fix: remove private from private section

This PR adds warnings when registering `@[simp]` theorems whose
left-hand side has a problematic head symbol in the discrimination tree:

- **Variable head** (`.star` key): The theorem will be tried on every
`simp` step, which can be expensive. The warning notes this may be
acceptable for `local` or `scoped` simp lemmas. Controlled by
`warning.simp.varHead` (default: `true`).
- **Unrecognized head** (`.other` key, e.g. a lambda expression): The
theorem is unlikely to ever be applied by `simp`. Controlled by
`warning.simp.otherHead` (default: `true`).

.claude/CLAUDE.md

@@ -7,11 +7,6 @@ To build Lean you should use `make -j$(nproc) -C build/release`.
 The build uses `ccache`, and in a sandbox `ccache` may complain about read-only file systems.
 Use `CCACHE_READONLY` and `CCACHE_TEMPDIR` instead of disabling ccache completely.
 
-To rebuild individual modules without a full build, use Lake directly:
-```
-cd src && lake build Init.Prelude
-```
-
 ## Running Tests
 
 See `tests/README.md` for full documentation. Quick reference:

src/Init/Data/Array/Lemmas.lean

@@ -3096,13 +3096,13 @@ theorem foldl_eq_foldlM {f : β → α → β} {b} {xs : Array α} {start stop :
 theorem foldr_eq_foldrM {f : α → β → β} {b} {xs : Array α} {start stop : Nat} :
     xs.foldr f b start stop = (xs.foldrM (m := Id) (pure <| f · ·) b start stop).run := rfl
 
-public theorem foldl_eq_foldl_extract {xs : Array α} {f : β → α → β} {init : β} :
+theorem foldl_eq_foldl_extract {xs : Array α} {f : β → α → β} {init : β} :
     xs.foldl (init := init) (start := start) (stop := stop) f =
       (xs.extract start stop).foldl (init := init) f := by
   simp only [foldl_eq_foldlM]
   rw [foldlM_start_stop]
 
-public theorem foldr_eq_foldr_extract {xs : Array α} {f : α → β → β} {init : β} :
+theorem foldr_eq_foldr_extract {xs : Array α} {f : α → β → β} {init : β} :
     xs.foldr (init := init) (start := start) (stop := stop) f =
       (xs.extract stop start).foldr (init := init) f := by
   simp only [foldr_eq_foldrM]

src/Init/Data/Array/Subarray.lean

@@ -80,7 +80,7 @@ instance : SliceSize (Internal.SubarrayData α) where
   size s := s.internalRepresentation.stop - s.internalRepresentation.start
 
 @[grind =, suggest_for Subarray.size]
-public theorem size_eq {xs : Subarray α} :
+theorem size_eq {xs : Subarray α} :
     xs.size = xs.stop - xs.start := by
   simp [Std.Slice.size, SliceSize.size, start, stop]
 

src/Init/Data/Int/Compare.lean

@@ -74,7 +74,7 @@ protected theorem isGE_compare {a b : Int} :
   rw [← Int.compare_swap, Ordering.isGE_swap]
   exact Int.isLE_compare
 
-public instance : Std.LawfulOrderOrd Int where
+instance : Std.LawfulOrderOrd Int where
   isLE_compare _ _ := Int.isLE_compare
   isGE_compare _ _ := Int.isGE_compare
 

src/Init/Data/Iterators/Basic.lean

@@ -42,29 +42,29 @@ The conversion functions {name (scope := "Init.Data.Iterators.Basic")}`Shrink.de
 {name (scope := "Init.Data.Iterators.Basic")}`Shrink.inflate` form an equivalence between
 {name}`α` and {lean}`Shrink α`, but this equivalence is intentionally not definitional.
 -/
-public def Shrink (α : Type u) : Type u := Internal.idOpaque.1 α
+def Shrink (α : Type u) : Type u := Internal.idOpaque.1 α
 
 /-- Converts elements of {name}`α` into elements of {lean}`Shrink α`. -/
 @[always_inline]
-public def Shrink.deflate {α} (x : α) : Shrink α :=
+def Shrink.deflate {α} (x : α) : Shrink α :=
   cast (by simp [Shrink, Internal.idOpaque.property]) x
 
 /-- Converts elements of {lean}`Shrink α` into elements of {name}`α`. -/
 @[always_inline]
-public def Shrink.inflate {α} (x : Shrink α) : α :=
+def Shrink.inflate {α} (x : Shrink α) : α :=
   cast (by simp [Shrink, Internal.idOpaque.property]) x
 
 @[simp, grind =]
-public theorem Shrink.deflate_inflate {α} {x : Shrink α} :
+theorem Shrink.deflate_inflate {α} {x : Shrink α} :
     Shrink.deflate x.inflate = x := by
   simp [deflate, inflate]
 
 @[simp, grind =]
-public theorem Shrink.inflate_deflate {α} {x : α} :
+theorem Shrink.inflate_deflate {α} {x : α} :
     (Shrink.deflate x).inflate = x := by
   simp [deflate, inflate]
 
-public theorem Shrink.inflate_inj {α} {x y : Shrink α} :
+theorem Shrink.inflate_inj {α} {x y : Shrink α} :
     x.inflate = y.inflate ↔ x = y := by
   apply Iff.intro
   · intro h
@@ -72,7 +72,7 @@ public theorem Shrink.inflate_inj {α} {x y : Shrink α} :
   · rintro rfl
     rfl
 
-public theorem Shrink.deflate_inj {α} {x y : α} :
+theorem Shrink.deflate_inj {α} {x y : α} :
     Shrink.deflate x = Shrink.deflate y ↔ x = y := by
   apply Iff.intro
   · intro h

src/Init/Data/Iterators/Combinators/Monadic/Append.lean

@@ -190,7 +190,7 @@ def Append.instFinitenessRelation [Monad m] [Iterator α₁ m β] [Iterator α
       exact IterM.TerminationMeasures.Finite.rel_of_skip ‹_›
 
 @[no_expose]
-public instance Append.instFinite [Monad m] [Iterator α₁ m β] [Iterator α₂ m β]
+instance Append.instFinite [Monad m] [Iterator α₁ m β] [Iterator α₂ m β]
     [Finite α₁ m] [Finite α₂ m] : Finite (Append α₁ α₂ m β) m :=
   .of_finitenessRelation instFinitenessRelation
 

src/Init/Data/List/MinMax.lean

@@ -37,7 +37,7 @@ open Nat
 @[simp, grind =] theorem min?_nil [Min α] : ([] : List α).min? = none := rfl
 
 @[simp, grind =]
-public theorem min?_singleton [Min α] {x : α} : [x].min? = some x :=
+theorem min?_singleton [Min α] {x : α} : [x].min? = some x :=
   (rfl)
 
 -- We don't put `@[simp]` on `min?_cons'`,
@@ -52,7 +52,7 @@ theorem min?_cons' [Min α] {xs : List α} : (x :: xs).min? = some (foldl min x
   cases xs <;> simp [min?]
 
 @[simp, grind =]
-public theorem isSome_min?_iff [Min α] {xs : List α} : xs.min?.isSome ↔ xs ≠ [] := by
+theorem isSome_min?_iff [Min α] {xs : List α} : xs.min?.isSome ↔ xs ≠ [] := by
   cases xs <;> simp [min?]
 
 @[grind .]
@@ -247,7 +247,7 @@ theorem foldl_min_eq_min [Min α] [Std.IdempotentOp (min : α → α → α)] [S
 @[simp, grind =] theorem max?_nil [Max α] : ([] : List α).max? = none := rfl
 
 @[simp, grind =]
-public theorem max?_singleton [Max α] {x : α} : [x].max? = some x :=
+theorem max?_singleton [Max α] {x : α} : [x].max? = some x :=
   (rfl)
 
 -- We don't put `@[simp]` on `max?_cons'`,
@@ -262,7 +262,7 @@ theorem max?_cons' [Max α] {xs : List α} : (x :: xs).max? = some (foldl max x
   cases xs <;> simp [max?]
 
 @[simp, grind =]
-public theorem isSome_max?_iff [Max α] {xs : List α} : xs.max?.isSome ↔ xs ≠ [] := by
+theorem isSome_max?_iff [Max α] {xs : List α} : xs.max?.isSome ↔ xs ≠ [] := by
   cases xs <;> simp [max?]
 
 @[grind .]

src/Init/Data/Nat/Compare.lean

@@ -70,7 +70,7 @@ protected theorem isGE_compare {a b : Nat} :
   rw [← Nat.compare_swap, Ordering.isGE_swap]
   exact Nat.isLE_compare
 
-public instance : Std.LawfulOrderOrd Nat where
+instance : Std.LawfulOrderOrd Nat where
   isLE_compare _ _ := Nat.isLE_compare
   isGE_compare _ _ := Nat.isGE_compare
 

src/Init/Data/Option/Attach.lean

@@ -444,7 +444,7 @@ instance : MonadAttach Option where
   CanReturn x a := x = some a
   attach x := x.attach
 
-public instance : LawfulMonadAttach Option where
+instance : LawfulMonadAttach Option where
   map_attach {α} x := by simp [MonadAttach.attach]
   canReturn_map_imp {α P x a} := by
     cases x
@@ -455,7 +455,7 @@ end Option
 
 namespace OptionT
 
-public instance [Monad m] [MonadAttach m] [LawfulMonad m] [WeaklyLawfulMonadAttach m] :
+instance [Monad m] [MonadAttach m] [LawfulMonad m] [WeaklyLawfulMonadAttach m] :
     WeaklyLawfulMonadAttach (OptionT m) where
   map_attach {α} x := by
     apply OptionT.ext
@@ -466,7 +466,7 @@ public instance [Monad m] [MonadAttach m] [LawfulMonad m] [WeaklyLawfulMonadAtta
     | ⟨some a, _⟩ => simp [OptionT.pure, OptionT.mk]
     | ⟨none, _⟩ => simp
 
-public instance [Monad m] [MonadAttach m] [LawfulMonad m] [LawfulMonadAttach m] :
+instance [Monad m] [MonadAttach m] [LawfulMonad m] [LawfulMonadAttach m] :
     LawfulMonadAttach (OptionT m) where
   canReturn_map_imp {α P x a} h := by
     simp only [MonadAttach.CanReturn, OptionT.run_map] at h

src/Init/Data/Order/LemmasExtra.lean

@@ -152,7 +152,7 @@ public theorem max_eq_if_isGE_compare {α : Type u} [Ord α] [LE α] {_ : Max α
     {a b : α} : max a b = if (compare a b).isGE then a else b := by
   open Classical in simp [max_eq_if, isGE_compare]
 
-private theorem min_le_min [LE α] [Min α] [Std.LawfulOrderLeftLeaningMin α] [IsLinearOrder α] (a b : α) : min a b ≤ min b a := by
+theorem min_le_min [LE α] [Min α] [Std.LawfulOrderLeftLeaningMin α] [IsLinearOrder α] (a b : α) : min a b ≤ min b a := by
   apply (LawfulOrderInf.le_min_iff (min a b) b a).2
   rw [And.comm]
   by_cases h : a ≤ b

src/Init/Data/Range/Polymorphic/SInt.lean

@@ -248,11 +248,11 @@ instance : HasModel Int8 (BitVec 8) where
   le_iff_encode_le := by simp [LE.le, Int8.le]
   lt_iff_encode_lt := by simp [LT.lt, Int8.lt]
 
-private theorem succ?_eq_minValueSealed {x : Int8} :
+theorem succ?_eq_minValueSealed {x : Int8} :
     UpwardEnumerable.succ? x = if x + 1 = minValueSealed then none else some (x + 1) :=
   (rfl)
 
-private theorem succMany?_eq_maxValueSealed {i : Int8} :
+theorem succMany?_eq_maxValueSealed {i : Int8} :
     UpwardEnumerable.succMany? n i =
       have := i.minValue_le_toInt
       if h : i.toInt + n ≤ maxValueSealed.toInt then some (.ofIntLE _ (by omega) (maxValueSealed_def ▸ h)) else none :=
@@ -605,12 +605,12 @@ theorem minValueSealed_def : minValueSealed = ISize.minValue := (rfl)
 theorem maxValueSealed_def : maxValueSealed = ISize.maxValue := (rfl)
 seal minValueSealed maxValueSealed
 
-private theorem toBitVec_minValueSealed_eq_intMinSealed :
+theorem toBitVec_minValueSealed_eq_intMinSealed :
     minValueSealed.toBitVec = BitVec.Signed.intMinSealed System.Platform.numBits := by
   rw [minValueSealed_def, BitVec.Signed.intMinSealed_def, toBitVec_minValue]
   have := System.Platform.numBits_eq; generalize System.Platform.numBits = a at this ⊢
   rcases this with rfl | rfl <;> rfl
-private theorem toBitVec_maxValueSealed_eq_intMaxSealed :
+theorem toBitVec_maxValueSealed_eq_intMaxSealed :
     maxValueSealed.toBitVec = BitVec.Signed.intMaxSealed System.Platform.numBits := by
   rw [maxValueSealed_def, BitVec.Signed.intMaxSealed_def, toBitVec_maxValue]
   have := System.Platform.numBits_eq; generalize System.Platform.numBits = a at this ⊢

src/Init/Data/Slice/Array/Lemmas.lean

@@ -233,7 +233,7 @@ public theorem Subarray.toList_eq {xs : Subarray α} :
   simp [this, ListSlice.toList_eq, lslice]
 
 -- TODO: The current `List.extract_eq_drop_take` should be called `List.extract_eq_take_drop`
-private theorem Std.Internal.List.extract_eq_drop_take' {l : List α} {start stop : Nat} :
+theorem Std.Internal.List.extract_eq_drop_take' {l : List α} {start stop : Nat} :
     l.extract start stop = (l.take stop).drop start := by
   simp [List.take_drop]
   by_cases start ≤ stop

src/Init/Data/String/Decode.lean

@@ -94,7 +94,7 @@ public def String.utf8EncodeCharFast (c : Char) : List UInt8 :=
      (v >>>  6).toUInt8 &&& 0x3f ||| 0x80,
               v.toUInt8 &&& 0x3f ||| 0x80]
 
