (@eric-wieser).
-
-### Breaking changes
-
-* The syntax for providing arguments to deriving handlers has been removed, which was not used by any major Lean projects in the ecosystem. As a result, the  `applyDerivingHandlers` now takes one fewer argument, `registerDerivingHandlerWithArgs` is now simply `registerDerivingHandler`, `DerivingHandler` no longer includes the unused parameter, and `DerivingHandlerNoArgs` has been deprecated. To migrate code, delete the unused `none` argument and use `registerDerivingHandler` and `DerivingHandler`. ([#5265](https://github.com/leanprover/lean4/pull/5265))
-* The minimum supported Windows version has been raised to Windows 10 1903, released May 2019. ([#5753](https://github.com/leanprover/lean4/pull/5753))
-* The `--lean` CLI option for `lake` was removed. Use the `LEAN` environment variable instead. ([#5684](https://github.com/leanprover/lean4/pull/5684))
-* The `inductive ... :=`, `structure ... :=`, and `class ... :=` syntaxes have been deprecated in favor of the `... where` variants. The old syntax produces a warning, controlled by the `linter.deprecated` option. ([#5542](https://github.com/leanprover/lean4/pull/5542))
-* The generated tactic configuration elaborators now land in `TacticM` to make use of the current recovery state. Commands that wish to elaborate configurations should now use `declare_command_config_elab` instead of `declare_config_elab` to get an elaborator landing in `CommandElabM`. Syntaxes should migrate to `optConfig` instead of `(config)?`, but the elaborators are reverse compatible. ([#5883](https://github.com/leanprover/lean4/pull/5883))
-
+Release candidate, release notes will be copied from the branch `releases/v4.14.0` once completed.
 
 v4.13.0
 ----------
@@ -372,7 +88,7 @@ v4.13.0
   * [#4768](https://github.com/leanprover/lean4/pull/4768) fixes a parse error when `..` appears with a `.` on the next line
 
 * Metaprogramming
-  * [#3090](https://github.com/leanprover/lean4/pull/3090) handles level parameters in `Meta.evalExpr` (@eric-wieser)
+  * [#3090](https://github.com/leanprover/lean4/pull/3090) handles level parameters in `Meta.evalExpr` (@eric-wieser)  
   * [#5401](https://github.com/leanprover/lean4/pull/5401) instance for `Inhabited (TacticM α)` (@alexkeizer)
   * [#5412](https://github.com/leanprover/lean4/pull/5412) expose Kernel.check for debugging purposes
   * [#5556](https://github.com/leanprover/lean4/pull/5556) improves the "invalid projection" type inference error in `inferType`.

debug.log

@@ -0,0 +1 @@
+[0829/202002.254:ERROR:crashpad_client_win.cc(868)] not connected

doc/examples/test_single.sh

@@ -1,4 +1,4 @@
 #!/usr/bin/env bash
 source ../../tests/common.sh
 
-exec_check_raw lean -Dlinter.all=false "$f"
+exec_check lean -Dlinter.all=false "$f"

doc/lexical_structure.md

@@ -128,16 +128,16 @@ Numeric literals can be specified in various bases.
 
 ```
    numeral    : numeral10 | numeral2 | numeral8 | numeral16
-   numeral10  : [0-9]+ ("_"+ [0-9]+)*
-   numeral2   : "0" [bB] ("_"* [0-1]+)+
-   numeral8   : "0" [oO] ("_"* [0-7]+)+
-   numeral16  : "0" [xX] ("_"* hex_char+)+
+   numeral10  : [0-9]+
+   numeral2   : "0" [bB] [0-1]+
+   numeral8   : "0" [oO] [0-7]+
+   numeral16  : "0" [xX] hex_char+
 ```
 
 Floating point literals are also possible with optional exponent:
 
 ```
-   float    : numeral10 "." numeral10? [eE[+-]numeral10]
+   float    : [0-9]+ "." [0-9]+ [[eE[+-][0-9]+]
 ```
 
 For example:
@@ -147,7 +147,6 @@ constant w : Int := 55
 constant x : Nat := 26085
 constant y : Nat := 0x65E5
 constant z : Float := 2.548123e-05
-constant b : Bool := 0b_11_01_10_00
 ```
 
 Note: that negative numbers are created by applying the "-" negation prefix operator to the number, for example:

doc/monads/readers.lean

@@ -139,7 +139,7 @@ You might be wondering, how does the context actually move through the `ReaderM`
 add an input argument to a function by modifying its return type?  There is a special command in
 Lean that will show you the reduced types:
 -/
-#reduce (types := true) ReaderM Environment String   -- Environment → String
+#reduce ReaderM Environment String   -- Environment → String
 /-!
 And you can see here that this type is actually a function!  It's a function that takes an
 `Environment` as input and returns a `String`.
@@ -196,4 +196,4 @@ entirely.
 
 Now it's time to move on to [StateM Monad](states.lean.md) which is like a `ReaderM` that is
 also updatable.
--/
+-/

script/mathlib-bench

@@ -1,12 +0,0 @@
-#! /bin/env bash
-# Open a Mathlib4 PR for benchmarking a given Lean 4 PR
-
-set -euo pipefail
-
-[ $# -eq 1 ] || (echo "usage: $0 <lean4 PR #>"; exit 1)
-
-LEAN_PR=$1
-PR_RESPONSE=$(gh api repos/leanprover-community/mathlib4/pulls -X POST -f head=lean-pr-testing-$LEAN_PR -f base=nightly-testing -f title="leanprover/lean4#$LEAN_PR benchmarking" -f draft=true -f body="ignore me")
-PR_NUMBER=$(echo "$PR_RESPONSE" | jq '.number')
-echo "opened https://github.com/leanprover-community/mathlib4/pull/$PR_NUMBER"
-gh api repos/leanprover-community/mathlib4/issues/$PR_NUMBER/comments -X POST -f body="!bench" > /dev/null

src/CMakeLists.txt

@@ -10,7 +10,7 @@ endif()
 include(ExternalProject)
 project(LEAN CXX C)
 set(LEAN_VERSION_MAJOR 4)
-set(LEAN_VERSION_MINOR 16)
+set(LEAN_VERSION_MINOR 15)
 set(LEAN_VERSION_PATCH 0)
 set(LEAN_VERSION_IS_RELEASE 0)  # This number is 1 in the release revision, and 0 otherwise.
 set(LEAN_SPECIAL_VERSION_DESC "" CACHE STRING "Additional version description like 'nightly-2018-03-11'")
@@ -122,7 +122,7 @@ if(${CMAKE_SYSTEM_NAME} MATCHES "Emscripten")
     # From https://emscripten.org/docs/compiling/WebAssembly.html#backends:
     # > The simple and safe thing is to pass all -s flags at both compile and link time.
     set(EMSCRIPTEN_SETTINGS "-s ALLOW_MEMORY_GROWTH=1 -fwasm-exceptions -pthread -flto")
-    string(APPEND LEANC_EXTRA_CC_FLAGS " -pthread")
+    string(APPEND LEANC_EXTRA_FLAGS " -pthread")
     string(APPEND LEAN_EXTRA_CXX_FLAGS " -D LEAN_EMSCRIPTEN ${EMSCRIPTEN_SETTINGS}")
     string(APPEND LEAN_EXTRA_LINKER_FLAGS " ${EMSCRIPTEN_SETTINGS}")
 endif()
@@ -157,11 +157,11 @@ if ((${MULTI_THREAD} MATCHES "ON") AND (${CMAKE_SYSTEM_NAME} MATCHES "Darwin"))
 endif ()
 
 # We want explicit stack probes in huge Lean stack frames for robust stack overflow detection
-string(APPEND LEANC_EXTRA_CC_FLAGS " -fstack-clash-protection")
+string(APPEND LEANC_EXTRA_FLAGS " -fstack-clash-protection")
 
 # This makes signed integer overflow guaranteed to match 2's complement.
 string(APPEND CMAKE_CXX_FLAGS " -fwrapv")
-string(APPEND LEANC_EXTRA_CC_FLAGS " -fwrapv")
+string(APPEND LEANC_EXTRA_FLAGS " -fwrapv")
 
 if(NOT MULTI_THREAD)
   message(STATUS "Disabled multi-thread support, it will not be safe to run multiple threads in parallel")
@@ -451,7 +451,7 @@ if(${CMAKE_SYSTEM_NAME} MATCHES "Linux")
     string(APPEND TOOLCHAIN_SHARED_LINKER_FLAGS " -Wl,-Bsymbolic")
   endif()
   string(APPEND CMAKE_CXX_FLAGS " -fPIC -ftls-model=initial-exec")
-  string(APPEND LEANC_EXTRA_CC_FLAGS " -fPIC")
+  string(APPEND LEANC_EXTRA_FLAGS " -fPIC")
   string(APPEND TOOLCHAIN_SHARED_LINKER_FLAGS " -Wl,-rpath=\\$$ORIGIN/..:\\$$ORIGIN")
   string(APPEND LAKESHARED_LINKER_FLAGS " -Wl,--whole-archive ${CMAKE_BINARY_DIR}/lib/temp/libLake.a.export -Wl,--no-whole-archive")
   string(APPEND CMAKE_EXE_LINKER_FLAGS " -Wl,-rpath=\\\$ORIGIN/../lib:\\\$ORIGIN/../lib/lean")
@@ -464,7 +464,7 @@ elseif(${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
   string(APPEND CMAKE_EXE_LINKER_FLAGS " -Wl,-rpath,@executable_path/../lib -Wl,-rpath,@executable_path/../lib/lean")
 elseif(${CMAKE_SYSTEM_NAME} MATCHES "Emscripten")
   string(APPEND CMAKE_CXX_FLAGS " -fPIC")
-  string(APPEND LEANC_EXTRA_CC_FLAGS " -fPIC")
+  string(APPEND LEANC_EXTRA_FLAGS " -fPIC")
 elseif(${CMAKE_SYSTEM_NAME} MATCHES "Windows")
   string(APPEND LAKESHARED_LINKER_FLAGS " -Wl,--out-implib,${CMAKE_BINARY_DIR}/lib/lean/libLake_shared.dll.a -Wl,--whole-archive ${CMAKE_BINARY_DIR}/lib/temp/libLake.a.export -Wl,--no-whole-archive")
 endif()
@@ -479,7 +479,7 @@ if(NOT(${CMAKE_SYSTEM_NAME} MATCHES "Windows") AND NOT(${CMAKE_SYSTEM_NAME} MATC
   string(APPEND CMAKE_EXE_LINKER_FLAGS " -rdynamic")
   # hide all other symbols
   string(APPEND CMAKE_CXX_FLAGS " -fvisibility=hidden -fvisibility-inlines-hidden")
-  string(APPEND LEANC_EXTRA_CC_FLAGS " -fvisibility=hidden")
+  string(APPEND LEANC_EXTRA_FLAGS " -fvisibility=hidden")
 endif()
 
 # On Windows, add bcrypt for random number generation
@@ -544,10 +544,9 @@ include_directories(${CMAKE_BINARY_DIR}/include)  # config.h etc., "public" head
 string(TOUPPER "${CMAKE_BUILD_TYPE}" uppercase_CMAKE_BUILD_TYPE)
 string(APPEND LEANC_OPTS " ${CMAKE_CXX_FLAGS_${uppercase_CMAKE_BUILD_TYPE}}")
 
-# Do embed flag for finding system headers and libraries in dev builds
+# Do embed flag for finding system libraries in dev builds
 if(CMAKE_OSX_SYSROOT AND NOT LEAN_STANDALONE)
-  string(APPEND LEANC_EXTRA_CC_FLAGS " ${CMAKE_CXX_SYSROOT_FLAG}${CMAKE_OSX_SYSROOT}")
-  string(APPEND LEAN_EXTRA_LINKER_FLAGS " ${CMAKE_CXX_SYSROOT_FLAG}${CMAKE_OSX_SYSROOT}")
+  string(APPEND LEANC_EXTRA_FLAGS " ${CMAKE_CXX_SYSROOT_FLAG}${CMAKE_OSX_SYSROOT}")
 endif()
 
 add_subdirectory(initialize)

src/Init/Control/Lawful/Basic.lean

@@ -106,7 +106,7 @@ theorem seq_eq_bind_map {α β : Type u} [Monad m] [LawfulMonad m] (f : m (α
 theorem bind_congr [Bind m] {x : m α} {f g : α → m β} (h : ∀ a, f a = g a) : x >>= f = x >>= g := by
   simp [funext h]
 
-theorem bind_pure_unit [Monad m] [LawfulMonad m] {x : m PUnit} : (x >>= fun _ => pure ⟨⟩) = x := by
+@[simp] theorem bind_pure_unit [Monad m] [LawfulMonad m] {x : m PUnit} : (x >>= fun _ => pure ⟨⟩) = x := by
   rw [bind_pure]
 
 theorem map_congr [Functor m] {x : m α} {f g : α → β} (h : ∀ a, f a = g a) : (f <$> x : m β) = g <$> x := by
@@ -133,7 +133,7 @@ theorem seqLeft_eq_bind [Monad m] [LawfulMonad m] (x : m α) (y : m β) : x <* y
   rw [← bind_pure_comp]
   simp only [bind_assoc, pure_bind]
 
-theorem Functor.map_unit [Monad m] [LawfulMonad m] {a : m PUnit} : (fun _ => PUnit.unit) <$> a = a := by
+@[simp] theorem Functor.map_unit [Monad m] [LawfulMonad m] {a : m PUnit} : (fun _ => PUnit.unit) <$> a = a := by
   simp [map]
 
 /--

src/Init/Data.lean

@@ -21,7 +21,6 @@ import Init.Data.Fin
 import Init.Data.UInt
 import Init.Data.SInt
 import Init.Data.Float
-import Init.Data.Float32
 import Init.Data.Option
 import Init.Data.Ord
 import Init.Data.Random

src/Init/Data/Array.lean

@@ -21,4 +21,3 @@ import Init.Data.Array.Set
 import Init.Data.Array.Monadic
 import Init.Data.Array.FinRange
 import Init.Data.Array.Perm
-import Init.Data.Array.Find

src/Init/Data/Array/Attach.lean

@@ -150,6 +150,7 @@ theorem attach_map_coe (l : Array α) (f : α → β) :
 theorem attach_map_val (l : Array α) (f : α → β) : (l.attach.map fun i => f i.val) = l.map f :=
   attach_map_coe _ _
 
+@[simp]
 theorem attach_map_subtype_val (l : Array α) : l.attach.map Subtype.val = l := by
   cases l; simp
 
@@ -161,6 +162,7 @@ theorem attachWith_map_val {p : α → Prop} (f : α → β) (l : Array α) (H :
     ((l.attachWith p H).map fun i => f i.val) = l.map f :=
   attachWith_map_coe _ _ _
 
+@[simp]
 theorem attachWith_map_subtype_val {p : α → Prop} (l : Array α) (H : ∀ a ∈ l, p a) :
     (l.attachWith p H).map Subtype.val = l := by
   cases l; simp
@@ -202,8 +204,8 @@ theorem pmap_ne_empty_iff {P : α → Prop} (f : (a : α) → P a → β) {xs :
     (H : ∀ (a : α), a ∈ xs → P a) : xs.pmap f H ≠ #[] ↔ xs ≠ #[] := by
   cases xs; simp
 
-theorem pmap_eq_self {l : Array α} {p : α → Prop} {hp : ∀ (a : α), a ∈ l → p a}
-    {f : (a : α) → p a → α} : l.pmap f hp = l ↔ ∀ a (h : a ∈ l), f a (hp a h) = a := by
+theorem pmap_eq_self {l : Array α} {p : α → Prop} (hp : ∀ (a : α), a ∈ l → p a)
+    (f : (a : α) → p a → α) : l.pmap f hp = l ↔ ∀ a (h : a ∈ l), f a (hp a h) = a := by
   cases l; simp [List.pmap_eq_self]
 
 @[simp]
@@ -249,7 +251,7 @@ theorem getElem?_attach {xs : Array α} {i : Nat} :
 theorem getElem_attachWith {xs : Array α} {P : α → Prop} {H : ∀ a ∈ xs, P a}
     {i : Nat} (h : i < (xs.attachWith P H).size) :
     (xs.attachWith P H)[i] = ⟨xs[i]'(by simpa using h), H _ (getElem_mem (by simpa using h))⟩ :=
-  getElem_pmap _ _ h
+  getElem_pmap ..
 
 @[simp]
 theorem getElem_attach {xs : Array α} {i : Nat} (h : i < xs.attach.size) :

src/Init/Data/Array/Basic.lean

@@ -11,7 +11,7 @@ import Init.Data.UInt.BasicAux
 import Init.Data.Repr
 import Init.Data.ToString.Basic
 import Init.GetElem
-import Init.Data.List.ToArrayImpl
+import Init.Data.List.ToArray
 import Init.Data.Array.Set
 
 universe u v w
@@ -79,15 +79,12 @@ theorem ext' {as bs : Array α} (h : as.toList = bs.toList) : as = bs := by
 @[simp] theorem toArrayAux_eq (as : List α) (acc : Array α) : (as.toArrayAux acc).toList = acc.toList ++ as := by
   induction as generalizing acc <;> simp [*, List.toArrayAux, Array.push, List.append_assoc, List.concat_eq_append]
 
--- This does not need to be a simp lemma, as already after the `whnfR` the right hand side is `as`.
-theorem toList_toArray (as : List α) : as.toArray.toList = as := rfl
+@[simp] theorem toList_toArray (as : List α) : as.toArray.toList = as := rfl
 
 @[simp] theorem size_toArray (as : List α) : as.toArray.size = as.length := by simp [size]
 
 @[simp] theorem getElem_toList {a : Array α} {i : Nat} (h : i < a.size) : a.toList[i] = a[i] := rfl
 
-@[simp] theorem getElem?_toList {a : Array α} {i : Nat} : a.toList[i]? = a[i]? := rfl
-
 /-- `a ∈ as` is a predicate which asserts that `a` is in the array `as`. -/
 -- NB: This is defined as a structure rather than a plain def so that a lemma
 -- like `sizeOf_lt_of_mem` will not apply with no actual arrays around.
@@ -100,9 +97,6 @@ instance : Membership α (Array α) where
 theorem mem_def {a : α} {as : Array α} : a ∈ as ↔ a ∈ as.toList :=
   ⟨fun | .mk h => h, Array.Mem.mk⟩
 
-@[simp] theorem mem_toArray {a : α} {l : List α} : a ∈ l.toArray ↔ a ∈ l := by
-  simp [mem_def]
-
 @[simp] theorem getElem_mem {l : Array α} {i : Nat} (h : i < l.size) : l[i] ∈ l := by
   rw [Array.mem_def, ← getElem_toList]
   apply List.getElem_mem
@@ -209,7 +203,7 @@ instance : EmptyCollection (Array α) := ⟨Array.empty⟩
 instance : Inhabited (Array α) where
   default := Array.empty
 
-def isEmpty (a : Array α) : Bool :=
+@[simp] def isEmpty (a : Array α) : Bool :=
   a.size = 0
 
 @[specialize]
@@ -248,7 +242,7 @@ def singleton (v : α) : Array α :=
   mkArray 1 v
 
 def back! [Inhabited α] (a : Array α) : α :=
-  a[a.size - 1]!
+  a.get! (a.size - 1)
 
 @[deprecated back! (since := "2024-10-31")] abbrev back := @back!
 
@@ -480,10 +474,6 @@ def findSomeM? {α : Type u} {β : Type v} {m : Type v → Type w} [Monad m] (f
     | _      => pure ⟨⟩
   return none
 
-/--
-Note that the universe level is contrained to `Type` here,
-to avoid having to have the predicate live in `p : α → m (ULift Bool)`.
--/
 @[inline]
 def findM? {α : Type} {m : Type → Type} [Monad m] (p : α → m Bool) (as : Array α) : m (Option α) := do
   for a in as do
@@ -595,12 +585,8 @@ def zipWithIndex (arr : Array α) : Array (α × Nat) :=
   arr.mapIdx fun i a => (a, i)
 
 @[inline]
-def find? {α : Type u} (p : α → Bool) (as : Array α) : Option α :=
-  Id.run do
-    for a in as do
-      if p a then
-        return a
-    return none
+def find? {α : Type} (p : α → Bool) (as : Array α) : Option α :=
+  Id.run <| as.findM? p
 
 @[inline]
 def findSome? {α : Type u} {β : Type v} (f : α → Option β) (as : Array α) : Option β :=
@@ -663,15 +649,9 @@ def any (as : Array α) (p : α → Bool) (start := 0) (stop := as.size) : Bool
 def all (as : Array α) (p : α → Bool) (start := 0) (stop := as.size) : Bool :=
   Id.run <| as.allM p start stop
 
-/-- `as.contains a` is true if there is some element `b` in `as` such that `a == b`. -/
 def contains [BEq α] (as : Array α) (a : α) : Bool :=
-  as.any (a == ·)
+  as.any (· == a)
 
-/--
-Variant of `Array.contains` with arguments reversed.
-
-For verification purposes, we simplify this to `contains`.
--/
 def elem [BEq α] (a : α) (as : Array α) : Bool :=
   as.contains a
 
@@ -821,7 +801,7 @@ decreasing_by simp_wf; exact Nat.sub_succ_lt_self _ _ h
   induction a, i, h using Array.eraseIdx.induct with
   | @case1 a i h h' a' ih =>
     unfold eraseIdx
-    simp +zetaDelta [h', a', ih]
+    simp [h', a', ih]
   | case2 a i h h' =>
     unfold eraseIdx
     simp [h']

src/Init/Data/Array/BasicAux.lean

@@ -32,8 +32,10 @@ private theorem List.of_toArrayAux_eq_toArrayAux {as bs : List α} {cs ds : Arra
     have := Array.of_push_eq_push ih₂
     simp [this]
 
-theorem List.toArray_eq_toArray_eq (as bs : List α) : (as.toArray = bs.toArray) = (as = bs) := by
-  simp
+@[simp] theorem List.toArray_eq_toArray_eq (as bs : List α) : (as.toArray = bs.toArray) = (as = bs) := by
+  apply propext; apply Iff.intro
+  · intro h; simpa [toArray] using h
+  · intro h; rw [h]
 
 def Array.mapM' [Monad m] (f : α → m β) (as : Array α) : m { bs : Array β // bs.size = as.size } :=
   go 0 ⟨mkEmpty as.size, rfl⟩ (by simp)

src/Init/Data/Array/Bootstrap.lean

@@ -93,14 +93,11 @@ theorem foldrM_eq_reverse_foldlM_toList [Monad m] (f : α → β → m β) (init
 @[simp] theorem appendList_eq_append
     (arr : Array α) (l : List α) : arr.appendList l = arr ++ l := rfl
 
-@[simp] theorem toList_appendList (arr : Array α) (l : List α) :
+@[simp] theorem appendList_toList (arr : Array α) (l : List α) :
     (arr ++ l).toList = arr.toList ++ l := by
   rw [← appendList_eq_append]; unfold Array.appendList
   induction l generalizing arr <;> simp [*]
 
-@[deprecated toList_appendList (since := "2024-12-11")]
-abbrev appendList_toList := @toList_appendList
-
 @[deprecated "Use the reverse direction of `foldrM_toList`." (since := "2024-11-13")]
 theorem foldrM_eq_foldrM_toList [Monad m]
     (f : α → β → m β) (init : β) (arr : Array α) :
@@ -152,7 +149,7 @@ abbrev pop_data := @pop_toList
 @[deprecated toList_append (since := "2024-09-09")]
 abbrev append_data := @toList_append
 
-@[deprecated toList_appendList (since := "2024-09-09")]
-abbrev appendList_data := @toList_appendList
+@[deprecated appendList_toList (since := "2024-09-09")]
+abbrev appendList_data := @appendList_toList
 
 end Array

src/Init/Data/Array/DecidableEq.lean

@@ -42,7 +42,7 @@ theorem rel_of_isEqv {r : α → α → Bool} {a b : Array α} :
   · exact fun h' => ⟨h, fun i => rel_of_isEqvAux h (Nat.le_refl ..) h'⟩
   · intro; contradiction
 
-theorem isEqv_iff_rel {a b : Array α} {r} :
+theorem isEqv_iff_rel (a b : Array α) (r) :
     Array.isEqv a b r ↔ ∃ h : a.size = b.size, ∀ (i : Nat) (h' : i < a.size), r (a[i]) (b[i]'(h ▸ h')) :=
   ⟨rel_of_isEqv, fun ⟨h, w⟩ => by
     simp only [isEqv, ← h, ↓reduceDIte]

src/Init/Data/Array/Find.lean

@@ -81,7 +81,7 @@ theorem getElem_zero_flatten.proof {L : Array (Array α)} (h : 0 < L.flatten.siz
     (L.findSome? fun l => l[0]?).isSome := by
   cases L using array_array_induction
   simp only [List.findSome?_toArray, List.findSome?_map, Function.comp_def, List.getElem?_toArray,
-    List.findSome?_isSome_iff, isSome_getElem?]
+    List.findSome?_isSome_iff, List.isSome_getElem?]
   simp only [flatten_toArray_map_toArray, size_toArray, List.length_flatten,
     Nat.sum_pos_iff_exists_pos, List.mem_map] at h
   obtain ⟨_, ⟨xs, m, rfl⟩, h⟩ := h
@@ -99,7 +99,7 @@ theorem back?_flatten {L : Array (Array α)} :
   simp [List.getLast?_flatten, ← List.map_reverse, List.findSome?_map, Function.comp_def]
 
 theorem findSome?_mkArray : findSome? f (mkArray n a) = if n = 0 then none else f a := by
-  simp [← List.toArray_replicate, List.findSome?_replicate]
+  simp [mkArray_eq_toArray_replicate, List.findSome?_replicate]
 
 @[simp] theorem findSome?_mkArray_of_pos (h : 0 < n) : findSome? f (mkArray n a) = f a := by
   simp [findSome?_mkArray, Nat.ne_of_gt h]
@@ -246,7 +246,7 @@ theorem find?_flatMap_eq_none {xs : Array α} {f : α → Array β} {p : β →
 
 theorem find?_mkArray :
     find? p (mkArray n a) = if n = 0 then none else if p a then some a else none := by
-  simp [← List.toArray_replicate, List.find?_replicate]
+  simp [mkArray_eq_toArray_replicate, List.find?_replicate]
 
 @[simp] theorem find?_mkArray_of_length_pos (h : 0 < n) :
     find? p (mkArray n a) = if p a then some a else none := by
@@ -262,15 +262,15 @@ theorem find?_mkArray :
 -- This isn't a `@[simp]` lemma since there is already a lemma for `l.find? p = none` for any `l`.
 theorem find?_mkArray_eq_none {n : Nat} {a : α} {p : α → Bool} :
     (mkArray n a).find? p = none ↔ n = 0 ∨ !p a := by
-  simp [← List.toArray_replicate, List.find?_replicate_eq_none, Classical.or_iff_not_imp_left]
+  simp [mkArray_eq_toArray_replicate, List.find?_replicate_eq_none, Classical.or_iff_not_imp_left]
 
 @[simp] theorem find?_mkArray_eq_some {n : Nat} {a b : α} {p : α → Bool} :
     (mkArray n a).find? p = some b ↔ n ≠ 0 ∧ p a ∧ a = b := by
-  simp [← List.toArray_replicate]
+  simp [mkArray_eq_toArray_replicate]
 
 @[simp] theorem get_find?_mkArray (n : Nat) (a : α) (p : α → Bool) (h) :
     ((mkArray n a).find? p).get h = a := by
-  simp [← List.toArray_replicate]
+  simp [mkArray_eq_toArray_replicate]
 
 theorem find?_pmap {P : α → Prop} (f : (a : α) → P a → β) (xs : Array α)
     (H : ∀ (a : α), a ∈ xs → P a) (p : β → Bool) :

src/Init/Data/Array/TakeDrop.lean

@@ -12,7 +12,7 @@ namespace Array
 theorem exists_of_uset (self : Array α) (i d h) :
     ∃ l₁ l₂, self.toList = l₁ ++ self[i] :: l₂ ∧ List.length l₁ = i.toNat ∧
       (self.uset i d h).toList = l₁ ++ d :: l₂ := by
-  simpa only [ugetElem_eq_getElem, ← getElem_toList, uset, toList_set] using
+  simpa only [ugetElem_eq_getElem, getElem_eq_getElem_toList, uset, toList_set] using
     List.exists_of_set _
 
 end Array

src/Init/Data/BEq.lean

@@ -40,9 +40,6 @@ theorem BEq.symm [BEq α] [PartialEquivBEq α] {a b : α} : a == b → b == a :=
 theorem BEq.comm [BEq α] [PartialEquivBEq α] {a b : α} : (a == b) = (b == a) :=
   Bool.eq_iff_iff.2 ⟨BEq.symm, BEq.symm⟩
 
-theorem bne_comm [BEq α] [PartialEquivBEq α] {a b : α} : (a != b) = (b != a) := by
-  rw [bne, BEq.comm, bne]
-
 theorem BEq.symm_false [BEq α] [PartialEquivBEq α] {a b : α} : (a == b) = false → (b == a) = false :=
   BEq.comm (α := α) ▸ id
 

src/Init/Data/BitVec/Basic.lean

@@ -351,17 +351,17 @@ end relations
 section cast
 
 /-- `cast eq x` embeds `x` into an equal `BitVec` type. -/
-@[inline] protected def cast (eq : n = m) (x : BitVec n) : BitVec m := .ofNatLt x.toNat (eq ▸ x.isLt)
+@[inline] def cast (eq : n = m) (x : BitVec n) : BitVec m := .ofNatLt x.toNat (eq ▸ x.isLt)
 
 @[simp] theorem cast_ofNat {n m : Nat} (h : n = m) (x : Nat) :
-    (BitVec.ofNat n x).cast h = BitVec.ofNat m x := by
+    cast h (BitVec.ofNat n x) = BitVec.ofNat m x := by
   subst h; rfl
 
 @[simp] theorem cast_cast {n m k : Nat} (h₁ : n = m) (h₂ : m = k) (x : BitVec n) :
-    (x.cast h₁).cast h₂ = x.cast (h₁ ▸ h₂) :=
+    cast h₂ (cast h₁ x) = cast (h₁ ▸ h₂) x :=
   rfl
 
-@[simp] theorem cast_eq {n : Nat} (h : n = n) (x : BitVec n) : x.cast h = x := rfl
+@[simp] theorem cast_eq {n : Nat} (h : n = n) (x : BitVec n) : cast h x = x := rfl
 
 /--
 Extraction of bits `start` to `start + len - 1` from a bit vector of size `n` to yield a

src/Init/Data/BitVec/Bitblast.lean

@@ -462,7 +462,7 @@ theorem msb_neg {w : Nat} {x : BitVec w} :
       case true =>
         apply hmin
         apply eq_of_getMsbD_eq
-        intro i hi
+        rintro ⟨i, hi⟩
         simp only [getMsbD_intMin, w_pos, decide_true, Bool.true_and]
         cases i
         case zero => exact hmsb
@@ -470,7 +470,7 @@ theorem msb_neg {w : Nat} {x : BitVec w} :
       case false =>
         apply hzero
         apply eq_of_getMsbD_eq
-        intro i hi
+        rintro ⟨i, hi⟩
         simp only [getMsbD_zero]
         cases i
         case zero => exact hmsb
@@ -573,11 +573,11 @@ theorem setWidth_setWidth_succ_eq_setWidth_setWidth_add_twoPow (x : BitVec w) (i
     setWidth w (x.setWidth (i + 1)) =
       setWidth w (x.setWidth i) + (x &&& twoPow w i) := by
   rw [add_eq_or_of_and_eq_zero]
-  · ext k h
-    simp only [getLsbD_setWidth, h, decide_true, Bool.true_and, getLsbD_or, getLsbD_and]
+  · ext k
+    simp only [getLsbD_setWidth, Fin.is_lt, decide_true, Bool.true_and, getLsbD_or, getLsbD_and]
     by_cases hik : i = k
     · subst hik
-      simp [h]
+      simp
     · simp only [getLsbD_twoPow, hik, decide_false, Bool.and_false, Bool.or_false]
       by_cases hik' : k < (i + 1)
       · have hik'' : k < i := by omega

src/Init/Data/BitVec/Lemmas.lean

@@ -173,21 +173,21 @@ theorem getMsbD_eq_getMsb?_getD (x : BitVec w) (i : Nat) :
 -- We choose `eq_of_getLsbD_eq` as the `@[ext]` theorem for `BitVec`
 -- somewhat arbitrarily over `eq_of_getMsbD_eq`.
 @[ext] theorem eq_of_getLsbD_eq {x y : BitVec w}
-    (pred : ∀ i, i < w → x.getLsbD i = y.getLsbD i) : x = y := by
+    (pred : ∀(i : Fin w), x.getLsbD i.val = y.getLsbD i.val) : x = y := by
   apply eq_of_toNat_eq
   apply Nat.eq_of_testBit_eq
   intro i
   if i_lt : i < w then
-    exact pred i i_lt
+    exact pred ⟨i, i_lt⟩
   else
     have p : i ≥ w := Nat.le_of_not_gt i_lt
     simp [testBit_toNat, getLsbD_ge _ _ p]
 
 theorem eq_of_getMsbD_eq {x y : BitVec w}
-    (pred : ∀ i, i < w → x.getMsbD i = y.getMsbD i) : x = y := by
+    (pred : ∀(i : Fin w), x.getMsbD i.val = y.getMsbD i.val) : x = y := by
   simp only [getMsbD] at pred
   apply eq_of_getLsbD_eq
-  intro i i_lt
+  intro ⟨i, i_lt⟩
   if w_zero : w = 0 then
     simp [w_zero]
   else
@@ -199,7 +199,7 @@ theorem eq_of_getMsbD_eq {x y : BitVec w}
       simp only [Nat.sub_sub]
       apply Nat.sub_lt w_pos
       simp [Nat.succ_add]
-    have q := pred (w - 1 - i) q_lt
+    have q := pred ⟨w - 1 - i, q_lt⟩
     simpa [q_lt, Nat.sub_sub_self, r] using q
 
 -- This cannot be a `@[simp]` lemma, as it would be tried at every term.
@@ -241,11 +241,8 @@ theorem toFin_one  : toFin (1 : BitVec w) = 1 := by
 @[simp] theorem toNat_ofBool (b : Bool) : (ofBool b).toNat = b.toNat := by
   cases b <;> rfl
 
-@[simp] theorem toInt_ofBool (b : Bool) : (ofBool b).toInt = -b.toInt := by
-  cases b <;> rfl
-
-@[simp] theorem toFin_ofBool (b : Bool) : (ofBool b).toFin = Fin.ofNat' 2 (b.toNat) := by
-  cases b <;> rfl
+@[simp] theorem msb_ofBool (b : Bool) : (ofBool b).msb = b := by
+  cases b <;> simp [BitVec.msb, getMsbD, getLsbD]
 
 theorem ofNat_one (n : Nat) : BitVec.ofNat 1 n = BitVec.ofBool (n % 2 = 1) :=  by
   rcases (Nat.mod_two_eq_zero_or_one n) with h | h <;> simp [h, BitVec.ofNat, Fin.ofNat']
@@ -332,11 +329,11 @@ theorem getLsbD_ofNat (n : Nat) (x : Nat) (i : Nat) :
 private theorem lt_two_pow_of_le {x m n : Nat} (lt : x < 2 ^ m) (le : m ≤ n) : x < 2 ^ n :=
   Nat.lt_of_lt_of_le lt (Nat.pow_le_pow_of_le_right (by trivial : 0 < 2) le)
 
-theorem getElem_zero_ofNat_zero (i : Nat) (h : i < w) : (BitVec.ofNat w 0)[i] = false := by
-  simp
+@[simp] theorem getElem_zero_ofNat_zero (i : Nat) (h : i < w) : (BitVec.ofNat w 0)[i] = false := by
+  simp [getElem_eq_testBit_toNat]
 
-theorem getElem_zero_ofNat_one (h : 0 < w) : (BitVec.ofNat w 1)[0] = true := by
-  simp
+@[simp] theorem getElem_zero_ofNat_one (h : 0 < w) : (BitVec.ofNat w 1)[0] = true := by
+  simp [getElem_eq_testBit_toNat, h]
 
 theorem getElem?_zero_ofNat_zero : (BitVec.ofNat (w+1) 0)[0]? = some false := by
   simp
@@ -362,13 +359,12 @@ theorem getLsbD_ofBool (b : Bool) (i : Nat) : (ofBool b).getLsbD i = ((i = 0) &&
   · simp only [ofBool, ofNat_eq_ofNat, cond_true, getLsbD_ofNat, Bool.and_true]
     by_cases hi : i = 0 <;> simp [hi] <;> omega
 
-theorem getElem_ofBool {b : Bool} : (ofBool b)[0] = b := by simp
-
-@[simp] theorem getMsbD_ofBool (b : Bool) : (ofBool b).getMsbD i = (decide (i = 0) && b) := by
-  cases b <;> simp [getMsbD]
-
-@[simp] theorem msb_ofBool (b : Bool) : (ofBool b).msb = b := by
-  cases b <;> simp [BitVec.msb]
+@[simp]
+theorem getElem_ofBool {b : Bool} {i : Nat} : (ofBool b)[0] = b := by
+  rcases b with rfl | rfl
+  · simp [ofBool]
+  · simp only [ofBool]
+    by_cases hi : i = 0 <;> simp [hi] <;> omega
 
 /-! ### msb -/
 
@@ -414,21 +410,21 @@ theorem toNat_ge_of_msb_true {x : BitVec n} (p : BitVec.msb x = true) : x.toNat
 
 /-! ### cast -/
 
-@[simp, bv_toNat] theorem toNat_cast (h : w = v) (x : BitVec w) : (x.cast h).toNat = x.toNat := rfl
+@[simp, bv_toNat] theorem toNat_cast (h : w = v) (x : BitVec w) : (cast h x).toNat = x.toNat := rfl
 @[simp] theorem toFin_cast (h : w = v) (x : BitVec w) :
-    (x.cast h).toFin = x.toFin.cast (by rw [h]) :=
+    (cast h x).toFin = x.toFin.cast (by rw [h]) :=
   rfl
 
-@[simp] theorem getLsbD_cast (h : w = v) (x : BitVec w) : (x.cast h).getLsbD i = x.getLsbD i := by
+@[simp] theorem getLsbD_cast (h : w = v) (x : BitVec w) : (cast h x).getLsbD i = x.getLsbD i := by
   subst h; simp
 
-@[simp] theorem getMsbD_cast (h : w = v) (x : BitVec w) : (x.cast h).getMsbD i = x.getMsbD i := by
+@[simp] theorem getMsbD_cast (h : w = v) (x : BitVec w) : (cast h x).getMsbD i = x.getMsbD i := by
   subst h; simp
 
-@[simp] theorem getElem_cast (h : w = v) (x : BitVec w) (p : i < v) : (x.cast h)[i] = x[i] := by
+@[simp] theorem getElem_cast (h : w = v) (x : BitVec w) (p : i < v) : (cast h x)[i] = x[i] := by
   subst h; simp
 
-@[simp] theorem msb_cast (h : w = v) (x : BitVec w) : (x.cast h).msb = x.msb := by
+@[simp] theorem msb_cast (h : w = v) (x : BitVec w) : (cast h x).msb = x.msb := by
   simp [BitVec.msb]
 
 /-! ### toInt/ofInt -/
@@ -502,9 +498,6 @@ theorem toInt_ofNat {n : Nat} (x : Nat) :
 @[simp] theorem ofInt_ofNat (w n : Nat) :
   BitVec.ofInt w (no_index (OfNat.ofNat n)) = BitVec.ofNat w (OfNat.ofNat n) := rfl
 
-@[simp] theorem ofInt_toInt {x : BitVec w} : BitVec.ofInt w x.toInt = x := by
-  by_cases h : 2 * x.toNat < 2^w <;> ext <;> simp [getLsbD, h, BitVec.toInt]
-
 theorem toInt_neg_iff {w : Nat} {x : BitVec w} :
     BitVec.toInt x < 0 ↔ 2 ^ w ≤ 2 * x.toNat := by
   simp [toInt_eq_toNat_cond]; omega
@@ -533,7 +526,7 @@ theorem toInt_zero {w : Nat} : (0#w).toInt = 0 := by
 A bitvector, when interpreted as an integer, is less than zero iff
 its most significant bit is true.