-private theorem Nat.add_two_pow_eq_or_of_lt {b : Nat} (i : Nat) (b_lt : b < 2 ^ i) (a : Nat) :
+theorem Nat.add_two_pow_eq_or_of_lt {b : Nat} (i : Nat) (b_lt : b < 2 ^ i) (a : Nat) :
     b + 2 ^ i * a = b ||| 2 ^ i * a := by
   rw [Nat.add_comm, Nat.or_comm, Nat.two_pow_add_eq_or_of_lt b_lt]
 

src/Lean/AuxRecursor.lean

@@ -56,11 +56,11 @@ def markSparseCasesOn (env : Environment) (declName : Name) : Environment :=
   sparseCasesOnExt.tag env declName
 
 /-- Is this a constructor elimination or a sparse casesOn? -/
-public def isSparseCasesOn (env : Environment) (declName : Name) : Bool :=
+def isSparseCasesOn (env : Environment) (declName : Name) : Bool :=
   sparseCasesOnExt.isTagged env declName
 
 /-- Is this a `.casesOn`, a constructor elimination or a sparse casesOn? -/
-public def isCasesOnLike (env : Environment) (declName : Name) : Bool :=
+def isCasesOnLike (env : Environment) (declName : Name) : Bool :=
   isCasesOnRecursor env declName || isSparseCasesOn env declName
 
 /--

src/Lean/Compiler/LCNF/EmitC.lean

@@ -774,7 +774,7 @@ where
 
 mutual
 
-private partial def emitBasicBlock (code : Code .impure) : EmitM Unit := do
+partial def emitBasicBlock (code : Code .impure) : EmitM Unit := do
   match code with
   | .jp (k := k) .. => emitBasicBlock k
   | .let decl k =>
@@ -896,7 +896,7 @@ where
   emitUnreach : EmitM Unit := do
     emitLn "lean_internal_panic_unreachable();"
 
-private partial def emitJoinPoints (code : Code .impure) : EmitM Unit := do
+partial def emitJoinPoints (code : Code .impure) : EmitM Unit := do
   match code with
   | .jp decl k =>
     emit decl.binderName; emitLn ":"
@@ -906,7 +906,7 @@ private partial def emitJoinPoints (code : Code .impure) : EmitM Unit := do
   | .sset (k := k) .. | .uset (k := k) .. | .oset (k := k) .. => emitJoinPoints k
   | .cases .. | .return .. | .jmp .. | .unreach .. => return ()
 
-private partial def emitCode (code : Code .impure) : EmitM Unit := do
+partial def emitCode (code : Code .impure) : EmitM Unit := do
   withEmitBlock do
     let declared ← declareVars code
     if declared then emitLn ""

src/Lean/Compiler/LCNF/EmitUtil.lean

@@ -12,7 +12,7 @@ import Lean.Compiler.InitAttr
 
 namespace Lean.Compiler.LCNF
 
-private structure CollectUsedDeclsState where
+structure CollectUsedDeclsState where
   visited : NameSet := {}
   localDecls : Array (Decl .impure) := #[]
   extSigs : Array (Signature .impure) := #[]

src/Lean/Compiler/LCNF/PublicDeclsExt.lean

@@ -29,7 +29,7 @@ public def mkOrderedDeclSetExt : IO (EnvExtension (List Name × NameSet)) :=
 /--
 Set of declarations to be exported to other modules; visibility shared by base/mono/IR phases.
 -/
-private builtin_initialize publicDeclsExt : EnvExtension (List Name × NameSet) ← mkOrderedDeclSetExt
+builtin_initialize publicDeclsExt : EnvExtension (List Name × NameSet) ← mkOrderedDeclSetExt
 
 public def isDeclPublic (env : Environment) (declName : Name) : Bool := Id.run do
   if !env.header.isModule then

src/Lean/Compiler/LCNF/ToExpr.lean

@@ -142,10 +142,10 @@ partial def Code.toExprM (code : Code pu) : ToExprM Expr := do
     return .letE `dummy (mkConst ``Unit) value body true
 end
 
-public def Code.toExpr (code : Code pu) (xs : Array FVarId := #[]) : Expr :=
+def Code.toExpr (code : Code pu) (xs : Array FVarId := #[]) : Expr :=
   run' code.toExprM xs
 
-public def FunDecl.toExpr (decl : FunDecl pu) (xs : Array FVarId := #[]) : Expr :=
+def FunDecl.toExpr (decl : FunDecl pu) (xs : Array FVarId := #[]) : Expr :=
   run' decl.toExprM xs
 
 end Lean.Compiler.LCNF

src/Lean/Compiler/LCNF/ToLCNF.lean

@@ -213,11 +213,22 @@ structure Context where
   -/
   expectedType : Option Expr
 
+/--
+Key for the LCNF translation cache. `ignoreNoncomputable` is part of the key
+because entries cached in irrelevant positions skip the `checkComputable`
+check and must not be reused in relevant positions.
+-/
+structure CacheKey where
+  expr : Expr
+  expectedType? : Option Expr
+  ignoreNoncomputable : Bool
+  deriving BEq, Hashable
+
 structure State where
   /-- Local context containing the original Lean types (not LCNF ones). -/
   lctx : LocalContext := {}
   /-- Cache from Lean regular expression to LCNF argument. -/
-  cache : PHashMap (Expr × Option Expr) (Arg .pure) := {}
+  cache : PHashMap CacheKey (Arg .pure) := {}
   /--
   Determines whether caching has been disabled due to finding a use of
   a constant marked with `never_extract`.
@@ -473,7 +484,9 @@ partial def toLCNF (e : Expr) (eType : Expr) : CompilerM (Code .pure) := do
 where
   visitCore (e : Expr) : M (Arg .pure) := withIncRecDepth do
     let eType? := (← read).expectedType
-    if let some arg := (← get).cache.find? (e, eType?) then
+    let ignoreNoncomputable := (← read).ignoreNoncomputable
+    let key : CacheKey := { expr := e, expectedType? := eType?, ignoreNoncomputable }
+    if let some arg := (← get).cache.find? key then
       return arg
     let r : Arg .pure ← match e with
       | .app ..      => visitApp e
@@ -485,7 +498,7 @@ where
       | .lit lit     => visitLit lit
       | .fvar fvarId => if (← get).toAny.contains fvarId then pure .erased else pure (.fvar fvarId)
       | .forallE .. | .mvar .. | .bvar .. | .sort ..  => unreachable!
-    modify fun s => if s.shouldCache then { s with cache := s.cache.insert (e, eType?) r } else s
+    modify fun s => if s.shouldCache then { s with cache := s.cache.insert key r } else s
     return r
 
   visit (e : Expr) : M (Arg .pure) := withIncRecDepth do

src/Lean/Compiler/ModPkgExt.lean

@@ -37,7 +37,7 @@ public def getStateByIdx? [Inhabited σ] (ext : ModuleEnvExtension σ) (env : En
 
 end ModuleEnvExtension
 
-private initialize modPkgExt : ModuleEnvExtension (Option PkgId) ←
+initialize modPkgExt : ModuleEnvExtension (Option PkgId) ←
   registerModuleEnvExtension (pure none)
 
 /-- Returns the package (if any) of an imported module (by its index). -/

src/Lean/Compiler/NameDemangling.lean

@@ -20,13 +20,13 @@ line parsing. Called from the C runtime via `@[export]` for backtrace display. -
 namespace Lean.Name.Demangle
 
 /-- `String.dropPrefix?` returning a `String` instead of a `Slice`. -/
-private def dropPrefix? (s : String) (pre : String) : Option String :=
+def dropPrefix? (s : String) (pre : String) : Option String :=
   (s.dropPrefix? pre).map (·.toString)
 
-private def isAllDigits (s : String) : Bool :=
+def isAllDigits (s : String) : Bool :=
   !s.isEmpty && s.all (·.isDigit)
 
-private def nameToNameParts (n : Name) : Array NamePart :=
+def nameToNameParts (n : Name) : Array NamePart :=
   go n [] |>.toArray
 where
   go : Name → List NamePart → List NamePart
@@ -34,17 +34,17 @@ where
     | .str pre s, acc => go pre (NamePart.str s :: acc)
     | .num pre n, acc => go pre (NamePart.num n :: acc)
 
-private def namePartsToName (parts : Array NamePart) : Name :=
+def namePartsToName (parts : Array NamePart) : Name :=
   parts.foldl (fun acc p =>
     match p with
     | .str s => acc.mkStr s
     | .num n => acc.mkNum n) .anonymous
 
 /-- Format name parts using `Name.toString` for correct escaping. -/
-private def formatNameParts (comps : Array NamePart) : String :=
+def formatNameParts (comps : Array NamePart) : String :=
   if comps.isEmpty then "" else (namePartsToName comps).toString
 
-private def matchSuffix (c : NamePart) : Option String :=
+def matchSuffix (c : NamePart) : Option String :=
   match c with
   | NamePart.str s =>
     if s == "_redArg" then some "arity↓"
@@ -58,12 +58,12 @@ private def matchSuffix (c : NamePart) : Option String :=
     else none
   | _ => none
 
-private def isSpecIndex (c : NamePart) : Bool :=
+def isSpecIndex (c : NamePart) : Bool :=
   match c with
   | NamePart.str s => (dropPrefix? s "spec_").any isAllDigits
   | _ => false
 
-private def stripPrivate (comps : Array NamePart) (start stop : Nat) :
+def stripPrivate (comps : Array NamePart) (start stop : Nat) :
     Nat × Bool :=
   if stop - start >= 3 && comps[start]? == some (NamePart.str "_private") then
     Id.run do
@@ -75,11 +75,11 @@ private def stripPrivate (comps : Array NamePart) (start stop : Nat) :
   else
     (start, false)
 
-private structure SpecEntry where
+structure SpecEntry where
   name : String
   flags : Array String
 
-private def processSpecContext (comps : Array NamePart) : SpecEntry := Id.run do
+def processSpecContext (comps : Array NamePart) : SpecEntry := Id.run do
   let mut begin_ := 0
   if comps.size >= 3 && comps[0]? == some (NamePart.str "_private") then
     for i in [1:comps.size] do
@@ -99,7 +99,7 @@ private def processSpecContext (comps : Array NamePart) : SpecEntry := Id.run do
       else parts := parts.push c
   { name := formatNameParts parts, flags }
 
-private def postprocessNameParts (components : Array NamePart) : String := Id.run do
+def postprocessNameParts (components : Array NamePart) : String := Id.run do
   if components.isEmpty then return ""
 
   let (privStart, isPrivate) := stripPrivate components 0 components.size
@@ -206,14 +206,14 @@ private def postprocessNameParts (components : Array NamePart) : String := Id.ru
 
   return result
 
-private def demangleBody (body : String) : String :=
+def demangleBody (body : String) : String :=
   let name := Name.demangle body
   postprocessNameParts (nameToNameParts name)
 
 /-- Split a `lp_`-prefixed symbol into (demangled body, package name).
 Tries each underscore as a split point; the first valid split (shortest single-component
 package where the remainder is a valid mangled name) is correct. -/
-private def demangleWithPkg (s : String) : Option (String × String) := do
+def demangleWithPkg (s : String) : Option (String × String) := do
   for ⟨pos, h⟩ in s.positions do
     if pos.get h == '_' && pos ≠ s.startPos then
       let nextPos := pos.next h
@@ -230,12 +230,12 @@ private def demangleWithPkg (s : String) : Option (String × String) := do
         return (demangleBody body, pkgName)
   none
 
-private def stripColdSuffix (s : String) : String × String :=
+def stripColdSuffix (s : String) : String × String :=
   match s.find? ".cold" with
   | some pos => (s.extract s.startPos pos, s.extract pos s.endPos)
   | none => (s, "")
 
-private def demangleCore (s : String) : Option String := do
+def demangleCore (s : String) : Option String := do
   -- _init_l_
   if let some body := dropPrefix? s "_init_l_" then
     if !body.isEmpty then return s!"[init] {demangleBody body}"
@@ -291,17 +291,17 @@ public def demangleSymbol (symbol : String) : Option String := do
   if coldSuffix.isEmpty then return result
   else return s!"{result} {coldSuffix}"
 
-private def skipWhile (s : String) (pos : s.Pos) (pred : Char → Bool) : s.Pos :=
+def skipWhile (s : String) (pos : s.Pos) (pred : Char → Bool) : s.Pos :=
   if h : pos = s.endPos then pos
   else if pred (pos.get h) then skipWhile s (pos.next h) pred
   else pos
 termination_by pos
 
-private def splitAt₂ (s : String) (p₁ p₂ : s.Pos) : String × String × String :=
+def splitAt₂ (s : String) (p₁ p₂ : s.Pos) : String × String × String :=
   (s.extract s.startPos p₁, s.extract p₁ p₂, s.extract p₂ s.endPos)
 
 /-- Extract the symbol from a backtrace line (Linux glibc or macOS format). -/
-private def extractSymbol (line : String) :
+def extractSymbol (line : String) :
     Option (String × String × String) :=
   tryLinux line |>.orElse (fun _ => tryMacOS line)
 where

src/Lean/Data/JsonRpc.lean

@@ -400,7 +400,7 @@ Namely:
 def parseMessageMetaData (input : String) : Except String MessageMetaData :=
   messageMetaDataParser input |>.run input
 
-public inductive MessageDirection where
+inductive MessageDirection where
   | clientToServer
   | serverToClient
   deriving Inhabited, FromJson, ToJson

src/Lean/DocString/Markdown.lean

@@ -43,14 +43,14 @@ public structure State where
   /-- Footnotes -/
   footnotes : Array (String × String) := #[]
 
-private def combineBlocks (prior current : String) :=
+def combineBlocks (prior current : String) :=
   if prior.isEmpty then current
   else if current.isEmpty then prior
   else if prior.endsWith "\n\n" then prior ++ current
   else if prior.endsWith "\n" then prior ++ "\n" ++ current
   else prior ++ "\n\n" ++ current
 
-private def State.endBlock (state : State) : State :=
+def State.endBlock (state : State) : State :=
   { state with
     priorBlocks :=
       combineBlocks state.priorBlocks state.currentBlock ++
@@ -60,13 +60,13 @@ private def State.endBlock (state : State) : State :=
     footnotes := #[]
   }
 
-private def State.render (state : State) : String :=
+def State.render (state : State) : String :=
   state.endBlock.priorBlocks
 
-private def State.push (state : State) (txt : String) : State :=
+def State.push (state : State) (txt : String) : State :=
   { state with currentBlock := state.currentBlock ++ txt }
 
-private def State.endsWith (state : State) (txt : String) : Bool :=
+def State.endsWith (state : State) (txt : String) : Bool :=
   state.currentBlock.endsWith txt || (state.currentBlock.isEmpty && state.priorBlocks.endsWith txt)
 
 end MarkdownM
@@ -150,7 +150,7 @@ public class MarkdownBlock (i : Type u) (b : Type v) where
 public instance : MarkdownBlock i Empty where
   toMarkdown := nofun
 
-private def escape (s : String) : String := Id.run do
+def escape (s : String) : String := Id.run do
   let mut s' := ""
   let mut iter := s.startPos
   while h : ¬iter.IsAtEnd do
@@ -163,7 +163,7 @@ private def escape (s : String) : String := Id.run do
 where
   isSpecial c := "*_`-+.!<>[]{}()#".any (· == c)
 
-private def quoteCode (str : String) : String := Id.run do
+def quoteCode (str : String) : String := Id.run do
   let mut longest := 0
   let mut current := 0
   let mut iter := str.startPos
@@ -179,7 +179,7 @@ private def quoteCode (str : String) : String := Id.run do
   let str := if str.startsWith "`" || str.endsWith "`" then " " ++ str ++ " " else str
   backticks ++ str ++ backticks
 
-private partial def trimLeft (inline : Inline i) : (String × Inline i) := go [inline]
+partial def trimLeft (inline : Inline i) : (String × Inline i) := go [inline]
 where
   go : List (Inline i) → String × Inline i
     | [] => ("", .empty)
@@ -194,7 +194,7 @@ where
     | .concat xs :: more => go (xs.toList ++ more)
     | here :: more => ("", here ++ .concat more.toArray)
 
-private partial def trimRight (inline : Inline i) : (Inline i × String) := go [inline]
+partial def trimRight (inline : Inline i) : (Inline i × String) := go [inline]
 where
   go : List (Inline i) → Inline i × String
     | [] => (.empty, "")
@@ -209,13 +209,13 @@ where
     | .concat xs :: more => go (xs.reverse.toList ++ more)
     | here :: more => (.concat more.toArray.reverse ++ here, "")
 
-private def trim (inline : Inline i) : (String × Inline i × String) :=
+def trim (inline : Inline i) : (String × Inline i × String) :=
   let (pre, more) := trimLeft inline
   let (mid, post) := trimRight more
   (pre, mid, post)
 
 open MarkdownM in
-private partial def inlineMarkdown [MarkdownInline i] : Inline i → MarkdownM Unit
+partial def inlineMarkdown [MarkdownInline i] : Inline i → MarkdownM Unit
   | .text s =>
     push (escape s)
   | .linebreak s => do
@@ -271,7 +271,7 @@ private partial def inlineMarkdown [MarkdownInline i] : Inline i → MarkdownM U
 public instance [MarkdownInline i] : ToMarkdown (Inline i) where
   toMarkdown inline := private inlineMarkdown inline
 
-private def quoteCodeBlock (indent : Nat) (str : String) : String := Id.run do
+def quoteCodeBlock (indent : Nat) (str : String) : String := Id.run do
   let mut longest := 2
   let mut current := 0
   let mut iter := str.startPos
@@ -292,7 +292,7 @@ private def quoteCodeBlock (indent : Nat) (str : String) : String := Id.run do
   backticks ++ "\n" ++ out ++ backticks ++ "\n"
 
 open MarkdownM in
-private partial def blockMarkdown [MarkdownInline i] [MarkdownBlock i b] : Block i b → MarkdownM Unit
+partial def blockMarkdown [MarkdownInline i] [MarkdownBlock i b] : Block i b → MarkdownM Unit
   | .para xs => do
     for i in xs do
       ToMarkdown.toMarkdown i
@@ -345,7 +345,7 @@ public instance [MarkdownInline i] [MarkdownBlock i b] : ToMarkdown (Block i b)
 
 open MarkdownM in
 open ToMarkdown in
-private partial def partMarkdown [MarkdownInline i] [MarkdownBlock i b] (level : Nat) (part : Part i b p) : MarkdownM Unit := do
+partial def partMarkdown [MarkdownInline i] [MarkdownBlock i b] (level : Nat) (part : Part i b p) : MarkdownM Unit := do
   push ("".pushn '#' (level + 1))
   push " "
   for i in part.title do

src/Lean/DocString/Parser.lean

@@ -18,7 +18,7 @@ open Lean.Doc.Syntax
 local instance : Coe Char ParserFn where
   coe := chFn
 
-private partial def atLeastAux (n : Nat) (p : ParserFn) : ParserFn := fun c s => Id.run do
+partial def atLeastAux (n : Nat) (p : ParserFn) : ParserFn := fun c s => Id.run do
   let iniSz  := s.stackSize
   let iniPos := s.pos
   let mut s  := p c s
@@ -30,7 +30,7 @@ private partial def atLeastAux (n : Nat) (p : ParserFn) : ParserFn := fun c s =>
     s := s.mkNode nullKind iniSz
   atLeastAux (n - 1) p c s
 
-private def atLeastFn (n : Nat) (p : ParserFn) : ParserFn := fun c s =>
+def atLeastFn (n : Nat) (p : ParserFn) : ParserFn := fun c s =>
   let iniSz  := s.stackSize
   let s := atLeastAux n p c s
   s.mkNode nullKind iniSz
@@ -40,9 +40,9 @@ A parser that does nothing.
 -/
 public def skipFn : ParserFn := fun _ s => s
 
-private def eatSpaces := takeWhileFn (· == ' ')
+def eatSpaces := takeWhileFn (· == ' ')
 
-private def repFn : Nat → ParserFn → ParserFn
+def repFn : Nat → ParserFn → ParserFn
   | 0, _ => skipFn
   | n+1, p => p >> repFn n p
 
@@ -55,7 +55,7 @@ partial def satisfyFn' (p : Char → Bool)
   else if p (c.get' i h) then s.next' c i h
   else s.mkUnexpectedError errorMsg
 
-private partial def atMostAux (n : Nat) (p : ParserFn) (msg : String) : ParserFn :=
+partial def atMostAux (n : Nat) (p : ParserFn) (msg : String) : ParserFn :=
   fun c s => Id.run do
     let iniSz  := s.stackSize
     let iniPos := s.pos
@@ -70,13 +70,13 @@ private partial def atMostAux (n : Nat) (p : ParserFn) (msg : String) : ParserFn
       s := s.mkNode nullKind iniSz
     atMostAux (n - 1) p msg c s
 
-private def atMostFn (n : Nat) (p : ParserFn) (msg : String) : ParserFn := fun c s =>
+def atMostFn (n : Nat) (p : ParserFn) (msg : String) : ParserFn := fun c s =>
   let iniSz  := s.stackSize
   let s := atMostAux n p msg c s
   s.mkNode nullKind iniSz
 
 /-- Like `satisfyFn`, but allows any escape sequence through -/
-private partial def satisfyEscFn (p : Char → Bool)
+partial def satisfyEscFn (p : Char → Bool)
     (errorMsg : String := "unexpected character") :
     ParserFn := fun c s =>
   let i := s.pos
@@ -89,7 +89,7 @@ private partial def satisfyEscFn (p : Char → Bool)
   else if p (c.get' i h) then s.next' c i h
   else s.mkUnexpectedError errorMsg
 
-private partial def takeUntilEscFn (p : Char → Bool) : ParserFn := fun c s =>
+partial def takeUntilEscFn (p : Char → Bool) : ParserFn := fun c s =>
   let i := s.pos
   if h : c.atEnd i then s
   else if c.get' i h == '\\' then
@@ -100,7 +100,7 @@ private partial def takeUntilEscFn (p : Char → Bool) : ParserFn := fun c s =>
   else if p (c.get' i h) then s
   else takeUntilEscFn p c (s.next' c i h)
 
-private partial def takeWhileEscFn (p : Char → Bool) : ParserFn := takeUntilEscFn (not ∘ p)
+partial def takeWhileEscFn (p : Char → Bool) : ParserFn := takeUntilEscFn (not ∘ p)
 
 /--
 Parses as `p`, but discards the result.
@@ -111,7 +111,7 @@ public def ignoreFn (p : ParserFn) : ParserFn := fun c s =>
   s'.shrinkStack iniSz
 
 
-private def withInfoSyntaxFn (p : ParserFn) (infoP : SourceInfo → ParserFn) : ParserFn := fun c s =>
+def withInfoSyntaxFn (p : ParserFn) (infoP : SourceInfo → ParserFn) : ParserFn := fun c s =>
   let iniSz := s.stxStack.size
   let startPos := s.pos
   let s := p c s
@@ -121,7 +121,7 @@ private def withInfoSyntaxFn (p : ParserFn) (infoP : SourceInfo → ParserFn) :
   let info     := SourceInfo.original leading startPos trailing stopPos
   infoP info c (s.shrinkStack iniSz)
 
-private def unescapeStr (str : String) : String := Id.run do
+def unescapeStr (str : String) : String := Id.run do
   let mut out := ""
   let mut iter := str.startPos
   while h : ¬iter.IsAtEnd do
@@ -135,7 +135,7 @@ private def unescapeStr (str : String) : String := Id.run do
       out := out.push c
   out
 
-private def asStringAux (quoted : Bool) (startPos : String.Pos.Raw) (transform : String → String) :
+def asStringAux (quoted : Bool) (startPos : String.Pos.Raw) (transform : String → String) :
     ParserFn := fun c s =>
   let stopPos  := s.pos
   let leading  := c.mkEmptySubstringAt startPos
@@ -156,26 +156,26 @@ public def asStringFn (p : ParserFn) (quoted := false) (transform : String → S
   if s.hasError then s
   else asStringAux quoted startPos transform c (s.shrinkStack iniSz)
 
-private def checkCol0Fn (errorMsg : String) : ParserFn := fun c s =>
+def checkCol0Fn (errorMsg : String) : ParserFn := fun c s =>
   let pos      := c.fileMap.toPosition s.pos
   if pos.column = 1 then s
   else s.mkError errorMsg
 
-private def _root_.Lean.Parser.ParserContext.currentColumn
+def _root_.Lean.Parser.ParserContext.currentColumn
     (c : ParserContext) (s : ParserState) : Nat :=
   c.fileMap.toPosition s.pos |>.column
 
-private def pushColumn : ParserFn := fun c s =>
+def pushColumn : ParserFn := fun c s =>
   let col := c.fileMap.toPosition s.pos |>.column
   s.pushSyntax <| Syntax.mkLit `column (toString col) (SourceInfo.synthetic s.pos s.pos)
 
-private def guardColumn (p : Nat → Bool) (message : String) : ParserFn := fun c s =>
+def guardColumn (p : Nat → Bool) (message : String) : ParserFn := fun c s =>
   if p (c.currentColumn s) then s else s.mkErrorAt message s.pos
 
-private def guardMinColumn (min : Nat) (description : String := s!"expected column at least {min}") : ParserFn :=
+def guardMinColumn (min : Nat) (description : String := s!"expected column at least {min}") : ParserFn :=
   guardColumn (· ≥ min) description
 
-private def withCurrentColumn (p : Nat → ParserFn) : ParserFn := fun c s =>
+def withCurrentColumn (p : Nat → ParserFn) : ParserFn := fun c s =>
   p (c.currentColumn s) c s
 
 
@@ -183,7 +183,7 @@ private def withCurrentColumn (p : Nat → ParserFn) : ParserFn := fun c s =>
 We can only start a nestable block if we're immediately after a newline followed by a sequence of
 nestable block openers
 -/
-private def onlyBlockOpeners : ParserFn := fun c s =>
+def onlyBlockOpeners : ParserFn := fun c s =>
   let position := c.fileMap.toPosition s.pos
   let lineStart := c.fileMap.lineStart position.line
   let ok : Bool := Id.run do
@@ -206,7 +206,7 @@ private def onlyBlockOpeners : ParserFn := fun c s =>
   if ok then s
   else s.mkErrorAt "beginning of line or sequence of nestable block openers" s.pos
 
-private def nl := satisfyFn (· == '\n') "newline"
+def nl := satisfyFn (· == '\n') "newline"
 
 /--
 Construct a “fake” atom with the given string content and source information.
@@ -225,13 +225,13 @@ current position.
 Normally, atoms are always substrings of the original input; however, Verso's concrete syntax is
 different enough from Lean's that this isn't always a good match.
 -/
-private def fakeAtomHere (str : String) : ParserFn :=
+def fakeAtomHere (str : String) : ParserFn :=
   withInfoSyntaxFn skip.fn (fun info => fakeAtom str (info := info))
 
-private def pushMissing : ParserFn := fun _c s =>
+def pushMissing : ParserFn := fun _c s =>
   s.pushSyntax .missing
 
-private def strFn (str : String) : ParserFn := asStringFn <| fun c s =>
+def strFn (str : String) : ParserFn := asStringFn <| fun c s =>
   let rec go (iter : str.Pos) (s : ParserState) :=
     if h : iter.IsAtEnd then s
     else
@@ -260,10 +260,10 @@ public instance : Ord OrderedListType where
     | .parenAfter, .numDot => .gt
     | .parenAfter, .parenAfter => .eq
 
-private def OrderedListType.all : List OrderedListType :=
+def OrderedListType.all : List OrderedListType :=
   [.numDot, .parenAfter]
 
-private theorem OrderedListType.all_complete : ∀ x : OrderedListType, x ∈ all := by
+theorem OrderedListType.all_complete : ∀ x : OrderedListType, x ∈ all := by
   unfold all; intro x; cases x <;> repeat constructor
 
 /--
@@ -288,40 +288,40 @@ public instance : Ord UnorderedListType where
     | .plus, .plus => .eq
     | .plus, _ => .gt
 
-private def UnorderedListType.all : List UnorderedListType :=
+def UnorderedListType.all : List UnorderedListType :=
   [.asterisk, .dash, .plus]
 
-private theorem UnorderedListType.all_complete : ∀ x : UnorderedListType, x ∈ all := by
+theorem UnorderedListType.all_complete : ∀ x : UnorderedListType, x ∈ all := by
   unfold all; intro x; cases x <;> repeat constructor
 