 -/
-theorem slt_zero_iff_msb_cond {x : BitVec w} : x.slt 0#w ↔ x.msb = true := by
+theorem slt_zero_iff_msb_cond (x : BitVec w) : x.slt 0#w ↔ x.msb = true := by
   have := toInt_eq_msb_cond x
   constructor
   · intros h
@@ -576,10 +569,6 @@ theorem zeroExtend_eq_setWidth {v : Nat} {x : BitVec w} :
     (x.setWidth v).toInt = Int.bmod x.toNat (2^v) := by
   simp [toInt_eq_toNat_bmod, toNat_setWidth, Int.emod_bmod]
 
-@[simp] theorem toFin_setWidth {x : BitVec w} :
-    (x.setWidth v).toFin = Fin.ofNat' (2^v) x.toNat := by
-  ext; simp
-
 theorem setWidth'_eq {x : BitVec w} (h : w ≤ v) : x.setWidth' h = x.setWidth v := by
   apply eq_of_toNat_eq
   rw [toNat_setWidth, toNat_setWidth']
@@ -656,20 +645,6 @@ theorem getElem?_setWidth (m : Nat) (x : BitVec n) (i : Nat) :
     getLsbD (setWidth m x) i = (decide (i < m) && getLsbD x i) := by
   simp [getLsbD, toNat_setWidth, Nat.testBit_mod_two_pow]
 
-theorem getMsbD_setWidth {m : Nat} {x : BitVec n} {i : Nat} :
-    getMsbD (setWidth m x) i = (decide (m - n ≤ i) && getMsbD x (i + n - m)) := by
-  unfold setWidth
-  by_cases h : n ≤ m <;> simp only [h]
-  · by_cases h' : m - n ≤ i
-    <;> simp [h', show i - (m - n) = i + n - m by omega]
-  · simp only [show m - n = 0 by omega, getMsbD, getLsbD_setWidth]
-    by_cases h' : i < m
-    · simp [show m - 1 - i < m by omega, show i + n - m < n by omega,
-        show n - 1 - (i + n - m) = m - 1 - i by omega]
-      omega
-    · simp [h']
-      omega
-
 @[simp] theorem getMsbD_setWidth_add {x : BitVec w} (h : k ≤ i) :
     (x.setWidth (w + k)).getMsbD i = x.getMsbD (i - k) := by
   by_cases h : w = 0
@@ -683,7 +658,7 @@ theorem getMsbD_setWidth {m : Nat} {x : BitVec n} {i : Nat} :
     <;> omega
 
 @[simp] theorem cast_setWidth (h : v = v') (x : BitVec w) :
-    (x.setWidth v).cast h = x.setWidth v' := by
+    cast h (setWidth v x) = setWidth v' x := by
   subst h
   ext
   simp
@@ -696,7 +671,7 @@ theorem getMsbD_setWidth {m : Nat} {x : BitVec n} {i : Nat} :
   revert p
   cases getLsbD x i <;> simp; omega
 
-@[simp] theorem setWidth_cast {x : BitVec w} {h : w = v} : (x.cast h).setWidth k = x.setWidth k := by
+@[simp] theorem setWidth_cast {h : w = v} : (cast h x).setWidth k = x.setWidth k := by
   apply eq_of_getLsbD_eq
   simp
 
@@ -714,15 +689,14 @@ theorem msb_setWidth'' (x : BitVec w) : (x.setWidth (k + 1)).msb = x.getLsbD k :
 /-- zero extending a bitvector to width 1 equals the boolean of the lsb. -/
 theorem setWidth_one_eq_ofBool_getLsb_zero (x : BitVec w) :
     x.setWidth 1 = BitVec.ofBool (x.getLsbD 0) := by
-  ext i h
-  simp at h
-  simp [getLsbD_setWidth, h]
+  ext i
+  simp [getLsbD_setWidth, Fin.fin_one_eq_zero i]
 
 /-- Zero extending `1#v` to `1#w` equals `1#w` when `v > 0`. -/
 theorem setWidth_ofNat_one_eq_ofNat_one_of_lt {v w : Nat} (hv : 0 < v) :
     (BitVec.ofNat v 1).setWidth w = BitVec.ofNat w 1 := by
-  ext i h
-  simp only [getLsbD_setWidth, h, decide_true, getLsbD_ofNat, Bool.true_and,
+  ext ⟨i, hilt⟩
+  simp only [getLsbD_setWidth, hilt, decide_true, getLsbD_ofNat, Bool.true_and,
     Bool.and_iff_right_iff_imp, decide_eq_true_eq]
   intros hi₁
   have hv := Nat.testBit_one_eq_true_iff_self_eq_zero.mp hi₁
@@ -749,7 +723,8 @@ protected theorem extractLsb_ofFin {n} (x : Fin (2^n)) (hi lo : Nat) :
 @[simp]
 protected theorem extractLsb_ofNat (x n : Nat) (hi lo : Nat) :
   extractLsb hi lo (BitVec.ofNat n x) = .ofNat (hi - lo + 1) ((x % 2^n) >>> lo) := by
-  ext i
+  apply eq_of_getLsbD_eq
+  intro ⟨i, _lt⟩
   simp [BitVec.ofNat]
 
 @[simp] theorem extractLsb'_toNat (s m : Nat) (x : BitVec n) :
@@ -836,8 +811,8 @@ theorem extractLsb'_eq_extractLsb {w : Nat} (x : BitVec w) (start len : Nat) (h
 
 @[simp] theorem setWidth_or {x y : BitVec w} :
     (x ||| y).setWidth k = x.setWidth k ||| y.setWidth k := by
-  ext i h
-  simp [h]
+  ext
+  simp
 
 theorem or_assoc (x y z : BitVec w) :
     x ||| y ||| z = x ||| (y ||| z) := by
@@ -870,12 +845,12 @@ instance : Std.LawfulCommIdentity (α := BitVec n) (· ||| · ) (0#n) where
   simp
 
 @[simp] theorem or_allOnes {x : BitVec w} : x ||| allOnes w = allOnes w := by
-  ext i h
-  simp [h]
+  ext i
+  simp
 
 @[simp] theorem allOnes_or {x : BitVec w} : allOnes w ||| x = allOnes w := by
-  ext i h
-  simp [h]
+  ext i
+  simp
 
 /-! ### and -/
 
@@ -909,8 +884,8 @@ instance : Std.LawfulCommIdentity (α := BitVec n) (· ||| · ) (0#n) where
 
 @[simp] theorem setWidth_and {x y : BitVec w} :
     (x &&& y).setWidth k = x.setWidth k &&& y.setWidth k := by
-  ext i h
-  simp [h]
+  ext
+  simp
 
 theorem and_assoc (x y z : BitVec w) :
     x &&& y &&& z = x &&& (y &&& z) := by
@@ -940,15 +915,15 @@ instance : Std.IdempotentOp (α := BitVec n) (· &&& · ) where
   simp
 
 @[simp] theorem and_allOnes {x : BitVec w} : x &&& allOnes w = x := by
-  ext i h
-  simp [h]
+  ext i
+  simp
 
 instance : Std.LawfulCommIdentity (α := BitVec n) (· &&& · ) (allOnes n) where
   right_id _ := BitVec.and_allOnes
 
 @[simp] theorem allOnes_and {x : BitVec w} : allOnes w &&& x = x := by
-  ext i h
-  simp [h]
+  ext i
+  simp
 
 /-! ### xor -/
 
@@ -985,8 +960,8 @@ instance : Std.LawfulCommIdentity (α := BitVec n) (· &&& · ) (allOnes n) wher
 
 @[simp] theorem setWidth_xor {x y : BitVec w} :
     (x ^^^ y).setWidth k = x.setWidth k ^^^ y.setWidth k := by
-  ext i h
-  simp [h]
+  ext
+  simp
 
 theorem xor_assoc (x y z : BitVec w) :
     x ^^^ y ^^^ z = x ^^^ (y ^^^ z) := by
@@ -1079,9 +1054,9 @@ theorem not_def {x : BitVec v} : ~~~x = allOnes v ^^^ x := rfl
   rw [Nat.testBit_two_pow_sub_succ x.isLt]
   simp [h]
 
-@[simp] theorem setWidth_not {x : BitVec w} (_ : k ≤ w) :
+@[simp] theorem setWidth_not {x : BitVec w} (h : k ≤ w) :
     (~~~x).setWidth k = ~~~(x.setWidth k) := by
-  ext i h
+  ext
   simp [h]
   omega
 
@@ -1094,17 +1069,17 @@ theorem not_def {x : BitVec v} : ~~~x = allOnes v ^^^ x := rfl
   simp
 
 @[simp] theorem xor_allOnes {x : BitVec w} : x ^^^ allOnes w = ~~~ x := by
-  ext i h
-  simp [h]
+  ext i
+  simp
 
 @[simp] theorem allOnes_xor {x : BitVec w} : allOnes w ^^^ x = ~~~ x := by
-  ext i h
-  simp [h]
+  ext i
+  simp
 
 @[simp]
 theorem not_not {b : BitVec w} : ~~~(~~~b) = b := by
-  ext i h
-  simp [h]
+  ext i
+  simp
 
 theorem not_eq_comm {x y : BitVec w} : ~~~ x = y ↔ x = ~~~ y := by
   constructor
@@ -1115,27 +1090,31 @@ theorem not_eq_comm {x y : BitVec w} : ~~~ x = y ↔ x = ~~~ y := by
     rw [h]
     simp
 
-theorem getMsb_not {x : BitVec w} :
-    (~~~x).getMsbD i = (decide (i < w) && !(x.getMsbD i)) := by simp
+@[simp] theorem getMsb_not {x : BitVec w} :
+    (~~~x).getMsbD i = (decide (i < w) && !(x.getMsbD i)) := by
+  simp only [getMsbD]
+  by_cases h : i < w
+  · simp [h]; omega
+  · simp [h];
 
 @[simp] theorem msb_not {x : BitVec w} : (~~~x).msb = (decide (0 < w) && !x.msb) := by
   simp [BitVec.msb]
 
 /-! ### cast -/
 
-@[simp] theorem not_cast {x : BitVec w} (h : w = w') : ~~~(x.cast h) = (~~~x).cast h := by
+@[simp] theorem not_cast {x : BitVec w} (h : w = w') : ~~~(cast h x) = cast h (~~~x) := by
   ext
   simp_all [lt_of_getLsbD]
 
-@[simp] theorem and_cast {x y : BitVec w} (h : w = w') : x.cast h &&& y.cast h = (x &&& y).cast h := by
+@[simp] theorem and_cast {x y : BitVec w} (h : w = w') : cast h x &&& cast h y = cast h (x &&& y) := by
   ext
   simp_all [lt_of_getLsbD]
 
-@[simp] theorem or_cast {x y : BitVec w} (h : w = w') : x.cast h ||| y.cast h = (x ||| y).cast h := by
+@[simp] theorem or_cast {x y : BitVec w} (h : w = w') : cast h x ||| cast h y = cast h (x ||| y) := by
   ext
   simp_all [lt_of_getLsbD]
 
-@[simp] theorem xor_cast {x y : BitVec w} (h : w = w') : x.cast h ^^^ y.cast h = (x ^^^ y).cast h := by
+@[simp] theorem xor_cast {x y : BitVec w} (h : w = w') : cast h x ^^^ cast h y = cast h (x ^^^ y) := by
   ext
   simp_all [lt_of_getLsbD]
 
@@ -1175,21 +1154,24 @@ theorem zero_shiftLeft (n : Nat) : 0#w <<< n = 0#w := by
 
 theorem shiftLeft_xor_distrib (x y : BitVec w) (n : Nat) :
     (x ^^^ y) <<< n = (x <<< n) ^^^ (y <<< n) := by
-  ext i h
-  simp only [getLsbD_shiftLeft, h, decide_true, Bool.true_and, getLsbD_xor]
-  by_cases h' : i < n <;> simp [h']
+  ext i
+  simp only [getLsbD_shiftLeft, Fin.is_lt, decide_true, Bool.true_and, getLsbD_xor]
+  by_cases h : i < n
+    <;> simp [h]
 
 theorem shiftLeft_and_distrib (x y : BitVec w) (n : Nat) :
     (x &&& y) <<< n = (x <<< n) &&& (y <<< n) := by
-  ext i h
-  simp only [getLsbD_shiftLeft, h, decide_true, Bool.true_and, getLsbD_and]
-  by_cases h' : i < n <;> simp [h']
+  ext i
+  simp only [getLsbD_shiftLeft, Fin.is_lt, decide_true, Bool.true_and, getLsbD_and]
+  by_cases h : i < n
+    <;> simp [h]
 
 theorem shiftLeft_or_distrib (x y : BitVec w) (n : Nat) :
     (x ||| y) <<< n = (x <<< n) ||| (y <<< n) := by
-  ext i h
-  simp only [getLsbD_shiftLeft, h, decide_true, Bool.true_and, getLsbD_or]
-  by_cases h' : i < n <;> simp [h']
+  ext i
+  simp only [getLsbD_shiftLeft, Fin.is_lt, decide_true, Bool.true_and, getLsbD_or]
+  by_cases h : i < n
+    <;> simp [h]
 
 @[simp] theorem getMsbD_shiftLeft (x : BitVec w) (i) :
     (x <<< i).getMsbD k = x.getMsbD (k + i) := by
@@ -1234,6 +1216,7 @@ theorem shiftLeftZeroExtend_eq {x : BitVec w} :
 
 @[simp] theorem getMsbD_shiftLeftZeroExtend (x : BitVec m) (n : Nat) :
     getMsbD (shiftLeftZeroExtend x n) i = getMsbD x i := by
+  have : n ≤ i + n := by omega
   simp_all [shiftLeftZeroExtend_eq]
 
 @[simp] theorem msb_shiftLeftZeroExtend (x : BitVec w) (i : Nat) :
@@ -1281,9 +1264,10 @@ theorem getLsbD_shiftLeft' {x : BitVec w₁} {y : BitVec w₂} {i : Nat} :
     (x <<< y).getLsbD i = (decide (i < w₁) && !decide (i < y.toNat) && x.getLsbD (i - y.toNat)) := by
   simp [shiftLeft_eq', getLsbD_shiftLeft]
 
+@[simp]
 theorem getElem_shiftLeft' {x : BitVec w₁} {y : BitVec w₂} {i : Nat} (h : i < w₁) :
     (x <<< y)[i] = (!decide (i < y.toNat) && x.getLsbD (i - y.toNat)) := by
-  simp
+  simp [shiftLeft_eq', getLsbD_shiftLeft]
 
 /-! ### ushiftRight -/
 
@@ -1332,61 +1316,6 @@ theorem toNat_ushiftRight_lt (x : BitVec w) (n : Nat) (hn : n ≤ w) :
     · apply hn
   · apply Nat.pow_pos (by decide)
 
-
-/-- Shifting right by `n`, which is larger than the bitwidth `w` produces `0. -/
-theorem ushiftRight_eq_zero {x : BitVec w} {n : Nat} (hn : w ≤ n) :
-    x >>> n = 0#w := by
-  simp only [toNat_eq, toNat_ushiftRight, toNat_ofNat, Nat.zero_mod]
-  have : 2^w ≤ 2^n := Nat.pow_le_pow_of_le Nat.one_lt_two hn
-  rw [Nat.shiftRight_eq_div_pow, Nat.div_eq_of_lt (by omega)]
-
-
-/--
-Unsigned shift right by at least one bit makes the interpretations of the bitvector as an `Int` or `Nat` agree,
-because it makes the value of the bitvector less than or equal to `2^(w-1)`.
--/
-theorem toInt_ushiftRight_of_lt {x : BitVec w} {n : Nat} (hn : 0 < n) :
-    (x >>> n).toInt = x.toNat >>> n := by
-  rw [toInt_eq_toNat_cond]
-  simp only [toNat_ushiftRight, ite_eq_left_iff, Nat.not_lt]
-  intros h
-  by_cases hn : n ≤ w
-  · have h1 := Nat.mul_lt_mul_of_pos_left (toNat_ushiftRight_lt x n hn) Nat.two_pos
-    simp only [toNat_ushiftRight, Nat.zero_lt_succ, Nat.mul_lt_mul_left] at h1
-    have : 2 ^ (w - n).succ ≤ 2^ w := Nat.pow_le_pow_of_le (by decide) (by omega)
-    have := show 2 * x.toNat >>> n < 2 ^ w by
-      omega
-    omega
-  · have : x.toNat >>> n = 0 := by
-      apply Nat.shiftRight_eq_zero
-      have : 2^w ≤ 2^n := Nat.pow_le_pow_of_le (by decide) (by omega)
-      omega
-    simp [this] at h
-    omega
-
-/--
-Unsigned shift right by at least one bit makes the interpretations of the bitvector as an `Int` or `Nat` agree,
-because it makes the value of the bitvector less than or equal to `2^(w-1)`.
-In the case when `n = 0`, then the shift right value equals the integer interpretation.
--/
-@[simp]
-theorem toInt_ushiftRight {x : BitVec w} {n : Nat} :
-    (x >>> n).toInt = if n = 0 then x.toInt else x.toNat >>> n := by
-  by_cases hn : n = 0
-  · simp [hn]
-  · rw [toInt_ushiftRight_of_lt (by omega), toInt_eq_toNat_cond]
-    simp [hn]
-
-@[simp]
-theorem toFin_uShiftRight {x : BitVec w} {n : Nat} :
-    (x >>> n).toFin = x.toFin / (Fin.ofNat' (2^w) (2^n)) := by
-  apply Fin.eq_of_val_eq
-  by_cases hn : n < w
-  · simp [Nat.shiftRight_eq_div_pow, Nat.mod_eq_of_lt (Nat.pow_lt_pow_of_lt Nat.one_lt_two hn)]
-  · simp only [Nat.not_lt] at hn
-    rw [ushiftRight_eq_zero (by omega)]
-    simp [Nat.dvd_iff_mod_eq_zero.mp (Nat.pow_dvd_pow 2 hn)]
-
 @[simp]
 theorem getMsbD_ushiftRight {x : BitVec w} {i n : Nat} :
     (x >>> n).getMsbD i = (decide (i < w) && (!decide (i < n) && x.getMsbD (i - n))) := by
@@ -1526,12 +1455,12 @@ theorem msb_sshiftRight {n : Nat} {x : BitVec w} :
     simp [show n = 0 by omega]
 
 @[simp] theorem sshiftRight_zero {x : BitVec w} : x.sshiftRight 0 = x := by
-  ext i h
-  simp [getLsbD_sshiftRight, h]
+  ext i
+  simp [getLsbD_sshiftRight]
 
 @[simp] theorem zero_sshiftRight {n : Nat} : (0#w).sshiftRight n = 0#w := by
-  ext i h
-  simp [getLsbD_sshiftRight, h]
+  ext i
+  simp [getLsbD_sshiftRight]
 
 theorem sshiftRight_add {x : BitVec w} {m n : Nat} :
     x.sshiftRight (m + n) = (x.sshiftRight m).sshiftRight n := by
@@ -1586,25 +1515,39 @@ theorem getMsbD_sshiftRight {x : BitVec w} {i n : Nat} :
 @[simp]
 theorem sshiftRight_eq' (x : BitVec w) : x.sshiftRight' y = x.sshiftRight y.toNat := rfl
 
--- This should not be a `@[simp]` lemma as the left hand side is not in simp normal form.
-theorem getLsbD_sshiftRight' {x y : BitVec w} {i : Nat} :
+@[simp]
+theorem getLsbD_sshiftRight' {x y: BitVec w} {i : Nat} :
     getLsbD (x.sshiftRight' y) i =
       (!decide (w ≤ i) && if y.toNat + i < w then x.getLsbD (y.toNat + i) else x.msb) := by
   simp only [BitVec.sshiftRight', BitVec.getLsbD_sshiftRight]
 
--- This should not be a `@[simp]` lemma as the left hand side is not in simp normal form.
+@[simp]
 theorem getElem_sshiftRight' {x y : BitVec w} {i : Nat} (h : i < w) :
     (x.sshiftRight' y)[i] =
       (!decide (w ≤ i) && if y.toNat + i < w then x.getLsbD (y.toNat + i) else x.msb) := by
   simp only [← getLsbD_eq_getElem, BitVec.sshiftRight', BitVec.getLsbD_sshiftRight]
 
+@[simp]
 theorem getMsbD_sshiftRight' {x y: BitVec w} {i : Nat} :
-    (x.sshiftRight y.toNat).getMsbD i =
-      (decide (i < w) && if i < y.toNat then x.msb else x.getMsbD (i - y.toNat)) := by
-  simp
+    (x.sshiftRight y.toNat).getMsbD i = (decide (i < w) && if i < y.toNat then x.msb else x.getMsbD (i - y.toNat)) := by
+  simp only [BitVec.sshiftRight', getMsbD, BitVec.getLsbD_sshiftRight]
+  by_cases h : i < w
+  · simp only [h, decide_true, Bool.true_and]
+    by_cases h₁ : w ≤ w - 1 - i
+    · simp [h₁]
+      omega
+    · simp only [h₁, decide_false, Bool.not_false, Bool.true_and]
+      by_cases h₂ : i < y.toNat
+      · simp only [h₂, ↓reduceIte, ite_eq_right_iff]
+        omega
+      · simp only [show i - y.toNat < w by omega, h₂, ↓reduceIte, decide_true, Bool.true_and]
+        by_cases h₄ : y.toNat + (w - 1 - i) < w <;> (simp only [h₄, ↓reduceIte]; congr; omega)
+  · simp [h]
 
+@[simp]
 theorem msb_sshiftRight' {x y: BitVec w} :
-    (x.sshiftRight' y).msb = x.msb := by simp
+    (x.sshiftRight' y).msb = x.msb := by
+  simp [BitVec.sshiftRight', BitVec.msb_sshiftRight]
 
 /-! ### signExtend -/
 
@@ -1618,7 +1561,7 @@ private theorem Int.negSucc_emod (m : Nat) (n : Int) :
     -(m + 1) % n = Int.subNatNat (Int.natAbs n) ((m % Int.natAbs n) + 1) := rfl
 
 /-- The sign extension is the same as zero extending when `msb = false`. -/
-theorem signExtend_eq_setWidth_of_msb_false {x : BitVec w} {v : Nat} (hmsb : x.msb = false) :
+theorem signExtend_eq_not_setWidth_not_of_msb_false {x : BitVec w} {v : Nat} (hmsb : x.msb = false) :
     x.signExtend v = x.setWidth v := by
   ext i
   by_cases hv : i < v
@@ -1654,36 +1597,21 @@ theorem signExtend_eq_not_setWidth_not_of_msb_true {x : BitVec w} {v : Nat} (hms
 theorem getLsbD_signExtend (x  : BitVec w) {v i : Nat} :
     (x.signExtend v).getLsbD i = (decide (i < v) && if i < w then x.getLsbD i else x.msb) := by
   rcases hmsb : x.msb with rfl | rfl
-  · rw [signExtend_eq_setWidth_of_msb_false hmsb]
+  · rw [signExtend_eq_not_setWidth_not_of_msb_false hmsb]
     by_cases (i < v) <;> by_cases (i < w) <;> simp_all <;> omega
   · rw [signExtend_eq_not_setWidth_not_of_msb_true hmsb]
     by_cases (i < v) <;> by_cases (i < w) <;> simp_all <;> omega
 
-theorem getMsbD_signExtend {x : BitVec w} {v i : Nat} :
-    (x.signExtend v).getMsbD i =
-      (decide (i < v) && if v - w ≤ i then x.getMsbD (i + w - v) else x.msb) := by
-  rcases hmsb : x.msb with rfl | rfl
-  · simp only [signExtend_eq_setWidth_of_msb_false hmsb, getMsbD_setWidth]
-    by_cases h : v - w ≤ i <;> simp [h, getMsbD] <;> omega
-  · simp only [signExtend_eq_not_setWidth_not_of_msb_true hmsb, getMsbD_not, getMsbD_setWidth]
-    by_cases h : i < v <;> by_cases h' : v - w ≤ i <;> simp [h, h'] <;> omega
-
 theorem getElem_signExtend {x  : BitVec w} {v i : Nat} (h : i < v) :
     (x.signExtend v)[i] = if i < w then x.getLsbD i else x.msb := by
   rw [←getLsbD_eq_getElem, getLsbD_signExtend]
   simp [h]
 
-theorem msb_signExtend {x : BitVec w} :
-    (x.signExtend v).msb = (decide (0 < v) && if w ≥ v then x.getMsbD (w - v) else x.msb) := by
-  by_cases h : w ≥ v
-  · simp [h, BitVec.msb, getMsbD_signExtend, show v - w = 0 by omega]
-  · simp [h, BitVec.msb, getMsbD_signExtend, show ¬ (v - w = 0) by omega]
-
 /-- Sign extending to a width smaller than the starting width is a truncation. -/
 theorem signExtend_eq_setWidth_of_lt (x : BitVec w) {v : Nat} (hv : v ≤ w):
   x.signExtend v = x.setWidth v := by
-  ext i h
-  simp only [getLsbD_signExtend, h, decide_true, Bool.true_and, getLsbD_setWidth,
+  ext i
+  simp only [getLsbD_signExtend, Fin.is_lt, decide_true, Bool.true_and, getLsbD_setWidth,
     ite_eq_left_iff, Nat.not_lt]
   omega
 
@@ -1777,34 +1705,35 @@ theorem append_def (x : BitVec v) (y : BitVec w) :
   rfl
 
 theorem getLsbD_append {x : BitVec n} {y : BitVec m} :
-    getLsbD (x ++ y) i = if i < m then getLsbD y i else getLsbD x (i - m) := by
+    getLsbD (x ++ y) i = bif i < m then getLsbD y i else getLsbD x (i - m) := by
   simp only [append_def, getLsbD_or, getLsbD_shiftLeftZeroExtend, getLsbD_setWidth']
   by_cases h : i < m
   · simp [h]
   · simp_all [h]
 
 theorem getElem_append {x : BitVec n} {y : BitVec m} (h : i < n + m) :
-    (x ++ y)[i] = if i < m then getLsbD y i else getLsbD x (i - m) := by
+    (x ++ y)[i] = bif i < m then getLsbD y i else getLsbD x (i - m) := by
   simp only [append_def, getElem_or, getElem_shiftLeftZeroExtend, getElem_setWidth']
   by_cases h' : i < m
   · simp [h']
   · simp_all [h']
 
 @[simp] theorem getMsbD_append {x : BitVec n} {y : BitVec m} :
-    getMsbD (x ++ y) i = if n ≤ i then getMsbD y (i - n) else getMsbD x i := by
+    getMsbD (x ++ y) i = bif n ≤ i then getMsbD y (i - n) else getMsbD x i := by
   simp only [append_def]
   by_cases h : n ≤ i
   · simp [h]
   · simp [h]
 
 theorem msb_append {x : BitVec w} {y : BitVec v} :
-    (x ++ y).msb = if w = 0 then y.msb else x.msb := by
+    (x ++ y).msb = bif (w == 0) then (y.msb) else (x.msb) := by
   rw [← append_eq, append]
   simp only [msb_or, msb_shiftLeftZeroExtend, msb_setWidth']
   by_cases h : w = 0
   · subst h
     simp [BitVec.msb, getMsbD]
-  · have q : 0 < w + v := by omega
+  · rw [cond_eq_if]
+    have q : 0 < w + v := by omega
     have t : y.getLsbD (w + v - 1) = false := getLsbD_ge _ _ (by omega)
     simp [h, q, t, BitVec.msb, getMsbD]
 
@@ -1813,17 +1742,17 @@ theorem msb_append {x : BitVec w} {y : BitVec v} :
   rw [getLsbD_append] -- Why does this not work with `simp [getLsbD_append]`?
   simp
 
-@[simp] theorem zero_width_append (x : BitVec 0) (y : BitVec v) : x ++ y = y.cast (by omega) := by
+@[simp] theorem zero_width_append (x : BitVec 0) (y : BitVec v) : x ++ y = cast (by omega) y := by
   ext
   rw [getLsbD_append]
   simpa using lt_of_getLsbD
 
 @[simp] theorem zero_append_zero : 0#v ++ 0#w = 0#(v + w) := by
   ext
-  simp only [getLsbD_append, getLsbD_zero, ite_self]
+  simp only [getLsbD_append, getLsbD_zero, Bool.cond_self]
 
 @[simp] theorem cast_append_right (h : w + v = w + v') (x : BitVec w) (y : BitVec v) :
-    (x ++ y).cast h = x ++ y.cast (by omega) := by
+    cast h (x ++ y) = x ++ cast (by omega) y := by
   ext
   simp only [getLsbD_cast, getLsbD_append, cond_eq_if, decide_eq_true_eq]
   split <;> split
@@ -1834,30 +1763,33 @@ theorem msb_append {x : BitVec w} {y : BitVec v} :
     omega
 
 @[simp] theorem cast_append_left (h : w + v = w' + v) (x : BitVec w) (y : BitVec v) :
-    (x ++ y).cast h = x.cast (by omega) ++ y := by
+    cast h (x ++ y) = cast (by omega) x ++ y := by
   ext
   simp [getLsbD_append]
 
 theorem setWidth_append {x : BitVec w} {y : BitVec v} :
     (x ++ y).setWidth k = if h : k ≤ v then y.setWidth k else (x.setWidth (k - v) ++ y).cast (by omega) := by
-  ext i h
-  simp only [getLsbD_setWidth, h, getLsbD_append]
-  split <;> rename_i h₁ <;> split <;> rename_i h₂
-  · simp [h]
-  · simp [getLsbD_append, h₁]
-  · omega
-  · simp [getLsbD_append, h₁]
-    omega
+  apply eq_of_getLsbD_eq
+  intro i
+  simp only [getLsbD_setWidth, Fin.is_lt, decide_true, getLsbD_append, Bool.true_and]
+  split
+  · have t : i < v := by omega
+    simp [t]
+  · by_cases t : i < v
+    · simp [t, getLsbD_append]
+    · have t' : i - v < k - v := by omega
+      simp [t, t', getLsbD_append]
 
 @[simp] theorem setWidth_append_of_eq {x : BitVec v} {y : BitVec w} (h : w' = w) : setWidth (v' + w') (x ++ y) = setWidth v' x ++ setWidth w' y := by
   subst h
-  ext i h
-  simp only [getLsbD_setWidth, h, decide_true, getLsbD_append, cond_eq_if,
+  ext i
+  simp only [getLsbD_setWidth, Fin.is_lt, decide_true, getLsbD_append, cond_eq_if,
     decide_eq_true_eq, Bool.true_and, setWidth_eq]
   split
   · simp_all
   · simp_all only [Bool.iff_and_self, decide_eq_true_eq]
     intro h
+    have := BitVec.lt_of_getLsbD h
     omega
 
 @[simp] theorem setWidth_cons {x : BitVec w} : (cons a x).setWidth w = x := by
@@ -1901,12 +1833,12 @@ theorem shiftLeft_ushiftRight {x : BitVec w} {n : Nat}:
   case succ n ih =>
     rw [BitVec.shiftLeft_add, Nat.add_comm, BitVec.shiftRight_add, ih,
        Nat.add_comm, BitVec.shiftLeft_add, BitVec.shiftLeft_and_distrib]
-    ext i h
+    ext i
     by_cases hw : w = 0
     · simp [hw]
-    · by_cases hi₂ : i = 0
+    · by_cases hi₂ : i.val = 0
       · simp [hi₂]
-      · simp [Nat.lt_one_iff, hi₂, h, show 1 + (i - 1) = i by omega]
+      · simp [Nat.lt_one_iff, hi₂, show 1 + (i.val - 1) = i by omega]
 
 @[simp]
 theorem msb_shiftLeft {x : BitVec w} {n : Nat} :
@@ -1991,12 +1923,13 @@ theorem getElem_cons {b : Bool} {n} {x : BitVec n} {i : Nat} (h : i < n + 1) :
 
 theorem setWidth_succ (x : BitVec w) :
     setWidth (i+1) x = cons (getLsbD x i) (setWidth i x) := by
-  ext j h
-  simp only [getLsbD_setWidth, getLsbD_cons, h, decide_true, Bool.true_and]
-  if j_eq : j = i then
+  apply eq_of_getLsbD_eq
+  intro j
+  simp only [getLsbD_setWidth, getLsbD_cons, j.isLt, decide_true, Bool.true_and]
+  if j_eq : j.val = i then
     simp [j_eq]
   else
-    have j_lt : j < i := Nat.lt_of_le_of_ne (Nat.le_of_succ_le_succ h) j_eq
+    have j_lt : j.val < i := Nat.lt_of_le_of_ne (Nat.le_of_succ_le_succ j.isLt) j_eq
     simp [j_eq, j_lt]
 
 @[simp] theorem cons_msb_setWidth (x : BitVec (w+1)) : (cons x.msb (x.setWidth w)) = x := by
@@ -2065,11 +1998,74 @@ theorem getElem_concat (x : BitVec w) (b : Bool) (i : Nat) (h : i < w + 1) :
 @[simp] theorem getLsbD_concat_succ : (concat x b).getLsbD (i + 1) = x.getLsbD i := by
   simp [getLsbD_concat]
 
-@[simp] theorem getElem_concat_succ {x : BitVec w} {i : Nat} (h : i + 1 < w + 1) :
+@[simp] theorem getElem_concat_succ {x : BitVec w} {i : Nat} (h : i < w) :
     (concat x b)[i + 1] = x[i] := by
-  simp only [Nat.add_lt_add_iff_right] at h
   simp [getElem_concat, h, getLsbD_eq_getElem]
 
+@[simp] theorem not_concat (x : BitVec w) (b : Bool) : ~~~(concat x b) = concat (~~~x) !b := by
+  ext i; cases i using Fin.succRecOn <;> simp [*, Nat.succ_lt_succ]
+
+@[simp] theorem concat_or_concat (x y : BitVec w) (a b : Bool) :
+    (concat x a) ||| (concat y b) = concat (x ||| y) (a || b) := by
+  ext i; cases i using Fin.succRecOn <;> simp
+
+@[simp] theorem concat_and_concat (x y : BitVec w) (a b : Bool) :
+    (concat x a) &&& (concat y b) = concat (x &&& y) (a && b) := by
+  ext i; cases i using Fin.succRecOn <;> simp
+
+@[simp] theorem concat_xor_concat (x y : BitVec w) (a b : Bool) :
+    (concat x a) ^^^ (concat y b) = concat (x ^^^ y) (a ^^ b) := by
+  ext i; cases i using Fin.succRecOn <;> simp
+
+/-! ### shiftConcat -/
+
+theorem getLsbD_shiftConcat (x : BitVec w) (b : Bool) (i : Nat) :
+    (shiftConcat x b).getLsbD i
+    = (decide (i < w) && (if (i = 0) then b else x.getLsbD (i - 1))) := by
+  simp only [shiftConcat, getLsbD_setWidth, getLsbD_concat]
+
+theorem getLsbD_shiftConcat_eq_decide (x : BitVec w) (b : Bool) (i : Nat) :
+    (shiftConcat x b).getLsbD i
+    = (decide (i < w) && ((decide (i = 0) && b) || (decide (0 < i) && x.getLsbD (i - 1)))) := by
+  simp only [getLsbD_shiftConcat]
+  split <;> simp [*, show ((0 < i) ↔ ¬(i = 0)) by omega]
+
+theorem shiftRight_sub_one_eq_shiftConcat (n : BitVec w) (hwn : 0 < wn) :
+    n >>> (wn - 1) = (n >>> wn).shiftConcat (n.getLsbD (wn - 1)) := by
+  ext i
+  simp only [getLsbD_ushiftRight, getLsbD_shiftConcat, Fin.is_lt, decide_true, Bool.true_and]
+  split
+  · simp [*]
+  · congr 1; omega
+
+@[simp, bv_toNat]
+theorem toNat_shiftConcat {x : BitVec w} {b : Bool} :
+    (x.shiftConcat b).toNat
+    = (x.toNat <<< 1 + b.toNat) % 2 ^ w  := by
+  simp [shiftConcat, Nat.shiftLeft_eq]
+
+/-- `x.shiftConcat b` does not overflow if `x < 2^k` for `k < w`, and so
+`x.shiftConcat b |>.toNat = x.toNat * 2 + b.toNat`. -/
+theorem toNat_shiftConcat_eq_of_lt {x : BitVec w} {b : Bool} {k : Nat}
+    (hk : k < w) (hx : x.toNat < 2 ^ k) :
+    (x.shiftConcat b).toNat = x.toNat * 2 + b.toNat := by
+  simp only [toNat_shiftConcat, Nat.shiftLeft_eq, Nat.pow_one]
+  have : 2 ^ k < 2 ^ w := Nat.pow_lt_pow_of_lt (by omega) (by omega)
+  have : 2 ^ k * 2 ≤ 2 ^ w := (Nat.pow_lt_pow_iff_pow_mul_le_pow (by omega)).mp this
+  rw [Nat.mod_eq_of_lt (by cases b <;> simp [bv_toNat] <;> omega)]
+
+theorem toNat_shiftConcat_lt_of_lt {x : BitVec w} {b : Bool} {k : Nat}
+    (hk : k < w) (hx : x.toNat < 2 ^ k) :
+    (x.shiftConcat b).toNat < 2 ^ (k + 1) := by
+  rw [toNat_shiftConcat_eq_of_lt hk hx]
+  have : 2 ^ (k + 1) ≤ 2 ^ w := Nat.pow_le_pow_of_le_right (by decide) (by assumption)
+  have := Bool.toNat_lt b
+  omega
+
+@[simp] theorem zero_concat_false : concat 0#w false = 0#(w + 1) := by
+  ext
+  simp [getLsbD_concat]
+
 @[simp]
 theorem getMsbD_concat {i w : Nat} {b : Bool} {x : BitVec w} :
     (x.concat b).getMsbD i = if i < w then x.getMsbD i else decide (i = w) && b := by
@@ -2095,84 +2091,6 @@ theorem msb_concat {w : Nat} {b : Bool} {x : BitVec w} :
     omega
   · simp [h₀, show w = 0 by omega]
 
-@[simp] theorem toInt_concat (x : BitVec w) (b : Bool) :
-    (concat x b).toInt = if w = 0 then -b.toInt else x.toInt * 2 + b.toInt := by
-  simp only [BitVec.toInt, toNat_concat]
-  cases w
-  · cases b <;> simp [eq_nil x]
-  · cases b <;> simp <;> omega
-
-@[simp] theorem toFin_concat (x : BitVec w) (b : Bool) :
-    (concat x b).toFin = Fin.mk (x.toNat * 2 + b.toNat) (by
-      have := Bool.toNat_lt b
-      simp [← Nat.two_pow_pred_add_two_pow_pred, Bool.toNat_lt b]
-      omega
-    ) := by
-  simp [← Fin.val_inj]
-
-@[simp] theorem not_concat (x : BitVec w) (b : Bool) : ~~~(concat x b) = concat (~~~x) !b := by
-  ext (_ | i) h <;> simp [getLsbD_concat]
-
-@[simp] theorem concat_or_concat (x y : BitVec w) (a b : Bool) :
-    (concat x a) ||| (concat y b) = concat (x ||| y) (a || b) := by
-  ext (_ | i) h <;> simp [getLsbD_concat]
-
-@[simp] theorem concat_and_concat (x y : BitVec w) (a b : Bool) :
-    (concat x a) &&& (concat y b) = concat (x &&& y) (a && b) := by
-  ext (_ | i) h <;> simp [getLsbD_concat]
-
-@[simp] theorem concat_xor_concat (x y : BitVec w) (a b : Bool) :
-    (concat x a) ^^^ (concat y b) = concat (x ^^^ y) (a ^^ b) := by
-  ext (_ | i) h <;> simp [getLsbD_concat]
-
-@[simp] theorem zero_concat_false : concat 0#w false = 0#(w + 1) := by
-  ext
-  simp [getLsbD_concat]
-
-/-! ### shiftConcat -/
-
-theorem getLsbD_shiftConcat (x : BitVec w) (b : Bool) (i : Nat) :
-    (shiftConcat x b).getLsbD i
-    = (decide (i < w) && (if (i = 0) then b else x.getLsbD (i - 1))) := by
-  simp only [shiftConcat, getLsbD_setWidth, getLsbD_concat]
-
-theorem getLsbD_shiftConcat_eq_decide (x : BitVec w) (b : Bool) (i : Nat) :
-    (shiftConcat x b).getLsbD i
-    = (decide (i < w) && ((decide (i = 0) && b) || (decide (0 < i) && x.getLsbD (i - 1)))) := by
-  simp only [getLsbD_shiftConcat]
-  split <;> simp [*, show ((0 < i) ↔ ¬(i = 0)) by omega]
-
-theorem shiftRight_sub_one_eq_shiftConcat (n : BitVec w) (hwn : 0 < wn) :
-    n >>> (wn - 1) = (n >>> wn).shiftConcat (n.getLsbD (wn - 1)) := by
-  ext i h
-  simp only [getLsbD_ushiftRight, getLsbD_shiftConcat, h, decide_true, Bool.true_and]
-  split
-  · simp [*]
-  · congr 1; omega
-
-@[simp, bv_toNat]
-theorem toNat_shiftConcat {x : BitVec w} {b : Bool} :
-    (x.shiftConcat b).toNat
-    = (x.toNat <<< 1 + b.toNat) % 2 ^ w  := by
-  simp [shiftConcat, Nat.shiftLeft_eq]
-
-/-- `x.shiftConcat b` does not overflow if `x < 2^k` for `k < w`, and so
-`x.shiftConcat b |>.toNat = x.toNat * 2 + b.toNat`. -/
-theorem toNat_shiftConcat_eq_of_lt {x : BitVec w} {b : Bool} {k : Nat}
-    (hk : k < w) (hx : x.toNat < 2 ^ k) :
-    (x.shiftConcat b).toNat = x.toNat * 2 + b.toNat := by
-  simp only [toNat_shiftConcat, Nat.shiftLeft_eq, Nat.pow_one]
-  have : 2 ^ k < 2 ^ w := Nat.pow_lt_pow_of_lt (by omega) (by omega)
-  have : 2 ^ k * 2 ≤ 2 ^ w := (Nat.pow_lt_pow_iff_pow_mul_le_pow (by omega)).mp this
-  rw [Nat.mod_eq_of_lt (by cases b <;> simp [bv_toNat] <;> omega)]
-
-theorem toNat_shiftConcat_lt_of_lt {x : BitVec w} {b : Bool} {k : Nat}
-    (hk : k < w) (hx : x.toNat < 2 ^ k) :
-    (x.shiftConcat b).toNat < 2 ^ (k + 1) := by
-  rw [toNat_shiftConcat_eq_of_lt hk hx]
-  have := Bool.toNat_lt b
-  omega
-
 /-! ### add -/
 
 theorem add_def {n} (x y : BitVec n) : x + y = .ofNat n (x.toNat + y.toNat) := rfl
@@ -2678,7 +2596,7 @@ theorem smtSDiv_eq (x y : BitVec w) : smtSDiv x y =
 
 @[simp]
 theorem smtSDiv_zero {x : BitVec n} : x.smtSDiv 0#n = if x.slt 0#n then 1#n else (allOnes n) := by
-  rcases hx : x.msb <;> simp [smtSDiv, slt_zero_iff_msb_cond, hx, ← negOne_eq_allOnes]
+  rcases hx : x.msb <;> simp [smtSDiv, slt_zero_iff_msb_cond x, hx, ← negOne_eq_allOnes]
 
 /-! ### srem -/
 
@@ -2998,10 +2916,10 @@ theorem getMsbD_rotateRightAux_of_ge {x : BitVec w} {r : Nat} {i : Nat} (hi : i
   simp [rotateRightAux, show ¬ i < r by omega, show i + (w - r) ≥ w by omega]
 
 /-- When `m < w`, we give a formula for `(x.rotateLeft m).getMsbD i`. -/
--- This should not be a simp lemma as `getMsbD_rotateRight` will apply first.