-private def unorderedListIndicator (type : UnorderedListType) : ParserFn :=
+def unorderedListIndicator (type : UnorderedListType) : ParserFn :=
   asStringFn <|
     match type with
     | .asterisk => chFn '*'
     | .dash => chFn '-'
     | .plus => chFn '+'
 
-private def orderedListIndicator (type : OrderedListType) : ParserFn :=
+def orderedListIndicator (type : OrderedListType) : ParserFn :=
   asStringFn <|
     takeWhile1Fn (·.isDigit) "digits" >>
     match type with
     | .numDot => chFn '.'
     | .parenAfter => chFn ')'
 
-private def blankLine : ParserFn :=
+def blankLine : ParserFn :=
   nodeFn `blankLine <| atomicFn <| asStringFn <| takeWhileFn (· == ' ') >> nl
 
-private def endLine : ParserFn :=
+def endLine : ParserFn :=
   ignoreFn <| atomicFn <| asStringFn <| takeWhileFn (· == ' ') >> eoiFn
 
-private def bullet := atomicFn (go UnorderedListType.all)
+def bullet := atomicFn (go UnorderedListType.all)
 where
   go
     | [] => fun _ s => s.mkError "no list type"
     | [x] => atomicFn (unorderedListIndicator x)
     | x :: xs => atomicFn (unorderedListIndicator x) <|> go xs
 
-private def numbering := atomicFn (go OrderedListType.all)
+def numbering := atomicFn (go OrderedListType.all)
 where
   go
     | [] => fun _ s => s.mkError "no list type"
@@ -374,7 +374,7 @@ public def inlineTextChar : ParserFn := fun c s =>
 /-- Return some inline text up to the next inline opener or the end of
 the line, whichever is first. Always consumes at least one
 logical character on success, taking escaping into account. -/
-private def inlineText : ParserFn :=
+def inlineText : ParserFn :=
   asStringFn (transform := unescapeStr) <| atomicFn inlineTextChar >> manyFn inlineTextChar
 
 /--
@@ -410,23 +410,23 @@ public def val : ParserFn := fun c s =>
     else
       s.mkError "expected identifier, string, or number"
 
-private def withCurrentStackSize (p : Nat → ParserFn) : ParserFn := fun c s =>
+def withCurrentStackSize (p : Nat → ParserFn) : ParserFn := fun c s =>
   p s.stxStack.size c s
 
 /-- Match the character indicated, pushing nothing to the stack in case of success -/
-private def skipChFn (c : Char) : ParserFn :=
+def skipChFn (c : Char) : ParserFn :=
   satisfyFn (· == c) c.toString
 
-private def skipToNewline : ParserFn :=
+def skipToNewline : ParserFn :=
     takeUntilFn (· == '\n')
 
-private def skipToSpace : ParserFn :=
+def skipToSpace : ParserFn :=
     takeUntilFn (· == ' ')
 
-private def skipRestOfLine : ParserFn :=
+def skipRestOfLine : ParserFn :=
     skipToNewline >> (eoiFn <|> nl)
 
-private def skipBlock : ParserFn :=
+def skipBlock : ParserFn :=
   skipToNewline >> manyFn nonEmptyLine >> takeWhileFn (· == '\n')
 where
   nonEmptyLine : ParserFn :=
@@ -444,7 +444,7 @@ public def recoverBlock (p : ParserFn) (final : ParserFn := skipFn) : ParserFn :
     ignoreFn skipBlock >> final
 
 -- Like `recoverBlock` but stores recovered errors at the original error position.
-private def recoverBlockAtErrPos (p : ParserFn) : ParserFn := fun c s =>
+def recoverBlockAtErrPos (p : ParserFn) : ParserFn := fun c s =>
   let s := p c s
   if let some msg := s.errorMsg then
     let errPos := s.pos
@@ -457,36 +457,36 @@ private def recoverBlockAtErrPos (p : ParserFn) : ParserFn := fun c s =>
       recoveredErrors := s.recoveredErrors.push (errPos, s'.stxStack, msg)}
   else s
 
-private def recoverBlockWith (stxs : Array Syntax) (p : ParserFn) : ParserFn :=
+def recoverBlockWith (stxs : Array Syntax) (p : ParserFn) : ParserFn :=
   recoverFn p fun rctx =>
     ignoreFn skipBlock >>
     show ParserFn from
       fun _ s => stxs.foldl (init := s.shrinkStack rctx.initialSize) (·.pushSyntax ·)
 
-private def recoverLine (p : ParserFn) : ParserFn :=
+def recoverLine (p : ParserFn) : ParserFn :=
   recoverFn p fun _ =>
     ignoreFn skipRestOfLine
 
-private def recoverWs (p : ParserFn) : ParserFn :=
+def recoverWs (p : ParserFn) : ParserFn :=
   recoverFn p fun _ =>
     ignoreFn <| takeUntilFn (fun c =>  c == ' ' || c == '\n')
 
-private def recoverNonSpace (p : ParserFn) : ParserFn :=
+def recoverNonSpace (p : ParserFn) : ParserFn :=
   recoverFn p fun rctx =>
     ignoreFn (takeUntilFn (fun c => c != ' ')) >>
     show ParserFn from
       fun _ s => s.shrinkStack rctx.initialSize
 
-private def recoverWsWith (stxs : Array Syntax) (p : ParserFn) : ParserFn :=
+def recoverWsWith (stxs : Array Syntax) (p : ParserFn) : ParserFn :=
   recoverFn p fun rctx =>
     ignoreFn <| takeUntilFn (fun c =>  c == ' ' || c == '\n') >>
     show ParserFn from
       fun _ s => stxs.foldl (init := s.shrinkStack rctx.initialSize) (·.pushSyntax ·)
 
-private def recoverEol (p : ParserFn) : ParserFn :=
+def recoverEol (p : ParserFn) : ParserFn :=
   recoverFn p fun _ => ignoreFn <| skipToNewline
 
-private def recoverEolWith (stxs : Array Syntax) (p : ParserFn) : ParserFn :=
+def recoverEolWith (stxs : Array Syntax) (p : ParserFn) : ParserFn :=
   recoverFn p fun rctx =>
     ignoreFn skipToNewline >>
     show ParserFn from
@@ -494,7 +494,7 @@ private def recoverEolWith (stxs : Array Syntax) (p : ParserFn) : ParserFn :=
 
 -- Like `recoverEol` but stores recovered errors at the original error position
 -- rather than the post-recovery position.
-private def recoverEolAtErrPos (p : ParserFn) : ParserFn := fun c s =>
+def recoverEolAtErrPos (p : ParserFn) : ParserFn := fun c s =>
   let s := p c s
   if let some msg := s.errorMsg then
     let errPos := s.pos
@@ -509,7 +509,7 @@ private def recoverEolAtErrPos (p : ParserFn) : ParserFn := fun c s =>
 
 -- Like `recoverEolWith` but stores recovered errors at the original error position
 -- rather than the post-recovery position.
-private def recoverEolWithAtErrPos (stxs : Array Syntax) (p : ParserFn) : ParserFn := fun c s =>
+def recoverEolWithAtErrPos (stxs : Array Syntax) (p : ParserFn) : ParserFn := fun c s =>
   let iniSz := s.stxStack.size
   let s := p c s
   if let some msg := s.errorMsg then
@@ -521,10 +521,10 @@ private def recoverEolWithAtErrPos (stxs : Array Syntax) (p : ParserFn) : Parser
       {s' with recoveredErrors := s.recoveredErrors.push (errPos, s'.stxStack, msg)}
   else s
 
-private def recoverSkip (p : ParserFn) : ParserFn :=
+def recoverSkip (p : ParserFn) : ParserFn :=
   recoverFn p fun _ => skipFn
 
-private def recoverSkipWith (stxs : Array Syntax) (p : ParserFn) : ParserFn :=
+def recoverSkipWith (stxs : Array Syntax) (p : ParserFn) : ParserFn :=
   recoverFn p fun rctx =>
     show ParserFn from
       fun _ s => stxs.foldl (init := s.shrinkStack rctx.initialSize) (·.pushSyntax ·)
@@ -535,7 +535,7 @@ def recoverHereWith (stxs : Array Syntax) (p : ParserFn) : ParserFn :=
     show ParserFn from
       fun _ s => stxs.foldl (init := s.restore rctx.initialSize rctx.initialPos) (·.pushSyntax ·)
 
-private def recoverHereWithKeeping (stxs : Array Syntax) (keep : Nat) (p : ParserFn) : ParserFn :=
+def recoverHereWithKeeping (stxs : Array Syntax) (keep : Nat) (p : ParserFn) : ParserFn :=
   recoverFn p fun rctx =>
     show ParserFn from
       fun _ s => stxs.foldl (init := s.restore (rctx.initialSize + keep) rctx.initialPos) (·.pushSyntax ·)
@@ -584,7 +584,7 @@ it's in a single-line context and whitespace may only be the space
 character. If it's `some N`, then newlines are allowed, but `N` is the
 minimum indentation column.
 -/
-private def nameArgWhitespace : (multiline : Option Nat) → ParserFn
+def nameArgWhitespace : (multiline : Option Nat) → ParserFn
   | none => eatSpaces
   | some n => takeWhileFn (fun c => c == ' ' || c == '\n') >> guardMinColumn n
 
@@ -598,7 +598,7 @@ each sub-parser of `delimitedInline` contributes a clear expected-token name, an
 unhelpful generic "unexpected" messages from inner parsers so that the more informative message
 from `inlineTextChar` survives error merging via `<|>`.
 -/
-private def expectedFn (msg : String) (p : ParserFn) : ParserFn := fun c s =>
+def expectedFn (msg : String) (p : ParserFn) : ParserFn := fun c s =>
   let iniPos := s.pos
   let s := p c s
   if s.hasError && s.pos == iniPos then
@@ -649,18 +649,18 @@ def linebreak (ctxt : InlineCtxt) : ParserFn :=
   else
     errorFn "Newlines not allowed here"
 
-private partial def notInLink (ctxt : InlineCtxt) : ParserFn := fun _ s =>
+partial def notInLink (ctxt : InlineCtxt) : ParserFn := fun _ s =>
   if ctxt.inLink then s.mkError "Already in a link" else s
 
 -- Like `satisfyFn (· == '\n')` but with a better error message that mentions what was expected.
-private def newlineOrUnexpected (msg : String) : ParserFn := fun c s =>
+def newlineOrUnexpected (msg : String) : ParserFn := fun c s =>
   let i := s.pos
   if h : c.atEnd i then s.mkEOIError
   else if c.get' i h == '\n' then s.next' c i h
   else s.mkUnexpectedError s!"unexpected '{c.get' i h}'" [msg]
 
 mutual
-  private partial def emphLike
+  partial def emphLike
     (name : SyntaxNodeKind) (char : Char) (what plural : String)
     (getter : InlineCtxt → Option Nat) (setter : InlineCtxt → Option Nat → InlineCtxt)
     (ctxt : InlineCtxt) : ParserFn :=
@@ -799,7 +799,7 @@ mutual
         nodeFn `str (asStringFn (quoted := true) (many1Fn (satisfyEscFn (fun c => c != ']' && c != '\n') "other than ']' or newline"))) >>
         strFn "]")
 
-  private partial def linkTarget : ParserFn := fun c s =>
+  partial def linkTarget : ParserFn := fun c s =>
     let s := (ref <|> url) c s
     if s.hasError then
       match s.errorMsg with
@@ -922,7 +922,7 @@ deriving Inhabited, Repr
 Finds the minimum column of the first non-whitespace character on each non-empty content line
 between `startPos` and `endPos`, returning `init` if no such line exists.
 -/
-private def minContentIndent (text : FileMap) (startPos endPos : String.Pos.Raw)
+def minContentIndent (text : FileMap) (startPos endPos : String.Pos.Raw)
     (init : Nat) : Nat := Id.run do
   let mut result := init
   let mut thisLineCol := 0
@@ -980,13 +980,13 @@ public def BlockCtxt.forDocString (text : FileMap)
       else text.source.rawEndPos
     { docStartPosition := text.toPosition pos, baseColumn }
 
-private def bol (ctxt : BlockCtxt) : ParserFn := fun c s =>
+def bol (ctxt : BlockCtxt) : ParserFn := fun c s =>
   let pos := c.fileMap.toPosition s.pos
   if pos.column ≤ ctxt.baseColumn then s
   else if pos.line == ctxt.docStartPosition.line && pos.column ≤ ctxt.docStartPosition.column then s
   else s.mkErrorAt s!"beginning of line at {pos}" s.pos
 
-private def bolThen (ctxt : BlockCtxt) (p : ParserFn) (description : String) : ParserFn := fun c s =>
+def bolThen (ctxt : BlockCtxt) (p : ParserFn) (description : String) : ParserFn := fun c s =>
   let position := c.fileMap.toPosition s.pos
   let positionOk :=
     position.column ≤ ctxt.baseColumn ||
@@ -1075,16 +1075,16 @@ public def lookaheadUnorderedListIndicator (ctxt : BlockCtxt) (p : UnorderedList
     if s.hasError then s.setPos iniPos
     else p type c (s.shrinkStack iniSz |>.setPos bulletPos)
 
-private def skipUntilDedent (indent : Nat) : ParserFn :=
+def skipUntilDedent (indent : Nat) : ParserFn :=
   skipRestOfLine >>
   manyFn (chFn ' ' >> takeWhileFn (· == ' ') >> guardColumn (· ≥ indent) s!"indentation at {indent}" >> skipRestOfLine)
 
-private def recoverUnindent (indent : Nat) (p : ParserFn) (finish : ParserFn := skipFn) :
+def recoverUnindent (indent : Nat) (p : ParserFn) (finish : ParserFn := skipFn) :
     ParserFn :=
   recoverFn p (fun _ => ignoreFn (skipUntilDedent indent) >> finish)
 