-theorem getMsbD_rotateRight_of_lt {w n m : Nat} {x : BitVec w} (hr : m < w) :
+@[simp]
+theorem getMsbD_rotateRight_of_lt {w n m : Nat} {x : BitVec w} (hr : m < w):
     (x.rotateRight m).getMsbD n = (decide (n < w) && (if (n < m % w)
-    then x.getMsbD ((w + n - m % w) % w) else x.getMsbD (n - m % w))) := by
+    then x.getMsbD ((w + n - m % w) % w) else x.getMsbD (n - m % w))):= by
   rcases w with rfl | w
   · simp
   · rw [rotateRight_eq_rotateRightAux_of_lt (by omega)]
@@ -3155,8 +3073,8 @@ theorem setWidth_setWidth_succ_eq_setWidth_setWidth_of_getLsbD_false
   {x : BitVec w} {i : Nat} (hx : x.getLsbD i = false) :
     setWidth w (x.setWidth (i + 1)) =
       setWidth w (x.setWidth i) := by
-  ext k h
-  simp only [getLsbD_setWidth, h, decide_true, Bool.true_and, getLsbD_or, getLsbD_and]
+  ext k
+  simp only [getLsbD_setWidth, Fin.is_lt, decide_true, Bool.true_and, getLsbD_or, getLsbD_and]
   by_cases hik : i = k
   · subst hik
     simp [hx]
@@ -3171,17 +3089,20 @@ theorem setWidth_setWidth_succ_eq_setWidth_setWidth_or_twoPow_of_getLsbD_true
     {x : BitVec w} {i : Nat} (hx : x.getLsbD i = true) :
     setWidth w (x.setWidth (i + 1)) =
       setWidth w (x.setWidth i) ||| (twoPow w i) := by
-  ext k h
-  simp only [getLsbD_setWidth, h, decide_true, Bool.true_and, getLsbD_or, getLsbD_and]
+  ext k
+  simp only [getLsbD_setWidth, Fin.is_lt, decide_true, Bool.true_and, getLsbD_or, getLsbD_and]
   by_cases hik : i = k
   · subst hik
-    simp [hx, h]
+    simp [hx]
   · by_cases hik' : k < i + 1 <;> simp [hik, hik'] <;> omega
 
 /-- Bitwise and of `(x : BitVec w)` with `1#w` equals zero extending `x.lsb` to `w`. -/
 theorem and_one_eq_setWidth_ofBool_getLsbD {x : BitVec w} :
     (x &&& 1#w) = setWidth w (ofBool (x.getLsbD 0)) := by
-  ext (_ | i) h <;> simp [Bool.and_comm]
+  ext i
+  simp only [getLsbD_and, getLsbD_one, getLsbD_setWidth, Fin.is_lt, decide_true, getLsbD_ofBool,
+    Bool.true_and]
+  by_cases h : ((i : Nat) = 0) <;> simp [h] <;> omega
 
 @[simp]
 theorem replicate_zero_eq {x : BitVec w} : x.replicate 0 = 0#0 := by
@@ -3205,7 +3126,7 @@ theorem getLsbD_replicate {n w : Nat} (x : BitVec w) :
     · simp only [hi, decide_true, Bool.true_and]
       by_cases hi' : i < w * n
       · simp [hi', ih]
-      · simp [hi', decide_false]
+      · simp only [hi', decide_false, cond_false]
         rw [Nat.sub_mul_eq_mod_of_lt_of_le] <;> omega
     · rw [Nat.mul_succ] at hi ⊢
       simp only [show ¬i < w * n by omega, decide_false, cond_false, hi, Bool.false_and]
@@ -3511,7 +3432,7 @@ theorem forall_zero_iff {P : BitVec 0 → Prop} :
   · intro h
     apply h
   · intro h v
-    obtain (rfl : v = 0#0) := (by ext i ⟨⟩)
+    obtain (rfl : v = 0#0) := (by ext ⟨i, h⟩; simp at h)
     apply h
 
 theorem forall_cons_iff {P : BitVec (n + 1) → Prop} :
@@ -3527,7 +3448,7 @@ theorem forall_cons_iff {P : BitVec (n + 1) → Prop} :
 instance instDecidableForallBitVecZero (P : BitVec 0 → Prop) :
     ∀ [Decidable (P 0#0)], Decidable (∀ v, P v)
   | .isTrue h => .isTrue fun v => by
-    obtain (rfl : v = 0#0) := (by ext i ⟨⟩)
+    obtain (rfl : v = 0#0) := (by ext ⟨i, h⟩; cases h)
     exact h
   | .isFalse h => .isFalse (fun w => h (w _))
 
@@ -3564,15 +3485,14 @@ Note, however, that for large numerals the decision procedure may be very slow.
 instance instDecidableExistsBitVec :
     ∀ (n : Nat) (P : BitVec n → Prop) [DecidablePred P], Decidable (∃ v, P v)
   | 0, _, _ => inferInstance
-  | _ + 1, _, _ => inferInstance
+  | n + 1, _, _ =>
+    have := instDecidableExistsBitVec n
+    inferInstance
 
 /-! ### Deprecations -/
 
 set_option linter.missingDocs false
 
-@[deprecated signExtend_eq_setWidth_of_msb_false (since := "2024-12-08")]
-abbrev signExtend_eq_not_setWidth_not_of_msb_false := @signExtend_eq_setWidth_of_msb_false
-
 @[deprecated truncate_eq_setWidth (since := "2024-09-18")]
 abbrev truncate_eq_zeroExtend := @truncate_eq_setWidth
 
@@ -3675,8 +3595,8 @@ abbrev truncate_xor := @setWidth_xor
 @[deprecated setWidth_not (since := "2024-09-18")]
 abbrev truncate_not := @setWidth_not
 
-@[deprecated signExtend_eq_setWidth_of_msb_false  (since := "2024-09-18")]
-abbrev signExtend_eq_not_zeroExtend_not_of_msb_false  := @signExtend_eq_setWidth_of_msb_false
+@[deprecated signExtend_eq_not_setWidth_not_of_msb_false  (since := "2024-09-18")]
+abbrev signExtend_eq_not_zeroExtend_not_of_msb_false  := @signExtend_eq_not_setWidth_not_of_msb_false
 
 @[deprecated signExtend_eq_not_setWidth_not_of_msb_true (since := "2024-09-18")]
 abbrev signExtend_eq_not_zeroExtend_not_of_msb_true := @signExtend_eq_not_setWidth_not_of_msb_true

src/Init/Data/Bool.lean

@@ -225,7 +225,7 @@ theorem bne_not_self : ∀ (x : Bool), (x   != !x) = true := by decide
 Added for equivalence with `Bool.not_beq_self` and needed for confluence
 due to `beq_iff_eq`.
 -/
-theorem not_eq_self : ∀(b : Bool), ((!b) = b) ↔ False := by simp
+@[simp] theorem not_eq_self : ∀(b : Bool), ((!b) = b) ↔ False := by decide
 @[simp] theorem eq_not_self : ∀(b : Bool), (b = (!b)) ↔ False := by decide
 
 @[simp] theorem beq_self_left  : ∀(a b : Bool), (a == (a == b)) = b := by decide
@@ -384,15 +384,6 @@ theorem toNat_lt (b : Bool) : b.toNat < 2 :=
 @[simp] theorem toNat_eq_one  {b : Bool} : b.toNat = 1 ↔ b = true := by
   cases b <;> simp
 
-/-! ## toInt -/
-
-/-- convert a `Bool` to an `Int`, `false -> 0`, `true -> 1` -/
-def toInt (b : Bool) : Int := cond b 1 0
-
-@[simp] theorem toInt_false : false.toInt = 0 := rfl
-
-@[simp] theorem toInt_true : true.toInt = 1 := rfl
-
 /-! ### ite -/
 
 @[simp] theorem if_true_left  (p : Prop) [h : Decidable p] (f : Bool) :
@@ -420,7 +411,7 @@ def toInt (b : Bool) : Int := cond b 1 0
 
 @[simp] theorem ite_eq_true_else_eq_false {q : Prop} :
     (if b = true then q else b = false) ↔ (b = true → q) := by
-  cases b <;> simp [not_eq_self]
+  cases b <;> simp
 
 /-
 `not_ite_eq_true_eq_true` and related theorems below are added for

src/Init/Data/Channel.lean

@@ -8,8 +8,6 @@ import Init.Data.Queue
 import Init.System.Promise
 import Init.System.Mutex
 
-set_option linter.deprecated false
-
 namespace IO
 
 /--
@@ -17,7 +15,6 @@ Internal state of an `Channel`.
 
 We maintain the invariant that at all times either `consumers` or `values` is empty.
 -/
-@[deprecated "Use Std.Channel.State from Std.Sync.Channel instead" (since := "2024-12-02")]
 structure Channel.State (α : Type) where
   values : Std.Queue α := ∅
   consumers : Std.Queue (Promise (Option α)) := ∅
@@ -30,14 +27,12 @@ FIFO channel with unbounded buffer, where `recv?` returns a `Task`.
 A channel can be closed.  Once it is closed, all `send`s are ignored, and
 `recv?` returns `none` once the queue is empty.
 -/
-@[deprecated "Use Std.Channel from Std.Sync.Channel instead" (since := "2024-12-02")]
 def Channel (α : Type) : Type := Mutex (Channel.State α)
 
 instance : Nonempty (Channel α) :=
   inferInstanceAs (Nonempty (Mutex _))
 
 /-- Creates a new `Channel`. -/
-@[deprecated "Use Std.Channel.new from Std.Sync.Channel instead" (since := "2024-12-02")]
 def Channel.new : BaseIO (Channel α) :=
   Mutex.new {}
 
@@ -46,7 +41,6 @@ Sends a message on an `Channel`.
 
 This function does not block.
 -/
-@[deprecated "Use Std.Channel.send from Std.Sync.Channel instead" (since := "2024-12-02")]
 def Channel.send (ch : Channel α) (v : α) : BaseIO Unit :=
   ch.atomically do
     let st ← get
@@ -60,7 +54,6 @@ def Channel.send (ch : Channel α) (v : α) : BaseIO Unit :=
 /--
 Closes an `Channel`.
 -/
-@[deprecated "Use Std.Channel.close from Std.Sync.Channel instead" (since := "2024-12-02")]
 def Channel.close (ch : Channel α) : BaseIO Unit :=
   ch.atomically do
     let st ← get
@@ -74,7 +67,6 @@ Every message is only received once.
 
 Returns `none` if the channel is closed and the queue is empty.
 -/
-@[deprecated "Use Std.Channel.recv? from Std.Sync.Channel instead" (since := "2024-12-02")]
 def Channel.recv? (ch : Channel α) : BaseIO (Task (Option α)) :=
   ch.atomically do
     let st ← get
@@ -93,7 +85,6 @@ def Channel.recv? (ch : Channel α) : BaseIO (Task (Option α)) :=
 
 Note that if this function is called twice, each `forAsync` only gets half the messages.
 -/
-@[deprecated "Use Std.Channel.forAsync from Std.Sync.Channel instead" (since := "2024-12-02")]
 partial def Channel.forAsync (f : α → BaseIO Unit) (ch : Channel α)
     (prio : Task.Priority := .default) : BaseIO (Task Unit) := do
   BaseIO.bindTask (prio := prio) (← ch.recv?) fun
@@ -105,13 +96,11 @@ Receives all currently queued messages from the channel.
 
 Those messages are dequeued and will not be returned by `recv?`.
 -/
-@[deprecated "Use Std.Channel.recvAllCurrent from Std.Sync.Channel instead" (since := "2024-12-02")]
 def Channel.recvAllCurrent (ch : Channel α) : BaseIO (Array α) :=
   ch.atomically do
     modifyGet fun st => (st.values.toArray, { st with values := ∅ })
 
 /-- Type tag for synchronous (blocking) operations on a `Channel`. -/
-@[deprecated "Use Std.Channel.Sync from Std.Sync.Channel instead" (since := "2024-12-02")]
 def Channel.Sync := Channel
 
 /--
@@ -121,7 +110,6 @@ For example, `ch.sync.recv?` blocks until the next message,
 and `for msg in ch.sync do ...` iterates synchronously over the channel.
 These functions should only be used in dedicated threads.
 -/
-@[deprecated "Use Std.Channel.sync from Std.Sync.Channel instead" (since := "2024-12-02")]
 def Channel.sync (ch : Channel α) : Channel.Sync α := ch
 
 /--
@@ -130,11 +118,9 @@ Synchronously receives a message from the channel.
 Every message is only received once.
 Returns `none` if the channel is closed and the queue is empty.
 -/
-@[deprecated "Use Std.Channel.Sync.recv? from Std.Sync.Channel instead" (since := "2024-12-02")]
 def Channel.Sync.recv? (ch : Channel.Sync α) : BaseIO (Option α) := do
   IO.wait (← Channel.recv? ch)
 
-@[deprecated "Use Std.Channel.Sync.forIn from Std.Sync.Channel instead" (since := "2024-12-02")]
 private partial def Channel.Sync.forIn [Monad m] [MonadLiftT BaseIO m]
     (ch : Channel.Sync α) (f : α → β → m (ForInStep β)) : β → m β := fun b => do
   match ← ch.recv? with

src/Init/Data/Fin/Basic.lean

@@ -176,7 +176,7 @@ protected theorem pos (i : Fin n) : 0 < n :=
 @[inline] def castLE (h : n ≤ m) (i : Fin n) : Fin m := ⟨i, Nat.lt_of_lt_of_le i.2 h⟩
 
 /-- `cast eq i` embeds `i` into an equal `Fin` type. -/
-@[inline] protected def cast (eq : n = m) (i : Fin n) : Fin m := ⟨i, eq ▸ i.2⟩
+@[inline] def cast (eq : n = m) (i : Fin n) : Fin m := ⟨i, eq ▸ i.2⟩
 
 /-- `castAdd m i` embeds `i : Fin n` in `Fin (n+m)`. See also `Fin.natAdd` and `Fin.addNat`. -/
 @[inline] def castAdd (m) : Fin n → Fin (n + m) :=

src/Init/Data/Fin/Fold.lean

@@ -13,14 +13,14 @@ namespace Fin
 /-- Folds over `Fin n` from the left: `foldl 3 f x = f (f (f x 0) 1) 2`. -/
 @[inline] def foldl (n) (f : α → Fin n → α) (init : α) : α := loop init 0 where
   /-- Inner loop for `Fin.foldl`. `Fin.foldl.loop n f x i = f (f (f x i) ...) (n-1)`  -/
-  @[semireducible, specialize] loop (x : α) (i : Nat) : α :=
+  @[semireducible] loop (x : α) (i : Nat) : α :=
     if h : i < n then loop (f x ⟨i, h⟩) (i+1) else x
   termination_by n - i
 
 /-- Folds over `Fin n` from the right: `foldr 3 f x = f 0 (f 1 (f 2 x))`. -/
 @[inline] def foldr (n) (f : Fin n → α → α) (init : α) : α := loop n (Nat.le_refl n) init where
   /-- Inner loop for `Fin.foldr`. `Fin.foldr.loop n f i x = f 0 (f ... (f (i-1) x))`  -/
-  @[specialize] loop : (i : _) → i ≤ n → α → α
+  loop : (i : _) → i ≤ n → α → α
   | 0, _, x => x
   | i+1, h, x => loop i (Nat.le_of_lt h) (f ⟨i, h⟩ x)
   termination_by structural i => i
@@ -47,7 +47,7 @@ Fin.foldlM n f x₀ = do
     pure xₙ
   ```
   -/
-  @[semireducible, specialize] loop (x : α) (i : Nat) : m α := do
+  loop (x : α) (i : Nat) : m α := do
     if h : i < n then f x ⟨i, h⟩ >>= (loop · (i+1)) else pure x
   termination_by n - i
   decreasing_by decreasing_trivial_pre_omega
@@ -76,7 +76,7 @@ Fin.foldrM n f xₙ = do
     pure x₀
   ```
   -/
-  @[semireducible, specialize] loop : {i // i ≤ n} → α → m α
+  loop : {i // i ≤ n} → α → m α
   | ⟨0, _⟩, x => pure x
   | ⟨i+1, h⟩, x => f ⟨i, h⟩ x >>= loop ⟨i, Nat.le_of_lt h⟩
 
@@ -125,7 +125,7 @@ theorem foldrM_loop [Monad m] [LawfulMonad m] (f : Fin (n+1) → α → m α) (x
   | zero =>
     rw [foldrM_loop_zero, foldrM_loop_succ, pure_bind]
     conv => rhs; rw [←bind_pure (f 0 x)]
-    congr; funext
+    congr; funext; exact foldrM_loop_zero ..
   | succ i ih =>
     rw [foldrM_loop_succ, foldrM_loop_succ, bind_assoc]
     congr; funext; exact ih ..

src/Init/Data/Fin/Lemmas.lean

@@ -370,25 +370,25 @@ theorem succ_succ_ne_one (a : Fin n) : Fin.succ (Fin.succ a) ≠ 1 :=
     Fin.castLE mn ∘ Fin.castLE km = Fin.castLE (Nat.le_trans km mn) :=
   funext (castLE_castLE km mn)
 
-@[simp] theorem coe_cast (h : n = m) (i : Fin n) : (i.cast h : Nat) = i := rfl
+@[simp] theorem coe_cast (h : n = m) (i : Fin n) : (cast h i : Nat) = i := rfl
 
-@[simp] theorem cast_last {n' : Nat} {h : n + 1 = n' + 1} : (last n).cast h  = last n' :=
+@[simp] theorem cast_last {n' : Nat} {h : n + 1 = n' + 1} : cast h (last n) = last n' :=
   Fin.ext (by rw [coe_cast, val_last, val_last, Nat.succ.inj h])
 
-@[simp] theorem cast_mk (h : n = m) (i : Nat) (hn : i < n) : Fin.cast h ⟨i, hn⟩ = ⟨i, h ▸ hn⟩ := rfl
+@[simp] theorem cast_mk (h : n = m) (i : Nat) (hn : i < n) : cast h ⟨i, hn⟩ = ⟨i, h ▸ hn⟩ := rfl
 
-@[simp] theorem cast_refl (n : Nat) (h : n = n) : Fin.cast h = id := by
+@[simp] theorem cast_refl (n : Nat) (h : n = n) : cast h = id := by
   ext
   simp
 
 @[simp] theorem cast_trans {k : Nat} (h : n = m) (h' : m = k) {i : Fin n} :
-    (i.cast h).cast h' = i.cast (Eq.trans h h') := rfl
+    cast h' (cast h i) = cast (Eq.trans h h') i := rfl
 
 theorem castLE_of_eq {m n : Nat} (h : m = n) {h' : m ≤ n} : castLE h' = Fin.cast h := rfl
 
 @[simp] theorem coe_castAdd (m : Nat) (i : Fin n) : (castAdd m i : Nat) = i := rfl
 
-@[simp] theorem castAdd_zero : (castAdd 0 : Fin n → Fin (n + 0)) = Fin.cast rfl := rfl
+@[simp] theorem castAdd_zero : (castAdd 0 : Fin n → Fin (n + 0)) = cast rfl := rfl
 
 theorem castAdd_lt {m : Nat} (n : Nat) (i : Fin m) : (castAdd n i : Nat) < m := by simp
 
@@ -406,37 +406,37 @@ theorem castAdd_cast {n n' : Nat} (m : Nat) (i : Fin n') (h : n' = n) :
     castAdd m (Fin.cast h i) = Fin.cast (congrArg (. + m) h) (castAdd m i) := Fin.ext rfl
 
 theorem cast_castAdd_left {n n' m : Nat} (i : Fin n') (h : n' + m = n + m) :
-    (i.castAdd m).cast h = (i.cast (Nat.add_right_cancel h)).castAdd m := rfl
+    cast h (castAdd m i) = castAdd m (cast (Nat.add_right_cancel h) i) := rfl
 
 @[simp] theorem cast_castAdd_right {n m m' : Nat} (i : Fin n) (h : n + m' = n + m) :
-    (i.castAdd m').cast h = i.castAdd m := rfl
+    cast h (castAdd m' i) = castAdd m i := rfl
 
 theorem castAdd_castAdd {m n p : Nat} (i : Fin m) :
-    (i.castAdd n).castAdd p = (i.castAdd (n + p)).cast (Nat.add_assoc ..).symm  := rfl
+    castAdd p (castAdd n i) = cast (Nat.add_assoc ..).symm (castAdd (n + p) i) := rfl
 
 /-- The cast of the successor is the successor of the cast. See `Fin.succ_cast_eq` for rewriting in
 the reverse direction. -/
 @[simp] theorem cast_succ_eq {n' : Nat} (i : Fin n) (h : n.succ = n'.succ) :
-    i.succ.cast h = (i.cast (Nat.succ.inj h)).succ := rfl
+    cast h i.succ = (cast (Nat.succ.inj h) i).succ := rfl
 
 theorem succ_cast_eq {n' : Nat} (i : Fin n) (h : n = n') :
-    (i.cast h).succ = i.succ.cast (by rw [h]) := rfl
+    (cast h i).succ = cast (by rw [h]) i.succ := rfl
 
-@[simp] theorem coe_castSucc (i : Fin n) : (i.castSucc : Nat) = i := rfl
+@[simp] theorem coe_castSucc (i : Fin n) : (Fin.castSucc i : Nat) = i := rfl
 
 @[simp] theorem castSucc_mk (n i : Nat) (h : i < n) : castSucc ⟨i, h⟩ = ⟨i, Nat.lt.step h⟩ := rfl
 
 @[simp] theorem cast_castSucc {n' : Nat} {h : n + 1 = n' + 1} {i : Fin n} :
-    i.castSucc.cast h = (i.cast (Nat.succ.inj h)).castSucc := rfl
+    cast h (castSucc i) = castSucc (cast (Nat.succ.inj h) i) := rfl
 
-theorem castSucc_lt_succ (i : Fin n) : i.castSucc < i.succ :=
+theorem castSucc_lt_succ (i : Fin n) : Fin.castSucc i < i.succ :=
   lt_def.2 <| by simp only [coe_castSucc, val_succ, Nat.lt_succ_self]
 
-theorem le_castSucc_iff {i : Fin (n + 1)} {j : Fin n} : i ≤ j.castSucc ↔ i < j.succ := by
+theorem le_castSucc_iff {i : Fin (n + 1)} {j : Fin n} : i ≤ Fin.castSucc j ↔ i < j.succ := by
   simpa only [lt_def, le_def] using Nat.add_one_le_add_one_iff.symm
 
 theorem castSucc_lt_iff_succ_le {n : Nat} {i : Fin n} {j : Fin (n + 1)} :
-    i.castSucc < j ↔ i.succ ≤ j := .rfl
+    Fin.castSucc i < j ↔ i.succ ≤ j := .rfl
 
 @[simp] theorem succ_last (n : Nat) : (last n).succ = last n.succ := rfl
 
@@ -444,48 +444,48 @@ theorem castSucc_lt_iff_succ_le {n : Nat} {i : Fin n} {j : Fin (n + 1)} :
     i.succ = last (n + 1) ↔ i = last n := by rw [← succ_last, succ_inj]
 
 @[simp] theorem castSucc_castLT (i : Fin (n + 1)) (h : (i : Nat) < n) :
-    (castLT i h).castSucc = i := rfl
+    castSucc (castLT i h) = i := rfl
 
 @[simp] theorem castLT_castSucc {n : Nat} (a : Fin n) (h : (a : Nat) < n) :
-    castLT a.castSucc h = a := rfl
+    castLT (castSucc a) h = a := rfl
 
 @[simp] theorem castSucc_lt_castSucc_iff {a b : Fin n} :
-    a.castSucc < b.castSucc ↔ a < b := .rfl
+    Fin.castSucc a < Fin.castSucc b ↔ a < b := .rfl
 
-theorem castSucc_inj {a b : Fin n} : a.castSucc = b.castSucc ↔ a = b := by simp [Fin.ext_iff]
+theorem castSucc_inj {a b : Fin n} : castSucc a = castSucc b ↔ a = b := by simp [Fin.ext_iff]
 
-theorem castSucc_lt_last (a : Fin n) : a.castSucc < last n := a.is_lt
+theorem castSucc_lt_last (a : Fin n) : castSucc a < last n := a.is_lt
 
 @[simp] theorem castSucc_zero : castSucc (0 : Fin (n + 1)) = 0 := rfl
 
 @[simp] theorem castSucc_one {n : Nat} : castSucc (1 : Fin (n + 2)) = 1 := rfl
 
 /-- `castSucc i` is positive when `i` is positive -/
-theorem castSucc_pos {i : Fin (n + 1)} (h : 0 < i) : 0 < i.castSucc := by
+theorem castSucc_pos {i : Fin (n + 1)} (h : 0 < i) : 0 < castSucc i := by
   simpa [lt_def] using h
 
-@[simp] theorem castSucc_eq_zero_iff {a : Fin (n + 1)} : a.castSucc = 0 ↔ a = 0 := by simp [Fin.ext_iff]
+@[simp] theorem castSucc_eq_zero_iff {a : Fin (n + 1)} : castSucc a = 0 ↔ a = 0 := by simp [Fin.ext_iff]
 
-theorem castSucc_ne_zero_iff {a : Fin (n + 1)} : a.castSucc ≠ 0 ↔ a ≠ 0 :=
+theorem castSucc_ne_zero_iff {a : Fin (n + 1)} : castSucc a ≠ 0 ↔ a ≠ 0 :=
   not_congr <| castSucc_eq_zero_iff
 
 theorem castSucc_fin_succ (n : Nat) (j : Fin n) :
-    j.succ.castSucc = (j.castSucc).succ := by simp [Fin.ext_iff]
+    castSucc (Fin.succ j) = Fin.succ (castSucc j) := by simp [Fin.ext_iff]
 
 @[simp]
-theorem coeSucc_eq_succ {a : Fin n} : a.castSucc + 1 = a.succ := by
+theorem coeSucc_eq_succ {a : Fin n} : castSucc a + 1 = a.succ := by
   cases n
   · exact a.elim0
   · simp [Fin.ext_iff, add_def, Nat.mod_eq_of_lt (Nat.succ_lt_succ a.is_lt)]
 
-theorem lt_succ {a : Fin n} : a.castSucc < a.succ := by
+theorem lt_succ {a : Fin n} : castSucc a < a.succ := by
   rw [castSucc, lt_def, coe_castAdd, val_succ]; exact Nat.lt_succ_self a.val
 
 theorem exists_castSucc_eq {n : Nat} {i : Fin (n + 1)} : (∃ j, castSucc j = i) ↔ i ≠ last n :=
   ⟨fun ⟨j, hj⟩ => hj ▸ Fin.ne_of_lt j.castSucc_lt_last,
    fun hi => ⟨i.castLT <| Fin.val_lt_last hi, rfl⟩⟩
 
-theorem succ_castSucc {n : Nat} (i : Fin n) : i.castSucc.succ = i.succ.castSucc := rfl
+theorem succ_castSucc {n : Nat} (i : Fin n) : i.castSucc.succ = castSucc i.succ := rfl
 
 @[simp] theorem coe_addNat (m : Nat) (i : Fin n) : (addNat i m : Nat) = i + m := rfl
 
@@ -502,17 +502,17 @@ theorem le_coe_addNat (m : Nat) (i : Fin n) : m ≤ addNat i m :=
     addNat ⟨i, hi⟩ n = ⟨i + n, Nat.add_lt_add_right hi n⟩ := rfl
 
 @[simp] theorem cast_addNat_zero {n n' : Nat} (i : Fin n) (h : n + 0 = n') :
-    (addNat i 0).cast h = i.cast ((Nat.add_zero _).symm.trans h) := rfl
+    cast h (addNat i 0) = cast ((Nat.add_zero _).symm.trans h) i := rfl
 
 /-- For rewriting in the reverse direction, see `Fin.cast_addNat_left`. -/
 theorem addNat_cast {n n' m : Nat} (i : Fin n') (h : n' = n) :
-    addNat (i.cast h) m = (addNat i m).cast (congrArg (. + m) h) := rfl
+    addNat (cast h i) m = cast (congrArg (. + m) h) (addNat i m) := rfl
 
 theorem cast_addNat_left {n n' m : Nat} (i : Fin n') (h : n' + m = n + m) :
-    (addNat i m).cast h = addNat (i.cast (Nat.add_right_cancel h)) m := rfl
+    cast h (addNat i m) = addNat (cast (Nat.add_right_cancel h) i) m := rfl
 
 @[simp] theorem cast_addNat_right {n m m' : Nat} (i : Fin n) (h : n + m' = n + m) :
-    (addNat i m').cast h = addNat i m :=
+    cast h (addNat i m') = addNat i m :=
   Fin.ext <| (congrArg ((· + ·) (i : Nat)) (Nat.add_left_cancel h) : _)
 
 @[simp] theorem coe_natAdd (n : Nat) {m : Nat} (i : Fin m) : (natAdd n i : Nat) = n + i := rfl
@@ -522,44 +522,46 @@ theorem cast_addNat_left {n n' m : Nat} (i : Fin n') (h : n' + m = n + m) :
 
 theorem le_coe_natAdd (m : Nat) (i : Fin n) : m ≤ natAdd m i := Nat.le_add_right ..
 
-@[simp] theorem natAdd_zero {n : Nat} : natAdd 0 = Fin.cast (Nat.zero_add n).symm := by ext; simp
+@[simp] theorem natAdd_zero {n : Nat} : natAdd 0 = cast (Nat.zero_add n).symm := by ext; simp
 
 /-- For rewriting in the reverse direction, see `Fin.cast_natAdd_right`. -/
 theorem natAdd_cast {n n' : Nat} (m : Nat) (i : Fin n') (h : n' = n) :
-    natAdd m (i.cast h) = (natAdd m i).cast (congrArg _ h) := rfl
+    natAdd m (cast h i) = cast (congrArg _ h) (natAdd m i) := rfl
 
 theorem cast_natAdd_right {n n' m : Nat} (i : Fin n') (h : m + n' = m + n) :
-    (natAdd m i).cast h  = natAdd m (i.cast (Nat.add_left_cancel h)) := rfl
+    cast h (natAdd m i) = natAdd m (cast (Nat.add_left_cancel h) i) := rfl
 
 @[simp] theorem cast_natAdd_left {n m m' : Nat} (i : Fin n) (h : m' + n = m + n) :
-    (natAdd m' i).cast h = natAdd m i :=
+    cast h (natAdd m' i) = natAdd m i :=
   Fin.ext <| (congrArg (· + (i : Nat)) (Nat.add_right_cancel h) : _)
 
 theorem castAdd_natAdd (p m : Nat) {n : Nat} (i : Fin n) :
-    castAdd p (natAdd m i) = (natAdd m (castAdd p i)).cast (Nat.add_assoc ..).symm := rfl
+    castAdd p (natAdd m i) = cast (Nat.add_assoc ..).symm (natAdd m (castAdd p i)) := rfl
 
 theorem natAdd_castAdd (p m : Nat) {n : Nat} (i : Fin n) :
-    natAdd m (castAdd p i) = (castAdd p (natAdd m i)).cast (Nat.add_assoc ..) := rfl
+    natAdd m (castAdd p i) = cast (Nat.add_assoc ..) (castAdd p (natAdd m i)) := rfl
 
 theorem natAdd_natAdd (m n : Nat) {p : Nat} (i : Fin p) :
-    natAdd m (natAdd n i) = (natAdd (m + n) i).cast (Nat.add_assoc ..) :=
+    natAdd m (natAdd n i) = cast (Nat.add_assoc ..) (natAdd (m + n) i) :=
   Fin.ext <| (Nat.add_assoc ..).symm
 
+@[simp]
 theorem cast_natAdd_zero {n n' : Nat} (i : Fin n) (h : 0 + n = n') :
-    (natAdd 0 i).cast h = i.cast ((Nat.zero_add _).symm.trans h) := by simp
+    cast h (natAdd 0 i) = cast ((Nat.zero_add _).symm.trans h) i :=
+  Fin.ext <| Nat.zero_add _
 
 @[simp]
 theorem cast_natAdd (n : Nat) {m : Nat} (i : Fin m) :
-    (natAdd n i).cast (Nat.add_comm ..) = addNat i n := Fin.ext <| Nat.add_comm ..
+    cast (Nat.add_comm ..) (natAdd n i) = addNat i n := Fin.ext <| Nat.add_comm ..
 
 @[simp]
 theorem cast_addNat {n : Nat} (m : Nat) (i : Fin n) :
-    (addNat i m).cast (Nat.add_comm ..) = natAdd m i := Fin.ext <| Nat.add_comm ..
+    cast (Nat.add_comm ..) (addNat i m) = natAdd m i := Fin.ext <| Nat.add_comm ..
 
 @[simp] theorem natAdd_last {m n : Nat} : natAdd n (last m) = last (n + m) := rfl
 
 @[simp] theorem addNat_last (n : Nat) :
-    addNat (last n) m = (last (n + m)).cast (by omega) := by
+    addNat (last n) m = cast (by omega) (last (n + m)) := by
   ext
   simp
 
@@ -655,7 +657,7 @@ theorem pred_add_one (i : Fin (n + 2)) (h : (i : Nat) < n + 1) :
     subNat m (addNat i m) h = i := Fin.ext <| Nat.add_sub_cancel i m
 
 @[simp] theorem natAdd_subNat_cast {i : Fin (n + m)} (h : n ≤ i) :
-    natAdd n (subNat n (i.cast (Nat.add_comm ..)) h) = i := by simp [← cast_addNat]
+    natAdd n (subNat n (cast (Nat.add_comm ..) i) h) = i := by simp [← cast_addNat]
 
 /-! ### recursion and induction principles -/
 

src/Init/Data/Float32.lean

@@ -1,179 +0,0 @@
-/-
-Copyright (c) 2023 Amazon.com, Inc. or its affiliates. All Rights Reserved.
-Released under Apache 2.0 license as described in the file LICENSE.
-Authors: Leonardo de Moura
--/
-prelude
-import Init.Core
-import Init.Data.Int.Basic
-import Init.Data.ToString.Basic
-import Init.Data.Float
-
--- Just show FloatSpec is inhabited.
-opaque float32Spec : FloatSpec := {
-  float := Unit,
-  val   := (),
-  lt    := fun _ _ => True,
-  le    := fun _ _ => True,
-  decLt := fun _ _ => inferInstanceAs (Decidable True),
-  decLe := fun _ _ => inferInstanceAs (Decidable True)
-}
-
-/-- Native floating point type, corresponding to the IEEE 754 *binary32* format
-(`float` in C or `f32` in Rust). -/
-structure Float32 where
-  val : float32Spec.float
-
-instance : Nonempty Float32 := ⟨{ val := float32Spec.val }⟩
-
-@[extern "lean_float32_add"] opaque Float32.add : Float32 → Float32 → Float32
-@[extern "lean_float32_sub"] opaque Float32.sub : Float32 → Float32 → Float32
-@[extern "lean_float32_mul"] opaque Float32.mul : Float32 → Float32 → Float32
-@[extern "lean_float32_div"] opaque Float32.div : Float32 → Float32 → Float32
-@[extern "lean_float32_negate"] opaque Float32.neg : Float32 → Float32
-
-set_option bootstrap.genMatcherCode false
-def Float32.lt : Float32 → Float32 → Prop := fun a b =>
-  match a, b with
-  | ⟨a⟩, ⟨b⟩ => float32Spec.lt a b
-
-def Float32.le : Float32 → Float32 → Prop := fun a b =>
-  float32Spec.le a.val b.val
-
-/--
-Raw transmutation from `UInt32`.
-
-Float32s and UInts have the same endianness on all supported platforms.
-IEEE 754 very precisely specifies the bit layout of floats.
--/
-@[extern "lean_float32_of_bits"] opaque Float32.ofBits : UInt32 → Float32
-
-/--
-Raw transmutation to `UInt32`.
-
-Float32s and UInts have the same endianness on all supported platforms.
-IEEE 754 very precisely specifies the bit layout of floats.
-
-Note that this function is distinct from `Float32.toUInt32`, which attempts
-to preserve the numeric value, and not the bitwise value.