 
-private def blockSep := ignoreFn (manyFn blankLine >> optionalFn endLine)
+def blockSep := ignoreFn (manyFn blankLine >> optionalFn endLine)
 
 mutual
   /-- Parses a list item according to the current nesting context. -/

src/Lean/Elab/AutoBound.lean

@@ -74,7 +74,7 @@ def isValidAutoBoundLevelName (n : Name) (relaxed : Bool) : Bool :=
 /--
 Tracks extra context needed within the scope of `Lean.Elab.Term.withAutoBoundImplicit`
 -/
-public structure AutoBoundImplicitContext where
+structure AutoBoundImplicitContext where
   /--
   This always matches the `autoImplicit` option; it is duplicated here in
   order to support the behavior of the deprecated `Lean.Elab.Term.Context.autoImplicit`
@@ -95,7 +95,7 @@ instance : EmptyCollection AutoBoundImplicitContext where
 Pushes a new variable onto the autoImplicit context, indicating that it needs
 to be bound as an implicit parameter.
 -/
-public def AutoBoundImplicitContext.push (ctx : AutoBoundImplicitContext) (x : Expr) :=
+def AutoBoundImplicitContext.push (ctx : AutoBoundImplicitContext) (x : Expr) :=
   { ctx with boundVariables := ctx.boundVariables.push x }
 
 end Lean.Elab

src/Lean/Elab/BuiltinCommand.lean

@@ -116,8 +116,9 @@ private def checkEndHeader : Name → List Scope → Option Name
       addScope (isNewNamespace := false) (isNoncomputable := ncTk.isSome) (isPublic := publicTk.isSome) (isMeta := metaTk.isSome) (attrs := attrs) "" (← getCurrNamespace)
   | _                        => throwUnsupportedSyntax
 
-@[builtin_command_elab InternalSyntax.end_local_scope] def elabEndLocalScope : CommandElab := fun _ => do
-  setDelimitsLocal
+@[builtin_command_elab InternalSyntax.end_local_scope] def elabEndLocalScope : CommandElab := fun stx => do
+  let depth := stx[1].toNat
+  setDelimitsLocal depth
 
 /--
 Produces a `Name` composed of the names of at most the innermost `n` scopes in `ss`, truncating if an
@@ -528,7 +529,7 @@ open Lean.Parser.Command.InternalSyntax in
 @[builtin_macro Lean.Parser.Command.«in»] def expandInCmd : Macro
   | `($cmd₁ in%$tk $cmd₂) =>
     -- Limit ref variability for incrementality; see Note [Incremental Macros]
-    withRef tk `(section $cmd₁:command $endLocalScopeSyntax:command $cmd₂ end)
+    withRef tk `(section $cmd₁:command $(endLocalScopeSyntax 1):command $cmd₂ end)
   | _                 => Macro.throwUnsupported
 
 @[builtin_command_elab Parser.Command.addDocString] def elabAddDeclDoc : CommandElab := fun stx => do

src/Lean/Elab/BuiltinTerm.lean

@@ -314,6 +314,23 @@ private def mkSilentAnnotationIfHole (e : Expr) : TermElabM Expr := do
     return val
   | _ => panic! "resolveId? returned an unexpected expression"
 
+/--
+Rebuild a type application with fresh synthetic metavariables for instance-implicit arguments.
+Non-instance-implicit arguments are assigned from the original application's arguments.
+If the function is over-applied, extra arguments are preserved.
+-/
+private def resynthInstImplicitArgs (type : Expr) : TermElabM Expr := do
+  let fn := type.getAppFn
+  let args := type.getAppArgs
+  let (mvars, bis, _) ← forallMetaTelescope (← inferType fn)
+  for i in [:mvars.size] do
+    if bis[i]!.isInstImplicit then
+      mvars[i]!.mvarId!.assign (← mkInstMVar (← inferType mvars[i]!))
+    else
+      mvars[i]!.mvarId!.assign args[i]!
+  let args := mvars ++ args.drop mvars.size
+  instantiateMVars (mkAppN fn args)
+
 @[builtin_term_elab Lean.Parser.Term.inferInstanceAs] def elabInferInstanceAs : TermElab := fun stx expectedType? => do
   -- The type argument is the last child (works for both `inferInstanceAs T` and `inferInstanceAs <| T`)
   let typeStx := stx[stx.getNumArgs - 1]!
@@ -325,19 +342,21 @@ private def mkSilentAnnotationIfHole (e : Expr) : TermElabM Expr := do
       .note "`inferInstanceAs` requires full knowledge of the expected (\"target\") type to do its \
         instance translation. If you do not intend to transport instances between two types, \
         consider using `inferInstance` or `(inferInstance : expectedType)` instead.")
-  let type ← withSynthesize (postpone := .yes) <| elabType typeStx
-  -- Unify with expected type to resolve metavariables (e.g., `_` placeholders)
-  discard <| isDefEq type expectedType
+  let type ← withSynthesize do
+    let type ← elabType typeStx
+    -- Unify with expected type to resolve metavariables (e.g., `_` placeholders)
+    discard <| isDefEq type expectedType
+    return type
+  -- Re-infer instance-implicit args, so that synthesis is not influenced by the expected type's
+  -- instance choices.
+  let type ← withSynthesize <| resynthInstImplicitArgs type
   let type ← instantiateMVars type
-  -- Rebuild type with fresh synthetic mvars for instance-implicit args, so that
-  -- synthesis is not influenced by the expected type's instance choices.
-  let type ← abstractInstImplicitArgs type
   let inst ← synthInstance type
   let inst ← if backward.inferInstanceAs.wrap.get (← getOptions) then
     -- Wrap instance so its type matches the expected type exactly.
     let logCompileErrors := !(← read).isNoncomputableSection && !(← read).declName?.any (Lean.isNoncomputable (← getEnv))
     let isMeta := (← read).declName?.any (isMarkedMeta (← getEnv))
-    withNewMCtxDepth <| wrapInstance inst expectedType (logCompileErrors := logCompileErrors) (isMeta := isMeta)
+    wrapInstance inst expectedType (logCompileErrors := logCompileErrors) (isMeta := isMeta)
   else
     pure inst
   ensureHasType expectedType? inst

src/Lean/Elab/DeclModifiers.lean

@@ -7,11 +7,19 @@ module
 
 prelude
 public import Lean.DocString.Add
+public import Lean.Linter.Basic
 meta import Lean.Parser.Command
 
 public section
 
-namespace Lean.Elab
+namespace Lean
+
+register_builtin_option linter.redundantVisibility : Bool := {
+  defValue := false
+  descr := "warn on redundant `private`/`public` visibility modifiers"
+}
+
+namespace Elab
 
 /--
 Ensure the environment does not contain a declaration with name `declName`.
@@ -77,14 +85,30 @@ def Visibility.isInferredPublic (env : Environment) (v : Visibility) : Bool :=
   if env.isExporting || !env.header.isModule then !v.isPrivate else v.isPublic
 
 /-- Converts optional visibility syntax to a `Visibility` value. -/
-def elabVisibility [Monad m] [MonadError m] (vis? : Option (TSyntax ``Parser.Command.visibility)) :
-    m Visibility :=
+def elabVisibility [Monad m] [MonadError m] [MonadEnv m] [MonadOptions m] [MonadLog m]
+    [AddMessageContext m]
+    (vis? : Option (TSyntax ``Parser.Command.visibility)) :
+    m Visibility := do
+  let env ← getEnv
   match vis? with
   | none   => pure .regular
   | some v =>
     match v with
-    | `(Parser.Command.visibility| private) => pure .private
-    | `(Parser.Command.visibility| public) => pure .public
+    | `(Parser.Command.visibility| private) =>
+      if v.raw.getHeadInfo matches .original .. then  -- skip macro output
+        if env.header.isModule && !env.isExporting then
+          Linter.logLintIf linter.redundantVisibility v
+            m!"`private` has no effect in a `module` file outside `public section`; \
+            declarations are already `private` by default"
+      pure .private
+    | `(Parser.Command.visibility| public) =>
+      if v.raw.getHeadInfo matches .original .. then  -- skip macro output
+        if env.isExporting || !env.header.isModule then
+          Linter.logLintIf linter.redundantVisibility v
+            m!"`public` is the default visibility{
+              if env.header.isModule then " inside a `public section`" else ""
+            }; the modifier has no effect"
+      pure .public
     | _ => throwErrorAt v "unexpected visibility modifier"
 
 /-- Whether a declaration is default, partial or nonrec. -/

src/Lean/Elab/Declaration.lean

@@ -152,8 +152,9 @@ def expandNamespacedDeclaration : Macro := fun stx => do
   | some (ns, newStx) => do
     -- Limit ref variability for incrementality; see Note [Incremental Macros]
     let declTk := stx[1][0]
+    let depth := ns.getNumParts
     let ns := mkIdentFrom declTk ns
-    withRef declTk `(namespace $ns $endLocalScopeSyntax:command $(⟨newStx⟩) end $ns)
+    withRef declTk `(namespace $ns $(endLocalScopeSyntax depth):command $(⟨newStx⟩) end $ns)
   | none => Macro.throwUnsupported
 
 @[builtin_command_elab declaration, builtin_incremental]

src/Lean/Elab/Deriving/BEq.lean

@@ -172,7 +172,7 @@ def mkMatchNew (header : Header) (indVal : InductiveVal) (auxFunName : Name) : T
   if indVal.numCtors == 1 then
     `( $(mkCIdent casesOnSameCtorName) $x1:term $x2:term rfl $alts:term* )
   else
-    `( match decEq ($(mkCIdent ctorIdxName) $x1:ident) ($(mkCIdent ctorIdxName) $x2:ident) with
+    `( match Nat.decEq ($(mkCIdent ctorIdxName) $x1:ident) ($(mkCIdent ctorIdxName) $x2:ident) with
       | .isTrue h => $(mkCIdent casesOnSameCtorName) $x1:term $x2:term h $alts:term*
       | .isFalse _ => false)
 

src/Lean/Elab/DocString.lean

@@ -1038,19 +1038,19 @@ builtin_initialize registerBuiltinAttribute {
 }
 end
 
-private unsafe def codeSuggestionsUnsafe : TermElabM (Array (StrLit → DocM (Array CodeSuggestion))) := do
+unsafe def codeSuggestionsUnsafe : TermElabM (Array (StrLit → DocM (Array CodeSuggestion))) := do
   let names := (codeSuggestionExt.getState (← getEnv)) |>.toArray
   return (← names.mapM (evalConst _)) ++ (← builtinCodeSuggestions.get).map (·.2)
 
 @[implemented_by codeSuggestionsUnsafe]
-private opaque codeSuggestions : TermElabM (Array (StrLit → DocM (Array CodeSuggestion)))
+opaque codeSuggestions : TermElabM (Array (StrLit → DocM (Array CodeSuggestion)))
 
-private unsafe def codeBlockSuggestionsUnsafe : TermElabM (Array (StrLit → DocM (Array CodeBlockSuggestion))) := do
+unsafe def codeBlockSuggestionsUnsafe : TermElabM (Array (StrLit → DocM (Array CodeBlockSuggestion))) := do
   let names := (codeBlockSuggestionExt.getState (← getEnv)) |>.toArray
   return (← names.mapM (evalConst _)) ++ (← builtinCodeBlockSuggestions.get).map (·.2)
 
 @[implemented_by codeBlockSuggestionsUnsafe]
-private opaque codeBlockSuggestions : TermElabM (Array (StrLit → DocM (Array CodeBlockSuggestion)))
+opaque codeBlockSuggestions : TermElabM (Array (StrLit → DocM (Array CodeBlockSuggestion)))
 
 /--
 Resolves a name against `NameMap` that contains a list of builtin expanders, taking into account
@@ -1060,7 +1060,7 @@ resolution (`realizeGlobalConstNoOverload`) won't find them.
 
 This is called as a fallback when the identifier can't be resolved.
 -/
-private def resolveBuiltinDocName {α : Type} (builtins : NameMap α) (x : Name) : TermElabM (Option α) := do
+def resolveBuiltinDocName {α : Type} (builtins : NameMap α) (x : Name) : TermElabM (Option α) := do
   if let some v := builtins.get? x then return some v
 
   -- Builtins shouldn't require a prefix, as they're part of the language.
@@ -1089,7 +1089,7 @@ private def resolveBuiltinDocName {α : Type} (builtins : NameMap α) (x : Name)
 
   return none
 
-private unsafe def roleExpandersForUnsafe (roleName : Ident) :
+unsafe def roleExpandersForUnsafe (roleName : Ident) :
     TermElabM (Array (Name × (TSyntaxArray `inline → StateT (Array (TSyntax `doc_arg)) DocM (Inline ElabInline)))) := do
   let x? ←
     try some <$> realizeGlobalConstNoOverload roleName
@@ -1105,10 +1105,10 @@ private unsafe def roleExpandersForUnsafe (roleName : Ident) :
 
 
 @[implemented_by roleExpandersForUnsafe]
-private opaque roleExpandersFor (roleName : Ident) :
+opaque roleExpandersFor (roleName : Ident) :
   TermElabM (Array (Name × (TSyntaxArray `inline → StateT (Array (TSyntax `doc_arg)) DocM (Inline ElabInline))))
 
-private unsafe def codeBlockExpandersForUnsafe (codeBlockName : Ident) :
+unsafe def codeBlockExpandersForUnsafe (codeBlockName : Ident) :
     TermElabM (Array (Name × (StrLit → StateT (Array (TSyntax `doc_arg)) DocM (Block ElabInline ElabBlock)))) := do
   let x? ←
     try some <$> realizeGlobalConstNoOverload codeBlockName
@@ -1124,10 +1124,10 @@ private unsafe def codeBlockExpandersForUnsafe (codeBlockName : Ident) :
 
 
 @[implemented_by codeBlockExpandersForUnsafe]
-private opaque codeBlockExpandersFor (codeBlockName : Ident) :
+opaque codeBlockExpandersFor (codeBlockName : Ident) :
   TermElabM (Array (Name × (StrLit → StateT (Array (TSyntax `doc_arg)) DocM (Block ElabInline ElabBlock))))
 
-private unsafe def directiveExpandersForUnsafe (directiveName : Ident) :
+unsafe def directiveExpandersForUnsafe (directiveName : Ident) :
     TermElabM (Array (Name × (TSyntaxArray `block → StateT (Array (TSyntax `doc_arg)) DocM (Block ElabInline ElabBlock)))) := do
   let x? ←
     try some <$> realizeGlobalConstNoOverload directiveName
@@ -1142,10 +1142,10 @@ private unsafe def directiveExpandersForUnsafe (directiveName : Ident) :
     return hasBuiltin.toArray.flatten
 