--/
-@[extern "lean_float32_to_bits"] opaque Float32.toBits : Float32 → UInt32
-
-instance : Add Float32 := ⟨Float32.add⟩
-instance : Sub Float32 := ⟨Float32.sub⟩
-instance : Mul Float32 := ⟨Float32.mul⟩
-instance : Div Float32 := ⟨Float32.div⟩
-instance : Neg Float32 := ⟨Float32.neg⟩
-instance : LT Float32  := ⟨Float32.lt⟩
-instance : LE Float32  := ⟨Float32.le⟩
-
-/-- Note: this is not reflexive since `NaN != NaN`.-/
-@[extern "lean_float32_beq"] opaque Float32.beq (a b : Float32) : Bool
-
-instance : BEq Float32 := ⟨Float32.beq⟩
-
-@[extern "lean_float32_decLt"] opaque Float32.decLt (a b : Float32) : Decidable (a < b) :=
-  match a, b with
-  | ⟨a⟩, ⟨b⟩ => float32Spec.decLt a b
-
-@[extern "lean_float32_decLe"] opaque Float32.decLe (a b : Float32) : Decidable (a ≤ b) :=
-  match a, b with
-  | ⟨a⟩, ⟨b⟩ => float32Spec.decLe a b
-
-instance float32DecLt (a b : Float32) : Decidable (a < b) := Float32.decLt a b
-instance float32DecLe (a b : Float32) : Decidable (a ≤ b) := Float32.decLe a b
-
-@[extern "lean_float32_to_string"] opaque Float32.toString : Float32 → String
-/-- If the given float is non-negative, truncates the value to the nearest non-negative integer.
-If negative or NaN, returns `0`.
-If larger than the maximum value for `UInt8` (including Inf), returns the maximum value of `UInt8`
-(i.e. `UInt8.size - 1`).
--/
-@[extern "lean_float32_to_uint8"] opaque Float32.toUInt8 : Float32 → UInt8
-/-- If the given float is non-negative, truncates the value to the nearest non-negative integer.
-If negative or NaN, returns `0`.
-If larger than the maximum value for `UInt16` (including Inf), returns the maximum value of `UInt16`
-(i.e. `UInt16.size - 1`).
--/
-@[extern "lean_float32_to_uint16"] opaque Float32.toUInt16 : Float32 → UInt16
-/-- If the given float is non-negative, truncates the value to the nearest non-negative integer.
-If negative or NaN, returns `0`.
-If larger than the maximum value for `UInt32` (including Inf), returns the maximum value of `UInt32`
-(i.e. `UInt32.size - 1`).
--/
-@[extern "lean_float32_to_uint32"] opaque Float32.toUInt32 : Float32 → UInt32
-/-- If the given float is non-negative, truncates the value to the nearest non-negative integer.
-If negative or NaN, returns `0`.
-If larger than the maximum value for `UInt64` (including Inf), returns the maximum value of `UInt64`
-(i.e. `UInt64.size - 1`).
--/
-@[extern "lean_float32_to_uint64"] opaque Float32.toUInt64 : Float32 → UInt64
-/-- If the given float is non-negative, truncates the value to the nearest non-negative integer.
-If negative or NaN, returns `0`.
-If larger than the maximum value for `USize` (including Inf), returns the maximum value of `USize`
-(i.e. `USize.size - 1`). This value is platform dependent).
--/
-@[extern "lean_float32_to_usize"] opaque Float32.toUSize : Float32 → USize
-
-@[extern "lean_float32_isnan"] opaque Float32.isNaN : Float32 → Bool
-@[extern "lean_float32_isfinite"] opaque Float32.isFinite : Float32 → Bool
-@[extern "lean_float32_isinf"] opaque Float32.isInf : Float32 → Bool
-/-- Splits the given float `x` into a significand/exponent pair `(s, i)`
-such that `x = s * 2^i` where `s ∈ (-1;-0.5] ∪ [0.5; 1)`.
-Returns an undefined value if `x` is not finite.
--/
-@[extern "lean_float32_frexp"] opaque Float32.frExp : Float32 → Float32 × Int
-
-instance : ToString Float32 where
-  toString := Float32.toString
-
-@[extern "lean_uint64_to_float32"] opaque UInt64.toFloat32 (n : UInt64) : Float32
-
-instance : Inhabited Float32 where
-  default := UInt64.toFloat32 0
-
-instance : Repr Float32 where
-  reprPrec n prec := if n < UInt64.toFloat32 0 then Repr.addAppParen (toString n) prec else toString n
-
-instance : ReprAtom Float32  := ⟨⟩
-
-@[extern "sinf"] opaque Float32.sin : Float32 → Float32
-@[extern "cosf"] opaque Float32.cos : Float32 → Float32
-@[extern "tanf"] opaque Float32.tan : Float32 → Float32
-@[extern "asinf"] opaque Float32.asin : Float32 → Float32
-@[extern "acosf"] opaque Float32.acos : Float32 → Float32
-@[extern "atanf"] opaque Float32.atan : Float32 → Float32
-@[extern "atan2f"] opaque Float32.atan2 : Float32 → Float32 → Float32
-@[extern "sinhf"] opaque Float32.sinh : Float32 → Float32
-@[extern "coshf"] opaque Float32.cosh : Float32 → Float32
-@[extern "tanhf"] opaque Float32.tanh : Float32 → Float32
-@[extern "asinhf"] opaque Float32.asinh : Float32 → Float32
-@[extern "acoshf"] opaque Float32.acosh : Float32 → Float32
-@[extern "atanhf"] opaque Float32.atanh : Float32 → Float32
-@[extern "expf"] opaque Float32.exp : Float32 → Float32
-@[extern "exp2f"] opaque Float32.exp2 : Float32 → Float32
-@[extern "logf"] opaque Float32.log : Float32 → Float32
-@[extern "log2f"] opaque Float32.log2 : Float32 → Float32
-@[extern "log10f"] opaque Float32.log10 : Float32 → Float32
-@[extern "powf"] opaque Float32.pow : Float32 → Float32 → Float32
-@[extern "sqrtf"] opaque Float32.sqrt : Float32 → Float32
-@[extern "cbrtf"] opaque Float32.cbrt : Float32 → Float32
-@[extern "ceilf"] opaque Float32.ceil : Float32 → Float32
-@[extern "floorf"] opaque Float32.floor : Float32 → Float32
-@[extern "roundf"] opaque Float32.round : Float32 → Float32
-@[extern "fabsf"] opaque Float32.abs : Float32 → Float32
-
-instance : HomogeneousPow Float32 := ⟨Float32.pow⟩
-
-instance : Min Float32 := minOfLe
-
-instance : Max Float32 := maxOfLe
-
-/--
-Efficiently computes `x * 2^i`.
--/
-@[extern "lean_float32_scaleb"]
-opaque Float32.scaleB (x : Float32) (i : @& Int) : Float32
-
-@[extern "lean_float32_to_float"] opaque Float32.toFloat : Float32 → Float
-@[extern "lean_float_to_float32"] opaque Float.toFloat32 : Float → Float32

src/Init/Data/Int/Bitwise/Lemmas.lean

@@ -34,8 +34,4 @@ theorem shiftRight_eq_div_pow (m : Int) (n : Nat) :
 theorem zero_shiftRight (n : Nat) : (0 : Int) >>> n = 0 := by
   simp [Int.shiftRight_eq_div_pow]
 
-@[simp]
-theorem shiftRight_zero (n : Int) : n >>> 0 = n := by
-  simp [Int.shiftRight_eq_div_pow]
-
 end Int

src/Init/Data/Int/DivMod.lean

@@ -29,8 +29,6 @@ At that time, we did not rename `div` and `mod` to `tdiv` and `tmod` (along with
 In September 2024, we decided to do this rename (with deprecations in place),
 and later we intend to rename `ediv` and `emod` to `div` and `mod`, as nearly all users will only
 ever need to use these functions and their associated lemmas.
-
-In December 2024, we removed `tdiv` and `tmod`, but have not yet renamed `ediv` and `emod`.
 -/
 
 /-! ### T-rounding division -/
@@ -73,6 +71,8 @@ def tdiv : (@& Int) → (@& Int) → Int
   | -[m +1], ofNat n => -ofNat (succ m / n)
   | -[m +1], -[n +1] =>  ofNat (succ m / succ n)
 
+@[deprecated tdiv (since := "2024-09-11")] abbrev div := tdiv
+
 /-- Integer modulo. This function uses the
   [*"T-rounding"*][t-rounding] (**T**runcation-rounding) convention
   to pair with `Int.tdiv`, meaning that `tmod a b + b * (tdiv a b) = a`
@@ -107,6 +107,8 @@ def tmod : (@& Int) → (@& Int) → Int
   | -[m +1], ofNat n => -ofNat (succ m % n)
   | -[m +1], -[n +1] => -ofNat (succ m % succ n)
 
+@[deprecated tmod (since := "2024-09-11")] abbrev mod := tmod
+
 /-! ### F-rounding division
 This pair satisfies `fdiv x y = floor (x / y)`.
 -/
@@ -249,6 +251,8 @@ instance : Mod Int where
 
 theorem ofNat_tdiv (m n : Nat) : ↑(m / n) = tdiv ↑m ↑n := rfl
 
+@[deprecated ofNat_tdiv (since := "2024-09-11")] abbrev ofNat_div := ofNat_tdiv
+
 theorem ofNat_fdiv : ∀ m n : Nat, ↑(m / n) = fdiv ↑m ↑n
   | 0, _ => by simp [fdiv]
   | succ _, _ => rfl

src/Init/Data/Int/DivModLemmas.lean

@@ -125,7 +125,7 @@ theorem eq_one_of_mul_eq_one_right {a b : Int} (H : 0 ≤ a) (H' : a * b = 1) :
   eq_one_of_dvd_one H ⟨b, H'.symm⟩
 
 theorem eq_one_of_mul_eq_one_left {a b : Int} (H : 0 ≤ b) (H' : a * b = 1) : b = 1 :=
-  eq_one_of_mul_eq_one_right (b := a) H <| by rw [Int.mul_comm, H']
+  eq_one_of_mul_eq_one_right H <| by rw [Int.mul_comm, H']
 
 /-! ### *div zero  -/
 
@@ -1315,3 +1315,65 @@ theorem bmod_natAbs_plus_one (x : Int) (w : 1 < x.natAbs) : bmod x (x.natAbs + 1
           all_goals decide
     · exact ofNat_nonneg x
     · exact succ_ofNat_pos (x + 1)
+
+/-! ### Deprecations -/
+
+@[deprecated Int.zero_tdiv (since := "2024-09-11")] protected abbrev zero_div := @Int.zero_tdiv
+@[deprecated Int.tdiv_zero (since := "2024-09-11")] protected abbrev div_zero := @Int.tdiv_zero
+@[deprecated tdiv_eq_ediv (since := "2024-09-11")] abbrev div_eq_ediv := @tdiv_eq_ediv
+@[deprecated fdiv_eq_tdiv (since := "2024-09-11")] abbrev fdiv_eq_div := @fdiv_eq_tdiv
+@[deprecated zero_tmod (since := "2024-09-11")] abbrev zero_mod := @zero_tmod
+@[deprecated tmod_zero (since := "2024-09-11")] abbrev mod_zero := @tmod_zero
+@[deprecated tmod_add_tdiv (since := "2024-09-11")] abbrev mod_add_div := @tmod_add_tdiv
+@[deprecated tdiv_add_tmod (since := "2024-09-11")] abbrev div_add_mod := @tdiv_add_tmod
+@[deprecated tmod_add_tdiv' (since := "2024-09-11")] abbrev mod_add_div' := @tmod_add_tdiv'
+@[deprecated tdiv_add_tmod' (since := "2024-09-11")] abbrev div_add_mod' := @tdiv_add_tmod'
+@[deprecated tmod_def (since := "2024-09-11")] abbrev mod_def := @tmod_def
+@[deprecated tmod_eq_emod (since := "2024-09-11")] abbrev mod_eq_emod := @tmod_eq_emod
+@[deprecated fmod_eq_tmod (since := "2024-09-11")] abbrev fmod_eq_mod := @fmod_eq_tmod
+@[deprecated Int.tdiv_one (since := "2024-09-11")] protected abbrev div_one := @Int.tdiv_one
+@[deprecated Int.tdiv_neg (since := "2024-09-11")] protected abbrev div_neg := @Int.tdiv_neg
+@[deprecated Int.neg_tdiv (since := "2024-09-11")] protected abbrev neg_div := @Int.neg_tdiv
+@[deprecated Int.neg_tdiv_neg (since := "2024-09-11")] protected abbrev neg_div_neg := @Int.neg_tdiv_neg
+@[deprecated Int.tdiv_nonneg (since := "2024-09-11")] protected abbrev div_nonneg := @Int.tdiv_nonneg
+@[deprecated Int.tdiv_nonpos (since := "2024-09-11")] protected abbrev div_nonpos := @Int.tdiv_nonpos
+@[deprecated Int.tdiv_eq_zero_of_lt (since := "2024-09-11")] abbrev div_eq_zero_of_lt := @Int.tdiv_eq_zero_of_lt
+@[deprecated Int.mul_tdiv_cancel (since := "2024-09-11")] protected abbrev mul_div_cancel := @Int.mul_tdiv_cancel
+@[deprecated Int.mul_tdiv_cancel_left (since := "2024-09-11")] protected abbrev mul_div_cancel_left := @Int.mul_tdiv_cancel_left
+@[deprecated Int.tdiv_self (since := "2024-09-11")] protected abbrev div_self := @Int.tdiv_self
+@[deprecated Int.mul_tdiv_cancel_of_tmod_eq_zero (since := "2024-09-11")] abbrev mul_div_cancel_of_mod_eq_zero := @Int.mul_tdiv_cancel_of_tmod_eq_zero
+@[deprecated Int.tdiv_mul_cancel_of_tmod_eq_zero (since := "2024-09-11")] abbrev div_mul_cancel_of_mod_eq_zero := @Int.tdiv_mul_cancel_of_tmod_eq_zero
+@[deprecated Int.dvd_of_tmod_eq_zero (since := "2024-09-11")] abbrev dvd_of_mod_eq_zero := @Int.dvd_of_tmod_eq_zero
+@[deprecated Int.mul_tdiv_assoc (since := "2024-09-11")] protected abbrev mul_div_assoc := @Int.mul_tdiv_assoc
+@[deprecated Int.mul_tdiv_assoc' (since := "2024-09-11")] protected abbrev mul_div_assoc' := @Int.mul_tdiv_assoc'
+@[deprecated Int.tdiv_dvd_tdiv (since := "2024-09-11")] abbrev div_dvd_div := @Int.tdiv_dvd_tdiv
+@[deprecated Int.natAbs_tdiv (since := "2024-09-11")] abbrev natAbs_div := @Int.natAbs_tdiv
+@[deprecated Int.tdiv_eq_of_eq_mul_right (since := "2024-09-11")] protected abbrev div_eq_of_eq_mul_right := @Int.tdiv_eq_of_eq_mul_right
+@[deprecated Int.eq_tdiv_of_mul_eq_right (since := "2024-09-11")] protected abbrev eq_div_of_mul_eq_right := @Int.eq_tdiv_of_mul_eq_right
+@[deprecated Int.ofNat_tmod (since := "2024-09-11")] abbrev ofNat_mod := @Int.ofNat_tmod
+@[deprecated Int.tmod_one (since := "2024-09-11")] abbrev mod_one := @Int.tmod_one
+@[deprecated Int.tmod_eq_of_lt (since := "2024-09-11")] abbrev mod_eq_of_lt := @Int.tmod_eq_of_lt
+@[deprecated Int.tmod_lt_of_pos (since := "2024-09-11")] abbrev mod_lt_of_pos := @Int.tmod_lt_of_pos
+@[deprecated Int.tmod_nonneg (since := "2024-09-11")] abbrev mod_nonneg := @Int.tmod_nonneg
+@[deprecated Int.tmod_neg (since := "2024-09-11")] abbrev mod_neg := @Int.tmod_neg
+@[deprecated Int.mul_tmod_left (since := "2024-09-11")] abbrev mul_mod_left := @Int.mul_tmod_left
+@[deprecated Int.mul_tmod_right (since := "2024-09-11")] abbrev mul_mod_right := @Int.mul_tmod_right
+@[deprecated Int.tmod_eq_zero_of_dvd (since := "2024-09-11")] abbrev mod_eq_zero_of_dvd := @Int.tmod_eq_zero_of_dvd
+@[deprecated Int.dvd_iff_tmod_eq_zero (since := "2024-09-11")] abbrev dvd_iff_mod_eq_zero := @Int.dvd_iff_tmod_eq_zero
+@[deprecated Int.neg_mul_tmod_right (since := "2024-09-11")] abbrev neg_mul_mod_right := @Int.neg_mul_tmod_right
+@[deprecated Int.neg_mul_tmod_left (since := "2024-09-11")] abbrev neg_mul_mod_left := @Int.neg_mul_tmod_left
+@[deprecated Int.tdiv_mul_cancel (since := "2024-09-11")] protected abbrev div_mul_cancel := @Int.tdiv_mul_cancel
+@[deprecated Int.mul_tdiv_cancel' (since := "2024-09-11")] protected abbrev mul_div_cancel' := @Int.mul_tdiv_cancel'
+@[deprecated Int.eq_mul_of_tdiv_eq_right (since := "2024-09-11")] protected abbrev eq_mul_of_div_eq_right := @Int.eq_mul_of_tdiv_eq_right
+@[deprecated Int.tmod_self (since := "2024-09-11")] abbrev mod_self := @Int.tmod_self
+@[deprecated Int.neg_tmod_self (since := "2024-09-11")] abbrev neg_mod_self := @Int.neg_tmod_self
+@[deprecated Int.lt_tdiv_add_one_mul_self (since := "2024-09-11")] abbrev lt_div_add_one_mul_self := @Int.lt_tdiv_add_one_mul_self
+@[deprecated Int.tdiv_eq_iff_eq_mul_right (since := "2024-09-11")] protected abbrev div_eq_iff_eq_mul_right := @Int.tdiv_eq_iff_eq_mul_right
+@[deprecated Int.tdiv_eq_iff_eq_mul_left (since := "2024-09-11")] protected abbrev div_eq_iff_eq_mul_left := @Int.tdiv_eq_iff_eq_mul_left
+@[deprecated Int.eq_mul_of_tdiv_eq_left (since := "2024-09-11")] protected abbrev eq_mul_of_div_eq_left := @Int.eq_mul_of_tdiv_eq_left
+@[deprecated Int.tdiv_eq_of_eq_mul_left (since := "2024-09-11")] protected abbrev div_eq_of_eq_mul_left := @Int.tdiv_eq_of_eq_mul_left
+@[deprecated Int.eq_zero_of_tdiv_eq_zero (since := "2024-09-11")] protected abbrev eq_zero_of_div_eq_zero := @Int.eq_zero_of_tdiv_eq_zero
+@[deprecated Int.tdiv_left_inj (since := "2024-09-11")] protected abbrev div_left_inj := @Int.tdiv_left_inj
+@[deprecated Int.tdiv_sign (since := "2024-09-11")] abbrev div_sign := @Int.tdiv_sign
+@[deprecated Int.sign_eq_tdiv_abs (since := "2024-09-11")] protected abbrev sign_eq_div_abs := @Int.sign_eq_tdiv_abs
+@[deprecated Int.tdiv_eq_ediv_of_dvd (since := "2024-09-11")] abbrev div_eq_ediv_of_dvd := @Int.tdiv_eq_ediv_of_dvd

src/Init/Data/List.lean

@@ -24,7 +24,6 @@ import Init.Data.List.Zip
 import Init.Data.List.Perm
 import Init.Data.List.Sort
 import Init.Data.List.ToArray
-import Init.Data.List.ToArrayImpl
 import Init.Data.List.MapIdx
 import Init.Data.List.OfFn
 import Init.Data.List.FinRange

src/Init/Data/List/Attach.lean

@@ -118,6 +118,7 @@ theorem attach_map_coe (l : List α) (f : α → β) :
 theorem attach_map_val (l : List α) (f : α → β) : (l.attach.map fun i => f i.val) = l.map f :=
   attach_map_coe _ _
 
+@[simp]
 theorem attach_map_subtype_val (l : List α) : l.attach.map Subtype.val = l :=
   (attach_map_coe _ _).trans (List.map_id _)
 
@@ -129,6 +130,7 @@ theorem attachWith_map_val {p : α → Prop} (f : α → β) (l : List α) (H :
     ((l.attachWith p H).map fun i => f i.val) = l.map f :=
   attachWith_map_coe _ _ _
 
+@[simp]
 theorem attachWith_map_subtype_val {p : α → Prop} (l : List α) (H : ∀ a ∈ l, p a) :
     (l.attachWith p H).map Subtype.val = l :=
   (attachWith_map_coe _ _ _).trans (List.map_id _)
@@ -172,8 +174,8 @@ theorem pmap_ne_nil_iff {P : α → Prop} (f : (a : α) → P a → β) {xs : Li
     (H : ∀ (a : α), a ∈ xs → P a) : xs.pmap f H ≠ [] ↔ xs ≠ [] := by
   simp
 
-theorem pmap_eq_self {l : List α} {p : α → Prop} {hp : ∀ (a : α), a ∈ l → p a}
-    {f : (a : α) → p a → α} : l.pmap f hp = l ↔ ∀ a (h : a ∈ l), f a (hp a h) = a := by
+theorem pmap_eq_self {l : List α} {p : α → Prop} (hp : ∀ (a : α), a ∈ l → p a)
+    (f : (a : α) → p a → α) : l.pmap f hp = l ↔ ∀ a (h : a ∈ l), f a (hp a h) = a := by
   rw [pmap_eq_map_attach]
   conv => lhs; rhs; rw [← attach_map_subtype_val l]
   rw [map_inj_left]

src/Init/Data/List/Basic.lean

@@ -666,14 +666,10 @@ def isEmpty : List α → Bool
 /-! ### elem -/
 
 /--
-`O(|l|)`.
-`l.contains a` or `elem a l` is true if there is an element in `l` equal (according to `==`) to `a`.
+`O(|l|)`. `elem a l` or `l.contains a` is true if there is an element in `l` equal to `a`.
 
-* `[1, 4, 2, 3, 3, 7].contains 3 = true`
-* `[1, 4, 2, 3, 3, 7].contains 5 = false`
-
-The preferred simp normal form is `l.contains a`, and when `LawfulBEq α` is available,
-`l.contains a = true ↔ a ∈ l` and `l.contains a = false ↔ a ∉ l`.
+* `elem 3 [1, 4, 2, 3, 3, 7] = true`
+* `elem 5 [1, 4, 2, 3, 3, 7] = false`
 -/
 def elem [BEq α] (a : α) : List α → Bool
   | []    => false

src/Init/Data/List/BasicAux.lean

@@ -155,8 +155,7 @@ def mapMono (as : List α) (f : α → α) : List α :=
 
 /-! ## Additional lemmas required for bootstrapping `Array`. -/
 
-theorem getElem_append_left {as bs : List α} (h : i < as.length) {h' : i < (as ++ bs).length} :
-    (as ++ bs)[i] = as[i] := by
+theorem getElem_append_left {as bs : List α} (h : i < as.length) {h'} : (as ++ bs)[i] = as[i] := by
   induction as generalizing i with
   | nil => trivial
   | cons a as ih =>

src/Init/Data/List/Count.lean

@@ -162,10 +162,6 @@ theorem countP_filterMap (p : β → Bool) (f : α → Option β) (l : List α)
 
 @[deprecated countP_flatten (since := "2024-10-14")] abbrev countP_join := @countP_flatten
 
-theorem countP_flatMap (p : β → Bool) (l : List α) (f : α → List β) :
-    countP p (l.flatMap f) = sum (map (countP p ∘ f) l) := by
-  rw [List.flatMap, countP_flatten, map_map]
-
 @[simp] theorem countP_reverse (l : List α) : countP p l.reverse = countP p l := by
   simp [countP_eq_length_filter, filter_reverse]
 
@@ -330,9 +326,6 @@ theorem count_filterMap {α} [BEq β] (b : β) (f : α → Option β) (l : List
   · simp
   · simp
 
-theorem count_flatMap {α} [BEq β] (l : List α) (f : α → List β) (x : β) :
-    count x (l.flatMap f) = sum (map (count x ∘ f) l) := countP_flatMap _ _ _
-
 theorem count_erase (a b : α) :
     ∀ l : List α, count a (l.erase b) = count a l - if b == a then 1 else 0
   | [] => by simp

src/Init/Data/List/Find.lean

@@ -566,6 +566,7 @@ theorem not_of_lt_findIdx {p : α → Bool} {xs : List α} {i : Nat} (h : i < xs
     | inl e => simpa [e, Fin.zero_eta, get_cons_zero]
     | inr e =>
       have ipm := Nat.succ_pred_eq_of_pos e
+      have ilt := Nat.le_trans ho (findIdx_le_length p)
       simp +singlePass only [← ipm, getElem_cons_succ]
       rw [← ipm, Nat.succ_lt_succ_iff] at h
       simpa using ih h

src/Init/Data/List/Impl.lean

@@ -332,7 +332,7 @@ def enumFromTR (n : Nat) (l : List α) : List (Nat × α) :=
       rw [← show _ + as.length = n + (a::as).length from Nat.succ_add .., foldr, go as]
       simp [enumFrom, f]
   rw [← Array.foldr_toList]
-  simp +zetaDelta [go]
+  simp [go]
 
 /-! ## Other list operations -/
 

src/Init/Data/List/Lemmas.lean

@@ -154,9 +154,6 @@ theorem ne_nil_iff_exists_cons {l : List α} : l ≠ [] ↔ ∃ b L, l = b :: L
 theorem singleton_inj {α : Type _} {a b : α} : [a] = [b] ↔ a = b := by
   simp
 
-@[simp] theorem concat_ne_nil (a : α) (l : List α) : l ++ [a] ≠ [] := by
-  cases l <;> simp
-
 /-! ## L[i] and L[i]? -/
 
 /-! ### `get` and `get?`.
@@ -194,63 +191,61 @@ We simplify away `getD`, replacing `getD l n a` with `(l[n]?).getD a`.
 Because of this, there is only minimal API for `getD`.
 -/
 
-@[simp] theorem getD_eq_getElem?_getD (l) (i) (a : α) : getD l i a = (l[i]?).getD a := by
+@[simp] theorem getD_eq_getElem?_getD (l) (n) (a : α) : getD l n a = (l[n]?).getD a := by
   simp [getD]
 
 /-! ### get!
 
-We simplify `l.get! i` to `l[i]!`.
+We simplify `l.get! n` to `l[n]!`.
 -/
 
-theorem get!_eq_getD [Inhabited α] : ∀ (l : List α) i, l.get! i = l.getD i default
+theorem get!_eq_getD [Inhabited α] : ∀ (l : List α) n, l.get! n = l.getD n default
   | [], _      => rfl
   | _a::_, 0   => rfl
   | _a::l, n+1 => get!_eq_getD l n
 
-@[simp] theorem get!_eq_getElem! [Inhabited α] (l : List α) (i) : l.get! i = l[i]! := by
+@[simp] theorem get!_eq_getElem! [Inhabited α] (l : List α) (n) : l.get! n = l[n]! := by
   simp [get!_eq_getD]
   rfl
 
 /-! ### getElem!
 
-We simplify `l[i]!` to `(l[i]?).getD default`.
+We simplify `l[n]!` to `(l[n]?).getD default`.
 -/
 
-@[simp] theorem getElem!_eq_getElem?_getD [Inhabited α] (l : List α) (i : Nat) :
-    l[i]! = (l[i]?).getD (default : α) := by
+@[simp] theorem getElem!_eq_getElem?_getD [Inhabited α] (l : List α) (n : Nat) :
+    l[n]! = (l[n]?).getD (default : α) := by
   simp only [getElem!_def]
-  match l[i]? with
-  | some _ => simp
-  | none => simp
+  split <;> simp_all
 
 /-! ### getElem? and getElem -/
 
-@[simp] theorem getElem?_eq_none_iff : l[i]? = none ↔ length l ≤ i := by
-  simp only [← get?_eq_getElem?, get?_eq_none_iff]
+@[simp] theorem getElem?_eq_getElem {l : List α} {n} (h : n < l.length) : l[n]? = some l[n] := by
+  simp only [getElem?_def, h, ↓reduceDIte]
 
-@[simp] theorem none_eq_getElem?_iff {l : List α} {i : Nat} : none = l[i]? ↔ length l ≤ i := by
-  simp [eq_comm (a := none)]
-
-theorem getElem?_eq_none (h : length l ≤ i) : l[i]? = none := getElem?_eq_none_iff.mpr h
-
-@[simp] theorem getElem?_eq_getElem {l : List α} {i} (h : i < l.length) : l[i]? = some l[i] :=
-  getElem?_pos ..
-
-theorem getElem?_eq_some_iff {l : List α} : l[i]? = some a ↔ ∃ h : i < l.length, l[i] = a := by
+theorem getElem?_eq_some_iff {l : List α} : l[n]? = some a ↔ ∃ h : n < l.length, l[n] = a := by
   simp only [← get?_eq_getElem?, get?_eq_some_iff, get_eq_getElem]
 
-theorem some_eq_getElem?_iff {l : List α} : some a = l[i]? ↔ ∃ h : i < l.length, l[i] = a := by
+theorem some_eq_getElem?_iff {l : List α} : some a = l[n]? ↔ ∃ h : n < l.length, l[n] = a := by
   rw [eq_comm, getElem?_eq_some_iff]
 
-@[simp] theorem some_getElem_eq_getElem?_iff (xs : List α) (i : Nat) (h : i < xs.length) :
+@[simp] theorem getElem?_eq_none_iff : l[n]? = none ↔ length l ≤ n := by
+  simp only [← get?_eq_getElem?, get?_eq_none_iff]
+
+@[simp] theorem none_eq_getElem?_iff {l : List α} {n : Nat} : none = l[n]? ↔ length l ≤ n := by
+  simp [eq_comm (a := none)]
+
+theorem getElem?_eq_none (h : length l ≤ n) : l[n]? = none := getElem?_eq_none_iff.mpr h
+
+@[simp] theorem some_getElem_eq_getElem?_iff {α} (xs : List α) (i : Nat) (h : i < xs.length) :
     (some xs[i] = xs[i]?) ↔ True := by
   simp [h]
 
-@[simp] theorem getElem?_eq_some_getElem_iff (xs : List α) (i : Nat) (h : i < xs.length) :
+@[simp] theorem getElem?_eq_some_getElem_iff {α} (xs : List α) (i : Nat) (h : i < xs.length) :
     (xs[i]? = some xs[i]) ↔ True := by
   simp [h]
 
-theorem getElem_eq_iff {l : List α} {i : Nat} {h : i < l.length} : l[i] = x ↔ l[i]? = some x := by
+theorem getElem_eq_iff {l : List α} {n : Nat} {h : n < l.length} : l[n] = x ↔ l[n]? = some x := by
   simp only [getElem?_eq_some_iff]
   exact ⟨fun w => ⟨h, w⟩, fun h => h.2⟩
 
@@ -258,37 +253,17 @@ theorem getElem_eq_getElem?_get (l : List α) (i : Nat) (h : i < l.length) :
     l[i] = l[i]?.get (by simp [getElem?_eq_getElem, h]) := by
   simp [getElem_eq_iff]
 
-theorem getD_getElem? (l : List α) (i : Nat) (d : α) :
-    l[i]?.getD d = if p : i < l.length then l[i]'p else d := by
-  if h : i < l.length then
-    simp [h, getElem?_def]
-  else
-    have p : i ≥ l.length := Nat.le_of_not_gt h
-    simp [getElem?_eq_none p, h]
-
-@[simp] theorem getElem?_nil {i : Nat} : ([] : List α)[i]? = none := rfl
-
-theorem getElem_cons {l : List α} (w : i < (a :: l).length) :
-    (a :: l)[i] =
-      if h : i = 0 then a else l[i-1]'(match i, h with | i+1, _ => succ_lt_succ_iff.mp w) := by
-  cases i <;> simp
+@[simp] theorem getElem?_nil {n : Nat} : ([] : List α)[n]? = none := rfl
 
 theorem getElem?_cons_zero {l : List α} : (a::l)[0]? = some a := by simp
 
-@[simp] theorem getElem?_cons_succ {l : List α} : (a::l)[i+1]? = l[i]? := by
+@[simp] theorem getElem?_cons_succ {l : List α} : (a::l)[n+1]? = l[n]? := by
   simp only [← get?_eq_getElem?]
   rfl
 
 theorem getElem?_cons : (a :: l)[i]? = if i = 0 then some a else l[i-1]? := by
   cases i <;> simp
 
-@[simp] theorem getElem_singleton (a : α) (h : i < 1) : [a][i] = a :=
-  match i, h with
-  | 0, _ => rfl
-
-theorem getElem?_singleton (a : α) (i : Nat) : [a][i]? = if i = 0 then some a else none := by
-  simp [getElem?_cons]
-
 /--
 If one has `l[i]` in an expression and `h : l = l'`,
 `rw [h]` will give a "motive it not type correct" error, as it cannot rewrite the
@@ -298,15 +273,19 @@ such a rewrite, with `rw [getElem_of_eq h]`.
 theorem getElem_of_eq {l l' : List α} (h : l = l') {i : Nat} (w : i < l.length) :
     l[i] = l'[i]'(h ▸ w) := by cases h; rfl
 
+@[simp] theorem getElem_singleton (a : α) (h : i < 1) : [a][i] = a :=
+  match i, h with
+  | 0, _ => rfl
+
 theorem getElem_zero {l : List α} (h : 0 < l.length) : l[0] = l.head (length_pos.mp h) :=
   match l, h with
   | _ :: _, _ => rfl
 
-@[ext] theorem ext_getElem? {l₁ l₂ : List α} (h : ∀ i : Nat, l₁[i]? = l₂[i]?) : l₁ = l₂ :=
+@[ext] theorem ext_getElem? {l₁ l₂ : List α} (h : ∀ n : Nat, l₁[n]? = l₂[n]?) : l₁ = l₂ :=
   ext_get? fun n => by simp_all
 
 theorem ext_getElem {l₁ l₂ : List α} (hl : length l₁ = length l₂)
-    (h : ∀ (i : Nat) (h₁ : i < l₁.length) (h₂ : i < l₂.length), l₁[i]'h₁ = l₂[i]'h₂) : l₁ = l₂ :=
+    (h : ∀ (n : Nat) (h₁ : n < l₁.length) (h₂ : n < l₂.length), l₁[n]'h₁ = l₂[n]'h₂) : l₁ = l₂ :=
   ext_getElem? fun n =>
     if h₁ : n < length l₁ then by
       simp_all [getElem?_eq_getElem]
@@ -321,6 +300,12 @@ theorem ext_getElem {l₁ l₂ : List α} (hl : length l₁ = length l₂)
 theorem getElem?_concat_length (l : List α) (a : α) : (l ++ [a])[l.length]? = some a := by
   simp
 
+theorem isSome_getElem? {l : List α} {n : Nat} : l[n]?.isSome ↔ n < l.length := by
+  simp
+
+theorem isNone_getElem? {l : List α} {n : Nat} : l[n]?.isNone ↔ l.length ≤ n := by
+  simp
+
 /-! ### mem -/
 
 @[simp] theorem not_mem_nil (a : α) : ¬ a ∈ [] := nofun
@@ -427,25 +412,24 @@ theorem not_mem_cons_of_ne_of_not_mem {a y : α} {l : List α} : a ≠ y → a
 theorem ne_and_not_mem_of_not_mem_cons {a y : α} {l : List α} : a ∉ y :: l → a ≠ y ∧ a ∉ l :=
   fun p => ⟨ne_of_not_mem_cons p, not_mem_of_not_mem_cons p⟩
 
-theorem getElem_of_mem : ∀ {a} {l : List α}, a ∈ l → ∃ (i : Nat) (h : i < l.length), l[i]'h = a
+theorem getElem_of_mem : ∀ {a} {l : List α}, a ∈ l → ∃ (n : Nat) (h : n < l.length), l[n]'h = a
   | _, _ :: _, .head .. => ⟨0, Nat.succ_pos _, rfl⟩
-  | _, _ :: _, .tail _ m => let ⟨i, h, e⟩ := getElem_of_mem m; ⟨i+1, Nat.succ_lt_succ h, e⟩
+  | _, _ :: _, .tail _ m => let ⟨n, h, e⟩ := getElem_of_mem m; ⟨n+1, Nat.succ_lt_succ h, e⟩
 
-theorem getElem?_of_mem {a} {l : List α} (h : a ∈ l) : ∃ i : Nat, l[i]? = some a := by
-  let ⟨n, _, e⟩ := getElem_of_mem h
-  exact ⟨n, e ▸ getElem?_eq_getElem _⟩
+theorem getElem?_of_mem {a} {l : List α} (h : a ∈ l) : ∃ n : Nat, l[n]? = some a :=
+  let ⟨n, _, e⟩ := getElem_of_mem h; ⟨n, e ▸ getElem?_eq_getElem _⟩
 
-theorem mem_of_getElem? {l : List α} {i : Nat} {a : α} (e : l[i]? = some a) : a ∈ l :=
+theorem mem_of_getElem? {l : List α} {n : Nat} {a : α} (e : l[n]? = some a) : a ∈ l :=
   let ⟨_, e⟩ := getElem?_eq_some_iff.1 e; e ▸ getElem_mem ..
 
-theorem mem_iff_getElem {a} {l : List α} : a ∈ l ↔ ∃ (i : Nat) (h : i < l.length), l[i]'h = a :=
+theorem mem_iff_getElem {a} {l : List α} : a ∈ l ↔ ∃ (n : Nat) (h : n < l.length), l[n]'h = a :=
   ⟨getElem_of_mem, fun ⟨_, _, e⟩ => e ▸ getElem_mem ..⟩
 
-theorem mem_iff_getElem? {a} {l : List α} : a ∈ l ↔ ∃ i : Nat, l[i]? = some a := by
+theorem mem_iff_getElem? {a} {l : List α} : a ∈ l ↔ ∃ n : Nat, l[n]? = some a := by
   simp [getElem?_eq_some_iff, mem_iff_getElem]
 
 theorem forall_getElem {l : List α} {p : α → Prop} :
-    (∀ (i : Nat) h, p (l[i]'h)) ↔ ∀ a, a ∈ l → p a := by
+    (∀ (n : Nat) h, p (l[n]'h)) ↔ ∀ a, a ∈ l → p a := by
   induction l with
   | nil => simp
   | cons a l ih =>
@@ -464,10 +448,6 @@ theorem forall_getElem {l : List α} {p : α → Prop} :
         simp only [getElem_cons_succ]
         exact getElem_mem (lt_of_succ_lt_succ h)
 
-@[simp] theorem elem_eq_contains [BEq α] {a : α} {l : List α} :
-    elem a l = l.contains a := by
-  simp [contains]
-
 @[simp] theorem decide_mem_cons [BEq α] [LawfulBEq α] {l : List α} :
     decide (y ∈ a :: l) = (y == a || decide (y ∈ l)) := by
   cases h : y == a <;> simp_all
@@ -475,27 +455,16 @@ theorem forall_getElem {l : List α} {p : α → Prop} :
 theorem elem_iff [BEq α] [LawfulBEq α] {a : α} {as : List α} :
     elem a as = true ↔ a ∈ as := ⟨mem_of_elem_eq_true, elem_eq_true_of_mem⟩
 
-theorem contains_iff [BEq α] [LawfulBEq α] {a : α} {as : List α} :
-    as.contains a = true ↔ a ∈ as := ⟨mem_of_elem_eq_true, elem_eq_true_of_mem⟩
-
-theorem elem_eq_mem [BEq α] [LawfulBEq α] (a : α) (as : List α) :
+@[simp] theorem elem_eq_mem [BEq α] [LawfulBEq α] (a : α) (as : List α) :
     elem a as = decide (a ∈ as) := by rw [Bool.eq_iff_iff, elem_iff, decide_eq_true_iff]
 
-@[simp] theorem contains_eq_mem [BEq α] [LawfulBEq α] (a : α) (as : List α) :
-    as.contains a = decide (a ∈ as) := by rw [Bool.eq_iff_iff, elem_iff, decide_eq_true_iff]
-
-@[simp] theorem contains_cons [BEq α] {a : α} {b : α} {l : List α} :
-    (a :: l).contains b = (b == a || l.contains b) := by
-  simp only [contains, elem_cons]
-  split <;> simp_all
-
 /-! ### `isEmpty` -/
 
 theorem isEmpty_iff {l : List α} : l.isEmpty ↔ l = [] := by
   cases l <;> simp
 
 theorem isEmpty_eq_false_iff_exists_mem {xs : List α} :
-    xs.isEmpty = false ↔ ∃ x, x ∈ xs := by
+    (List.isEmpty xs = false) ↔ ∃ x, x ∈ xs := by
   cases xs <;> simp
 
 theorem isEmpty_iff_length_eq_zero {l : List α} : l.isEmpty ↔ l.length = 0 := by
@@ -533,21 +502,17 @@ theorem decide_forall_mem {l : List α} {p : α → Prop} [DecidablePred p] :
 @[simp] theorem all_eq_false {l : List α} : l.all p = false ↔ ∃ x, x ∈ l ∧ ¬p x := by
   simp [all_eq]
 
-theorem any_beq [BEq α] {l : List α} {a : α} : (l.any fun x => a == x) = l.contains a := by
-  induction l <;> simp_all [contains_cons]
+theorem any_beq [BEq α] [LawfulBEq α] {l : List α} : (l.any fun x => a == x) ↔ a ∈ l := by
+  simp
 
-/-- Variant of `any_beq` with `==` reversed. -/
-theorem any_beq' [BEq α] [PartialEquivBEq α] {l : List α} :
-    (l.any fun x => x == a) = l.contains a := by
-  simp only [BEq.comm, any_beq]
+theorem any_beq' [BEq α] [LawfulBEq α] {l : List α} : (l.any fun x => x == a) ↔ a ∈ l := by
+  simp
 
-theorem all_bne [BEq α] {l : List α} : (l.all fun x => a != x) = !l.contains a := by
-  induction l <;> simp_all [bne]
+theorem all_bne [BEq α] [LawfulBEq α] {l : List α} : (l.all fun x => a != x) ↔ a ∉ l := by
+  induction l <;> simp_all
 
-/-- Variant of `all_bne` with `!=` reversed. -/
-theorem all_bne' [BEq α] [PartialEquivBEq α] {l : List α} :
-    (l.all fun x => x != a) = !l.contains a := by
-  simp only [bne_comm, all_bne]
+theorem all_bne' [BEq α] [LawfulBEq α] {l : List α} : (l.all fun x => x != a) ↔ a ∉ l := by
+  induction l <;> simp_all [eq_comm (a := a)]
 
 /-! ### set -/
 
@@ -598,10 +563,10 @@ theorem getElem?_set_self' {l : List α} {i : Nat} {a : α} :
     simp_all
   · rw [getElem?_eq_none (by simp_all), getElem?_eq_none (by simp_all)]
 
-theorem getElem_set {l : List α} {i j} {a} (h) :
-    (set l i a)[j]'h = if i = j then a else l[j]'(length_set .. ▸ h) := by
-  if h : i = j then
-    subst h; simp only [getElem_set_self, ↓reduceIte]
+theorem getElem_set {l : List α} {m n} {a} (h) :
+    (set l m a)[n]'h = if m = n then a else l[n]'(length_set .. ▸ h) := by
+  if h : m = n then
+    subst m; simp only [getElem_set_self, ↓reduceIte]
   else
     simp [h]
 
@@ -720,15 +685,6 @@ theorem mem_or_eq_of_mem_set : ∀ {l : List α} {n : Nat} {a b : α}, a ∈ l.s
 @[simp] theorem cons_beq_cons [BEq α] {a b : α} {l₁ l₂ : List α} :
     (a :: l₁ == b :: l₂) = (a == b && l₁ == l₂) := rfl
 
-@[simp] theorem concat_beq_concat [BEq α] {a b : α} {l₁ l₂ : List α} :
-    (l₁ ++ [a] == l₂ ++ [b]) = (l₁ == l₂ && a == b) := by
-  induction l₁ generalizing l₂ with
-  | nil => cases l₂ <;> simp
-  | cons x l₁ ih =>
-    cases l₂ with
-    | nil => simp
-    | cons y l₂ => simp [ih, Bool.and_assoc]
-
 theorem length_eq_of_beq [BEq α] {l₁ l₂ : List α} (h : l₁ == l₂) : l₁.length = l₂.length :=
   match l₁, l₂ with
   | [], [] => rfl
@@ -993,7 +949,7 @@ theorem getLast_eq_getElem : ∀ (l : List α) (h : l ≠ []),
   | _ :: _ :: _, _ => by
     simp [getLast, get, Nat.succ_sub_succ, getLast_eq_getElem]
 
-theorem getElem_length_sub_one_eq_getLast (l : List α) (h : l.length - 1 < l.length) :
+theorem getElem_length_sub_one_eq_getLast (l : List α) (h) :
     l[l.length - 1] = getLast l (by cases l; simp at h; simp) := by
   rw [← getLast_eq_getElem]
 
@@ -1033,8 +989,8 @@ theorem getLastD_mem_cons : ∀ (l : List α) (a : α), getLastD l a ∈ a::l
   | [], _ => .head ..
   | _::_, _ => .tail _ <| getLast_mem _
 
-theorem getElem_cons_length (x : α) (xs : List α) (i : Nat) (h : i = xs.length) :
-    (x :: xs)[i]'(by simp [h]) = (x :: xs).getLast (cons_ne_nil x xs) := by
+theorem getElem_cons_length (x : α) (xs : List α) (n : Nat) (h : n = xs.length) :
+    (x :: xs)[n]'(by simp [h]) = (x :: xs).getLast (cons_ne_nil x xs) := by
   rw [getLast_eq_getElem]; cases h; rfl
 
 @[deprecated getElem_cons_length (since := "2024-06-12")]
@@ -1121,8 +1077,7 @@ theorem head_eq_getElem (l : List α) (h : l ≠ []) : head l h = l[0]'(length_p
   | nil => simp at h
   | cons _ _ => simp
 
-theorem getElem_zero_eq_head (l : List α) (h : 0 < l.length) :
-    l[0] = head l (by simpa [length_pos] using h) := by
+theorem getElem_zero_eq_head (l : List α) (h) : l[0] = head l (by simpa [length_pos] using h) := by
   cases l with
   | nil => simp at h
   | cons _ _ => simp
@@ -1266,24 +1221,24 @@ theorem map_singleton (f : α → β) (a : α) : map f [a] = [f a] := rfl
   | nil => simp [List.map]
   | cons _ as ih => simp [List.map, ih]
 
-@[simp] theorem getElem?_map (f : α → β) : ∀ (l : List α) (i : Nat), (map f l)[i]? = Option.map f l[i]?
+@[simp] theorem getElem?_map (f : α → β) : ∀ (l : List α) (n : Nat), (map f l)[n]? = Option.map f l[n]?
   | [], _ => rfl
   | _ :: _, 0 => by simp
-  | _ :: l, i+1 => by simp [getElem?_map f l i]
+  | _ :: l, n+1 => by simp [getElem?_map f l n]
 
 @[deprecated getElem?_map (since := "2024-06-12")]
-theorem get?_map (f : α → β) : ∀ l i, (map f l).get? i = (l.get? i).map f
+theorem get?_map (f : α → β) : ∀ l n, (map f l).get? n = (l.get? n).map f
   | [], _ => rfl
   | _ :: _, 0 => rfl
-  | _ :: l, i+1 => get?_map f l i
+  | _ :: l, n+1 => get?_map f l n
 
-@[simp] theorem getElem_map (f : α → β) {l} {i : Nat} {h : i < (map f l).length} :
-    (map f l)[i] = f (l[i]'(length_map l f ▸ h)) :=
+@[simp] theorem getElem_map (f : α → β) {l} {n : Nat} {h : n < (map f l).length} :
+    (map f l)[n] = f (l[n]'(length_map l f ▸ h)) :=
   Option.some.inj <| by rw [← getElem?_eq_getElem, getElem?_map, getElem?_eq_getElem]; rfl
 
 @[deprecated getElem_map (since := "2024-06-12")]
-theorem get_map (f : α → β) {l i} :
-    get (map f l) i = f (get l ⟨i, length_map l f ▸ i.2⟩) := by
+theorem get_map (f : α → β) {l n} :
+    get (map f l) n = f (get l ⟨n, length_map l f ▸ n.2⟩) := by
   simp
 
 @[simp] theorem mem_map {f : α → β} : ∀ {l : List α}, b ∈ l.map f ↔ ∃ a, a ∈ l ∧ f a = b
@@ -1714,71 +1669,71 @@ theorem filterMap_eq_cons_iff {l} {b} {bs} :
 @[simp] theorem cons_append_fun (a : α) (as : List α) :
     (fun bs => ((a :: as) ++ bs)) = fun bs => a :: (as ++ bs) := rfl
 
-theorem getElem_append {l₁ l₂ : List α} (i : Nat) (h : i < (l₁ ++ l₂).length) :
-    (l₁ ++ l₂)[i] = if h' : i < l₁.length then l₁[i] else l₂[i - l₁.length]'(by simp at h h'; exact Nat.sub_lt_left_of_lt_add h' h) := by
+theorem getElem_append {l₁ l₂ : List α} (n : Nat) (h) :
+    (l₁ ++ l₂)[n] = if h' : n < l₁.length then l₁[n] else l₂[n - l₁.length]'(by simp at h h'; exact Nat.sub_lt_left_of_lt_add h' h) := by
   split <;> rename_i h'
   · rw [getElem_append_left h']
   · rw [getElem_append_right (by simpa using h')]
 
-theorem getElem?_append_left {l₁ l₂ : List α} {i : Nat} (hn : i < l₁.length) :
-    (l₁ ++ l₂)[i]? = l₁[i]? := by
-  have hn' : i < (l₁ ++ l₂).length := Nat.lt_of_lt_of_le hn <|
+theorem getElem?_append_left {l₁ l₂ : List α} {n : Nat} (hn : n < l₁.length) :
+    (l₁ ++ l₂)[n]? = l₁[n]? := by
+  have hn' : n < (l₁ ++ l₂).length := Nat.lt_of_lt_of_le hn <|
     length_append .. ▸ Nat.le_add_right ..
   simp_all [getElem?_eq_getElem, getElem_append]
 
-theorem getElem?_append_right : ∀ {l₁ l₂ : List α} {i : Nat}, l₁.length ≤ i →
-  (l₁ ++ l₂)[i]? = l₂[i - l₁.length]?
+theorem getElem?_append_right : ∀ {l₁ l₂ : List α} {n : Nat}, l₁.length ≤ n →
+  (l₁ ++ l₂)[n]? = l₂[n - l₁.length]?
 | [], _, _, _ => rfl
-| a :: l, _, i+1, h₁ => by
+| a :: l, _, n+1, h₁ => by
   rw [cons_append]
   simp [Nat.succ_sub_succ_eq_sub, getElem?_append_right (Nat.lt_succ.1 h₁)]
 
-theorem getElem?_append {l₁ l₂ : List α} {i : Nat} :
-    (l₁ ++ l₂)[i]? = if i < l₁.length then l₁[i]? else l₂[i - l₁.length]? := by
+theorem getElem?_append {l₁ l₂ : List α} {n : Nat} :
+    (l₁ ++ l₂)[n]? = if n < l₁.length then l₁[n]? else l₂[n - l₁.length]? := by
   split <;> rename_i h
   · exact getElem?_append_left h
   · exact getElem?_append_right (by simpa using h)
 
 @[deprecated getElem?_append_right (since := "2024-06-12")]
-theorem get?_append_right {l₁ l₂ : List α} {i : Nat} (h : l₁.length ≤ i) :
-    (l₁ ++ l₂).get? i = l₂.get? (i - l₁.length) := by
+theorem get?_append_right {l₁ l₂ : List α} {n : Nat} (h : l₁.length ≤ n) :
+    (l₁ ++ l₂).get? n = l₂.get? (n - l₁.length) := by
   simp [getElem?_append_right, h]
 
 /-- Variant of `getElem_append_left` useful for rewriting from the small list to the big list. -/
-theorem getElem_append_left' (l₂ : List α) {l₁ : List α} {i : Nat} (hi : i < l₁.length) :
-    l₁[i] = (l₁ ++ l₂)[i]'(by simpa using Nat.lt_add_right l₂.length hi) := by
+theorem getElem_append_left' (l₂ : List α) {l₁ : List α} {n : Nat} (hn : n < l₁.length) :
+    l₁[n] = (l₁ ++ l₂)[n]'(by simpa using Nat.lt_add_right l₂.length hn) := by
   rw [getElem_append_left] <;> simp
 
 /-- Variant of `getElem_append_right` useful for rewriting from the small list to the big list. -/
-theorem getElem_append_right' (l₁ : List α) {l₂ : List α} {i : Nat} (hi : i < l₂.length) :
-    l₂[i] = (l₁ ++ l₂)[i + l₁.length]'(by simpa [Nat.add_comm] using Nat.add_lt_add_left hi _) := by
+theorem getElem_append_right' (l₁ : List α) {l₂ : List α} {n : Nat} (hn : n < l₂.length) :
+    l₂[n] = (l₁ ++ l₂)[n + l₁.length]'(by simpa [Nat.add_comm] using Nat.add_lt_add_left hn _) := by
   rw [getElem_append_right] <;> simp [*, le_add_left]
 
 @[deprecated "Deprecated without replacement." (since := "2024-06-12")]
-theorem get_append_right_aux {l₁ l₂ : List α} {i : Nat}
-  (h₁ : l₁.length ≤ i) (h₂ : i < (l₁ ++ l₂).length) : i - l₁.length < l₂.length := by
+theorem get_append_right_aux {l₁ l₂ : List α} {n : Nat}
+  (h₁ : l₁.length ≤ n) (h₂ : n < (l₁ ++ l₂).length) : n - l₁.length < l₂.length := by
   rw [length_append] at h₂
   exact Nat.sub_lt_left_of_lt_add h₁ h₂
 
 set_option linter.deprecated false in
 @[deprecated getElem_append_right (since := "2024-06-12")]
-theorem get_append_right' {l₁ l₂ : List α} {i : Nat} (h₁ : l₁.length ≤ i) (h₂) :
-    (l₁ ++ l₂).get ⟨i, h₂⟩ = l₂.get ⟨i - l₁.length, get_append_right_aux h₁ h₂⟩ :=
+theorem get_append_right' {l₁ l₂ : List α} {n : Nat} (h₁ : l₁.length ≤ n) (h₂) :
+    (l₁ ++ l₂).get ⟨n, h₂⟩ = l₂.get ⟨n - l₁.length, get_append_right_aux h₁ h₂⟩ :=
   Option.some.inj <| by rw [← get?_eq_get, ← get?_eq_get, get?_append_right h₁]
 
-theorem getElem_of_append {l : List α} (eq : l = l₁ ++ a :: l₂) (h : l₁.length = i) :
-    l[i]'(eq ▸ h ▸ by simp_arith) = a := Option.some.inj <| by
+theorem getElem_of_append {l : List α} (eq : l = l₁ ++ a :: l₂) (h : l₁.length = n) :
+    l[n]'(eq ▸ h ▸ by simp_arith) = a := Option.some.inj <| by
   rw [← getElem?_eq_getElem, eq, getElem?_append_right (h ▸ Nat.le_refl _), h]
   simp
 
 @[deprecated "Deprecated without replacement." (since := "2024-06-12")]
 theorem get_of_append_proof {l : List α}
-    (eq : l = l₁ ++ a :: l₂) (h : l₁.length = i) : i < length l := eq ▸ h ▸ by simp_arith
+    (eq : l = l₁ ++ a :: l₂) (h : l₁.length = n) : n < length l := eq ▸ h ▸ by simp_arith
 
 set_option linter.deprecated false in
 @[deprecated getElem_of_append (since := "2024-06-12")]
-theorem get_of_append {l : List α} (eq : l = l₁ ++ a :: l₂) (h : l₁.length = i) :
-    l.get ⟨i, get_of_append_proof eq h⟩ = a := Option.some.inj <| by
+theorem get_of_append {l : List α} (eq : l = l₁ ++ a :: l₂) (h : l₁.length = n) :
+    l.get ⟨n, get_of_append_proof eq h⟩ = a := Option.some.inj <| by
   rw [← get?_eq_get, eq, get?_append_right (h ▸ Nat.le_refl _), h, Nat.sub_self]; rfl
 
 /--
@@ -2086,6 +2041,8 @@ theorem concat_inj_right {l : List α} {a a' : α} : concat l a = concat l a'
 
 @[deprecated concat_inj (since := "2024-09-05")] abbrev concat_eq_concat := @concat_inj
 
+theorem concat_ne_nil (a : α) (l : List α) : concat l a ≠ [] := by cases l <;> simp
+
 theorem concat_append (a : α) (l₁ l₂ : List α) : concat l₁ a ++ l₂ = l₁ ++ a :: l₂ := by simp
 
 theorem append_concat (a : α) (l₁ l₂ : List α) : l₁ ++ concat l₂ a = concat (l₁ ++ l₂) a := by simp
@@ -2254,11 +2211,6 @@ theorem flatMap_def (l : List α) (f : α → List β) : l.flatMap f = flatten (
 
 @[simp] theorem flatMap_id (l : List (List α)) : List.flatMap l id = l.flatten := by simp [flatMap_def]
 
-@[simp]
-theorem length_flatMap (l : List α) (f : α → List β) :
-    length (l.flatMap f) = sum (map (length ∘ f) l) := by
-  rw [List.flatMap, length_flatten, map_map]
-
 @[simp] theorem mem_flatMap {f : α → List β} {b} {l : List α} : b ∈ l.flatMap f ↔ ∃ a, a ∈ l ∧ b ∈ f a := by
   simp [flatMap_def, mem_flatten]
   exact ⟨fun ⟨_, ⟨a, h₁, rfl⟩, h₂⟩ => ⟨a, h₁, h₂⟩, fun ⟨a, h₁, h₂⟩ => ⟨_, ⟨a, h₁, rfl⟩, h₂⟩⟩
@@ -2338,10 +2290,6 @@ theorem flatMap_eq_foldl (f : α → List β) (l : List α) :
 
 @[simp] theorem replicate_one : replicate 1 a = [a] := rfl
 
-/-- Variant of `replicate_succ` that concatenates `a` to the end of the list. -/
-theorem replicate_succ' : replicate (n + 1) a = replicate n a ++ [a] := by
-  induction n <;> simp_all [replicate_succ, ← cons_append]
-
 @[simp] theorem mem_replicate {a b : α} : ∀ {n}, b ∈ replicate n a ↔ n ≠ 0 ∧ b = a
   | 0 => by simp
   | n+1 => by simp [replicate_succ, mem_replicate, Nat.succ_ne_zero]
@@ -2871,6 +2819,11 @@ theorem leftpad_suffix (n : Nat) (a : α) (l : List α) : l <:+ (leftpad n a l)
 
 theorem elem_cons_self [BEq α] [LawfulBEq α] {a : α} : (a::as).elem a = true := by simp
 
+@[simp] theorem contains_cons [BEq α] :
+    (a :: as : List α).contains x = (x == a || as.contains x) := by
+  simp only [contains, elem]
+  split <;> simp_all
+
 theorem contains_eq_any_beq [BEq α] (l : List α) (a : α) : l.contains a = l.any (a == ·) := by
   induction l with simp | cons b l => cases b == a <;> simp [*]
 
@@ -2914,7 +2867,7 @@ are often used for theorems about `Array.pop`.
 @[simp] theorem getElem_dropLast : ∀ (xs : List α) (i : Nat) (h : i < xs.dropLast.length),
     xs.dropLast[i] = xs[i]'(Nat.lt_of_lt_of_le h (length_dropLast .. ▸ Nat.pred_le _))
   | _::_::_, 0, _ => rfl
-  | _::_::_, i+1, h => getElem_dropLast _ i (Nat.add_one_lt_add_one_iff.mp h)
+  | _::_::_, i+1, _ => getElem_dropLast _ i _
 
 @[deprecated getElem_dropLast (since := "2024-06-12")]
 theorem get_dropLast (xs : List α) (i : Fin xs.dropLast.length) :
@@ -3420,12 +3373,12 @@ theorem getElem!_nil [Inhabited α] {n : Nat} : ([] : List α)[n]! = default :=
 theorem getElem!_cons_zero [Inhabited α] {l : List α} : (a::l)[0]! = a := by
   rw [getElem!_pos] <;> simp
 
-theorem getElem!_cons_succ [Inhabited α] {l : List α} : (a::l)[i+1]! = l[i]! := by
-  by_cases h : i < l.length
+theorem getElem!_cons_succ [Inhabited α] {l : List α} : (a::l)[n+1]! = l[n]! := by
+  by_cases h : n < l.length
   · rw [getElem!_pos, getElem!_pos] <;> simp_all [Nat.succ_lt_succ_iff]
   · rw [getElem!_neg, getElem!_neg] <;> simp_all [Nat.succ_lt_succ_iff]
 
-theorem getElem!_of_getElem? [Inhabited α] : ∀ {l : List α} {i : Nat}, l[i]? = some a → l[i]! = a
+theorem getElem!_of_getElem? [Inhabited α] : ∀ {l : List α} {n : Nat}, l[n]? = some a → l[n]! = a
   | _a::_, 0, _ => by
     rw [getElem!_pos] <;> simp_all
   | _::l, _+1, e => by
@@ -3569,12 +3522,7 @@ theorem getElem?_eq (l : List α) (i : Nat) :
   getElem?_def _ _
 @[deprecated getElem?_eq_none (since := "2024-11-29")] abbrev getElem?_len_le := @getElem?_eq_none
 
-@[deprecated _root_.isSome_getElem? (since := "2024-12-09")]
-theorem isSome_getElem? {l : List α} {n : Nat} : l[n]?.isSome ↔ n < l.length := by
-  simp
 
-@[deprecated _root_.isNone_getElem? (since := "2024-12-09")]
-theorem isNone_getElem? {l : List α} {i : Nat} : l[i]?.isNone ↔ l.length ≤ i := by
-  simp
+
 
 end List

src/Init/Data/List/MapIdx.lean

@@ -237,15 +237,15 @@ theorem getElem?_mapIdx_go : ∀ {l : List α} {arr : Array β} {i : Nat},
       if h : i < arr.size then some arr[i] else Option.map (f i) l[i - arr.size]?
   | [], arr, i => by
     simp only [mapIdx.go, Array.toListImpl_eq, getElem?_def, Array.length_toList,
-      ← Array.getElem_toList, length_nil, Nat.not_lt_zero, ↓reduceDIte, Option.map_none']
+      Array.getElem_eq_getElem_toList, length_nil, Nat.not_lt_zero, ↓reduceDIte, Option.map_none']
   | a :: l, arr, i => by
     rw [mapIdx.go, getElem?_mapIdx_go]
     simp only [Array.size_push]
     split <;> split
     · simp only [Option.some.injEq]
-      rw [← Array.getElem_toList]
+      rw [Array.getElem_eq_getElem_toList]
       simp only [Array.push_toList]
-      rw [getElem_append_left, ← Array.getElem_toList]
+      rw [getElem_append_left, Array.getElem_eq_getElem_toList]
     · have : i = arr.size := by omega
       simp_all
     · omega

src/Init/Data/List/Nat/Modify.lean

@@ -68,8 +68,8 @@ theorem getElem?_modifyHead {l : List α} {f : α → α} {n} :
     (l.modifyHead f).drop n = l.drop n := by
   cases l <;> cases n <;> simp_all
 
-theorem eraseIdx_modifyHead_zero {f : α → α} {l : List α} :
-    (l.modifyHead f).eraseIdx 0 = l.eraseIdx 0 := by simp
+@[simp] theorem eraseIdx_modifyHead_zero {f : α → α} {l : List α} :
+    (l.modifyHead f).eraseIdx 0 = l.eraseIdx 0 := by cases l <;> simp
 
 @[simp] theorem eraseIdx_modifyHead_of_pos {f : α → α} {l : List α} {n} (h : 0 < n) :
     (l.modifyHead f).eraseIdx n = (l.eraseIdx n).modifyHead f := by cases l <;> cases n <;> simp_all
@@ -142,7 +142,7 @@ theorem modifyTailIdx_modifyTailIdx_self {f g : List α → List α} (n : Nat) (
 theorem modifyHead_eq_modify_zero (f : α → α) (l : List α) :
     l.modifyHead f = l.modify f 0 := by cases l <;> simp
 
-@[simp] theorem modify_eq_nil_iff {f : α → α} {n} {l : List α} :
+@[simp] theorem modify_eq_nil_iff (f : α → α) (n) (l : List α) :
     l.modify f n = [] ↔ l = [] := by cases l <;> cases n <;> simp
 
 theorem getElem?_modify (f : α → α) :

src/Init/Data/List/Sort/Basic.lean

@@ -40,15 +40,12 @@ def merge (xs ys : List α) (le : α → α → Bool := by exact fun a b => a
 
 /--
 Split a list in two equal parts. If the length is odd, the first part will be one element longer.
-
-This is an implementation detail of `mergeSort`.
 -/
-def MergeSort.Internal.splitInTwo (l : { l : List α // l.length = n }) :
+def splitInTwo (l : { l : List α // l.length = n }) :
     { l : List α // l.length = (n+1)/2 } × { l : List α // l.length = n/2 } :=
   let r := splitAt ((n+1)/2) l.1
   (⟨r.1, by simp [r, splitAt_eq, l.2]; omega⟩, ⟨r.2, by simp [r, splitAt_eq, l.2]; omega⟩)
 
-open MergeSort.Internal in
 set_option linter.unusedVariables false in
 /--
 Simplified implementation of stable merge sort.

src/Init/Data/List/Sort/Impl.lean

@@ -147,21 +147,23 @@ where
     mergeTR (run' r) (run l) le
 
 theorem splitRevInTwo'_fst (l : { l : List α // l.length = n }) :
-    (splitRevInTwo' l).1 = ⟨(splitInTwo ⟨l.1.reverse, by simpa using l.2⟩).2.1, by simp; omega⟩ := by
+    (splitRevInTwo' l).1 = ⟨(splitInTwo ⟨l.1.reverse, by simpa using l.2⟩).2.1, by have := l.2; simp; omega⟩ := by
   simp only [splitRevInTwo', splitRevAt_eq, reverse_take, splitInTwo_snd]
   congr
+  have := l.2
   omega
 theorem splitRevInTwo'_snd (l : { l : List α // l.length = n }) :
-    (splitRevInTwo' l).2 = ⟨(splitInTwo ⟨l.1.reverse, by simpa using l.2⟩).1.1.reverse, by simp; omega⟩ := by
+    (splitRevInTwo' l).2 = ⟨(splitInTwo ⟨l.1.reverse, by simpa using l.2⟩).1.1.reverse, by have := l.2; simp; omega⟩ := by
   simp only [splitRevInTwo', splitRevAt_eq, reverse_take, splitInTwo_fst, reverse_reverse]
   congr 2
+  have := l.2
   simp
   omega
 theorem splitRevInTwo_fst (l : { l : List α // l.length = n }) :
-    (splitRevInTwo l).1 = ⟨(splitInTwo l).1.1.reverse, by simp; omega⟩ := by
+    (splitRevInTwo l).1 = ⟨(splitInTwo l).1.1.reverse, by have := l.2; simp; omega⟩ := by
   simp only [splitRevInTwo, splitRevAt_eq, reverse_take, splitInTwo_fst]
 theorem splitRevInTwo_snd (l : { l : List α // l.length = n }) :
-    (splitRevInTwo l).2 = ⟨(splitInTwo l).2.1, by simp; omega⟩ := by
+    (splitRevInTwo l).2 = ⟨(splitInTwo l).2.1, by have := l.2; simp; omega⟩ := by
   simp only [splitRevInTwo, splitRevAt_eq, reverse_take, splitInTwo_snd]
 
 theorem mergeSortTR_run_eq_mergeSort : {n : Nat} → (l : { l : List α // l.length = n }) → mergeSortTR.run le l = mergeSort l.1 le

src/Init/Data/List/Sort/Lemmas.lean

@@ -25,8 +25,6 @@ namespace List
 
 /-! ### splitInTwo -/
 
-namespace MergeSort.Internal
-
 @[simp] theorem splitInTwo_fst (l : { l : List α // l.length = n }) :
     (splitInTwo l).1 = ⟨l.1.take ((n+1)/2), by simp [splitInTwo, splitAt_eq, l.2]; omega⟩ := by
   simp [splitInTwo, splitAt_eq]
@@ -84,10 +82,6 @@ theorem splitInTwo_fst_le_splitInTwo_snd {l : { l : List α // l.length = n }} (
   intro a b ma mb
   exact h.rel_of_mem_take_of_mem_drop ma mb
 
-end MergeSort.Internal
-
-open MergeSort.Internal
-
 /-! ### enumLE -/
 
 variable {le : α → α → Bool}
@@ -291,6 +285,8 @@ theorem sorted_mergeSort
   | [] => by simp [mergeSort]
   | [a] => by simp [mergeSort]
   | a :: b :: xs => by
+    have : (splitInTwo ⟨a :: b :: xs, rfl⟩).1.1.length < xs.length + 1 + 1 := by simp [splitInTwo_fst]; omega
+    have : (splitInTwo ⟨a :: b :: xs, rfl⟩).2.1.length < xs.length + 1 + 1 := by simp [splitInTwo_snd]; omega
     rw [mergeSort]
     apply sorted_merge @trans @total
     apply sorted_mergeSort trans total

src/Init/Data/List/Sublist.lean

@@ -841,7 +841,7 @@ theorem isPrefix_iff : l₁ <+: l₂ ↔ ∀ i (h : i < l₁.length), l₂[i]? =
 theorem isPrefix_iff_getElem {l₁ l₂ : List α} :
     l₁ <+: l₂ ↔ ∃ (h : l₁.length ≤ l₂.length), ∀ x (hx : x < l₁.length),
       l₁[x] = l₂[x]'(Nat.lt_of_lt_of_le hx h) where
-  mp h := ⟨h.length_le, fun _ h' ↦ h.getElem h'⟩
+  mp h := ⟨h.length_le, fun _ _ ↦ h.getElem _⟩
   mpr h := by
     obtain ⟨hl, h⟩ := h
     induction l₂ generalizing l₁ with

src/Init/Data/List/TakeDrop.lean

@@ -65,13 +65,13 @@ theorem lt_length_of_take_ne_self {l : List α} {n} (h : l.take n ≠ l) : n < l
 theorem getElem_cons_drop : ∀ (l : List α) (i : Nat) (h : i < l.length),
     l[i] :: drop (i + 1) l = drop i l
   | _::_, 0, _ => rfl
-  | _::_, i+1, h => getElem_cons_drop _ i (Nat.add_one_lt_add_one_iff.mp h)
+  | _::_, i+1, _ => getElem_cons_drop _ i _
 
 @[deprecated getElem_cons_drop (since := "2024-06-12")]
 theorem get_cons_drop (l : List α) (i) : get l i :: drop (i + 1) l = drop i l := by
   simp
 
-theorem drop_eq_getElem_cons {n} {l : List α} (h : n < l.length) : drop n l = l[n] :: drop (n + 1) l :=
+theorem drop_eq_getElem_cons {n} {l : List α} (h) : drop n l = l[n] :: drop (n + 1) l :=
   (getElem_cons_drop _ n h).symm
 
 @[deprecated drop_eq_getElem_cons (since := "2024-06-12")]

src/Init/Data/List/ToArray.lean

@@ -1,379 +1,23 @@
 /-
-Copyright (c) 2022 Mario Carneiro. All rights reserved.
+Copyright (c) 2024 Lean FRO. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
-Authors: Mario Carneiro
+Authors: Henrik Böving
 -/
 prelude
-import Init.Data.List.Impl
-import Init.Data.List.Nat.Erase
-import Init.Data.List.Monadic
+import Init.Data.List.Basic
 
-/-! ### Lemmas about `List.toArray`.
-
-We prefer to pull `List.toArray` outwards past `Array` operations.
+/--
+Auxiliary definition for `List.toArray`.
+`List.toArrayAux as r = r ++ as.toArray`
 -/
-namespace List
+@[inline_if_reduce]
+def List.toArrayAux : List α → Array α → Array α
+  | nil,       r => r
+  | cons a as, r => toArrayAux as (r.push a)
 
-open Array
-
-theorem toArray_inj {a b : List α} (h : a.toArray = b.toArray) : a = b := by
-  cases a with
-  | nil => simpa using h
-  | cons a as =>
-    cases b with
-    | nil => simp at h
-    | cons b bs => simpa using h
-
-@[simp] theorem size_toArrayAux {a : List α} {b : Array α} :
-    (a.toArrayAux b).size = b.size + a.length := by
-  simp [size]
-
-@[simp] theorem push_toArray (l : List α) (a : α) : l.toArray.push a = (l ++ [a]).toArray := by
-  apply ext'
-  simp
-
-/-- Unapplied variant of `push_toArray`, useful for monadic reasoning. -/
-@[simp] theorem push_toArray_fun (l : List α) : l.toArray.push = fun a => (l ++ [a]).toArray := by
-  funext a
-  simp
-
-@[simp] theorem isEmpty_toArray (l : List α) : l.toArray.isEmpty = l.isEmpty := by
-  cases l <;> simp [Array.isEmpty]
-
-@[simp] theorem toArray_singleton (a : α) : (List.singleton a).toArray = singleton a := rfl
-
-@[simp] theorem back!_toArray [Inhabited α] (l : List α) : l.toArray.back! = l.getLast! := by
-  simp only [back!, size_toArray, Array.get!_eq_getElem!, getElem!_toArray, getLast!_eq_getElem!]
-
-@[simp] theorem back?_toArray (l : List α) : l.toArray.back? = l.getLast? := by
-  simp [back?, List.getLast?_eq_getElem?]
-
-@[simp] theorem set_toArray (l : List α) (i : Nat) (a : α) (h : i < l.length) :
-    (l.toArray.set i a) = (l.set i a).toArray := rfl
-
-@[simp] theorem forIn'_loop_toArray [Monad m] (l : List α) (f : (a : α) → a ∈ l.toArray → β → m (ForInStep β)) (i : Nat)
-    (h : i ≤ l.length) (b : β) :
-    Array.forIn'.loop l.toArray f i h b =
-      forIn' (l.drop (l.length - i)) b (fun a m b => f a (by simpa using mem_of_mem_drop m) b) := by
-  induction i generalizing l b with
-  | zero =>
-    simp [Array.forIn'.loop]
-  | succ i ih =>
-    simp only [Array.forIn'.loop, size_toArray, getElem_toArray, ih]
-    have t : drop (l.length - (i + 1)) l = l[l.length - i - 1] :: drop (l.length - i) l := by
-      simp only [Nat.sub_add_eq]
-      rw [List.drop_sub_one (by omega), List.getElem?_eq_getElem (by omega)]
-      simp only [Option.toList_some, singleton_append]
-    simp [t]
-    have t : l.length - 1 - i = l.length - i - 1 := by omega
-    simp only [t]
-    congr
-
-@[simp] theorem forIn'_toArray [Monad m] (l : List α) (b : β) (f : (a : α) → a ∈ l.toArray → β → m (ForInStep β)) :
-    forIn' l.toArray b f = forIn' l b (fun a m b => f a (mem_toArray.mpr m) b) := by
-  change Array.forIn' _ _ _ = List.forIn' _ _ _
-  rw [Array.forIn', forIn'_loop_toArray]
-  simp
-
-@[simp] theorem forIn_toArray [Monad m] (l : List α) (b : β) (f : α → β → m (ForInStep β)) :
-    forIn l.toArray b f = forIn l b f := by
-  simpa using forIn'_toArray l b fun a m b => f a b
-
-theorem foldrM_toArray [Monad m] (f : α → β → m β) (init : β) (l : List α) :
-    l.toArray.foldrM f init = l.foldrM f init := by
-  rw [foldrM_eq_reverse_foldlM_toList]
-  simp
-
-theorem foldlM_toArray [Monad m] (f : β → α → m β) (init : β) (l : List α) :
-    l.toArray.foldlM f init = l.foldlM f init := by
-  rw [foldlM_toList]
-
-theorem foldr_toArray (f : α → β → β) (init : β) (l : List α) :
-    l.toArray.foldr f init = l.foldr f init := by
-  rw [foldr_toList]
-
-theorem foldl_toArray (f : β → α → β) (init : β) (l : List α) :
-    l.toArray.foldl f init = l.foldl f init := by
-  rw [foldl_toList]
-
-/-- Variant of `foldrM_toArray` with a side condition for the `start` argument. -/
-@[simp] theorem foldrM_toArray' [Monad m] (f : α → β → m β) (init : β) (l : List α)
-    (h : start = l.toArray.size) :
-    l.toArray.foldrM f init start 0 = l.foldrM f init := by
-  subst h
-  rw [foldrM_eq_reverse_foldlM_toList]
-  simp
-
-/-- Variant of `foldlM_toArray` with a side condition for the `stop` argument. -/
-@[simp] theorem foldlM_toArray' [Monad m] (f : β → α → m β) (init : β) (l : List α)
-    (h : stop = l.toArray.size) :
-    l.toArray.foldlM f init 0 stop = l.foldlM f init := by
-  subst h
-  rw [foldlM_toList]
-
-/-- Variant of `foldr_toArray` with a side condition for the `start` argument. -/
-@[simp] theorem foldr_toArray' (f : α → β → β) (init : β) (l : List α)
-    (h : start = l.toArray.size) :
-    l.toArray.foldr f init start 0 = l.foldr f init := by
-  subst h
-  rw [foldr_toList]
-
-/-- Variant of `foldl_toArray` with a side condition for the `stop` argument. -/
-@[simp] theorem foldl_toArray' (f : β → α → β) (init : β) (l : List α)
-    (h : stop = l.toArray.size) :
-    l.toArray.foldl f init 0 stop = l.foldl f init := by
-  subst h
-  rw [foldl_toList]
-
-@[simp] theorem append_toArray (l₁ l₂ : List α) :
-    l₁.toArray ++ l₂.toArray = (l₁ ++ l₂).toArray := by
-  apply ext'
-  simp
-
-@[simp] theorem push_append_toArray {as : Array α} {a : α} {bs : List α} : as.push a ++ bs.toArray = as ++ (a ::bs).toArray := by
-  cases as
-  simp
-
-@[simp] theorem foldl_push {l : List α} {as : Array α} : l.foldl Array.push as = as ++ l.toArray := by
-  induction l generalizing as <;> simp [*]
-
-@[simp] theorem foldr_push {l : List α} {as : Array α} : l.foldr (fun a b => push b a) as = as ++ l.reverse.toArray := by
-  rw [foldr_eq_foldl_reverse, foldl_push]
-
-@[simp] theorem findSomeM?_toArray [Monad m] [LawfulMonad m] (f : α → m (Option β)) (l : List α) :
-    l.toArray.findSomeM? f = l.findSomeM? f := by
-  rw [Array.findSomeM?]
-  simp only [bind_pure_comp, map_pure, forIn_toArray]
-  induction l with
-  | nil => simp
-  | cons a l ih =>
-    simp only [forIn_cons, LawfulMonad.bind_assoc, findSomeM?]
-    congr
-    ext1 (_|_) <;> simp [ih]
-
-theorem findSomeRevM?_find_toArray [Monad m] [LawfulMonad m] (f : α → m (Option β)) (l : List α)
-    (i : Nat) (h) :
-    findSomeRevM?.find f l.toArray i h = (l.take i).reverse.findSomeM? f := by
-  induction i generalizing l with
-  | zero => simp [Array.findSomeRevM?.find.eq_def]
-  | succ i ih =>
-    rw [size_toArray] at h
-    rw [Array.findSomeRevM?.find, take_succ, getElem?_eq_getElem (by omega)]
-    simp only [ih, reverse_append]
-    congr
-    ext1 (_|_) <;> simp
-
--- This is not marked as `@[simp]` as later we simplify all occurrences of `findSomeRevM?`.
-theorem findSomeRevM?_toArray [Monad m] [LawfulMonad m] (f : α → m (Option β)) (l : List α) :
-    l.toArray.findSomeRevM? f = l.reverse.findSomeM? f := by
-  simp [Array.findSomeRevM?, findSomeRevM?_find_toArray]
-
--- This is not marked as `@[simp]` as later we simplify all occurrences of `findRevM?`.