 @[implemented_by directiveExpandersForUnsafe]
-private opaque directiveExpandersFor (directiveName : Ident) :
+opaque directiveExpandersFor (directiveName : Ident) :
   TermElabM (Array (Name × (TSyntaxArray `block → StateT (Array (TSyntax `doc_arg)) DocM (Block ElabInline ElabBlock))))
 
-private unsafe def commandExpandersForUnsafe (commandName : Ident) :
+unsafe def commandExpandersForUnsafe (commandName : Ident) :
     TermElabM (Array (Name × StateT (Array (TSyntax `doc_arg)) DocM (Block ElabInline ElabBlock))) := do
   let x? ←
     try some <$> realizeGlobalConstNoOverload commandName
@@ -1161,18 +1161,18 @@ private unsafe def commandExpandersForUnsafe (commandName : Ident) :
     return hasBuiltin.toArray.flatten
 
 @[implemented_by commandExpandersForUnsafe]
-private opaque commandExpandersFor (commandName : Ident) :
+opaque commandExpandersFor (commandName : Ident) :
   TermElabM (Array (Name × StateT (Array (TSyntax `doc_arg)) DocM (Block ElabInline ElabBlock)))
 
 
-private def mkArgVal (arg : TSyntax `arg_val) : DocM Term :=
+def mkArgVal (arg : TSyntax `arg_val) : DocM Term :=
   match arg with
   | `(arg_val|$n:ident) => pure n
   | `(arg_val|$n:num) => pure n
   | `(arg_val|$s:str) => pure s
   | _ => throwErrorAt arg "Didn't understand as argument value"
 
-private def mkArg (arg : TSyntax `doc_arg) : DocM (TSyntax ``Parser.Term.argument) := do
+def mkArg (arg : TSyntax `doc_arg) : DocM (TSyntax ``Parser.Term.argument) := do
   match arg with
   | `(doc_arg|$x:arg_val) =>
     let x ← mkArgVal x
@@ -1190,7 +1190,7 @@ private def mkArg (arg : TSyntax `doc_arg) : DocM (TSyntax ``Parser.Term.argumen
     `(Parser.Term.argument| ($x := $v))
   | _ => throwErrorAt arg "Didn't understand as argument"
 
-private def mkAppStx (name : Ident) (args : TSyntaxArray `doc_arg) : DocM Term := do
+def mkAppStx (name : Ident) (args : TSyntaxArray `doc_arg) : DocM Term := do
   return ⟨mkNode ``Parser.Term.app #[name, mkNullNode (← args.mapM mkArg)]⟩
 
 /--
@@ -1204,7 +1204,7 @@ register_builtin_option doc.verso.suggestions : Bool := {
 -- Normally, name suggestions should be provided relative to the current scope. But
 -- during bootstrapping, the names in question may not yet be defined, so builtin
 -- names need special handling.
-private def suggestionName (name : Name) : TermElabM Name := do
+def suggestionName (name : Name) : TermElabM Name := do
   let name' ←
     -- Builtin expander names never need namespacing
     if (← builtinDocRoles.get).contains name then pure (some name)
@@ -1241,7 +1241,7 @@ private def suggestionName (name : Name) : TermElabM Name := do
         -- Fall back to doing nothing
         pure name
 
-private def sortSuggestions (ss : Array Meta.Hint.Suggestion) : Array Meta.Hint.Suggestion :=
+def sortSuggestions (ss : Array Meta.Hint.Suggestion) : Array Meta.Hint.Suggestion :=
   let cmp : (x y : Meta.Tactic.TryThis.SuggestionText) → Bool
     | .string s1, .string s2 => s1 < s2
     | .string _, _ => true
@@ -1250,7 +1250,7 @@ private def sortSuggestions (ss : Array Meta.Hint.Suggestion) : Array Meta.Hint.
   ss.qsort (cmp ·.suggestion ·.suggestion)
 
 open Diff in
-private def mkSuggestion
+def mkSuggestion
     (ref : Syntax) (hintTitle : MessageData)
     (newStrings : Array (String × Option String × Option String)) :
     DocM MessageData := do
@@ -1281,7 +1281,7 @@ def nameOrBuiltinName [Monad m] [MonadEnv m] (x : Name) : m Name := do
 Finds registered expander names that `x` is a suffix of, for use in error message hints when the
 name is shadowed. Returns display names suitable for `mkSuggestion`.
 -/
-private def findShadowedNames {α : Type}
+def findShadowedNames {α : Type}
     (nonBuiltIns : NameMap (Array Name)) (builtins : NameMap α) (x : Name) :
     TermElabM (Array Name) := do
   if x.isAnonymous then return #[]
@@ -1303,7 +1303,7 @@ private def findShadowedNames {α : Type}
 /--
 Builds a hint for an "Unknown role/directive/..." error when the name might be shadowed.
 -/
-private def shadowedHint {α : Type}
+def shadowedHint {α : Type}
     (envEntries : NameMap (Array Name)) (builtins : NameMap α)
     (name : Ident) (kind : String) : DocM MessageData := do
   let candidates ← findShadowedNames envEntries builtins name.getId
@@ -1316,7 +1316,7 @@ Throws an appropriate error for an unknown doc element (role/directive/code bloc
 Distinguishes "name resolves but isn't registered" from "name doesn't resolve at all",
 and includes shadowed-name suggestions when applicable.
 -/
-private def throwUnknownDocElem {α β : Type}
+def throwUnknownDocElem {α β : Type}
     (envEntries : NameMap (Array Name)) (builtins : NameMap α)
     (name : Ident) (kind : String) : DocM β := do
   let hint ← shadowedHint envEntries builtins name kind
@@ -1545,12 +1545,12 @@ where
   withSpace (s : String) : String :=
     if s.endsWith " " then s else s ++ " "
 
-private def takeFirst? (xs : Array α) : Option (α × Array α) :=
+def takeFirst? (xs : Array α) : Option (α × Array α) :=
   if h : xs.size > 0 then
     some (xs[0], xs.extract 1)
   else none
 
-private partial def elabBlocks' (level : Nat) :
+partial def elabBlocks' (level : Nat) :
     StateT (TSyntaxArray `block) DocM (Array (Block ElabInline ElabBlock) × Array (Part ElabInline ElabBlock Empty)) := do
   let mut pre := #[]
   let mut sub := #[]
@@ -1586,7 +1586,7 @@ private partial def elabBlocks' (level : Nat) :
       break
   return (pre, sub)
 
-private def elabModSnippet'
+def elabModSnippet'
     (range : DeclarationRange) (level : Nat) (blocks : TSyntaxArray `block) :
     DocM VersoModuleDocs.Snippet := do
   let mut snippet : VersoModuleDocs.Snippet := {
@@ -1616,7 +1616,7 @@ private def elabModSnippet'
         snippet := snippet.addBlock (← elabBlock b)
   return snippet
 
-private partial def fixupInline (inl : Inline ElabInline) : DocM (Inline ElabInline) := do
+partial def fixupInline (inl : Inline ElabInline) : DocM (Inline ElabInline) := do
   match inl with
   | .concat xs => .concat <$> xs.mapM fixupInline
   | .emph xs => .emph <$> xs.mapM fixupInline
@@ -1663,7 +1663,7 @@ private partial def fixupInline (inl : Inline ElabInline) : DocM (Inline ElabInl
         return .empty
     | _ => .other i <$> xs.mapM fixupInline
 
-private partial def fixupBlock (block : Block ElabInline ElabBlock) : DocM (Block ElabInline ElabBlock) := do
+partial def fixupBlock (block : Block ElabInline ElabBlock) : DocM (Block ElabInline ElabBlock) := do
   match block with
   | .para xs => .para <$> xs.mapM fixupInline
   | .concat xs => .concat <$> xs.mapM fixupBlock
@@ -1677,7 +1677,7 @@ private partial def fixupBlock (block : Block ElabInline ElabBlock) : DocM (Bloc
   | .code s => pure (.code s)
   | .other i xs => .other i <$> xs.mapM fixupBlock
 
-private partial def fixupPart (part : Part ElabInline ElabBlock Empty) : DocM (Part ElabInline ElabBlock Empty) := do
+partial def fixupPart (part : Part ElabInline ElabBlock Empty) : DocM (Part ElabInline ElabBlock Empty) := do
   return { part with
     title := ← part.title.mapM fixupInline
     content := ← part.content.mapM fixupBlock,
@@ -1685,13 +1685,13 @@ private partial def fixupPart (part : Part ElabInline ElabBlock Empty) : DocM (P
   }
 
 
-private partial def fixupBlocks : (Array (Block ElabInline ElabBlock) × Array (Part ElabInline ElabBlock Empty)) → DocM (Array (Block ElabInline ElabBlock) × Array (Part ElabInline ElabBlock Empty))
+partial def fixupBlocks : (Array (Block ElabInline ElabBlock) × Array (Part ElabInline ElabBlock Empty)) → DocM (Array (Block ElabInline ElabBlock) × Array (Part ElabInline ElabBlock Empty))
   | (bs, ps) => do
     let bs ← bs.mapM fixupBlock
     let ps ← ps.mapM fixupPart
     return (bs, ps)
 
-private partial def fixupSnippet (snippet : VersoModuleDocs.Snippet) : DocM VersoModuleDocs.Snippet := do
+partial def fixupSnippet (snippet : VersoModuleDocs.Snippet) : DocM VersoModuleDocs.Snippet := do
   return {snippet with
     text := ← snippet.text.mapM fixupBlock,
     sections := ← snippet.sections.mapM fun (level, range, content) => do
@@ -1700,7 +1700,7 @@ private partial def fixupSnippet (snippet : VersoModuleDocs.Snippet) : DocM Vers
 /--
 After fixing up the references, check to see which were not used and emit a suitable warning.
 -/
-private def warnUnusedRefs : DocM Unit := do
+def warnUnusedRefs : DocM Unit := do
   for (_, {location, seen, ..}) in (← getThe InternalState).urls do
     unless seen do
       logWarningAt location "Unused URL"

src/Lean/Elab/DocString/Builtin/Keywords.lean

@@ -31,7 +31,7 @@ structure Data.Atom where
 deriving TypeName
 
 
-private def onlyCode [Monad m] [MonadError m] (xs : TSyntaxArray `inline) : m StrLit := do
+def onlyCode [Monad m] [MonadError m] (xs : TSyntaxArray `inline) : m StrLit := do
   if h : xs.size = 1 then
     match xs[0] with
     | `(inline|code($s)) => return s
@@ -43,7 +43,7 @@ private def onlyCode [Monad m] [MonadError m] (xs : TSyntaxArray `inline) : m St
 /--
 Checks whether a syntax descriptor's value contains the given atom.
 -/
-private partial def containsAtom (e : Expr) (atom : String) : MetaM Bool := do
+partial def containsAtom (e : Expr) (atom : String) : MetaM Bool := do
   let rec attempt (p : Expr) (tryWhnf : Bool) : MetaM Bool := do
     match p.getAppFnArgs with
     | (``ParserDescr.node, #[_, _, p]) => containsAtom p atom
@@ -67,7 +67,7 @@ private partial def containsAtom (e : Expr) (atom : String) : MetaM Bool := do
 Checks whether a syntax descriptor's value contains the given atom. If so, the residual value after
 the atom is returned.
 -/
-private partial def containsAtom' (e : Expr) (atom : String) : MetaM (Option Expr) := do
+partial def containsAtom' (e : Expr) (atom : String) : MetaM (Option Expr) := do
   let rec attempt (p : Expr) (tryWhnf : Bool) : MetaM (Option Expr) := do
     match p.getAppFnArgs with
     | (``ParserDescr.node, #[_, _, p]) => containsAtom' p atom
@@ -92,7 +92,7 @@ private partial def containsAtom' (e : Expr) (atom : String) : MetaM (Option Exp
     | _ => if tryWhnf then attempt (← Meta.whnf p) false else pure none
   attempt e true
 
-private partial def canEpsilon (e : Expr) : MetaM Bool := do
+partial def canEpsilon (e : Expr) : MetaM Bool := do
   let rec attempt (p : Expr) (tryWhnf : Bool) : MetaM Bool := do
     match p.getAppFnArgs with
     | (``ParserDescr.node, #[_, _, p]) => canEpsilon p
@@ -118,7 +118,7 @@ private partial def canEpsilon (e : Expr) : MetaM Bool := do
 Checks whether a syntax descriptor's value begins with the given atom. If so, the residual value
 after the atom is returned.
 -/
-private partial def startsWithAtom? (e : Expr) (atom : String) : MetaM (Option Expr) := do
+partial def startsWithAtom? (e : Expr) (atom : String) : MetaM (Option Expr) := do
   let rec attempt (p : Expr) (tryWhnf : Bool) : MetaM (Option Expr) := do
     match p.getAppFnArgs with
     | (``ParserDescr.node, #[_, _, p]) => startsWithAtom? p atom
@@ -149,7 +149,7 @@ private partial def startsWithAtom? (e : Expr) (atom : String) : MetaM (Option E
 Checks whether a syntax descriptor's value begins with the given atoms. If so, the residual value
 after the atoms is returned.
 -/
-private partial def startsWithAtoms? (e : Expr) (atoms : List String) : MetaM (Option Expr) := do
+partial def startsWithAtoms? (e : Expr) (atoms : List String) : MetaM (Option Expr) := do
   match atoms with
   | [] => pure e
   | a :: as =>
@@ -157,7 +157,7 @@ private partial def startsWithAtoms? (e : Expr) (atoms : List String) : MetaM (O
       startsWithAtoms? e' as
     else pure none
 
-private partial def exprContainsAtoms (e : Expr) (atoms : List String) : MetaM Bool := do
+partial def exprContainsAtoms (e : Expr) (atoms : List String) : MetaM Bool := do
   match atoms with
   | [] => pure true
   | a :: as =>
@@ -165,7 +165,7 @@ private partial def exprContainsAtoms (e : Expr) (atoms : List String) : MetaM B
       (startsWithAtoms? e' as <&> Option.isSome) <||> exprContainsAtoms e' (a :: as)
     else pure false
 