-theorem findRevM?_toArray [Monad m] [LawfulMonad m] (f : α → m Bool) (l : List α) :
-    l.toArray.findRevM? f = l.reverse.findM? f := by
-  rw [Array.findRevM?, findSomeRevM?_toArray, findM?_eq_findSomeM?]
-
-@[simp] theorem findM?_toArray [Monad m] [LawfulMonad m] (f : α → m Bool) (l : List α) :
-    l.toArray.findM? f = l.findM? f := by
-  rw [Array.findM?]
-  simp only [bind_pure_comp, map_pure, forIn_toArray]
-  induction l with
-  | nil => simp
-  | cons a l ih =>
-    simp only [forIn_cons, LawfulMonad.bind_assoc, findM?]
-    congr
-    ext1 (_|_) <;> simp [ih]
-
-@[simp] theorem findSome?_toArray (f : α → Option β) (l : List α) :
-    l.toArray.findSome? f = l.findSome? f := by
-  rw [Array.findSome?, ← findSomeM?_id, findSomeM?_toArray, Id.run]
-
-@[simp] theorem find?_toArray (f : α → Bool) (l : List α) :
-    l.toArray.find? f = l.find? f := by
-  rw [Array.find?]
-  simp only [Id.run, Id, Id.pure_eq, Id.bind_eq, forIn_toArray]
-  induction l with
-  | nil => simp
-  | cons a l ih =>
-    simp only [forIn_cons, Id.pure_eq, Id.bind_eq, find?]
-    by_cases f a <;> simp_all
-
-theorem isPrefixOfAux_toArray_succ [BEq α] (l₁ l₂ : List α) (hle : l₁.length ≤ l₂.length) (i : Nat) :
-    Array.isPrefixOfAux l₁.toArray l₂.toArray hle (i + 1) =
-      Array.isPrefixOfAux l₁.tail.toArray l₂.tail.toArray (by simp; omega) i := by
-  rw [Array.isPrefixOfAux]
-  conv => rhs; rw [Array.isPrefixOfAux]
-  simp only [size_toArray, getElem_toArray, Bool.if_false_right, length_tail, getElem_tail]
-  split <;> rename_i h₁ <;> split <;> rename_i h₂
-  · rw [isPrefixOfAux_toArray_succ]
-  · omega
-  · omega
-  · rfl
-
-theorem isPrefixOfAux_toArray_succ' [BEq α] (l₁ l₂ : List α) (hle : l₁.length ≤ l₂.length) (i : Nat) :
-    Array.isPrefixOfAux l₁.toArray l₂.toArray hle (i + 1) =
-      Array.isPrefixOfAux (l₁.drop (i+1)).toArray (l₂.drop (i+1)).toArray (by simp; omega) 0 := by
-  induction i generalizing l₁ l₂ with
-  | zero => simp [isPrefixOfAux_toArray_succ]
-  | succ i ih =>
-    rw [isPrefixOfAux_toArray_succ, ih]
-    simp
-
-theorem isPrefixOfAux_toArray_zero [BEq α] (l₁ l₂ : List α) (hle : l₁.length ≤ l₂.length) :
-    Array.isPrefixOfAux l₁.toArray l₂.toArray hle 0 =
-      l₁.isPrefixOf l₂ := by
-  rw [Array.isPrefixOfAux]
-  match l₁, l₂ with
-  | [], _ => rw [dif_neg] <;> simp
-  | _::_, [] => simp at hle
-  | a::l₁, b::l₂ =>
-    simp [isPrefixOf_cons₂, isPrefixOfAux_toArray_succ', isPrefixOfAux_toArray_zero]
-
-@[simp] theorem isPrefixOf_toArray [BEq α] (l₁ l₂ : List α) :
-    l₁.toArray.isPrefixOf l₂.toArray = l₁.isPrefixOf l₂ := by
-  rw [Array.isPrefixOf]
-  split <;> rename_i h
-  · simp [isPrefixOfAux_toArray_zero]
-  · simp only [Bool.false_eq]
-    induction l₁ generalizing l₂ with
-    | nil => simp at h
-    | cons a l₁ ih =>
-      cases l₂ with
-      | nil => simp
-      | cons b l₂ =>
-        simp only [isPrefixOf_cons₂, Bool.and_eq_false_imp]
-        intro w
-        rw [ih]
-        simp_all
-
-theorem zipWithAux_toArray_succ (as : List α) (bs : List β) (f : α → β → γ) (i : Nat) (cs : Array γ) :
-    zipWithAux as.toArray bs.toArray f (i + 1) cs = zipWithAux as.tail.toArray bs.tail.toArray f i cs := by
-  rw [zipWithAux]
-  conv => rhs; rw [zipWithAux]
-  simp only [size_toArray, getElem_toArray, length_tail, getElem_tail]
-  split <;> rename_i h₁
-  · split <;> rename_i h₂
-    · rw [dif_pos (by omega), dif_pos (by omega), zipWithAux_toArray_succ]
-    · rw [dif_pos (by omega)]
-      rw [dif_neg (by omega)]
-  · rw [dif_neg (by omega)]
-
-theorem zipWithAux_toArray_succ' (as : List α) (bs : List β) (f : α → β → γ) (i : Nat) (cs : Array γ) :
-    zipWithAux as.toArray bs.toArray f (i + 1) cs = zipWithAux (as.drop (i+1)).toArray (bs.drop (i+1)).toArray f 0 cs := by
-  induction i generalizing as bs cs with
-  | zero => simp [zipWithAux_toArray_succ]
-  | succ i ih =>
-    rw [zipWithAux_toArray_succ, ih]
-    simp
-
-theorem zipWithAux_toArray_zero (f : α → β → γ) (as : List α) (bs : List β) (cs : Array γ) :
-    zipWithAux as.toArray bs.toArray f 0 cs = cs ++ (List.zipWith f as bs).toArray := by
-  rw [Array.zipWithAux]
-  match as, bs with
-  | [], _ => simp
-  | _, [] => simp
-  | a :: as, b :: bs =>
-    simp [zipWith_cons_cons, zipWithAux_toArray_succ', zipWithAux_toArray_zero, push_append_toArray]
-
-@[simp] theorem zipWith_toArray (as : List α) (bs : List β) (f : α → β → γ) :
-    Array.zipWith as.toArray bs.toArray f = (List.zipWith f as bs).toArray := by
-  rw [Array.zipWith]
-  simp [zipWithAux_toArray_zero]
-
-@[simp] theorem zip_toArray (as : List α) (bs : List β) :
-    Array.zip as.toArray bs.toArray = (List.zip as bs).toArray := by
-  simp [Array.zip, zipWith_toArray, zip]
-
-theorem zipWithAll_go_toArray (as : List α) (bs : List β) (f : Option α → Option β → γ) (i : Nat) (cs : Array γ) :
-    zipWithAll.go f as.toArray bs.toArray i cs = cs ++ (List.zipWithAll f (as.drop i) (bs.drop i)).toArray := by
-  unfold zipWithAll.go
-  split <;> rename_i h
-  · rw [zipWithAll_go_toArray]
-    simp at h
-    simp only [getElem?_toArray, push_append_toArray]
-    if ha : i < as.length then
-      if hb : i < bs.length then
-        rw [List.drop_eq_getElem_cons ha, List.drop_eq_getElem_cons hb]
-        simp only [ha, hb, getElem?_eq_getElem, zipWithAll_cons_cons]
-      else
-        simp only [Nat.not_lt] at hb
-        rw [List.drop_eq_getElem_cons ha]
-        rw [(drop_eq_nil_iff (l := bs)).mpr (by omega), (drop_eq_nil_iff (l := bs)).mpr (by omega)]
-        simp only [zipWithAll_nil, map_drop, map_cons]
-        rw [getElem?_eq_getElem ha]
-        rw [getElem?_eq_none hb]
-    else
-      if hb : i < bs.length then
-        simp only [Nat.not_lt] at ha
-        rw [List.drop_eq_getElem_cons hb]
-        rw [(drop_eq_nil_iff (l := as)).mpr (by omega), (drop_eq_nil_iff (l := as)).mpr (by omega)]
-        simp only [nil_zipWithAll, map_drop, map_cons]
-        rw [getElem?_eq_getElem hb]
-        rw [getElem?_eq_none ha]
-      else
-        omega
-  · simp only [size_toArray, Nat.not_lt] at h
-    rw [drop_eq_nil_of_le (by omega), drop_eq_nil_of_le (by omega)]
-    simp
-  termination_by max as.length bs.length - i
-  decreasing_by simp_wf; decreasing_trivial_pre_omega
-
-@[simp] theorem zipWithAll_toArray (f : Option α → Option β → γ) (as : List α) (bs : List β) :
-    Array.zipWithAll as.toArray bs.toArray f = (List.zipWithAll f as bs).toArray := by
-  simp [Array.zipWithAll, zipWithAll_go_toArray]
-
-@[simp] theorem toArray_appendList (l₁ l₂ : List α) :
-    l₁.toArray ++ l₂ = (l₁ ++ l₂).toArray := by
-  apply ext'
-  simp
-
-@[simp] theorem pop_toArray (l : List α) : l.toArray.pop = l.dropLast.toArray := by
-  apply ext'
-  simp
-
-theorem takeWhile_go_succ (p : α → Bool) (a : α) (l : List α) (i : Nat) :
-    takeWhile.go p (a :: l).toArray (i+1) r = takeWhile.go p l.toArray i r := by
-  rw [takeWhile.go, takeWhile.go]
-  simp only [size_toArray, length_cons, Nat.add_lt_add_iff_right, Array.get_eq_getElem,
-    getElem_toArray, getElem_cons_succ]
-  split
-  rw [takeWhile_go_succ]
-  rfl
-
-theorem takeWhile_go_toArray (p : α → Bool) (l : List α) (i : Nat) :
-    Array.takeWhile.go p l.toArray i r = r ++ (takeWhile p (l.drop i)).toArray := by
-  induction l generalizing i r with
-  | nil => simp [takeWhile.go]
-  | cons a l ih =>
-    rw [takeWhile.go]
-    cases i with
-    | zero =>
-      simp [takeWhile_go_succ, ih, takeWhile_cons]
-      split <;> simp
-    | succ i =>
-      simp only [size_toArray, length_cons, Nat.add_lt_add_iff_right, Array.get_eq_getElem,
-        getElem_toArray, getElem_cons_succ, drop_succ_cons]
-      split <;> rename_i h₁
-      · rw [takeWhile_go_succ, ih]
-        rw [← getElem_cons_drop_succ_eq_drop h₁, takeWhile_cons]
-        split <;> simp_all
-      · simp_all [drop_eq_nil_of_le]
-
-@[simp] theorem takeWhile_toArray (p : α → Bool) (l : List α) :
-    l.toArray.takeWhile p = (l.takeWhile p).toArray := by
-  simp [Array.takeWhile, takeWhile_go_toArray]
-
-@[simp] theorem setIfInBounds_toArray (l : List α) (i : Nat) (a : α) :
-    l.toArray.setIfInBounds i a  = (l.set i a).toArray := by
-  apply ext'
-  simp only [setIfInBounds]
-  split
-  · simp
-  · simp_all [List.set_eq_of_length_le]
-
-@[simp] theorem toArray_replicate (n : Nat) (v : α) : (List.replicate n v).toArray = mkArray n v := rfl
-
-@[deprecated toArray_replicate (since := "2024-12-13")]
-abbrev _root_.Array.mkArray_eq_toArray_replicate := @toArray_replicate
-
-end List
+/-- Convert a `List α` into an `Array α`. This is O(n) in the length of the list.  -/
+-- This function is exported to C, where it is called by `Array.mk`
+-- (the constructor) to implement this functionality.
+@[inline, match_pattern, pp_nodot, export lean_list_to_array]
+def List.toArrayImpl (as : List α) : Array α :=
+  as.toArrayAux (Array.mkEmpty as.length)

src/Init/Data/List/ToArrayImpl.lean

@@ -1,23 +0,0 @@
-/-
-Copyright (c) 2024 Lean FRO. All rights reserved.
-Released under Apache 2.0 license as described in the file LICENSE.
-Authors: Henrik Böving
--/
-prelude
-import Init.Data.List.Basic
-
-/--
-Auxiliary definition for `List.toArray`.
-`List.toArrayAux as r = r ++ as.toArray`
--/
-@[inline_if_reduce]
-def List.toArrayAux : List α → Array α → Array α
-  | nil,       r => r
-  | cons a as, r => toArrayAux as (r.push a)
-
-/-- Convert a `List α` into an `Array α`. This is O(n) in the length of the list.  -/
--- This function is exported to C, where it is called by `Array.mk`
--- (the constructor) to implement this functionality.
-@[inline, match_pattern, pp_nodot, export lean_list_to_array]
-def List.toArrayImpl (as : List α) : Array α :=
-  as.toArrayAux (Array.mkEmpty as.length)

src/Init/Data/Nat/Bitwise/Basic.lean

@@ -71,9 +71,6 @@ theorem shiftRight_eq_div_pow (m : Nat) : ∀ n, m >>> n = m / 2 ^ n
     rw [shiftRight_add, shiftRight_eq_div_pow m k]
     simp [Nat.div_div_eq_div_mul, ← Nat.pow_succ, shiftRight_succ]
 
-theorem shiftRight_eq_zero (m n : Nat) (hn : m < 2^n) : m >>> n = 0 := by
-  simp [Nat.shiftRight_eq_div_pow, Nat.div_eq_of_lt hn]
-
 /-!
 ### testBit
 We define an operation for testing individual bits in the binary representation

src/Init/Data/Nat/Bitwise/Lemmas.lean

@@ -106,21 +106,9 @@ theorem testBit_add_one (x i : Nat) : testBit x (i + 1) = testBit (x/2) i := by
   unfold testBit
   simp [shiftRight_succ_inside]
 
-theorem testBit_add (x i n : Nat) : testBit x (i + n) = testBit (x / 2 ^ n) i := by
-  revert x
-  induction n with
-  | zero => simp
-  | succ n ih =>
-    intro x
-    rw [← Nat.add_assoc, testBit_add_one, ih (x / 2),
-      Nat.pow_succ, Nat.div_div_eq_div_mul, Nat.mul_comm]
-
 theorem testBit_div_two (x i : Nat) : testBit (x / 2) i = testBit x (i + 1) := by
   simp
 
-theorem testBit_div_two_pow (x i : Nat) : testBit (x / 2 ^ n) i = testBit x (i + n) :=
-  testBit_add .. |>.symm
-
 theorem testBit_to_div_mod {x : Nat} : testBit x i = decide (x / 2^i % 2 = 1) := by
   induction i generalizing x with
   | zero =>
@@ -377,7 +365,7 @@ theorem testBit_two_pow_of_ne {n m : Nat} (hm : n ≠ m) : testBit (2 ^ n) m = f
 
 /-! ### bitwise -/
 
-theorem testBit_bitwise (of_false_false : f false false = false) (x y i : Nat) :
+theorem testBit_bitwise (false_false_axiom : f false false = false) (x y i : Nat) :
     (bitwise f x y).testBit i = f (x.testBit i) (y.testBit i) := by
   induction i using Nat.strongRecOn generalizing x y with
   | ind i hyp =>
@@ -385,12 +373,12 @@ theorem testBit_bitwise (of_false_false : f false false = false) (x y i : Nat) :
     if x_zero : x = 0 then
       cases p : f false true <;>
         cases yi : testBit y i <;>
-          simp [x_zero, p, yi, of_false_false]
+          simp [x_zero, p, yi, false_false_axiom]
     else if y_zero : y = 0 then
       simp [x_zero, y_zero]
       cases p : f true false <;>
         cases xi : testBit x i <;>
-          simp [p, xi, of_false_false]
+          simp [p, xi, false_false_axiom]
     else
       simp only [x_zero, y_zero, ←Nat.two_mul]
       cases i with
@@ -452,11 +440,6 @@ theorem bitwise_lt_two_pow (left : x < 2^n) (right : y < 2^n) : (Nat.bitwise f x
       case neg =>
         apply Nat.add_lt_add <;> exact hyp1
 
-theorem bitwise_div_two_pow (of_false_false : f false false = false := by rfl) :
-  (bitwise f x y) / 2 ^ n = bitwise f (x / 2 ^ n) (y / 2 ^ n) := by
-  apply Nat.eq_of_testBit_eq
-  simp [testBit_bitwise of_false_false, testBit_div_two_pow]
-
 /-! ### and -/
 
 @[simp] theorem testBit_and (x y i : Nat) : (x &&& y).testBit i = (x.testBit i && y.testBit i) := by
@@ -512,11 +495,9 @@ theorem and_pow_two_sub_one_of_lt_two_pow {x : Nat} (lt : x < 2^n) : x &&& 2^n -
   rw [testBit_and]
   simp
 
-theorem and_div_two_pow : (a &&& b) / 2 ^ n = a / 2 ^ n &&& b / 2 ^ n :=
-  bitwise_div_two_pow
-
-theorem and_div_two : (a &&& b) / 2 = a / 2 &&& b / 2 :=
-  and_div_two_pow (n := 1)
+theorem and_div_two : (a &&& b) / 2 = a / 2 &&& b / 2 := by
+  apply Nat.eq_of_testBit_eq
+  simp [testBit_and, ← testBit_add_one]
 
 /-! ### lor -/
 
@@ -582,11 +563,9 @@ theorem or_lt_two_pow {x y n : Nat} (left : x < 2^n) (right : y < 2^n) : x ||| y
   rw [testBit_or]
   simp
 
-theorem or_div_two_pow : (a ||| b) / 2 ^ n = a / 2 ^ n ||| b / 2 ^ n :=
-  bitwise_div_two_pow
-
-theorem or_div_two : (a ||| b) / 2 = a / 2 ||| b / 2 :=
-  or_div_two_pow (n := 1)
+theorem or_div_two : (a ||| b) / 2 = a / 2 ||| b / 2 := by
+  apply Nat.eq_of_testBit_eq
+  simp [testBit_or, ← testBit_add_one]
 
 /-! ### xor -/
 
@@ -640,11 +619,9 @@ theorem and_xor_distrib_left {a b c : Nat} : a &&& (b ^^^ c) = (a &&& b) ^^^ (a
   rw [testBit_xor]
   simp
 
-theorem xor_div_two_pow : (a ^^^ b) / 2 ^ n = a / 2 ^ n ^^^ b / 2 ^ n :=
-  bitwise_div_two_pow
-
-theorem xor_div_two : (a ^^^ b) / 2 = a / 2 ^^^ b / 2 :=
-  xor_div_two_pow (n := 1)
+theorem xor_div_two : (a ^^^ b) / 2 = a / 2 ^^^ b / 2 := by
+  apply Nat.eq_of_testBit_eq
+  simp [testBit_xor, ← testBit_add_one]
 
 /-! ### Arithmetic -/
 
@@ -716,19 +693,6 @@ theorem mul_add_lt_is_or {b : Nat} (b_lt : b < 2^i) (a : Nat) : 2^i * a + b = 2^
   simp only [testBit, one_and_eq_mod_two, mod_two_bne_zero]
   exact (Bool.beq_eq_decide_eq _ _).symm
 
-theorem shiftRight_bitwise_distrib {a b : Nat} (of_false_false : f false false = false := by rfl) :
-    (bitwise f a b) >>> i = bitwise f (a >>> i) (b >>> i) := by
-  simp [shiftRight_eq_div_pow, bitwise_div_two_pow of_false_false]
-
-theorem shiftRight_and_distrib {a b : Nat} : (a &&& b) >>> i = a >>> i &&& b >>> i :=
-  shiftRight_bitwise_distrib
-
-theorem shiftRight_or_distrib {a b : Nat} : (a ||| b) >>> i = a >>> i ||| b >>> i :=
-  shiftRight_bitwise_distrib
-
-theorem shiftRight_xor_distrib {a b : Nat} : (a ^^^ b) >>> i = a >>> i ^^^ b >>> i :=
-  shiftRight_bitwise_distrib
-
 /-! ### le -/
 
 theorem le_of_testBit {n m : Nat} (h : ∀ i, n.testBit i = true → m.testBit i = true) : n ≤ m := by

src/Init/Data/Nat/Dvd.lean

@@ -39,9 +39,9 @@ protected theorem dvd_add_iff_right {k m n : Nat} (h : k ∣ m) : k ∣ n ↔ k
 protected theorem dvd_add_iff_left {k m n : Nat} (h : k ∣ n) : k ∣ m ↔ k ∣ m + n := by
   rw [Nat.add_comm]; exact Nat.dvd_add_iff_right h
 
-theorem dvd_mod_iff {k m n : Nat} (h: k ∣ n) : k ∣ m % n ↔ k ∣ m := by
-  have := Nat.dvd_add_iff_left (m := m % n) <| Nat.dvd_trans h <| Nat.dvd_mul_right n (m / n)
-  rwa [mod_add_div] at this
+theorem dvd_mod_iff {k m n : Nat} (h: k ∣ n) : k ∣ m % n ↔ k ∣ m :=
+  have := Nat.dvd_add_iff_left <| Nat.dvd_trans h <| Nat.dvd_mul_right n (m / n)
+  by rwa [mod_add_div] at this
 
 theorem le_of_dvd {m n : Nat} (h : 0 < n) : m ∣ n → m ≤ n
   | ⟨k, e⟩ => by
@@ -77,7 +77,7 @@ theorem dvd_of_mod_eq_zero {m n : Nat} (H : n % m = 0) : m ∣ n := by
 theorem dvd_iff_mod_eq_zero {m n : Nat} : m ∣ n ↔ n % m = 0 :=
   ⟨mod_eq_zero_of_dvd, dvd_of_mod_eq_zero⟩
 
-instance decidable_dvd : @DecidableRel Nat Nat (·∣·) :=
+instance decidable_dvd : @DecidableRel Nat (·∣·) :=
   fun _ _ => decidable_of_decidable_of_iff dvd_iff_mod_eq_zero.symm
 
 theorem emod_pos_of_not_dvd {a b : Nat} (h : ¬ a ∣ b) : 0 < b % a := by

src/Init/Data/Nat/Lemmas.lean

@@ -1046,25 +1046,6 @@ instance decidableExistsLE [DecidablePred p] : DecidablePred fun n => ∃ m : Na
   fun n => decidable_of_iff (∃ m, m < n + 1 ∧ p m)
     (exists_congr fun _ => and_congr_left' Nat.lt_succ_iff)
 
-/-- Dependent version of `decidableExistsLT`. -/
-instance decidableExistsLT' {p : (m : Nat) → m < k → Prop} [I : ∀ m h, Decidable (p m h)] :
-    Decidable (∃ m : Nat, ∃ h : m < k, p m h) :=
-  match k, p, I with
-  | 0, _, _ => isFalse (by simp)
-  | (k + 1), p, I => @decidable_of_iff _ ((∃ m, ∃ h : m < k, p m (by omega)) ∨ p k (by omega))
-      ⟨by rintro (⟨m, h, w⟩ | w); exact ⟨m, by omega, w⟩; exact ⟨k, by omega, w⟩,
-        fun ⟨m, h, w⟩ => if h' : m < k then .inl ⟨m, h', w⟩ else
-          by obtain rfl := (by omega : m = k); exact .inr w⟩
-      (@instDecidableOr _ _
-        (decidableExistsLT' (p := fun m h => p m (by omega)) (I := fun m h => I m (by omega)))
-        inferInstance)
-
-/-- Dependent version of `decidableExistsLE`. -/
-instance decidableExistsLE' {p : (m : Nat) → m ≤ k → Prop} [I : ∀ m h, Decidable (p m h)] :
-    Decidable (∃ m : Nat, ∃ h : m ≤ k, p m h) :=
-  decidable_of_iff (∃ m, ∃ h : m < k + 1, p m (by omega)) (exists_congr fun _ =>
-    ⟨fun ⟨h, w⟩ => ⟨le_of_lt_succ h, w⟩, fun ⟨h, w⟩ => ⟨lt_add_one_of_le h, w⟩⟩)
-
 /-! ### Results about `List.sum` specialized to `Nat` -/
 
 protected theorem sum_pos_iff_exists_pos {l : List Nat} : 0 < l.sum ↔ ∃ x ∈ l, 0 < x := by

src/Init/Data/OfScientific.lean

@@ -6,7 +6,6 @@ Authors: Leonardo de Moura
 prelude
 import Init.Meta
 import Init.Data.Float
-import Init.Data.Float32
 import Init.Data.Nat.Log2
 
 /-- For decimal and scientific numbers (e.g., `1.23`, `3.12e10`).
@@ -57,34 +56,3 @@ instance : OfNat Float n   := ⟨Float.ofNat n⟩
 
 abbrev Nat.toFloat (n : Nat) : Float :=
   Float.ofNat n
-
-/-- Computes `m * 2^e`. -/
-def Float32.ofBinaryScientific (m : Nat) (e : Int) : Float32 :=
-  let s := m.log2 - 63
-  let m := (m >>> s).toUInt64
-  let e := e + s
-  m.toFloat32.scaleB e
-
-protected opaque Float32.ofScientific (m : Nat) (s : Bool) (e : Nat) : Float32 :=
-  if s then
-    let s := 64 - m.log2 -- ensure we have 64 bits of mantissa left after division
-    let m := (m <<< (3 * e + s)) / 5^e
-    Float32.ofBinaryScientific m (-4 * e - s)
-  else
-    Float32.ofBinaryScientific (m * 5^e) e
-
-instance : OfScientific Float32 where
-  ofScientific := Float32.ofScientific
-
-@[export lean_float32_of_nat]
-def Float32.ofNat (n : Nat) : Float32 :=
-  OfScientific.ofScientific n false 0
-
-def Float32.ofInt : Int → Float
-  | Int.ofNat n => Float.ofNat n
-  | Int.negSucc n => Float.neg (Float.ofNat (Nat.succ n))
-
-instance : OfNat Float32 n   := ⟨Float32.ofNat n⟩
-
-abbrev Nat.toFloat32 (n : Nat) : Float32 :=
-  Float32.ofNat n

src/Init/Data/Option.lean

@@ -10,4 +10,3 @@ import Init.Data.Option.Instances
 import Init.Data.Option.Lemmas
 import Init.Data.Option.Attach
 import Init.Data.Option.List
-import Init.Data.Option.Monadic

src/Init/Data/Option/Attach.lean

@@ -56,6 +56,7 @@ theorem attach_map_val (o : Option α) (f : α → β) :
     (o.attach.map fun i => f i.val) = o.map f :=
   attach_map_coe _ _
 
+@[simp]
 theorem attach_map_subtype_val (o : Option α) :
     o.attach.map Subtype.val = o :=
   (attach_map_coe _ _).trans (congrFun Option.map_id _)
@@ -68,11 +69,12 @@ theorem attachWith_map_val {p : α → Prop} (f : α → β) (o : Option α) (H
     ((o.attachWith p H).map fun i => f i.val) = o.map f :=
   attachWith_map_coe _ _ _
 
+@[simp]
 theorem attachWith_map_subtype_val {p : α → Prop} (o : Option α) (H : ∀ a ∈ o, p a) :
     (o.attachWith p H).map Subtype.val = o :=
   (attachWith_map_coe _ _ _).trans (congrFun Option.map_id _)
 
-theorem mem_attach : ∀ (o : Option α) (x : {x // x ∈ o}), x ∈ o.attach
+@[simp] theorem mem_attach : ∀ (o : Option α) (x : {x // x ∈ o}), x ∈ o.attach
   | none, ⟨x, h⟩ => by simp at h
   | some a, ⟨x, h⟩ => by simpa using h
 
@@ -90,14 +92,14 @@ theorem mem_attach : ∀ (o : Option α) (x : {x // x ∈ o}), x ∈ o.attach
     (o.attachWith p H).isSome = o.isSome := by
   cases o <;> simp
 
-@[simp] theorem attach_eq_none_iff {o : Option α} : o.attach = none ↔ o = none := by
+@[simp] theorem attach_eq_none_iff (o : Option α) : o.attach = none ↔ o = none := by
   cases o <;> simp
 
 @[simp] theorem attach_eq_some_iff {o : Option α} {x : {x // x ∈ o}} :
     o.attach = some x ↔ o = some x.val := by
   cases o <;> cases x <;> simp
 
-@[simp] theorem attachWith_eq_none_iff {p : α → Prop} {o : Option α} (H : ∀ a ∈ o, p a) :
+@[simp] theorem attachWith_eq_none_iff {p : α → Prop} (o : Option α) (H : ∀ a ∈ o, p a) :
     o.attachWith p H = none ↔ o = none := by
   cases o <;> simp
 
@@ -117,14 +119,10 @@ theorem mem_attach : ∀ (o : Option α) (x : {x // x ∈ o}), x ∈ o.attach
   · simp at h
   · simp [get_some]
 
-theorem toList_attach (o : Option α) :
+@[simp] theorem toList_attach (o : Option α) :
     o.attach.toList = o.toList.attach.map fun ⟨x, h⟩ => ⟨x, by simpa using h⟩ := by
   cases o <;> simp
 
-@[simp] theorem attach_toList (o : Option α) :
-    o.toList.attach = (o.attach.map fun ⟨a, h⟩ => ⟨a, by simpa using h⟩).toList := by
-  cases o <;> simp
-
 theorem attach_map {o : Option α} (f : α → β) :
     (o.map f).attach = o.attach.map (fun ⟨x, h⟩ => ⟨f x, mem_map_of_mem f h⟩) := by
   cases o <;> simp

src/Init/Data/Option/Basic.lean

@@ -96,12 +96,12 @@ This is similar to `<|>`/`orElse`, but it is strict in the second argument. -/
   | some a, _ => some a
   | none,   b => b
 
-@[inline] protected def lt (r : α → β → Prop) : Option α → Option β → Prop
+@[inline] protected def lt (r : α → α → Prop) : Option α → Option α → Prop
   | none, some _     => True
   | some x,   some y => r x y
   | _, _             => False
 
-instance (r : α → β → Prop) [s : DecidableRel r] : DecidableRel (Option.lt r)
+instance (r : α → α → Prop) [s : DecidableRel r] : DecidableRel (Option.lt r)
   | none,   some _ => isTrue  trivial
   | some x, some y => s x y
   | some _, none   => isFalse not_false

src/Init/Data/Option/Instances.lean

@@ -70,13 +70,6 @@ satisfy `p`, using the proof to apply `f`.
   | none, _ => none
   | some a, H => f a (H a rfl)
 
-/-- Partial elimination. If `o : Option α` and `f : (a : α) → a ∈ o → β`, then `o.pelim b f` is
-the same as `o.elim b f` but `f` is passed the proof that `a ∈ o`. -/
-@[inline] def pelim (o : Option α) (b : β) (f : (a : α) → a ∈ o → β) : β :=
-  match o with
-  | none => b
-  | some a => f a rfl
-
 /-- Map a monadic function which returns `Unit` over an `Option`. -/
 @[inline] protected def forM [Pure m] : Option α → (α → m PUnit) → m PUnit
   | none  , _ => pure ⟨⟩

src/Init/Data/Option/Lemmas.lean

@@ -629,12 +629,4 @@ theorem pbind_eq_some_iff {o : Option α} {f : (a : α) → a ∈ o → Option
     · rintro ⟨h, rfl⟩
       rfl
 
-/-! ### pelim -/
-
-@[simp] theorem pelim_none : pelim none b f = b := rfl
-@[simp] theorem pelim_some : pelim (some a) b f = f a rfl := rfl
-
-@[simp] theorem pelim_eq_elim : pelim o b (fun a _ => f a) = o.elim b f := by
-  cases o <;> simp
-
 end Option

src/Init/Data/Option/List.lean

@@ -15,25 +15,17 @@ namespace Option
     forIn' none b f = pure b := by
   rfl
 
-@[simp] theorem forIn'_some [Monad m] [LawfulMonad m] (a : α) (b : β) (f : (a' : α) → a' ∈ some a → β → m (ForInStep β)) :
-    forIn' (some a) b f = bind (f a rfl b) (fun r => pure (ForInStep.value r)) := by
-  simp only [forIn', bind_pure_comp]
-  rw [map_eq_pure_bind]
-  congr
-  funext x
-  split <;> rfl
+@[simp] theorem forIn'_some [Monad m] (a : α) (b : β) (f : (a' : α) → a' ∈ some a → β → m (ForInStep β)) :
+    forIn' (some a) b f = bind (f a rfl b) (fun | .done r | .yield r => pure r) := by
+  rfl
 
 @[simp] theorem forIn_none [Monad m] (b : β) (f : α → β → m (ForInStep β)) :
     forIn none b f = pure b := by
   rfl
 
-@[simp] theorem forIn_some [Monad m] [LawfulMonad m] (a : α) (b : β) (f : α → β → m (ForInStep β)) :
-    forIn (some a) b f = bind (f a b) (fun r => pure (ForInStep.value r)) := by
-  simp only [forIn, forIn', bind_pure_comp]
-  rw [map_eq_pure_bind]
-  congr
-  funext x
-  split <;> rfl
+@[simp] theorem forIn_some [Monad m] (a : α) (b : β) (f : α → β → m (ForInStep β)) :
+    forIn (some a) b f = bind (f a b) (fun | .done r | .yield r => pure r) := by
+  rfl
 
 @[simp] theorem forIn'_toList [Monad m] (o : Option α) (b : β) (f : (a : α) → a ∈ o.toList → β → m (ForInStep β)) :
     forIn' o.toList b f = forIn' o b fun a m b => f a (by simpa using m) b := by
@@ -43,20 +35,4 @@ namespace Option
     forIn o.toList b f = forIn o b f := by
   cases o <;> rfl
 
-@[simp] theorem foldlM_toList [Monad m] [LawfulMonad m] (o : Option β) (a : α) (f : α → β → m α) :
-    o.toList.foldlM f a = o.elim (pure a) (fun b => f a b) := by
-  cases o <;> simp
-
-@[simp] theorem foldrM_toList [Monad m] [LawfulMonad m] (o : Option β) (a : α) (f : β → α → m α) :
-    o.toList.foldrM f a = o.elim (pure a) (fun b => f b a) := by
-  cases o <;> simp
-
-@[simp] theorem foldl_toList (o : Option β) (a : α) (f : α → β → α) :
-    o.toList.foldl f a = o.elim a (fun b => f a b) := by
-  cases o <;> simp
-
-@[simp] theorem foldr_toList (o : Option β) (a : α) (f : β → α → α) :
-    o.toList.foldr f a = o.elim a (fun b => f b a) := by
-  cases o <;> simp
-
 end Option

src/Init/Data/Option/Monadic.lean

@@ -1,75 +0,0 @@
-/-
-Copyright (c) 2024 Lean FRO. All rights reserved.
-Released under Apache 2.0 license as described in the file LICENSE.
-Authors: Kim Morrison
--/
-prelude
-
-import Init.Data.Option.Attach
-import Init.Control.Lawful.Basic
-
-namespace Option
-
-@[congr] theorem forIn'_congr [Monad m] [LawfulMonad m]{as bs : Option α} (w : as = bs)
-    {b b' : β} (hb : b = b')
-    {f : (a' : α) → a' ∈ as → β → m (ForInStep β)}
-    {g : (a' : α) → a' ∈ bs → β → m (ForInStep β)}
-    (h : ∀ a m b, f a (by simpa [w] using m) b = g a m b) :
-    forIn' as b f = forIn' bs b' g := by
-  cases as <;> cases bs
-  · simp [hb]
-  · simp at w
-  · simp at w
-  · simp only [some.injEq] at w
-    subst w
-    simp [hb, h]
-
-theorem forIn'_eq_pelim [Monad m] [LawfulMonad m]
-    (o : Option α) (f : (a : α) → a ∈ o → β → m (ForInStep β)) (b : β) :
-    forIn' o b f =
-      o.pelim (pure b) (fun a h => ForInStep.value <$> f a h b) := by
-  cases o <;> simp
-
-@[simp] theorem forIn'_yield_eq_pelim [Monad m] [LawfulMonad m] (o : Option α)
-    (f : (a : α) → a ∈ o → β → m γ) (g : (a : α) → a ∈ o → β → γ → β) (b : β) :
-    forIn' o b (fun a m b => (fun c => .yield (g a m b c)) <$> f a m b) =
-      o.pelim (pure b) (fun a h => g a h b <$> f a h b) := by
-  cases o <;> simp
-
-theorem forIn'_pure_yield_eq_pelim [Monad m] [LawfulMonad m]
-    (o : Option α) (f : (a : α) → a ∈ o → β → β) (b : β) :
-    forIn' o b (fun a m b => pure (.yield (f a m b))) =
-      pure (f := m) (o.pelim b (fun a h => f a h b)) := by
-  cases o <;> simp
-
-@[simp] theorem forIn'_id_yield_eq_pelim
-    (o : Option α) (f : (a : α) → a ∈ o → β → β) (b : β) :
-    forIn' (m := Id) o b (fun a m b => .yield (f a m b)) =
-      o.pelim b (fun a h => f a h b) := by
-  cases o <;> simp
-
-theorem forIn_eq_elim [Monad m] [LawfulMonad m]
-    (o : Option α) (f : (a : α) → β → m (ForInStep β)) (b : β) :
-    forIn o b f =
-      o.elim (pure b) (fun a => ForInStep.value <$> f a b) := by
-  cases o <;> simp
-
-@[simp] theorem forIn_yield_eq_elim [Monad m] [LawfulMonad m] (o : Option α)
-    (f : (a : α) → β → m γ) (g : (a : α) → β → γ → β) (b : β) :
-    forIn o b (fun a b => (fun c => .yield (g a b c)) <$> f a b) =
-      o.elim (pure b) (fun a => g a b <$> f a b) := by
-  cases o <;> simp
-
-theorem forIn_pure_yield_eq_elim [Monad m] [LawfulMonad m]
-    (o : Option α) (f : (a : α) → β → β) (b : β) :
-    forIn o b (fun a b => pure (.yield (f a b))) =
-      pure (f := m) (o.elim b (fun a => f a b)) := by
-  cases o <;> simp
-
-@[simp] theorem forIn_id_yield_eq_elim
-    (o : Option α) (f : (a : α) → β → β) (b : β) :
-    forIn (m := Id) o b (fun a b => .yield (f a b)) =
-      o.elim b (fun a => f a b) := by
-  cases o <;> simp
-
-end Option

src/Init/Data/Sum/Lemmas.lean

@@ -30,7 +30,7 @@ protected theorem «exists» {p : α ⊕ β → Prop} :
     | Or.inl ⟨a, h⟩ => ⟨inl a, h⟩
     | Or.inr ⟨b, h⟩ => ⟨inr b, h⟩⟩
 
-theorem forall_sum {γ : α ⊕ β → Sort _} {p : (∀ ab, γ ab) → Prop} :
+theorem forall_sum {γ : α ⊕ β → Sort _} (p : (∀ ab, γ ab) → Prop) :
     (∀ fab, p fab) ↔ (∀ fa fb, p (Sum.rec fa fb)) := by
   refine ⟨fun h fa fb => h _, fun h fab => ?_⟩
   have h1 : fab = Sum.rec (fun a => fab (Sum.inl a)) (fun b => fab (Sum.inr b)) := by

src/Init/Data/UInt/Bitwise.lean

@@ -1,39 +1,25 @@
 /-
 Copyright (c) 2024 Lean FRO, LLC. All Rights Reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
-Authors: Markus Himmel, Mac Malone
+Authors: Markus Himmel
 -/
 prelude
-import Init.Data.UInt.Lemmas
+import Init.Data.UInt.Basic
 import Init.Data.Fin.Bitwise
 import Init.Data.BitVec.Lemmas
 
 set_option hygiene false in
-macro "declare_bitwise_uint_theorems" typeName:ident bits:term:arg : command =>
+macro "declare_bitwise_uint_theorems" typeName:ident : command =>
 `(
 namespace $typeName
 
-@[simp] protected theorem toBitVec_and (a b : $typeName) : (a &&& b).toBitVec = a.toBitVec &&& b.toBitVec := rfl
-@[simp] protected theorem toBitVec_or (a b : $typeName) : (a ||| b).toBitVec = a.toBitVec ||| b.toBitVec := rfl
-@[simp] protected theorem toBitVec_xor (a b : $typeName) : (a ^^^ b).toBitVec = a.toBitVec ^^^ b.toBitVec := rfl
-@[simp] protected theorem toBitVec_shiftLeft (a b : $typeName) : (a <<< b).toBitVec = a.toBitVec <<< (b.toBitVec % $bits) := rfl
-@[simp] protected theorem toBitVec_shiftRight (a b : $typeName) : (a >>> b).toBitVec = a.toBitVec >>> (b.toBitVec % $bits) := rfl
-
-@[simp] protected theorem toNat_and (a b : $typeName) : (a &&& b).toNat = a.toNat &&& b.toNat := by simp [toNat]
-@[simp] protected theorem toNat_or (a b : $typeName) : (a ||| b).toNat = a.toNat ||| b.toNat := by simp [toNat]
-@[simp] protected theorem toNat_xor (a b : $typeName) : (a ^^^ b).toNat = a.toNat ^^^ b.toNat := by simp [toNat]
-@[simp] protected theorem toNat_shiftLeft (a b : $typeName) : (a <<< b).toNat = a.toNat <<< (b.toNat % $bits) % 2 ^ $bits := by simp [toNat]
-@[simp] protected theorem toNat_shiftRight (a b : $typeName) : (a >>> b).toNat = a.toNat >>> (b.toNat % $bits) := by simp [toNat]
-
-open $typeName (toNat_and) in
-@[deprecated toNat_and (since := "2024-11-28")]
-protected theorem and_toNat (a b : $typeName) : (a &&& b).toNat = a.toNat &&& b.toNat := BitVec.toNat_and ..