-private def withAtom (cat : Name) (atom : String) : DocM (Array Name) := do
+def withAtom (cat : Name) (atom : String) : DocM (Array Name) := do
   let env ← getEnv
   let some catContents := (Lean.Parser.parserExtension.getState env).categories.find? cat
     | return #[]
@@ -177,7 +177,7 @@ private def withAtom (cat : Name) (atom : String) : DocM (Array Name) := do
         found := found.push k
   return found
 
-private partial def isAtoms (atoms : List String) (stx : Syntax) : Bool :=
+partial def isAtoms (atoms : List String) (stx : Syntax) : Bool :=
   StateT.run (go [stx]) atoms |>.fst
 where
   go (stxs : List Syntax) : StateM (List String) Bool := do
@@ -196,7 +196,7 @@ where
       | .node _ _ args :: ss =>
         go (args.toList ++ ss)
 
-private def parserHasAtomPrefix (atoms : List String) (p : Parser) : TermElabM Bool := do
+def parserHasAtomPrefix (atoms : List String) (p : Parser) : TermElabM Bool := do
   let str := " ".intercalate atoms
   let env ← getEnv
   let options ← getOptions
@@ -206,16 +206,16 @@ private def parserHasAtomPrefix (atoms : List String) (p : Parser) : TermElabM B
   let s := p.fn.run {inputString := str, fileName := "", fileMap := FileMap.ofString str} {env, options} (getTokenTable env) s
   return isAtoms atoms (mkNullNode (s.stxStack.extract 1 s.stxStack.size))
 
-private unsafe def namedParserHasAtomPrefixUnsafe (atoms : List String) (parserName : Name) : TermElabM Bool := do
+unsafe def namedParserHasAtomPrefixUnsafe (atoms : List String) (parserName : Name) : TermElabM Bool := do
   try
     let p ← evalConstCheck Parser ``Parser parserName
     parserHasAtomPrefix atoms p
   catch | _ => pure false
 
 @[implemented_by namedParserHasAtomPrefixUnsafe]
-private opaque namedParserHasAtomPrefix (atoms : List String) (parserName : Name) : TermElabM Bool
+opaque namedParserHasAtomPrefix (atoms : List String) (parserName : Name) : TermElabM Bool
 
-private def parserDescrCanEps : ParserDescr → Bool
+def parserDescrCanEps : ParserDescr → Bool
   | .node _ _ p | .trailingNode _ _ _ p => parserDescrCanEps p
   | .binary ``Parser.andthen p1 p2 => parserDescrCanEps p1 && parserDescrCanEps p2
   | .binary ``Parser.orelse p1 p2 => parserDescrCanEps p1 || parserDescrCanEps p2
@@ -227,7 +227,7 @@ private def parserDescrCanEps : ParserDescr → Bool
   | .const ``Parser.ppHardSpace => true
   | _ => false
 
-private def parserDescrHasAtom (atom : String) (p : ParserDescr) : TermElabM (Option ParserDescr) := do
+def parserDescrHasAtom (atom : String) (p : ParserDescr) : TermElabM (Option ParserDescr) := do
   match p with
   | .node _ _ p | .trailingNode _ _ _ p | .unary _ p =>
     parserDescrHasAtom atom p
@@ -249,7 +249,7 @@ private def parserDescrHasAtom (atom : String) (p : ParserDescr) : TermElabM (Op
     | none, none => pure none
   | _ => pure none
 
-private def parserDescrStartsWithAtom (atom : String) (p : ParserDescr) : TermElabM (Option ParserDescr) := do
+def parserDescrStartsWithAtom (atom : String) (p : ParserDescr) : TermElabM (Option ParserDescr) := do
   match p with
   | .node _ _ p | .trailingNode _ _ _ p | .unary _ p =>
     parserDescrStartsWithAtom atom p
@@ -272,7 +272,7 @@ private def parserDescrStartsWithAtom (atom : String) (p : ParserDescr) : TermEl
     | none, none => pure none
   | _ => pure none
 
-private def parserDescrStartsWithAtoms (atoms : List String) (p : ParserDescr) : TermElabM Bool := do
+def parserDescrStartsWithAtoms (atoms : List String) (p : ParserDescr) : TermElabM Bool := do
   match atoms with
   | [] => pure true
   | a :: as =>
@@ -280,7 +280,7 @@ private def parserDescrStartsWithAtoms (atoms : List String) (p : ParserDescr) :
       parserDescrStartsWithAtoms as p'
     else pure false
 
-private partial def parserDescrHasAtoms (atoms : List String) (p : ParserDescr) : TermElabM Bool := do
+partial def parserDescrHasAtoms (atoms : List String) (p : ParserDescr) : TermElabM Bool := do
   match atoms with
   | [] => pure true
   | a :: as =>
@@ -289,16 +289,16 @@ private partial def parserDescrHasAtoms (atoms : List String) (p : ParserDescr)
       else parserDescrHasAtoms (a :: as) p'
     else pure false
 
-private unsafe def parserDescrNameHasAtomsUnsafe (atoms : List String) (p : Name) : TermElabM Bool := do
+unsafe def parserDescrNameHasAtomsUnsafe (atoms : List String) (p : Name) : TermElabM Bool := do
   try
     let p ← evalConstCheck ParserDescr ``ParserDescr p
     parserDescrHasAtoms atoms p
   catch | _ => pure false
 
 @[implemented_by parserDescrNameHasAtomsUnsafe]
-private opaque parserDescrNameHasAtoms (atoms : List String) (p : Name) : TermElabM Bool
+opaque parserDescrNameHasAtoms (atoms : List String) (p : Name) : TermElabM Bool
 
-private def kindHasAtoms (k : Name) (atoms : List String) : TermElabM Bool := do
+def kindHasAtoms (k : Name) (atoms : List String) : TermElabM Bool := do
   let env ← getEnv
   if let some ci := env.find? k then
     if let some d := ci.value? then
@@ -312,7 +312,7 @@ private def kindHasAtoms (k : Name) (atoms : List String) : TermElabM Bool := do
         return true
   return false
 
-private def withAtoms (cat : Name) (atoms : List String) : TermElabM (Array Name) := do
+def withAtoms (cat : Name) (atoms : List String) : TermElabM (Array Name) := do
   let env ← getEnv
   let some catContents := (Lean.Parser.parserExtension.getState env).categories.find? cat
     | return #[]
@@ -323,7 +323,7 @@ private def withAtoms (cat : Name) (atoms : List String) : TermElabM (Array Name
       found := found.push k
   return found
 
-private def kwImpl (cat : Ident := mkIdent .anonymous) (of : Ident := mkIdent .anonymous)
+def kwImpl (cat : Ident := mkIdent .anonymous) (of : Ident := mkIdent .anonymous)
     (suggest : Bool)
     (s : StrLit) : TermElabM (Inline ElabInline) := do
   let atoms := s.getString |>.split Char.isWhitespace |>.toStringList

src/Lean/Elab/PreDefinition/Eqns.lean

@@ -55,7 +55,7 @@ def unfoldLHS (declName : Name) (mvarId : MVarId) : MetaM MVarId := mvarId.withC
     -- Else use delta reduction
     deltaLHS mvarId
 
-private partial def mkEqnProof (declName : Name) (type : Expr) : MetaM Expr := do
+partial def mkEqnProof (declName : Name) (type : Expr) : MetaM Expr := do
   withTraceNode `Elab.definition.eqns (fun _ => return m!"proving:{indentExpr type}") do
   withNewMCtxDepth do
     let main ← mkFreshExprSyntheticOpaqueMVar type
@@ -102,7 +102,7 @@ private partial def mkEqnProof (declName : Name) (type : Expr) : MetaM Expr := d
         else
           throwError "failed to generate equational theorem for `{.ofConstName declName}`\n{MessageData.ofGoal mvarId}"
 
-private def lhsDependsOn (type : Expr) (fvarId : FVarId) : MetaM Bool :=
+def lhsDependsOn (type : Expr) (fvarId : FVarId) : MetaM Bool :=
   forallTelescope type fun _ type => do
     if let some (_, lhs, _) ← matchEq? type then
       dependsOn lhs fvarId

src/Lean/ErrorExplanation.lean

@@ -73,19 +73,19 @@ def hasErrorExplanation [Monad m] [MonadEnv m] (name : Name) : m Bool :=
   return errorExplanationExt.getState (← getEnv) |>.contains name
 
 /-- Returns all error explanations with their names, sorted by name. -/
-public def getErrorExplanations [Monad m] [MonadEnv m] : m (Array (Name × ErrorExplanation)) := do
+def getErrorExplanations [Monad m] [MonadEnv m] : m (Array (Name × ErrorExplanation)) := do
   return errorExplanationExt.getState (← getEnv)
     |>.toArray
     |>.qsort fun e e' => e.1.toString < e'.1.toString
 
 @[deprecated getErrorExplanations (since := "2026-12-20")]
-public def getErrorExplanationsRaw (env : Environment) : Array (Name × ErrorExplanation) :=
+def getErrorExplanationsRaw (env : Environment) : Array (Name × ErrorExplanation) :=
   errorExplanationExt.getState env
     |>.toArray
     |>.qsort fun e e' => e.1.toString < e'.1.toString
 
 @[deprecated getErrorExplanations (since := "2026-12-20")]
-public def getErrorExplanationsSorted [Monad m] [MonadEnv m] : m (Array (Name × ErrorExplanation)) := do
+def getErrorExplanationsSorted [Monad m] [MonadEnv m] : m (Array (Name × ErrorExplanation)) := do
   getErrorExplanations
 
 end Lean

src/Lean/Linter.lean

@@ -19,3 +19,4 @@ public import Lean.Linter.Sets
 public import Lean.Linter.UnusedSimpArgs
 public import Lean.Linter.Coe
 public import Lean.Linter.GlobalAttributeIn
+public import Lean.Linter.EnvLinter

src/Lean/Linter/EnvLinter.lean

@@ -0,0 +1,10 @@
+/-
+Copyright (c) 2026 Lean FRO, LLC. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Wojciech Różowski
+-/
+module
+
+prelude
+public import Lean.Linter.EnvLinter.Basic
+public import Lean.Linter.EnvLinter.Frontend

src/Lean/Linter/EnvLinter/Basic.lean

@@ -0,0 +1,163 @@
+/-
+Copyright (c) 2026 Lean FRO, LLC. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Wojciech Różowski
+
+Copyright (c) 2020 Floris van Doorn. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Floris van Doorn, Robert Y. Lewis, Gabriel Ebner
+-/
+module
+
+prelude
+public import Lean.Structure
+public import Lean.Elab.InfoTree.Main
+import Lean.ExtraModUses
+
+public section
+
+open Lean Meta
+
+namespace Lean.Linter.EnvLinter
+
+/-!
+# Basic environment linter types and attributes
+
+This file defines the basic types and attributes used by the environment
+linting framework. An environment linter consists of a function
+`(declaration : Name) → MetaM (Option MessageData)`, this function together with some
+metadata is stored in the `EnvLinter` structure. We define two attributes:
+
+ * `@[builtin_env_linter]` applies to a declaration of type `EnvLinter`
+   and adds it to the default linter set.
+
+ * `@[builtin_nolint linterName]` omits the tagged declaration from being checked by
+   the linter with name `linterName`.
+-/
+
+/--
+Returns true if `decl` is an automatically generated declaration.
+
+Also returns true if `decl` is an internal name or created during macro
+expansion.
+-/
+def isAutoDecl (decl : Name) : CoreM Bool := do
+  if decl.hasMacroScopes then return true
+  if decl.isInternal then return true
+  let env ← getEnv
+  if isReservedName env decl then return true
+  if let Name.str n s := decl then
+    if (← isAutoDecl n) then return true
+    if s.startsWith "proof_"
+        || s.startsWith "match_"
+        || s.startsWith "unsafe_"
+        || s.startsWith "grind_"
+    then return true
+    if env.isConstructor n && s ∈ ["injEq", "inj", "sizeOf_spec", "elim", "noConfusion"] then
+      return true
+    if let ConstantInfo.inductInfo _ := env.find? n then
+      if s.startsWith "brecOn_" || s.startsWith "below_" then return true
+      if s ∈ [casesOnSuffix, recOnSuffix, brecOnSuffix, belowSuffix,
+          "ndrec", "ndrecOn", "noConfusionType", "noConfusion", "ofNat", "toCtorIdx", "ctorIdx",
+          "ctorElim", "ctorElimType"] then
+        return true
+      if let some _ := isSubobjectField? env n (.mkSimple s) then
+        return true
+    -- Coinductive/inductive lattice-theoretic predicates:
+    if let ConstantInfo.inductInfo _ := env.find? (Name.str n "_functor") then
+      if s == "functor_unfold" || s == casesOnSuffix || s == "mutual" then return true
+      if env.isConstructor (Name.str (Name.str n "_functor") s) then return true
+  pure false
+
+/-- An environment linting test for the `lake builtin-lint` command. -/
+structure EnvLinter where
+  /-- `test` defines a test to perform on every declaration. It should never fail. Returning `none`
+  signifies a passing test. Returning `some msg` reports a failing test with error `msg`. -/
+  test : Name → MetaM (Option MessageData)
+  /-- `noErrorsFound` is the message printed when all tests are negative -/
+  noErrorsFound : MessageData
+  /-- `errorsFound` is printed when at least one test is positive -/
+  errorsFound : MessageData
+  /-- If `isDefault` is false, this linter is only run when `--clippy` is passed. -/
+  isDefault := true
+
+/-- A `NamedEnvLinter` is an environment linter associated to a particular declaration. -/
+structure NamedEnvLinter extends EnvLinter where
+  /-- The name of the named linter. This is just the declaration name without the namespace. -/
+  name : Name
+  /-- The linter declaration name -/
+  declName : Name
+
+/-- Gets an environment linter by declaration name. -/
+def getEnvLinter (name declName : Name) : CoreM NamedEnvLinter := unsafe
+  return { ← evalConstCheck EnvLinter ``EnvLinter declName with name, declName }
+
+/-- Defines the `envLinterExt` extension for adding an environment linter to the default set. -/
+builtin_initialize envLinterExt :
+    SimplePersistentEnvExtension (Name × Bool) (NameMap (Name × Bool)) ←
+  let addEntryFn := fun m (n, b) => m.insert (n.updatePrefix .anonymous) (n, b)
+  registerSimplePersistentEnvExtension {
+    addImportedFn := fun nss =>
+      nss.foldl (init := {}) fun m ns => ns.foldl (init := m) addEntryFn
+    addEntryFn
+  }
+
+/--
+Defines the `@[builtin_env_linter]` attribute for adding a linter to the default set.
+The form `@[builtin_env_linter clippy]` will not add the linter to the default set,
+but it can be selected by `lake builtin-lint --clippy`.
+
+Linters are named using their declaration names, without the namespace. These must be distinct.
+-/
+syntax (name := builtin_env_linter) "builtin_env_linter" &" clippy"? : attr
+
+builtin_initialize registerBuiltinAttribute {
+  name := `builtin_env_linter
+  descr := "Use this declaration as a linting test in `lake builtin-lint`"
+  add   := fun decl stx kind => do
+    let dflt := stx[1].isNone
+    unless kind == .global do throwError "invalid attribute `builtin_env_linter`, must be global"
+    let shortName := decl.updatePrefix .anonymous
+    if let some (declName, _) := (envLinterExt.getState (← getEnv)).find? shortName then
+      Elab.addConstInfo stx declName
+      throwError
+        "invalid attribute `builtin_env_linter`, linter `{shortName}` has already been declared"
+    let isPublic := !isPrivateName decl; let isMeta := isMarkedMeta (← getEnv) decl
+    unless isPublic && isMeta do
+      throwError "invalid attribute `builtin_env_linter`, \
+        declaration `{.ofConstName decl}` must be marked as `public` and `meta`\
+        {if isPublic then " but is only marked `public`" else ""}\
+        {if isMeta then " but is only marked `meta`" else ""}"
+    let constInfo ← getConstInfo decl
+    unless ← (isDefEq constInfo.type (mkConst ``EnvLinter)).run' do
+      throwError "`{.ofConstName decl}` must have type `{.ofConstName ``EnvLinter}`, got \
+        `{constInfo.type}`"
+    modifyEnv fun env => envLinterExt.addEntry env (decl, dflt)
+}
+
+/-- `@[builtin_nolint linterName]` omits the tagged declaration from being checked by
+the linter with name `linterName`. -/
+syntax (name := builtin_nolint) "builtin_nolint" (ppSpace ident)+ : attr
+
+/-- Defines the user attribute `builtin_nolint` for skipping environment linters. -/
+builtin_initialize builtinNolintAttr : ParametricAttribute (Array Name) ←
+  registerParametricAttribute {
+    name := `builtin_nolint
+    descr := "Do not report this declaration in any of the tests of `lake builtin-lint`"
+    getParam := fun _ => fun
+      | `(attr| builtin_nolint $[$ids]*) => ids.mapM fun id => withRef id <| do
+        let shortName := id.getId.eraseMacroScopes
+        let some (declName, _) := (envLinterExt.getState (← getEnv)).find? shortName
+          | throwError "linter '{shortName}' not found"
+        Elab.addConstInfo id declName
+        recordExtraModUseFromDecl (isMeta := false) declName
+        pure shortName
+      | _ => Elab.throwUnsupportedSyntax
+  }
+
+/-- Returns true if `decl` should be checked
+using `linter`, i.e., if there is no `builtin_nolint` attribute. -/
+def shouldBeLinted [Monad m] [MonadEnv m] (linter : Name) (decl : Name) : m Bool :=
+  return !((builtinNolintAttr.getParam? (← getEnv) decl).getD #[]).contains linter
+
+end Lean.Linter.EnvLinter