+@[simp] protected theorem and_toNat (a b : $typeName) : (a &&& b).toNat = a.toNat &&& b.toNat := BitVec.toNat_and ..
 
 end $typeName
 )
 
-declare_bitwise_uint_theorems UInt8 8
-declare_bitwise_uint_theorems UInt16 16
-declare_bitwise_uint_theorems UInt32 32
-declare_bitwise_uint_theorems UInt64 64
-declare_bitwise_uint_theorems USize System.Platform.numBits
+declare_bitwise_uint_theorems UInt8
+declare_bitwise_uint_theorems UInt16
+declare_bitwise_uint_theorems UInt32
+declare_bitwise_uint_theorems UInt64
+declare_bitwise_uint_theorems USize

src/Init/Data/Vector/Basic.lean

@@ -70,16 +70,6 @@ instance [Inhabited α] : Inhabited (Vector α n) where
 instance : GetElem (Vector α n) Nat α fun _ i => i < n where
   getElem x i h := get x ⟨i, h⟩
 
-/-- Check if there is an element which satisfies `a == ·`. -/
-def contains [BEq α] (v : Vector α n) (a : α) : Bool := v.toArray.contains a
-
-/-- `a ∈ v` is a predicate which asserts that `a` is in the vector `v`. -/
-structure Mem (as : Vector α n) (a : α) : Prop where
-  val : a ∈ as.toArray
-
-instance : Membership α (Vector α n) where
-  mem := Mem
-
 /--
 Get an element of a vector using a `Nat` index. Returns the given default value if the index is out
 of bounds.
@@ -264,19 +254,3 @@ no element of the index matches the given value.
 /-- Returns `true` when `v` is a prefix of the vector `w`. -/
 @[inline] def isPrefixOf [BEq α] (v : Vector α m) (w : Vector α n) : Bool :=
   v.toArray.isPrefixOf w.toArray
-
-/-- Returns `true` with the monad if `p` returns `true` for any element of the vector. -/
-@[inline] def anyM [Monad m] (p : α → m Bool) (v : Vector α n) : m Bool :=
-  v.toArray.anyM p
-
-/-- Returns `true` with the monad if `p` returns `true` for all elements of the vector. -/
-@[inline] def allM [Monad m] (p : α → m Bool) (v : Vector α n) : m Bool :=
-  v.toArray.allM p
-
-/-- Returns `true` if `p` returns `true` for any element of the vector. -/
-@[inline] def any (v : Vector α n) (p : α → Bool) : Bool :=
-  v.toArray.any p
-
-/-- Returns `true` if `p` returns `true` for all elements of the vector. -/
-@[inline] def all (v : Vector α n) (p : α → Bool) : Bool :=
-  v.toArray.all p

src/Init/GetElem.lean

@@ -118,16 +118,12 @@ instance (priority := low) [GetElem coll idx elem valid] [∀ xs i, Decidable (v
     GetElem? coll idx elem valid where
   getElem? xs i := decidableGetElem? xs i
 
-theorem getElem_congr [GetElem coll idx elem valid] {c d : coll} (h : c = d)
-    {i j : idx} (h' : i = j) (w : valid c i) : c[i] = d[j]'(h' ▸ h ▸ w) := by
-  cases h; cases h'; rfl
+theorem getElem_congr_coll [GetElem coll idx elem valid] {c d : coll} {i : idx} {h : valid c i}
+    (h' : c = d) : c[i] = d[i]'(h' ▸ h) := by
+  cases h'; rfl
 
-theorem getElem_congr_coll [GetElem coll idx elem valid] {c d : coll} {i : idx} {w : valid c i}
-    (h : c = d) : c[i] = d[i]'(h ▸ w) := by
-  cases h; rfl
-
-theorem getElem_congr_idx [GetElem coll idx elem valid] {c : coll} {i j : idx} {w : valid c i}
-    (h' : i = j) : c[i] = c[j]'(h' ▸ w) := by
+theorem getElem_congr [GetElem coll idx elem valid] {c : coll} {i j : idx} {h : valid c i}
+    (h' : i = j) : c[i] = c[j]'(h' ▸ h) := by
   cases h'; rfl
 
 class LawfulGetElem (cont : Type u) (idx : Type v) (elem : outParam (Type w))
@@ -176,14 +172,11 @@ theorem getElem!_neg [GetElem? cont idx elem dom] [LawfulGetElem cont idx elem d
   simp only [getElem?_def] at h ⊢
   split <;> simp_all
 
-@[simp] theorem getElem?_eq_none [GetElem? cont idx elem dom] [LawfulGetElem cont idx elem dom]
-    (c : cont) (i : idx) [Decidable (dom c i)] : c[i]? = none ↔ ¬dom c i := by
+@[simp] theorem isNone_getElem? [GetElem? cont idx elem dom] [LawfulGetElem cont idx elem dom]
+    (c : cont) (i : idx) [Decidable (dom c i)] : c[i]?.isNone = ¬dom c i := by
   simp only [getElem?_def]
   split <;> simp_all
 
-@[deprecated getElem?_eq_none (since := "2024-12-11")]
-abbrev isNone_getElem? := @getElem?_eq_none
-
 @[simp] theorem isSome_getElem? [GetElem? cont idx elem dom] [LawfulGetElem cont idx elem dom]
     (c : cont) (i : idx) [Decidable (dom c i)] : c[i]?.isSome = dom c i := by
   simp only [getElem?_def]
@@ -223,9 +216,13 @@ instance : GetElem (List α) Nat α fun as i => i < as.length where
 @[simp] theorem getElem_cons_zero (a : α) (as : List α) (h : 0 < (a :: as).length) : getElem (a :: as) 0 h = a := by
   rfl
 
+@[deprecated getElem_cons_zero (since := "2024-06-12")] abbrev cons_getElem_zero := @getElem_cons_zero
+
 @[simp] theorem getElem_cons_succ (a : α) (as : List α) (i : Nat) (h : i + 1 < (a :: as).length) : getElem (a :: as) (i+1) h = getElem as i (Nat.lt_of_succ_lt_succ h) := by
   rfl
 
+@[deprecated getElem_cons_succ (since := "2024-06-12")] abbrev cons_getElem_succ := @getElem_cons_succ
+
 @[simp] theorem getElem_mem : ∀ {l : List α} {n} (h : n < l.length), l[n]'h ∈ l
   | _ :: _, 0, _ => .head ..
   | _ :: l, _+1, _ => .tail _ (getElem_mem (l := l) ..)
@@ -234,7 +231,7 @@ theorem getElem_cons_drop_succ_eq_drop {as : List α} {i : Nat} (h : i < as.leng
     as[i] :: as.drop (i+1) = as.drop i :=
   match as, i with
   | _::_, 0   => rfl
-  | _::_, i+1 => getElem_cons_drop_succ_eq_drop (i := i) (Nat.add_one_lt_add_one_iff.mp h)
+  | _::_, i+1 => getElem_cons_drop_succ_eq_drop (i := i) _
 
 @[deprecated getElem_cons_drop_succ_eq_drop (since := "2024-11-05")]
 abbrev get_drop_eq_drop := @getElem_cons_drop_succ_eq_drop
@@ -246,12 +243,6 @@ namespace Array
 instance : GetElem (Array α) Nat α fun xs i => i < xs.size where
   getElem xs i h := xs.get i h
 
-@[simp] theorem get_eq_getElem (a : Array α) (i : Nat) (h) : a.get i h = a[i] := rfl
-
-@[simp] theorem get!_eq_getElem! [Inhabited α] (a : Array α) (i : Nat) : a.get! i = a[i]! := by
-  simp only [get!, getD, get_eq_getElem, getElem!_def]
-  split <;> simp_all [getElem?_pos, getElem?_neg]
-
 end Array
 
 namespace Lean.Syntax

src/Init/Meta.lean

@@ -679,7 +679,6 @@ private partial def decodeBinLitAux (s : String) (i : String.Pos) (val : Nat) :
     let c := s.get i
     if c == '0' then decodeBinLitAux s (s.next i) (2*val)
     else if c == '1' then decodeBinLitAux s (s.next i) (2*val + 1)
-    else if c == '_' then decodeBinLitAux s (s.next i) val
     else none
 
 private partial def decodeOctalLitAux (s : String) (i : String.Pos) (val : Nat) : Option Nat :=
@@ -687,7 +686,6 @@ private partial def decodeOctalLitAux (s : String) (i : String.Pos) (val : Nat)
   else
     let c := s.get i
     if '0' ≤ c && c ≤ '7' then decodeOctalLitAux s (s.next i) (8*val + c.toNat - '0'.toNat)
-    else if c == '_' then decodeOctalLitAux s (s.next i) val
     else none
 
 private def decodeHexDigit (s : String) (i : String.Pos) : Option (Nat × String.Pos) :=
@@ -702,16 +700,13 @@ private partial def decodeHexLitAux (s : String) (i : String.Pos) (val : Nat) :
   if s.atEnd i then some val
   else match decodeHexDigit s i with
     | some (d, i) => decodeHexLitAux s i (16*val + d)
-    | none        =>
-      if s.get i == '_' then decodeHexLitAux s (s.next i) val
-      else none
+    | none        => none
 
 private partial def decodeDecimalLitAux (s : String) (i : String.Pos) (val : Nat) : Option Nat :=
   if s.atEnd i then some val
   else
     let c := s.get i
     if '0' ≤ c && c ≤ '9' then decodeDecimalLitAux s (s.next i) (10*val + c.toNat - '0'.toNat)
-    else if c == '_' then decodeDecimalLitAux s (s.next i) val
     else none
 
 def decodeNatLitVal? (s : String) : Option Nat :=
@@ -778,8 +773,6 @@ where
       let c := s.get i
       if '0' ≤ c && c ≤ '9' then
         decodeAfterExp (s.next i) val e sign (10*exp + c.toNat - '0'.toNat)
-      else if c == '_' then
-        decodeAfterExp (s.next i) val e sign exp
       else
         none
 
@@ -800,8 +793,6 @@ where
       let c := s.get i
       if '0' ≤ c && c ≤ '9' then
         decodeAfterDot (s.next i) (10*val + c.toNat - '0'.toNat) (e+1)
-      else if c == '_' then
-        decodeAfterDot (s.next i) val e
       else if c == 'e' || c == 'E' then
         decodeExp (s.next i) val e
       else
@@ -814,8 +805,6 @@ where
       let c := s.get i
       if '0' ≤ c && c ≤ '9' then
         decode (s.next i) (10*val + c.toNat - '0'.toNat)
-      else if c == '_' then
-        decode (s.next i) val
       else if c == '.' then
         decodeAfterDot (s.next i) val 0
       else if c == 'e' || c == 'E' then

src/Init/MetaTypes.lean

@@ -250,13 +250,6 @@ def neutralConfig : Simp.Config := {
   zetaDelta         := false
 }
 
-structure NormCastConfig extends Simp.Config where
-    zeta := false
-    beta := false
-    eta  := false
-    proj := false
-    iota := false
-
 end Simp
 
 /-- Configuration for which occurrences that match an expression should be rewritten. -/

src/Init/NotationExtra.lean

@@ -168,6 +168,11 @@ end Lean
   | `($(_) $c $t $e) => `(if $c then $t else $e)
   | _                => throw ()
 
+@[app_unexpander sorryAx] def unexpandSorryAx : Lean.PrettyPrinter.Unexpander
+  | `($(_) $_)    => `(sorry)
+  | `($(_) $_ $_) => `(sorry)
+  | _             => throw ()
+
 @[app_unexpander Eq.ndrec] def unexpandEqNDRec : Lean.PrettyPrinter.Unexpander
   | `($(_) $m $h) => `($h ▸ $m)
   | _             => throw ()

src/Init/Prelude.lean

@@ -645,22 +645,23 @@ set_option linter.unusedVariables.funArgs false in
 @[reducible] def namedPattern {α : Sort u} (x a : α) (h : Eq x a) : α := a
 
 /--
-Auxiliary axiom used to implement the `sorry` term and tactic.
+Auxiliary axiom used to implement `sorry`.
 
-The `sorry` term/tactic expands to `sorryAx _ (synthetic := false)`.
-It is intended for stubbing-out incomplete parts of a value or proof while still having a syntactically correct skeleton.
-Lean will give a warning whenever a declaration uses `sorry`, so you aren't likely to miss it,
-but you can check if a declaration depends on `sorry` either directly or indirectly by looking for `sorryAx` in the output
-of the `#print axioms my_thm` command.
+The `sorry` term/tactic expands to `sorryAx _ (synthetic := false)`. This is a
+proof of anything, which is intended for stubbing out incomplete parts of a
+proof while still having a syntactically correct proof skeleton. Lean will give
+a warning whenever a proof uses `sorry`, so you aren't likely to miss it, but
+you can double check if a theorem depends on `sorry` by using
+`#print axioms my_thm` and looking for `sorryAx` in the axiom list.
 
-The `synthetic` flag is false when a `sorry` is written explicitly by the user, but it is
+The `synthetic` flag is false when written explicitly by the user, but it is
 set to `true` when a tactic fails to prove a goal, or if there is a type error
 in the expression. A synthetic `sorry` acts like a regular one, except that it
-suppresses follow-up errors in order to prevent an error from causing a cascade
+suppresses follow-up errors in order to prevent one error from causing a cascade
 of other errors because the desired term was not constructed.
 -/
 @[extern "lean_sorry", never_extract]
-axiom sorryAx (α : Sort u) (synthetic : Bool) : α
+axiom sorryAx (α : Sort u) (synthetic := false) : α
 
 theorem eq_false_of_ne_true : {b : Bool} → Not (Eq b true) → Eq b false
   | true, h => False.elim (h rfl)
@@ -859,8 +860,8 @@ abbrev DecidablePred {α : Sort u} (r : α → Prop) :=
   (a : α) → Decidable (r a)
 
 /-- A decidable relation. See `Decidable`. -/
-abbrev DecidableRel {α : Sort u} {β : Sort v} (r : α → β → Prop) :=
-  (a : α) → (b : β) → Decidable (r a b)
+abbrev DecidableRel {α : Sort u} (r : α → α → Prop) :=
+  (a b : α) → Decidable (r a b)
 
 /--
 Asserts that `α` has decidable equality, that is, `a = b` is decidable
@@ -3931,13 +3932,6 @@ def getId : Syntax → Name
   | ident _ _ val _ => val
   | _               => Name.anonymous
 
-/-- Retrieve the immediate info from the Syntax node. -/
-def getInfo? : Syntax → Option SourceInfo
-  | atom info ..  => some info
-  | ident info .. => some info
-  | node info ..  => some info
-  | missing       => none
-
 /-- Retrieve the left-most node or leaf's info in the Syntax tree. -/
 partial def getHeadInfo? : Syntax → Option SourceInfo
   | atom info _   => some info

src/Init/PropLemmas.lean

@@ -386,15 +386,6 @@ theorem exists_comm {p : α → β → Prop} : (∃ a b, p a b) ↔ (∃ b a, p
 theorem forall_prop_of_false {p : Prop} {q : p → Prop} (hn : ¬p) : (∀ h' : p, q h') ↔ True :=
   iff_true_intro fun h => hn.elim h
 
-@[simp] theorem and_exists_self (P : Prop) (Q : P → Prop) : (P ∧ ∃ p, Q p) ↔ ∃ p, Q p :=
-  ⟨fun ⟨_, h⟩ => h, fun ⟨p, q⟩ => ⟨p, ⟨p, q⟩⟩⟩
-
-@[simp] theorem exists_and_self (P : Prop) (Q : P → Prop) : ((∃ p, Q p) ∧ P) ↔ ∃ p, Q p :=
-  ⟨fun ⟨h, _⟩ => h, fun ⟨p, q⟩ => ⟨⟨p, q⟩, p⟩⟩
-
-@[simp] theorem forall_self_imp (P : Prop) (Q : P → Prop) : (∀ p : P, P → Q p) ↔ ∀ p, Q p :=
-  ⟨fun h p => h p p, fun h _ p => h p⟩
-
 end quantifiers
 
 /-! ## membership -/

src/Init/SimpLemmas.lean

@@ -153,7 +153,6 @@ instance : Std.LawfulIdentity Or False where
 @[simp] theorem false_implies (p : Prop) : (False → p) = True := eq_true False.elim
 @[simp] theorem forall_false (p : False → Prop) : (∀ h : False, p h) = True := eq_true (False.elim ·)
 @[simp] theorem implies_true (α : Sort u) : (α → True) = True := eq_true fun _ => trivial
--- This is later proved by the simp lemma `forall_const`, but this is useful during bootstrapping.
 @[simp] theorem true_implies (p : Prop) : (True → p) = p := propext ⟨(· trivial), (fun _ => ·)⟩
 @[simp] theorem not_false_eq_true : (¬ False) = True := eq_true False.elim
 @[simp] theorem not_true_eq_false : (¬ True) = False := by decide

src/Init/System/IO.lean

@@ -981,14 +981,3 @@ not used concurrently or which are already persistent.
 -/
 @[extern "lean_runtime_mark_persistent"]
 unsafe def Runtime.markPersistent (a : α) : BaseIO α := return a
-
-set_option linter.unusedVariables false in
-/--
-Discards the passed owned reference. This leads to `a` any any object reachable from it never being
-freed. This can be a useful optimization for eliding deallocation time of big object graphs that are
-kept alive close to the end of the process anyway (in which case calling `Runtime.markPersistent`
-would be similarly costly to deallocation). It is still considered a safe operation as it cannot
-lead to undefined behavior.
--/
-@[extern "lean_runtime_forget"]
-def Runtime.forget (a : α) : BaseIO Unit := return

src/Init/System/Mutex.lean

@@ -7,9 +7,6 @@ prelude
 import Init.System.IO
 import Init.Control.StateRef
 
-
-set_option linter.deprecated false
-
 namespace IO
 
 private opaque BaseMutexImpl : NonemptyType.{0}
@@ -19,13 +16,12 @@ Mutual exclusion primitive (a lock).
 
 If you want to guard shared state, use `Mutex α` instead.
 -/
-@[deprecated "Use Std.BaseMutex from Std.Sync.Mutex instead" (since := "2024-12-02")]
 def BaseMutex : Type := BaseMutexImpl.type
 
 instance : Nonempty BaseMutex := BaseMutexImpl.property
 
 /-- Creates a new `BaseMutex`. -/
-@[extern "lean_io_basemutex_new", deprecated "Use Std.BaseMutex.new from Std.Sync.Mutex instead" (since := "2024-12-02")]
+@[extern "lean_io_basemutex_new"]
 opaque BaseMutex.new : BaseIO BaseMutex
 
 /--
@@ -34,7 +30,7 @@ Locks a `BaseMutex`.  Waits until no other thread has locked the mutex.
 The current thread must not have already locked the mutex.
 Reentrant locking is undefined behavior (inherited from the C++ implementation).
 -/
-@[extern "lean_io_basemutex_lock", deprecated "Use Std.BaseMutex.lock from Std.Sync.Mutex instead" (since := "2024-12-02")]
+@[extern "lean_io_basemutex_lock"]
 opaque BaseMutex.lock (mutex : @& BaseMutex) : BaseIO Unit
 
 /--
@@ -43,35 +39,33 @@ Unlocks a `BaseMutex`.
 The current thread must have already locked the mutex.
 Unlocking an unlocked mutex is undefined behavior (inherited from the C++ implementation).
 -/
-@[extern "lean_io_basemutex_unlock", deprecated "Use Std.BaseMutex.unlock from Std.Sync.Mutex instead" (since := "2024-12-02")]
+@[extern "lean_io_basemutex_unlock"]
 opaque BaseMutex.unlock (mutex : @& BaseMutex) : BaseIO Unit
 
 private opaque CondvarImpl : NonemptyType.{0}
 
 /-- Condition variable. -/
-@[deprecated "Use Std.Condvar from Std.Sync.Mutex instead" (since := "2024-12-02")]
 def Condvar : Type := CondvarImpl.type
 
 instance : Nonempty Condvar := CondvarImpl.property
 
 /-- Creates a new condition variable. -/
-@[extern "lean_io_condvar_new", deprecated "Use Std.Condvar.new from Std.Sync.Mutex instead" (since := "2024-12-02")]
+@[extern "lean_io_condvar_new"]
 opaque Condvar.new : BaseIO Condvar
 
 /-- Waits until another thread calls `notifyOne` or `notifyAll`. -/
-@[extern "lean_io_condvar_wait", deprecated "Use Std.Condvar.wait from Std.Sync.Mutex instead" (since := "2024-12-02")]
+@[extern "lean_io_condvar_wait"]
 opaque Condvar.wait (condvar : @& Condvar) (mutex : @& BaseMutex) : BaseIO Unit
 
 /-- Wakes up a single other thread executing `wait`. -/
-@[extern "lean_io_condvar_notify_one", deprecated "Use Std.Condvar.notifyOne from Std.Sync.Mutex instead" (since := "2024-12-02")]
+@[extern "lean_io_condvar_notify_one"]
 opaque Condvar.notifyOne (condvar : @& Condvar) : BaseIO Unit
 
 /-- Wakes up all other threads executing `wait`. -/
-@[extern "lean_io_condvar_notify_all", deprecated "Use Std.Condvar.notifyAll from Std.Sync.Mutex instead" (since := "2024-12-02")]
+@[extern "lean_io_condvar_notify_all"]
 opaque Condvar.notifyAll (condvar : @& Condvar) : BaseIO Unit
 
 /-- Waits on the condition variable until the predicate is true. -/
-@[deprecated "Use Std.Condvar.waitUntil from Std.Sync.Mutex instead" (since := "2024-12-02")]
 def Condvar.waitUntil [Monad m] [MonadLift BaseIO m]
     (condvar : Condvar) (mutex : BaseMutex) (pred : m Bool) : m Unit := do
   while !(← pred) do
@@ -84,7 +78,6 @@ The type `Mutex α` is similar to `IO.Ref α`,
 except that concurrent accesses are guarded by a mutex
 instead of atomic pointer operations and busy-waiting.
 -/
-@[deprecated "Use Std.Mutex from Std.Sync.Mutex instead" (since := "2024-12-02")]
 structure Mutex (α : Type) where private mk ::
   private ref : IO.Ref α
   mutex : BaseMutex
@@ -93,7 +86,6 @@ structure Mutex (α : Type) where private mk ::
 instance : CoeOut (Mutex α) BaseMutex where coe := Mutex.mutex
 
 /-- Creates a new mutex. -/
-@[deprecated "Use Std.Mutex.new from Std.Sync.Mutex instead" (since := "2024-12-02")]
 def Mutex.new (a : α) : BaseIO (Mutex α) :=
   return { ref := ← mkRef a, mutex := ← BaseMutex.new }
 
@@ -102,11 +94,9 @@ def Mutex.new (a : α) : BaseIO (Mutex α) :=
 with outside monad `m`.
 The action has access to the state `α` of the mutex (via `get` and `set`).
 -/
-@[deprecated "Use Std.AtomicT from Std.Sync.Mutex instead" (since := "2024-12-02")]
 abbrev AtomicT := StateRefT' IO.RealWorld
 
 /-- `mutex.atomically k` runs `k` with access to the mutex's state while locking the mutex. -/
-@[deprecated "Use Std.Mutex.atomically from Std.Sync.Mutex instead" (since := "2024-12-02")]
 def Mutex.atomically [Monad m] [MonadLiftT BaseIO m] [MonadFinally m]
     (mutex : Mutex α) (k : AtomicT α m β) : m β := do
   try
@@ -120,7 +110,6 @@ def Mutex.atomically [Monad m] [MonadLiftT BaseIO m] [MonadFinally m]
 waiting on `condvar` until `pred` returns true.
 Both `k` and `pred` have access to the mutex's state.
 -/
-@[deprecated "Use Std.Mutex.atomicallyOnce from Std.Sync.Mutex instead" (since := "2024-12-02")]
 def Mutex.atomicallyOnce [Monad m] [MonadLiftT BaseIO m] [MonadFinally m]
     (mutex : Mutex α) (condvar : Condvar)
     (pred : AtomicT α m Bool) (k : AtomicT α m β) : m β :=

src/Init/Tactics.lean

@@ -408,18 +408,16 @@ example (a b c d : Nat) : a + b + c + d = d + (b + c) + a := by ac_rfl
 syntax (name := acRfl) "ac_rfl" : tactic
 
 /--
-The `sorry` tactic is a temporary placeholder for an incomplete tactic proof,
-closing the main goal using `exact sorry`.
-
-This is intended for stubbing-out incomplete parts of a proof while still having a syntactically correct proof skeleton.
-Lean will give a warning whenever a proof uses `sorry`, so you aren't likely to miss it,
-but you can double check if a theorem depends on `sorry` by looking for `sorryAx` in the output
-of the `#print axioms my_thm` command, the axiom used by the implementation of `sorry`.
+The `sorry` tactic closes the goal using `sorryAx`. This is intended for stubbing out incomplete
+parts of a proof while still having a syntactically correct proof skeleton. Lean will give
+a warning whenever a proof uses `sorry`, so you aren't likely to miss it, but
+you can double check if a theorem depends on `sorry` by using
+`#print axioms my_thm` and looking for `sorryAx` in the axiom list.
 -/
-macro "sorry" : tactic => `(tactic| exact sorry)
+macro "sorry" : tactic => `(tactic| exact @sorryAx _ false)
 
-/-- `admit` is a synonym for `sorry`. -/
-macro "admit" : tactic => `(tactic| sorry)
+/-- `admit` is a shorthand for `exact sorry`. -/
+macro "admit" : tactic => `(tactic| exact @sorryAx _ false)
 
 /--
 `infer_instance` is an abbreviation for `exact inferInstance`.
@@ -1311,7 +1309,7 @@ macro "bv_omega" : tactic => `(tactic| (try simp only [bv_toNat] at *) <;> omega
 syntax (name := acNf0) "ac_nf0" (location)? : tactic
 
 /-- Implementation of `norm_cast` (the full `norm_cast` calls `trivial` afterwards). -/
-syntax (name := normCast0) "norm_cast0" optConfig (location)? : tactic
+syntax (name := normCast0) "norm_cast0" (location)? : tactic
 
 /-- `assumption_mod_cast` is a variant of `assumption` that solves the goal
 using a hypothesis. Unlike `assumption`, it first pre-processes the goal and
@@ -1320,7 +1318,7 @@ in more situations.
 
 Concretely, it runs `norm_cast` on the goal. For each local hypothesis `h`, it also
 normalizes `h` with `norm_cast` and tries to use that to close the goal. -/
-macro "assumption_mod_cast" cfg:optConfig : tactic => `(tactic| norm_cast0 $cfg at * <;> assumption)
+macro "assumption_mod_cast" : tactic => `(tactic| norm_cast0 at * <;> assumption)
 
 /--
 The `norm_cast` family of tactics is used to normalize certain coercions (*casts*) in expressions.
@@ -1357,9 +1355,26 @@ their operation, to make them more flexible about the expressions they accept
 
 See also `push_cast`, which moves casts inwards rather than lifting them outwards.
 -/
-macro "norm_cast" cfg:optConfig loc:(location)? : tactic =>
-  `(tactic| norm_cast0 $cfg $[$loc]? <;> try trivial)
+macro "norm_cast" loc:(location)? : tactic =>
+  `(tactic| norm_cast0 $[$loc]? <;> try trivial)
 
+/--
+`ac_nf` normalizes equalities up to application of an associative and commutative operator.
+- `ac_nf` normalizes all hypotheses and the goal target of the goal.
+- `ac_nf at l` normalizes at location(s) `l`, where `l` is either `*` or a
+  list of hypotheses in the local context. In the latter case, a turnstile `⊢` or `|-`
+  can also be used, to signify the target of the goal.
+```
+instance : Associative (α := Nat) (.+.) := ⟨Nat.add_assoc⟩
+instance : Commutative (α := Nat) (.+.) := ⟨Nat.add_comm⟩
+
+example (a b c d : Nat) : a + b + c + d = d + (b + c) + a := by
+ ac_nf
+ -- goal: a + (b + (c + d)) = a + (b + (c + d))
+```
+-/
+macro "ac_nf" loc:(location)? : tactic =>
+  `(tactic| ac_nf0 $[$loc]? <;> try trivial)
 
 /--
 `push_cast` rewrites the goal to move certain coercions (*casts*) inward, toward the leaf nodes.
@@ -1402,24 +1417,6 @@ syntax (name := pushCast) "push_cast" optConfig (discharger)? (&" only")?
 -/
 syntax (name := normCastAddElim) "norm_cast_add_elim" ident : command
 
-/--
-`ac_nf` normalizes equalities up to application of an associative and commutative operator.
-- `ac_nf` normalizes all hypotheses and the goal target of the goal.
-- `ac_nf at l` normalizes at location(s) `l`, where `l` is either `*` or a
-  list of hypotheses in the local context. In the latter case, a turnstile `⊢` or `|-`
-  can also be used, to signify the target of the goal.
-```
-instance : Associative (α := Nat) (.+.) := ⟨Nat.add_assoc⟩
-instance : Commutative (α := Nat) (.+.) := ⟨Nat.add_comm⟩
-
-example (a b c d : Nat) : a + b + c + d = d + (b + c) + a := by
- ac_nf
- -- goal: a + (b + (c + d)) = a + (b + (c + d))
-```
--/
-macro "ac_nf" loc:(location)? : tactic =>
-  `(tactic| ac_nf0 $[$loc]? <;> try trivial)
-
 /--
 * `symm` applies to a goal whose target has the form `t ~ u` where `~` is a symmetric relation,
   that is, a relation which has a symmetry lemma tagged with the attribute [symm].

src/Lean/Compiler/IR/Basic.lean

@@ -81,7 +81,6 @@ then one of the following must hold in each (execution) branch.
 inductive IRType where
   | float | uint8 | uint16 | uint32 | uint64 | usize
   | irrelevant | object | tobject
-  | float32
   | struct (leanTypeName : Option Name) (types : Array IRType) : IRType
   | union (leanTypeName : Name) (types : Array IRType) : IRType
   deriving Inhabited, Repr
@@ -90,7 +89,6 @@ namespace IRType
 
 partial def beq : IRType → IRType → Bool
   | float,          float          => true
-  | float32,        float32        => true
   | uint8,          uint8          => true
   | uint16,         uint16         => true
   | uint32,         uint32         => true
@@ -106,14 +104,13 @@ partial def beq : IRType → IRType → Bool
 instance : BEq IRType := ⟨beq⟩
 
 def isScalar : IRType → Bool
-  | float    => true
-  | float32  => true
-  | uint8    => true
-  | uint16   => true
-  | uint32   => true
-  | uint64   => true
-  | usize    => true
-  | _        => false
+  | float  => true
+  | uint8  => true
+  | uint16 => true
+  | uint32 => true
+  | uint64 => true
+  | usize  => true
+  | _      => false
 
 def isObj : IRType → Bool
   | object  => true
@@ -614,11 +611,10 @@ def mkIf (x : VarId) (t e : FnBody) : FnBody :=
 
 def getUnboxOpName (t : IRType) : String :=
   match t with
-  | IRType.usize    => "lean_unbox_usize"
-  | IRType.uint32   => "lean_unbox_uint32"
-  | IRType.uint64   => "lean_unbox_uint64"
-  | IRType.float    => "lean_unbox_float"
-  | IRType.float32  => "lean_unbox_float32"
-  | _               => "lean_unbox"
+  | IRType.usize  => "lean_unbox_usize"
+  | IRType.uint32 => "lean_unbox_uint32"
+  | IRType.uint64 => "lean_unbox_uint64"
+  | IRType.float  => "lean_unbox_float"
+  | _             => "lean_unbox"
 
 end Lean.IR

src/Lean/Compiler/IR/EmitC.lean

@@ -55,7 +55,6 @@ def emitArg (x : Arg) : M Unit :=
 
 def toCType : IRType → String
   | IRType.float      => "double"
-  | IRType.float32    => "float"
   | IRType.uint8      => "uint8_t"
   | IRType.uint16     => "uint16_t"
   | IRType.uint32     => "uint32_t"
@@ -312,13 +311,12 @@ def emitUSet (x : VarId) (n : Nat) (y : VarId) : M Unit := do
 
 def emitSSet (x : VarId) (n : Nat) (offset : Nat) (y : VarId) (t : IRType) : M Unit := do
   match t with
-  | IRType.float   => emit "lean_ctor_set_float"
-  | IRType.float32 => emit "lean_ctor_set_float32"
-  | IRType.uint8   => emit "lean_ctor_set_uint8"
-  | IRType.uint16  => emit "lean_ctor_set_uint16"
-  | IRType.uint32  => emit "lean_ctor_set_uint32"
-  | IRType.uint64  => emit "lean_ctor_set_uint64"
-  | _              => throw "invalid instruction";
+  | IRType.float  => emit "lean_ctor_set_float"
+  | IRType.uint8  => emit "lean_ctor_set_uint8"
+  | IRType.uint16 => emit "lean_ctor_set_uint16"
+  | IRType.uint32 => emit "lean_ctor_set_uint32"
+  | IRType.uint64 => emit "lean_ctor_set_uint64"
+  | _             => throw "invalid instruction";
   emit "("; emit x; emit ", "; emitOffset n offset; emit ", "; emit y; emitLn ");"
 
 def emitJmp (j : JoinPointId) (xs : Array Arg) : M Unit := do
@@ -388,13 +386,12 @@ def emitUProj (z : VarId) (i : Nat) (x : VarId) : M Unit := do
 def emitSProj (z : VarId) (t : IRType) (n offset : Nat) (x : VarId) : M Unit := do
   emitLhs z;
   match t with
-  | IRType.float    => emit "lean_ctor_get_float"
-  | IRType.float32  => emit "lean_ctor_get_float32"
-  | IRType.uint8    => emit "lean_ctor_get_uint8"
-  | IRType.uint16   => emit "lean_ctor_get_uint16"
-  | IRType.uint32   => emit "lean_ctor_get_uint32"
-  | IRType.uint64   => emit "lean_ctor_get_uint64"
-  | _               => throw "invalid instruction"
+  | IRType.float  => emit "lean_ctor_get_float"
+  | IRType.uint8  => emit "lean_ctor_get_uint8"
+  | IRType.uint16 => emit "lean_ctor_get_uint16"
+  | IRType.uint32 => emit "lean_ctor_get_uint32"
+  | IRType.uint64 => emit "lean_ctor_get_uint64"
+  | _             => throw "invalid instruction"
   emit "("; emit x; emit ", "; emitOffset n offset; emitLn ");"
 
 def toStringArgs (ys : Array Arg) : List String :=
@@ -449,12 +446,11 @@ def emitApp (z : VarId) (f : VarId) (ys : Array Arg) : M Unit :=
 
 def emitBoxFn (xType : IRType) : M Unit :=
   match xType with
-  | IRType.usize   => emit "lean_box_usize"
-  | IRType.uint32  => emit "lean_box_uint32"
-  | IRType.uint64  => emit "lean_box_uint64"
-  | IRType.float   => emit "lean_box_float"
-  | IRType.float32 => emit "lean_box_float32"
-  | _              => emit "lean_box"
+  | IRType.usize  => emit "lean_box_usize"
+  | IRType.uint32 => emit "lean_box_uint32"
+  | IRType.uint64 => emit "lean_box_uint64"
+  | IRType.float  => emit "lean_box_float"
+  | _             => emit "lean_box"
 
 def emitBox (z : VarId) (x : VarId) (xType : IRType) : M Unit := do
   emitLhs z; emitBoxFn xType; emit "("; emit x; emitLn ");"

src/Lean/Compiler/IR/EmitLLVM.lean

@@ -315,7 +315,6 @@ def callLeanCtorSetTag (builder : LLVM.Builder llvmctx)
 def toLLVMType (t : IRType) : M llvmctx (LLVM.LLVMType llvmctx) := do
   match t with
   | IRType.float      => LLVM.doubleTypeInContext llvmctx
-  | IRType.float32    => LLVM.floatTypeInContext llvmctx
   | IRType.uint8      => LLVM.intTypeInContext llvmctx 8
   | IRType.uint16     => LLVM.intTypeInContext llvmctx 16
   | IRType.uint32     => LLVM.intTypeInContext llvmctx 32
@@ -818,13 +817,12 @@ def emitSProj (builder : LLVM.Builder llvmctx)
     (z : VarId) (t : IRType) (n offset : Nat) (x : VarId) : M llvmctx Unit := do
   let (fnName, retty) ←
     match t with
-    | IRType.float   => pure ("lean_ctor_get_float", ← LLVM.doubleTypeInContext llvmctx)
-    | IRType.float32 => pure ("lean_ctor_get_float32", ← LLVM.floatTypeInContext llvmctx)
-    | IRType.uint8   => pure ("lean_ctor_get_uint8", ← LLVM.i8Type llvmctx)
-    | IRType.uint16  => pure ("lean_ctor_get_uint16", ←  LLVM.i16Type llvmctx)
-    | IRType.uint32  => pure ("lean_ctor_get_uint32", ← LLVM.i32Type llvmctx)
-    | IRType.uint64  => pure ("lean_ctor_get_uint64", ← LLVM.i64Type llvmctx)
-    | _              => throw s!"Invalid type for lean_ctor_get: '{t}'"
+    | IRType.float  => pure ("lean_ctor_get_float", ← LLVM.doubleTypeInContext llvmctx)
+    | IRType.uint8  => pure ("lean_ctor_get_uint8", ← LLVM.i8Type llvmctx)
+    | IRType.uint16 => pure ("lean_ctor_get_uint16", ←  LLVM.i16Type llvmctx)
+    | IRType.uint32 => pure ("lean_ctor_get_uint32", ← LLVM.i32Type llvmctx)
+    | IRType.uint64 => pure ("lean_ctor_get_uint64", ← LLVM.i64Type llvmctx)
+    | _             => throw s!"Invalid type for lean_ctor_get: '{t}'"
   let argtys := #[ ← LLVM.voidPtrType llvmctx, ← LLVM.unsignedType llvmctx]
   let fn ← getOrCreateFunctionPrototype (← getLLVMModule) retty fnName argtys
   let xval ← emitLhsVal builder x
@@ -864,12 +862,11 @@ def emitBox (builder : LLVM.Builder llvmctx) (z : VarId) (x : VarId) (xType : IR
   let xv ← emitLhsVal builder x
   let (fnName, argTy, xv) ←
     match xType with
-    | IRType.usize   => pure ("lean_box_usize", ← LLVM.size_tType llvmctx, xv)
-    | IRType.uint32  => pure ("lean_box_uint32", ← LLVM.i32Type llvmctx, xv)
-    | IRType.uint64  => pure ("lean_box_uint64", ← LLVM.size_tType llvmctx, xv)
-    | IRType.float   => pure ("lean_box_float", ← LLVM.doubleTypeInContext llvmctx, xv)
-    | IRType.float32 => pure ("lean_box_float32", ← LLVM.floatTypeInContext llvmctx, xv)
-    | _              =>
+    | IRType.usize  => pure ("lean_box_usize", ← LLVM.size_tType llvmctx, xv)
+    | IRType.uint32 => pure ("lean_box_uint32", ← LLVM.i32Type llvmctx, xv)
+    | IRType.uint64 => pure ("lean_box_uint64", ← LLVM.size_tType llvmctx, xv)
+    | IRType.float  => pure ("lean_box_float", ← LLVM.doubleTypeInContext llvmctx, xv)
+    | _             => do
          -- sign extend smaller values into i64
          let xv ← LLVM.buildSext builder xv (← LLVM.size_tType llvmctx)
          pure ("lean_box", ← LLVM.size_tType llvmctx, xv)
@@ -895,12 +892,11 @@ def callUnboxForType (builder : LLVM.Builder llvmctx)
     (retName : String := "") : M llvmctx (LLVM.Value llvmctx) := do
   let (fnName, retty) ←
      match t with
-     | IRType.usize   => pure ("lean_unbox_usize", ← toLLVMType t)
-     | IRType.uint32  => pure ("lean_unbox_uint32", ← toLLVMType t)
-     | IRType.uint64  => pure ("lean_unbox_uint64", ← toLLVMType t)
-     | IRType.float   => pure ("lean_unbox_float", ← toLLVMType t)
-     | IRType.float32 => pure ("lean_unbox_float32", ← toLLVMType t)
-     | _              => pure ("lean_unbox", ← LLVM.size_tType llvmctx)
+     | IRType.usize  => pure ("lean_unbox_usize", ← toLLVMType t)
+     | IRType.uint32 => pure ("lean_unbox_uint32", ← toLLVMType t)
+     | IRType.uint64 => pure ("lean_unbox_uint64", ← toLLVMType t)
+     | IRType.float  => pure ("lean_unbox_float", ← toLLVMType t)
+     | _             => pure ("lean_unbox", ← LLVM.size_tType llvmctx)
   let argtys := #[← LLVM.voidPtrType llvmctx ]
   let fn ← getOrCreateFunctionPrototype (← getLLVMModule) retty fnName argtys
   let fnty ← LLVM.functionType retty argtys
@@ -1045,13 +1041,12 @@ def emitJmp (builder : LLVM.Builder llvmctx) (jp : JoinPointId) (xs : Array Arg)
 def emitSSet (builder : LLVM.Builder llvmctx) (x : VarId) (n : Nat) (offset : Nat) (y : VarId) (t : IRType) : M llvmctx Unit := do
   let (fnName, setty) ←
   match t with
-  | IRType.float   => pure ("lean_ctor_set_float", ← LLVM.doubleTypeInContext llvmctx)
-  | IRType.float32 => pure ("lean_ctor_set_float32", ← LLVM.floatTypeInContext llvmctx)
-  | IRType.uint8   => pure ("lean_ctor_set_uint8", ← LLVM.i8Type llvmctx)
-  | IRType.uint16  => pure ("lean_ctor_set_uint16", ← LLVM.i16Type llvmctx)
-  | IRType.uint32  => pure ("lean_ctor_set_uint32", ← LLVM.i32Type llvmctx)
-  | IRType.uint64  => pure ("lean_ctor_set_uint64", ← LLVM.i64Type llvmctx)
-  | _              => throw s!"invalid type for 'lean_ctor_set': '{t}'"
+  | IRType.float  => pure ("lean_ctor_set_float", ← LLVM.doubleTypeInContext llvmctx)
+  | IRType.uint8  => pure ("lean_ctor_set_uint8", ← LLVM.i8Type llvmctx)
+  | IRType.uint16 => pure ("lean_ctor_set_uint16", ← LLVM.i16Type llvmctx)
+  | IRType.uint32 => pure ("lean_ctor_set_uint32", ← LLVM.i32Type llvmctx)
+  | IRType.uint64 => pure ("lean_ctor_set_uint64", ← LLVM.i64Type llvmctx)
+  | _             => throw s!"invalid type for 'lean_ctor_set': '{t}'"
   let argtys := #[ ← LLVM.voidPtrType llvmctx, ← LLVM.unsignedType llvmctx, setty]
   let retty  ← LLVM.voidType llvmctx
   let fn ← getOrCreateFunctionPrototype (← getLLVMModule) retty fnName argtys

src/Lean/Compiler/IR/Format.lean

@@ -55,7 +55,6 @@ instance : ToString Expr := ⟨fun e => Format.pretty (format e)⟩
 
 private partial def formatIRType : IRType → Format
   | IRType.float        => "float"
-  | IRType.float32      => "float32"
   | IRType.uint8        => "u8"
   | IRType.uint16       => "u16"
   | IRType.uint32       => "u32"

src/Lean/Compiler/LCNF.lean

@@ -35,6 +35,7 @@ import Lean.Compiler.LCNF.ToLCNF
 import Lean.Compiler.LCNF.Types
 import Lean.Compiler.LCNF.Util
 import Lean.Compiler.LCNF.ConfigOptions
+import Lean.Compiler.LCNF.ForEachExpr
 import Lean.Compiler.LCNF.MonoTypes
 import Lean.Compiler.LCNF.ToMono
 import Lean.Compiler.LCNF.MonadScope

src/Lean/Compiler/LCNF/ForEachExpr.lean

@@ -0,0 +1,14 @@
+/-
+Copyright (c) 2022 Microsoft Corporation. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Leonardo de Moura
+-/
+prelude
+import Lean.Util.ForEachExpr
+import Lean.Compiler.LCNF.Basic
+
+namespace Lean.Compiler.LCNF
+
+-- TODO: delete
+
+end Lean.Compiler.LCNF

src/Lean/Compiler/LCNF/Main.lean

@@ -29,7 +29,7 @@ and `[specialize]` since they can be partially applied.
 def shouldGenerateCode (declName : Name) : CoreM Bool := do
   if (← isCompIrrelevant |>.run') then return false
   let some info ← getDeclInfo? declName | return false
-  unless info.hasValue (allowOpaque := true) do return false
+  unless info.hasValue do return false
   let env ← getEnv
   if isExtern env declName then return false
   if hasMacroInlineAttribute env declName then return false

src/Lean/Compiler/LCNF/Probing.lean

@@ -7,6 +7,7 @@ prelude
 import Lean.Compiler.LCNF.CompilerM
 import Lean.Compiler.LCNF.PassManager
 import Lean.Compiler.LCNF.PhaseExt
+import Lean.Compiler.LCNF.ForEachExpr
 
 namespace Lean.Compiler.LCNF
 

src/Lean/Compiler/LCNF/ToDecl.lean

@@ -96,7 +96,7 @@ The steps for this are roughly:
 def toDecl (declName : Name) : CompilerM Decl := do
   let declName := if let some name := isUnsafeRecName? declName then name else declName
   let some info ← getDeclInfo? declName | throwError "declaration `{declName}` not found"
-  let some value := info.value? (allowOpaque := true) | throwError "declaration `{declName}` does not have a value"
+  let some value := info.value? | throwError "declaration `{declName}` does not have a value"
   let (type, value) ← Meta.MetaM.run' do
     let type  ← toLCNFType info.type
     let value ← Meta.lambdaTelescope value fun xs body => do Meta.mkLambdaFVars xs (← Meta.etaExpand body)
@@ -107,7 +107,7 @@ def toDecl (declName : Name) : CompilerM Decl := do
     /- Recall that `inlineMatchers` may have exposed `ite`s and `dite`s which are tagged as `[macro_inline]`. -/
     let value ← macroInline value
     /-
-    Remark: we have disabled the following transformatbion, we will perform it at phase 2, after code specialization.
+    Remark: we have disabled the following transformation, we will perform it at phase 2, after code specialization.
     It prevents many optimizations (e.g., "cases-of-ctor").
     -/
     -- let value ← applyCasesOnImplementedBy value

src/Lean/Compiler/LCNF/ToLCNF.lean

@@ -593,14 +593,6 @@ where
       let minor ← visit minor
       mkOverApplication minor args arity
 
-  visitHEqRec (e : Expr) : M Arg :=
-    let arity := 7
-    etaIfUnderApplied e arity do
-      let args := e.getAppArgs
-      let minor := if e.isAppOf ``HEq.rec || e.isAppOf ``HEq.ndrec then args[3]! else args[6]!
-      let minor ← visit minor
-      mkOverApplication minor args arity
-
   visitFalseRec (e : Expr) : M Arg :=
     let arity := 2
     etaIfUnderApplied e arity do
@@ -677,8 +669,6 @@ where
         visitCtor 3 e
       else if declName == ``Eq.casesOn || declName == ``Eq.rec || declName == ``Eq.ndrec then
         visitEqRec e
-      else if declName == ``HEq.casesOn || declName == ``HEq.rec || declName == ``HEq.ndrec then
-        visitHEqRec e
       else if declName == ``And.rec || declName == ``Iff.rec then
         visitAndIffRecCore e (minorPos := 3)
       else if declName == ``And.casesOn || declName == ``Iff.casesOn then

src/Lean/CoreM.lean

@@ -33,15 +33,7 @@ register_builtin_option maxHeartbeats : Nat := {
 
 register_builtin_option Elab.async : Bool := {
   defValue := false
-  descr := "perform elaboration using multiple threads where possible\
-    \n\
-    \nThis option defaults to `false` but (when not explicitly set) is overridden to `true` in \
-      `Lean.Language.Lean.process` as used by the cmdline driver and language server. \
-      Metaprogramming users driving elaboration directly via e.g. \
-      `Lean.Elab.Command.elabCommandTopLevel` can opt into asynchronous elaboration by setting \
-      this option but then are responsible for processing messages and other data not only in the \
-      resulting command state but also from async tasks in `Lean.Command.Context.snap?` and \
-      `Lean.Command.State.snapshotTasks`."
+  descr := "perform elaboration using multiple threads where possible"
 }
 
 /--
@@ -364,7 +356,9 @@ Returns the current log and then resets its messages while adjusting `MessageLog
 for incremental reporting during elaboration of a single command.
 -/
 def getAndEmptyMessageLog : CoreM MessageLog :=
-  modifyGet fun s => (s.messages, { s with messages := s.messages.markAllReported })
+  modifyGet fun s => (s.messages, { s with
+    messages.unreported := {}
+    messages.hadErrors  := s.messages.hasErrors })
 
 instance : MonadLog CoreM where
   getRef      := getRef
@@ -423,7 +417,7 @@ def wrapAsyncAsSnapshot (act : Unit → CoreM Unit) (desc : String := by exact d
     IO.FS.withIsolatedStreams (isolateStderr := stderrAsMessages.get (← getOptions)) do
       let tid ← IO.getTID
       -- reset trace state and message log so as not to report them twice
-      modify fun st => { st with messages := st.messages.markAllReported, traceState := { tid } }
+      modify ({ · with messages := {}, traceState := { tid } })
       try
         withTraceNode `Elab.async (fun _ => return desc) do
           act ()
@@ -612,14 +606,14 @@ instance : MonadRuntimeException CoreM where
 
 /--
 Returns `true` if the given message kind has not been reported in the message log,
-and then mark it as logged. Otherwise, returns `false`.
-We use this API to ensure we don't log the same kind of warning multiple times.
+and then mark it as reported. Otherwise, returns `false`.
+We use this API to ensure we don't report the same kind of warning multiple times.
 -/
-def logMessageKind (kind : Name) : CoreM Bool := do
-  if (← get).messages.loggedKinds.contains kind then
+def reportMessageKind (kind : Name) : CoreM Bool := do
+  if (← get).messages.reportedKinds.contains kind then
     return false
   else
-    modify fun s => { s with messages.loggedKinds := s.messages.loggedKinds.insert kind }
+    modify fun s => { s with messages.reportedKinds := s.messages.reportedKinds.insert kind }
     return true
 
 end Lean

src/Lean/Data/DeclarationRange.lean

@@ -1,49 +0,0 @@
-/-
-Copyright (c) 2021 Microsoft Corporation. All rights reserved.
-Released under Apache 2.0 license as described in the file LICENSE.
-Authors: Leonardo de Moura
--/
-prelude
-import Lean.Data.Position
-
-/-!
-# Data types for declaration ranges
-
-The environment extension for declaration ranges is in `Lean.DeclarationRange`.
--/
-
-namespace Lean
-
-/-- Store position information for declarations. -/
-structure DeclarationRange where
-  pos          : Position
-  /-- A precomputed UTF-16 `character` field as in `Lean.Lsp.Position`. We need to store this
-  because LSP clients want us to report the range in terms of UTF-16, but converting a Unicode
-  codepoint stored in `Lean.Position` to UTF-16 requires loading and mapping the target source
-  file, which is IO-heavy. -/
-  charUtf16    : Nat
-  endPos       : Position
-  /-- See `charUtf16`. -/
-  endCharUtf16 : Nat
-  deriving Inhabited, DecidableEq, Repr
-
-instance : ToExpr DeclarationRange where
-  toExpr r   := mkAppN (mkConst ``DeclarationRange.mk) #[toExpr r.pos, toExpr r.charUtf16, toExpr r.endPos, toExpr r.endCharUtf16]
-  toTypeExpr := mkConst ``DeclarationRange
-
-structure DeclarationRanges where
-  range          : DeclarationRange
-  selectionRange : DeclarationRange
-  deriving Inhabited, Repr
-
-instance : ToExpr DeclarationRanges where
-  toExpr r   := mkAppN (mkConst ``DeclarationRanges.mk) #[toExpr r.range, toExpr r.selectionRange]
-  toTypeExpr := mkConst ``DeclarationRanges
-
-/--
-A declaration location is a declaration range along with the name of the module the declaration resides in.
--/
-structure DeclarationLocation where
-  module : Name
-  range : DeclarationRange
-  deriving Inhabited, DecidableEq, Repr

src/Lean/Data/RArray.lean

@@ -35,7 +35,7 @@ theorem RArray.get_ofFn {n : Nat} (f : Fin n → α) (h : 0 < n) (i : Fin n) :
   go 0 n h (Nat.le_refl _) (Nat.zero_le _) i.2
 where
   go lb ub h1 h2 (h3 : lb ≤ i.val) (h3 : i.val < ub) : (ofFn.go f lb ub h1 h2).get i = f i := by
-    induction lb, ub, h1, h2 using RArray.ofFn.go.induct (n := n)
+    induction lb, ub, h1, h2 using RArray.ofFn.go.induct (f := f) (n := n)
     case case1 =>
       simp [ofFn.go, RArray.get_eq_getImpl, RArray.getImpl]
       congr
@@ -53,9 +53,9 @@ theorem RArray.size_ofFn {n : Nat} (f : Fin n → α) (h : 0 < n) :
   go 0 n h (Nat.le_refl _)
 where
   go lb ub h1 h2 : (ofFn.go f lb ub h1 h2).size = ub - lb := by
-    induction lb, ub, h1, h2 using RArray.ofFn.go.induct (n := n)
+    induction lb, ub, h1, h2 using RArray.ofFn.go.induct (f := f) (n := n)
     case case1 => simp [ofFn.go, size]; omega
-    case case2 ih1 ih2 hiu => rw [ofFn.go]; simp +zetaDelta [size, *]; omega
+    case case2 ih1 ih2 hiu => rw [ofFn.go]; simp [size, *]; omega
 
 section Meta
 open Lean

src/Lean/Declaration.lean

@@ -44,7 +44,7 @@ def mkReducibilityHintsRegularEx (h : UInt32) : ReducibilityHints :=
 @[export lean_reducibility_hints_get_height]
 def ReducibilityHints.getHeightEx (h : ReducibilityHints) : UInt32 :=
   match h with
-  | .regular h => h
+  | ReducibilityHints.regular h => h
   | _ => 0
 
 namespace ReducibilityHints
@@ -74,8 +74,8 @@ def isAbbrev : ReducibilityHints → Bool
   | _       => false
 
 def isRegular : ReducibilityHints → Bool
-  | .regular .. => true
-  | _           => false
+  | regular .. => true
+  | _          => false
 
 end ReducibilityHints
 
@@ -186,7 +186,7 @@ def mkInductiveDeclEs (lparams : List Name) (nparams : Nat) (types : List Induct
 
 @[export lean_is_unsafe_inductive_decl]
 def Declaration.isUnsafeInductiveDeclEx : Declaration → Bool
-  | .inductDecl _ _ _ isUnsafe => isUnsafe
+  | Declaration.inductDecl _ _ _ isUnsafe => isUnsafe
   | _ => false
 
 def Declaration.definitionVal! : Declaration → DefinitionVal
@@ -195,16 +195,18 @@ def Declaration.definitionVal! : Declaration → DefinitionVal
 
 @[specialize] def Declaration.foldExprM {α} {m : Type → Type} [Monad m] (d : Declaration) (f : α → Expr → m α) (a : α) : m α :=
   match d with
-  | .quotDecl                                        => pure a
-  | .axiomDecl { type := type, .. }                  => f a type
-  | .defnDecl { type := type, value := value, .. }   => do let a ← f a type; f a value
-  | .opaqueDecl { type := type, value := value, .. } => do let a ← f a type; f a value
-  | .thmDecl { type := type, value := value, .. }    => do let a ← f a type; f a value
-  | .mutualDefnDecl vals                             => vals.foldlM (fun a v => do let a ← f a v.type; f a v.value) a
-  | .inductDecl _ _ inductTypes _                    =>
-    inductTypes.foldlM (init := a) fun a inductType => do
-      let a ← f a inductType.type
-      inductType.ctors.foldlM (fun a ctor => f a ctor.type) a
+  | Declaration.quotDecl                                        => pure a
+  | Declaration.axiomDecl { type := type, .. }                  => f a type
+  | Declaration.defnDecl { type := type, value := value, .. }   => do let a ← f a type; f a value
+  | Declaration.opaqueDecl { type := type, value := value, .. } => do let a ← f a type; f a value
+  | Declaration.thmDecl { type := type, value := value, .. }    => do let a ← f a type; f a value
+  | Declaration.mutualDefnDecl vals                             => vals.foldlM (fun a v => do let a ← f a v.type; f a v.value) a
+  | Declaration.inductDecl _ _ inductTypes _                    =>
+    inductTypes.foldlM
+      (fun a inductType => do
+        let a ← f a inductType.type
+        inductType.ctors.foldlM (fun a ctor => f a ctor.type) a)
+      a
 
 @[inline] def Declaration.forExprM {m : Type → Type} [Monad m] (d : Declaration) (f : Expr → m Unit) : m Unit :=
   d.foldExprM (fun _ a => f a) ()
@@ -300,7 +302,14 @@ structure ConstructorVal extends ConstantVal where
 
 @[export lean_mk_constructor_val]
 def mkConstructorValEx (name : Name) (levelParams : List Name) (type : Expr) (induct : Name) (cidx numParams numFields : Nat) (isUnsafe : Bool) : ConstructorVal := {
-  name, levelParams, type, induct, cidx, numParams, numFields, isUnsafe
+  name := name,
+  levelParams := levelParams,
+  type := type,
+  induct := induct,
+  cidx := cidx,
+  numParams := numParams,
+  numFields := numFields,
+  isUnsafe := isUnsafe
 }
 
 @[export lean_constructor_val_is_unsafe] def ConstructorVal.isUnsafeEx (v : ConstructorVal) : Bool := v.isUnsafe
@@ -344,8 +353,8 @@ structure RecursorVal extends ConstantVal where
 @[export lean_mk_recursor_val]
 def mkRecursorValEx (name : Name) (levelParams : List Name) (type : Expr) (all : List Name) (numParams numIndices numMotives numMinors : Nat)
     (rules : List RecursorRule) (k isUnsafe : Bool) : RecursorVal := {
-  name, levelParams, type, all, numParams, numIndices,
-  numMotives, numMinors, rules, k, isUnsafe
+  name := name, levelParams := levelParams, type := type, all := all, numParams := numParams, numIndices := numIndices,
+  numMotives := numMotives, numMinors := numMinors, rules := rules, k := k, isUnsafe := isUnsafe
 }
 
 @[export lean_recursor_k] def RecursorVal.kEx (v : RecursorVal) : Bool := v.k
@@ -401,27 +410,27 @@ inductive ConstantInfo where
 namespace ConstantInfo
 
 def toConstantVal : ConstantInfo → ConstantVal
-  | .defnInfo     {toConstantVal := d, ..} => d
-  | .axiomInfo    {toConstantVal := d, ..} => d
-  | .thmInfo      {toConstantVal := d, ..} => d
-  | .opaqueInfo   {toConstantVal := d, ..} => d
-  | .quotInfo     {toConstantVal := d, ..} => d
-  | .inductInfo   {toConstantVal := d, ..} => d
-  | .ctorInfo     {toConstantVal := d, ..} => d
-  | .recInfo      {toConstantVal := d, ..} => d
+  | defnInfo     {toConstantVal := d, ..} => d
+  | axiomInfo    {toConstantVal := d, ..} => d
+  | thmInfo      {toConstantVal := d, ..} => d
+  | opaqueInfo   {toConstantVal := d, ..} => d
+  | quotInfo     {toConstantVal := d, ..} => d
+  | inductInfo   {toConstantVal := d, ..} => d
+  | ctorInfo     {toConstantVal := d, ..} => d
+  | recInfo      {toConstantVal := d, ..} => d
 
 def isUnsafe : ConstantInfo → Bool
-  | .defnInfo   v => v.safety == .unsafe
-  | .axiomInfo  v => v.isUnsafe
-  | .thmInfo    _ => false
-  | .opaqueInfo v => v.isUnsafe
-  | .quotInfo   _ => false
-  | .inductInfo v => v.isUnsafe
-  | .ctorInfo   v => v.isUnsafe
-  | .recInfo    v => v.isUnsafe
+  | defnInfo   v => v.safety == .unsafe
+  | axiomInfo  v => v.isUnsafe
+  | thmInfo    _ => false
+  | opaqueInfo v => v.isUnsafe
+  | quotInfo   _ => false
+  | inductInfo v => v.isUnsafe
+  | ctorInfo   v => v.isUnsafe
+  | recInfo    v => v.isUnsafe
 
 def isPartial : ConstantInfo → Bool
-  | .defnInfo v => v.safety == .partial
+  | defnInfo v => v.safety == .partial
   | _ => false
 
 def name (d : ConstantInfo) : Name :=
@@ -436,42 +445,36 @@ def numLevelParams (d : ConstantInfo) : Nat :=
 def type (d : ConstantInfo) : Expr :=
   d.toConstantVal.type
 
-def value? (info : ConstantInfo) (allowOpaque := false) : Option Expr :=
-  match info with
-  | .defnInfo {value, ..}   => some value
-  | .thmInfo  {value, ..}   => some value
-  | .opaqueInfo {value, ..} => if allowOpaque then some value else none
-  | _                       => none
+def value? : ConstantInfo → Option Expr
+  | defnInfo {value := r, ..} => some r
+  | thmInfo  {value := r, ..} => some r
+  | _                         => none
 
-def hasValue (info : ConstantInfo) (allowOpaque := false) : Bool :=
-  match info with
-  | .defnInfo _   => true
-  | .thmInfo  _   => true
-  | .opaqueInfo _ => allowOpaque
-  | _             => false
+def hasValue : ConstantInfo → Bool
+  | defnInfo _ => true
+  | thmInfo  _ => true
+  | _                         => false
 
-def value! (info : ConstantInfo) (allowOpaque := false) : Expr :=
-  match info with
-  | .defnInfo {value, ..}   => value
-  | .thmInfo  {value, ..}   => value
-  | .opaqueInfo {value, ..} => if allowOpaque then value else panic! "declaration with value expected"
-  | _                       => panic! "declaration with value expected"
+def value! : ConstantInfo → Expr
+  | defnInfo {value := r, ..} => r
+  | thmInfo  {value := r, ..} => r
+  | _                         => panic! "declaration with value expected"
 
 def hints : ConstantInfo → ReducibilityHints
-  | .defnInfo {hints, ..} => hints
-  | _                     => .opaque
+  | defnInfo {hints := r, ..} => r
+  | _                         => ReducibilityHints.opaque
 
 def isCtor : ConstantInfo → Bool
-  | .ctorInfo _ => true
-  | _           => false
+  | ctorInfo _ => true
+  | _          => false
 
 def isInductive : ConstantInfo → Bool
-  | .inductInfo _ => true
-  | _             => false
+  | inductInfo _ => true
+  | _            => false
 
 def isTheorem : ConstantInfo → Bool
-  | .thmInfo _ => true
-  | _          => false
+  | thmInfo _ => true
+  | _         => false
 
 def inductiveVal! : ConstantInfo → InductiveVal
   | .inductInfo val => val
@@ -481,11 +484,11 @@ def inductiveVal! : ConstantInfo → InductiveVal
   List of all (including this one) declarations in the same mutual block.
 -/
 def all : ConstantInfo → List Name
-  | .inductInfo val => val.all
-  | .defnInfo val   => val.all
-  | .thmInfo val    => val.all
-  | .opaqueInfo val => val.all
-  | info            => [info.name]
+  | inductInfo val => val.all
+  | defnInfo val   => val.all
+  | thmInfo val    => val.all
+  | opaqueInfo val => val.all
+  | info           => [info.name]
 
 end ConstantInfo
 

src/Lean/DeclarationRange.lean

@@ -4,15 +4,38 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Leonardo de Moura
 -/
 prelude
-import Lean.Data.DeclarationRange
 import Lean.MonadEnv
-
-/-!
-# Environment extension for declaration ranges
--/
+import Lean.AuxRecursor
+import Lean.ToExpr
 
 namespace Lean
 
+/-- Store position information for declarations. -/
+structure DeclarationRange where
+  pos          : Position
+  /-- A precomputed UTF-16 `character` field as in `Lean.Lsp.Position`. We need to store this
+  because LSP clients want us to report the range in terms of UTF-16, but converting a Unicode
+  codepoint stored in `Lean.Position` to UTF-16 requires loading and mapping the target source
+  file, which is IO-heavy. -/
+  charUtf16    : Nat
+  endPos       : Position
+  /-- See `charUtf16`. -/
+  endCharUtf16 : Nat
+  deriving Inhabited, DecidableEq, Repr
+
+instance : ToExpr DeclarationRange where
+  toExpr r   := mkAppN (mkConst ``DeclarationRange.mk) #[toExpr r.pos, toExpr r.charUtf16, toExpr r.endPos, toExpr r.endCharUtf16]
+  toTypeExpr := mkConst ``DeclarationRange
+
+structure DeclarationRanges where
+  range          : DeclarationRange
+  selectionRange : DeclarationRange
+  deriving Inhabited, Repr
+
+instance : ToExpr DeclarationRanges where
+  toExpr r   := mkAppN (mkConst ``DeclarationRanges.mk) #[toExpr r.range, toExpr r.selectionRange]
+  toTypeExpr := mkConst ``DeclarationRanges
+
 builtin_initialize builtinDeclRanges : IO.Ref (NameMap DeclarationRanges) ← IO.mkRef {}
 builtin_initialize declRangeExt : MapDeclarationExtension DeclarationRanges ← mkMapDeclarationExtension
 

src/Lean/Elab/BuiltinCommand.lean

@@ -488,9 +488,6 @@ where
     let mut lines : Array MessageData := #[]
     let decls ← getOptionDecls
     for (name, val) in opts do
-      -- `#guard_msgs` sets this option internally, we don't want it to end up in its output
-      if name == `Elab.async then
-        continue
       let (isSet, isUnknown) :=
         match decls.find? name with
         | some decl => (decl.defValue != val, false)

src/Lean/Elab/BuiltinNotation.lean

@@ -212,9 +212,9 @@ private def elabTParserMacroAux (prec lhsPrec e : Term) : TermElabM Syntax := do
   | `(dbg_trace $arg:term; $body)            => `(dbgTrace (toString $arg) fun _ => $body)
   | _                                        => Macro.throwUnsupported
 
-@[builtin_term_elab «sorry»] def elabSorry : TermElab := fun _ expectedType? => do
-  let type ← expectedType?.getDM mkFreshTypeMVar
-  mkLabeledSorry type (synthetic := false) (unique := true)
+@[builtin_term_elab «sorry»] def elabSorry : TermElab := fun stx expectedType? => do
+  let stxNew ← `(@sorryAx _ false) -- Remark: we use `@` to ensure `sorryAx` will not consume auto params
+  withMacroExpansion stx stxNew <| elabTerm stxNew expectedType?
 
 /-- Return syntax `Prod.mk elems[0] (Prod.mk elems[1] ... (Prod.mk elems[elems.size - 2] elems[elems.size - 1])))` -/
 partial def mkPairs (elems : Array Term) : MacroM Term :=

src/Lean/Elab/Command.lean

@@ -101,7 +101,7 @@ structure Context where
   (mutual) defs and contained tactics, in which case the `DynamicSnapshot` is a
   `HeadersParsedSnapshot`.
 
-  Definitely resolved in `Lean.Elab.Command.elabCommandTopLevel`.
+  Definitely resolved in `Language.Lean.process.doElab`.
 
   Invariant: if the bundle's `old?` is set, the context and state at the beginning of current and
   old elaboration are identical.
@@ -287,9 +287,7 @@ def runLinters (stx : Syntax) : CommandElabM Unit := do
               | Exception.internal _ _ =>
                 logException ex
             finally
-              -- TODO: it would be good to preserve even more state (#4363) but preserving info
-              -- trees currently breaks from linters adding context-less info nodes
-              modify fun s => { savedState with messages := s.messages, traceState := s.traceState }
+              modify fun s => { savedState with messages := s.messages }
 
 /--
 Catches and logs exceptions occurring in `x`. Unlike `try catch` in `CommandElabM`, this function
@@ -313,7 +311,7 @@ def wrapAsyncAsSnapshot (act : Unit → CommandElabM Unit)
     IO.FS.withIsolatedStreams (isolateStderr := Core.stderrAsMessages.get (← getOptions)) do
       let tid ← IO.getTID
       -- reset trace state and message log so as not to report them twice
-      modify fun st => { st with messages := st.messages.markAllReported, traceState := { tid } }
+      modify ({ · with messages := {}, traceState := { tid } })
       try
         withTraceNode `Elab.async (fun _ => return desc) do
           act ()
@@ -346,17 +344,6 @@ def wrapAsyncAsSnapshot (act : Unit → CommandElabM Unit)
 def logSnapshotTask (task : Language.SnapshotTask Language.SnapshotTree) : CommandElabM Unit :=
   modify fun s => { s with snapshotTasks := s.snapshotTasks.push task }
 
-def runLintersAsync (stx : Syntax) : CommandElabM Unit := do
-  if !Elab.async.get (← getOptions) then
-    withoutModifyingEnv do
-      runLinters stx
-    return
-
-  -- We only start one task for all linters for now as most linters are fast and we simply want
-  -- to unblock elaboration of the next command
-  let lintAct ← wrapAsyncAsSnapshot fun _ => runLinters stx
-  logSnapshotTask { range? := none, task := (← BaseIO.asTask lintAct) }
-
 protected def getCurrMacroScope : CommandElabM Nat  := do pure (← read).currMacroScope
 protected def getMainModule     : CommandElabM Name := do pure (← getEnv).mainModule
 
@@ -560,13 +547,8 @@ def elabCommandTopLevel (stx : Syntax) : CommandElabM Unit := withRef stx do pro
     -- rather than engineer a general solution.
     unless (stx.find? (·.isOfKind ``Lean.guardMsgsCmd)).isSome do
       withLogging do
-        runLintersAsync stx
+        runLinters stx
   finally
-    -- Make sure `snap?` is definitely resolved; we do not use it for reporting as `#guard_msgs` may
-    -- be the caller of this function and add new messages and info trees
-    if let some snap := (← read).snap? then
-      snap.new.resolve default
-
     -- note the order: first process current messages & info trees, then add back old messages & trees,
     -- then convert new traces to messages
     let mut msgs := (← get).messages

src/Lean/Elab/Extra.lean

@@ -581,7 +581,7 @@ def elabDefaultOrNonempty : TermElab :=  fun stx expectedType? => do
       else
         -- It is in the context of an `unsafe` constant. We can use sorry instead.
         -- Another option is to make a recursive application since it is unsafe.
-        mkLabeledSorry expectedType false (unique := true)
+        mkSorry expectedType false
 
 builtin_initialize
   registerTraceClass `Elab.binop

src/Lean/Elab/Frontend.lean

@@ -142,7 +142,6 @@ def runFrontend
     (trustLevel : UInt32 := 0)
     (ileanFileName? : Option String := none)
     (jsonOutput : Bool := false)
-    (errorOnKinds : Array Name := #[])
     : IO (Environment × Bool) := do
   let startTime := (← IO.monoNanosNow).toFloat / 1000000000
   let inputCtx := Parser.mkInputContext input fileName
@@ -151,8 +150,7 @@ def runFrontend
   let processor := Language.Lean.process
   let snap ← processor (fun _ => pure <| .ok { mainModuleName, opts, trustLevel }) none ctx
   let snaps := Language.toSnapshotTree snap
-  let severityOverrides := errorOnKinds.foldl (·.insert · .error) {}
-  let hasErrors ← snaps.runAndReport opts jsonOutput severityOverrides
+  snaps.runAndReport opts jsonOutput
 
   if let some ileanFileName := ileanFileName? then
     let trees := snaps.getAll.flatMap (match ·.infoTree? with | some t => #[t] | _ => #[])
@@ -170,8 +168,7 @@ def runFrontend
     let profile ← Firefox.Profile.export mainModuleName.toString startTime traceStates opts
     IO.FS.writeFile ⟨out⟩ <| Json.compress <| toJson profile
 
-  -- no point in freeing the snapshot graph and all referenced data this close to process exit
-  Runtime.forget snaps
+  let hasErrors := snaps.getAll.any (·.diagnostics.msgLog.hasErrors)
   pure (cmdState.env, !hasErrors)
 
 

src/Lean/Elab/GuardMsgs.lean

@@ -26,7 +26,7 @@ namespace Lean.Elab.Tactic.GuardMsgs
 
 /-- Gives a string representation of a message without source position information.
 Ensures the message ends with a '\n'. -/
-private def messageToStringWithoutPos (msg : Message) : BaseIO String := do
+private def messageToStringWithoutPos (msg : Message) : IO String := do
   let mut str ← msg.data.toString
   unless msg.caption == "" do
     str := msg.caption ++ ":\n" ++ str
@@ -140,15 +140,9 @@ def MessageOrdering.apply (mode : MessageOrdering) (msgs : List String) : List S
         |>.trim |> removeTrailingWhitespaceMarker
     let (whitespace, ordering, specFn) ← parseGuardMsgsSpec spec?
     let initMsgs ← modifyGet fun st => (st.messages, { st with messages := {} })
-    -- do not forward snapshot as we don't want messages assigned to it to leak outside
-    withReader ({ · with snap? := none }) do
-      -- The `#guard_msgs` command is special-cased in `elabCommandTopLevel` to ensure linters only run once.
-      elabCommandTopLevel cmd
-    -- collect sync and async messages
-    let msgs := (← get).messages ++
-      (← get).snapshotTasks.foldl (· ++ ·.get.getAll.foldl (· ++ ·.diagnostics.msgLog) {}) {}
-    -- clear async messages as we don't want them to leak outside
-    modify ({ · with snapshotTasks := #[] })
+    -- The `#guard_msgs` command is special-cased in `elabCommandTopLevel` to ensure linters only run once.
+    elabCommandTopLevel cmd
+    let msgs := (← get).messages
     let mut toCheck : MessageLog := .empty
     let mut toPassthrough : MessageLog := .empty
     for msg in msgs.toList do

src/Lean/Elab/InfoTree/Main.lean

@@ -192,12 +192,8 @@ def FVarAliasInfo.format (info : FVarAliasInfo) : Format :=
 def FieldRedeclInfo.format (ctx : ContextInfo) (info : FieldRedeclInfo) : Format :=
   f!"FieldRedecl @ {formatStxRange ctx info.stx}"
 
-def DelabTermInfo.format (ctx : ContextInfo) (info : DelabTermInfo) : IO Format := do
-  let loc := if let some loc := info.location? then f!"{loc.module} {loc.range.pos}-{loc.range.endPos}" else "none"
-  return f!"DelabTermInfo @ {← TermInfo.format ctx info.toTermInfo}\n\
-    Location: {loc}\n\
-    Docstring: {repr info.docString?}\n\
-    Explicit: {info.explicit}"
+def OmissionInfo.format (ctx : ContextInfo) (info : OmissionInfo) : IO Format := do
+  return f!"Omission @ {← TermInfo.format ctx info.toTermInfo}\nReason: {info.reason}"
 
 def ChoiceInfo.format (ctx : ContextInfo) (info : ChoiceInfo) : Format :=
   f!"Choice @ {formatElabInfo ctx info.toElabInfo}"
@@ -215,7 +211,7 @@ def Info.format (ctx : ContextInfo) : Info → IO Format
   | ofCustomInfo i         => pure <| Std.ToFormat.format i
   | ofFVarAliasInfo i      => pure <| i.format
   | ofFieldRedeclInfo i    => pure <| i.format ctx
-  | ofDelabTermInfo i      => i.format ctx
+  | ofOmissionInfo i       => i.format ctx
   | ofChoiceInfo i         => pure <| i.format ctx
 
 def Info.toElabInfo? : Info → Option ElabInfo
@@ -231,7 +227,7 @@ def Info.toElabInfo? : Info → Option ElabInfo
   | ofCustomInfo _         => none
   | ofFVarAliasInfo _      => none
   | ofFieldRedeclInfo _    => none
-  | ofDelabTermInfo i      => some i.toElabInfo
+  | ofOmissionInfo i       => some i.toElabInfo
   | ofChoiceInfo i         => some i.toElabInfo
 
 /--

src/Lean/Elab/InfoTree/Types.lean

@@ -5,7 +5,7 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Wojciech Nawrocki, Leonardo de Moura, Sebastian Ullrich
 -/
 prelude
-import Lean.Data.DeclarationRange
+import Lean.Data.Position
 import Lean.Data.OpenDecl
 import Lean.MetavarContext
 import Lean.Environment
@@ -168,22 +168,14 @@ structure FieldRedeclInfo where
   stx : Syntax
 
 /--
-Denotes TermInfo with additional configurations to control interactions with delaborated terms.
-
-For example, the omission term `⋯` that is emitted by the delaborator when omitting a term
-due to `pp.deepTerms false` or `pp.proofs false` uses this.
-Omission needs to be treated differently from regular terms because
+Denotes information for the term `⋯` that is emitted by the delaborator when omitting a term
+due to `pp.deepTerms false` or `pp.proofs false`. Omission needs to be treated differently from regular terms because
 it has to be delaborated differently in `Lean.Widget.InteractiveDiagnostics.infoToInteractive`:
 Regular terms are delaborated explicitly, whereas omitted terms are simply to be expanded with
-regular delaboration settings. Additionally, omissions come with a reason for omission.
+regular delaboration settings.
 -/
-structure DelabTermInfo extends TermInfo where
-  /-- A source position to use for "go to definition", to override the default. -/
-  location? : Option DeclarationLocation := none
-  /-- Text to use to override the docstring. -/
-  docString? : Option String := none
-  /-- Whether to use explicit mode when pretty printing the term on hover. -/
-  explicit : Bool := true
+structure OmissionInfo extends TermInfo where
+  reason : String
 
 /--
 Indicates that all overloaded elaborators failed. The subtrees of a `ChoiceInfo` node are the
@@ -206,7 +198,7 @@ inductive Info where
   | ofCustomInfo (i : CustomInfo)
   | ofFVarAliasInfo (i : FVarAliasInfo)
   | ofFieldRedeclInfo (i : FieldRedeclInfo)
-  | ofDelabTermInfo (i : DelabTermInfo)
+  | ofOmissionInfo (i : OmissionInfo)
   | ofChoiceInfo (i : ChoiceInfo)
   deriving Inhabited