src/Lean/Linter/EnvLinter/Frontend.lean

@@ -0,0 +1,180 @@
+/-
+Copyright (c) 2026 Lean FRO, LLC. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Wojciech Różowski
+
+Copyright (c) 2020 Floris van Doorn. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Floris van Doorn, Robert Y. Lewis, Gabriel Ebner
+-/
+module
+
+prelude
+public import Lean.Linter.EnvLinter.Basic
+import Lean.DeclarationRange
+import Lean.Util.Path
+import Lean.CoreM
+import Lean.Elab.Command
+
+public section
+
+open Lean Meta
+
+namespace Lean.Linter.EnvLinter
+
+/-- Verbosity for the linter output. -/
+inductive LintVerbosity
+  /-- `low`: only print failing checks, print nothing on success. -/
+  | low
+  /-- `medium`: only print failing checks, print confirmation on success. -/
+  | medium
+  /-- `high`: print output of every check. -/
+  | high
+  deriving Inhabited, DecidableEq, Repr
+
+/-- `getChecks clippy runOnly` produces a list of linters.
+`runOnly` is an optional list of names that should resolve to declarations with type
+`NamedEnvLinter`. If populated, only these linters are run (regardless of the default
+configuration). Otherwise, it uses all enabled linters in the environment tagged with
+`@[builtin_env_linter]`. If `clippy` is false, it only uses linters with `isDefault = true`. -/
+def getChecks (clippy : Bool) (runOnly : Option (List Name)) :
+    CoreM (Array NamedEnvLinter) := do
+  let mut result := #[]
+  for (name, declName, isDefault) in envLinterExt.getState (← getEnv) do
+    let shouldRun := match runOnly with
+      | some only => only.contains name
+      | none => clippy || isDefault
+    if shouldRun then
+      let linter ← getEnvLinter name declName
+      result := result.binInsert (·.name.lt ·.name) linter
+  pure result
+
+
+/--
+Runs all the specified linters on all the specified declarations in parallel,
+producing a list of results.
+-/
+def lintCore (decls : Array Name) (linters : Array NamedEnvLinter) :
+    CoreM (Array (NamedEnvLinter × Std.HashMap Name MessageData)) := do
+  let tasks : Array (NamedEnvLinter × Array (Name × Task (Except Exception <| Option MessageData))) ←
+    linters.mapM fun linter => do
+      let decls ← decls.filterM (shouldBeLinted linter.name)
+      (linter, ·) <$> decls.mapM fun decl => (decl, ·) <$> do
+        let act : MetaM (Option MessageData) := do
+          linter.test decl
+        EIO.asTask <| (← Core.wrapAsync (fun _ =>
+          act |>.run' Elab.Command.mkMetaContext
+        ) (cancelTk? := none)) ()
+
+  let result ← tasks.mapM fun (linter, decls) => do
+    let mut msgs : Std.HashMap Name MessageData := {}
+    for (declName, msgTask) in decls do
+      let msg? ← match msgTask.get with
+      | Except.ok msg? => pure msg?
+      | Except.error err => pure m!"LINTER FAILED:\n{err.toMessageData}"
+      if let .some msg := msg? then
+        msgs := msgs.insert declName msg
+    pure (linter, msgs)
+  return result
+
+/-- Sorts a map with declaration keys as names by line number. -/
+def sortResults (results : Std.HashMap Name α) : CoreM <| Array (Name × α) := do
+  let mut key : Std.HashMap Name Nat := {}
+  for (n, _) in results.toArray do
+    if let some range ← findDeclarationRanges? n then
+      key := key.insert n <| range.range.pos.line
+  pure $ results.toArray.qsort fun (a, _) (b, _) => key.getD a 0 < key.getD b 0
+
+/-- Formats a linter warning as `#check` command with comment. -/
+def printWarning (declName : Name) (warning : MessageData) (useErrorFormat : Bool := false)
+  (filePath : System.FilePath := default) : CoreM MessageData := do
+  if useErrorFormat then
+    if let some range ← findDeclarationRanges? declName then
+      let msg ← addMessageContextPartial
+        m!"{filePath}:{range.range.pos.line}:{range.range.pos.column + 1}: error: {
+          ← mkConstWithLevelParams declName} {warning}"
+      return msg
+  addMessageContextPartial m!"#check {← mkConstWithLevelParams declName} /- {warning} -/"
+
+/-- Formats a map of linter warnings using `printWarning`, sorted by line number. -/
+def printWarnings (results : Std.HashMap Name MessageData) (filePath : System.FilePath := default)
+    (useErrorFormat : Bool := false) : CoreM MessageData := do
+  (MessageData.joinSep ·.toList Format.line) <$>
+    (← sortResults results).mapM fun (declName, warning) =>
+      printWarning declName warning (useErrorFormat := useErrorFormat) (filePath := filePath)
+
+/--
+Formats a map of linter warnings grouped by filename with `-- filename` comments.
+-/
+def groupedByFilename (results : Std.HashMap Name MessageData) (useErrorFormat : Bool := false) :
+    CoreM MessageData := do
+  let sp ← if useErrorFormat then getSrcSearchPath else pure {}
+  let grouped : Std.HashMap Name (System.FilePath × Std.HashMap Name MessageData) ←
+    results.foldM (init := {}) fun grouped declName msg => do
+      let mod ← findModuleOf? declName
+      let mod := mod.getD (← getEnv).mainModule
+      grouped.insert mod <$>
+        match grouped[mod]? with
+        | some (fp, msgs) => pure (fp, msgs.insert declName msg)
+        | none => do
+          let fp ← if useErrorFormat then
+            pure <| (← sp.findWithExt "lean" mod).getD (modToFilePath "." mod "lean")
+          else pure default
+          pure (fp, .insert {} declName msg)
+  let grouped' := grouped.toArray.qsort fun (a, _) (b, _) => toString a < toString b
+  (MessageData.joinSep · (Format.line ++ Format.line)) <$>
+    grouped'.toList.mapM fun (mod, fp, msgs) => do
+      pure m!"-- {mod}\n{← printWarnings msgs (filePath := fp) (useErrorFormat := useErrorFormat)}"
+
+/--
+Formats the linter results as Lean code with comments and `#check` commands.
+-/
+def formatLinterResults
+    (results : Array (NamedEnvLinter × Std.HashMap Name MessageData))
+    (decls : Array Name)
+    (groupByFilename : Bool)
+    (whereDesc : String) (runClippyLinters : Bool)
+    (verbose : LintVerbosity) (numLinters : Nat) (useErrorFormat : Bool := false) :
+    CoreM MessageData := do
+  let formattedResults ← results.filterMapM fun (linter, results) => do
+    if !results.isEmpty then
+      let warnings ←
+        if groupByFilename || useErrorFormat then
+          groupedByFilename results (useErrorFormat := useErrorFormat)
+        else
+          printWarnings results
+      pure $ some m!"/- The `{linter.name}` linter reports:\n{linter.errorsFound} -/\n{warnings}\n"
+    else if verbose = LintVerbosity.high then
+      pure $ some m!"/- OK: {linter.noErrorsFound} -/"
+    else
+      pure none
+  let mut s := MessageData.joinSep formattedResults.toList Format.line
+  let numAutoDecls := (← decls.filterM isAutoDecl).size
+  let failed := results.map (·.2.size) |>.foldl (·+·) 0
+  unless verbose matches LintVerbosity.low do
+    s := m!"-- Found {failed} error{if failed == 1 then "" else "s"
+      } in {decls.size - numAutoDecls} declarations (plus {
+      numAutoDecls} automatically generated ones) {whereDesc
+      } with {numLinters} linters\n\n{s}"
+  unless runClippyLinters do s := m!"{s}-- (non-clippy linters skipped)\n"
+  pure s
+
+/-- Get the list of declarations in the current module. -/
+def getDeclsInCurrModule : CoreM (Array Name) := do
+  pure $ (← getEnv).constants.map₂.foldl (init := #[]) fun r k _ => r.push k
+
+/-- Get the list of all declarations in the environment. -/
+def getAllDecls : CoreM (Array Name) := do
+  pure $ (← getEnv).constants.map₁.fold (init := ← getDeclsInCurrModule) fun r k _ => r.push k
+
+/-- Get the list of all declarations in the specified package. -/
+def getDeclsInPackage (pkg : Name) : CoreM (Array Name) := do
+  let env ← getEnv
+  let mut decls ← getDeclsInCurrModule
+  let modules := env.header.moduleNames.map (pkg.isPrefixOf ·)
+  return env.constants.map₁.fold (init := decls) fun decls declName _ =>
+    if modules[env.const2ModIdx[declName]?.get!]! then
+      decls.push declName
+    else decls
+
+end Lean.Linter.EnvLinter

src/Lean/Meta/Constructions/BRecOn.lean

@@ -30,7 +30,7 @@ of type
 α → List α → Sort (max 1 u_1) → Sort (max 1 u_1)
 ```
 -/
-private def buildBelowMinorPremise (rlvl : Level) (motives : Array Expr) (minorType : Expr) : MetaM Expr :=
+def buildBelowMinorPremise (rlvl : Level) (motives : Array Expr) (minorType : Expr) : MetaM Expr :=
   forallTelescope minorType fun minor_args _ => do go #[] minor_args.toList
 where
   go (prods : Array Expr) : List Expr → MetaM Expr
@@ -56,7 +56,7 @@ For example for the `List` type, it constructs,
 fun {a} {motive} t => List.rec PUnit (fun a_1 a a_ih => motive a ×' a_ih) t
 ```
 -/
-private def mkBelowFromRec (recName : Name) (nParams : Nat)
+def mkBelowFromRec (recName : Name) (nParams : Nat)
   (belowName : Name) : MetaM Unit := do
   -- The construction follows the type of `ind.rec`
   let .recInfo recVal ← getConstInfo recName
@@ -146,7 +146,7 @@ of type
   PProd (motive (head :: tail)) (PProd (PProd (motive tail) (List.below tail)) PUnit)
 ```
 -/
-private def buildBRecOnMinorPremise (rlvl : Level) (motives : Array Expr)
+def buildBRecOnMinorPremise (rlvl : Level) (motives : Array Expr)
     (belows : Array Expr) (fs : Array Expr) (minorType : Expr) : MetaM Expr :=
   forallTelescope minorType fun minor_args minor_type => do
     let rec go (prods : Array Expr) : List Expr → MetaM Expr
@@ -188,7 +188,7 @@ protected theorem List.brecOn.eq.{u} : ∀ {a : Type} {motive : List a → Sort
   (F_1 : (t : List a) → List.below t → motive t), List.brecOn t F_1 = F_1 t (List.brecOn.go t F_1).2
 ```
 -/
-private def mkBRecOnFromRec (recName : Name) (nParams : Nat)
+def mkBRecOnFromRec (recName : Name) (nParams : Nat)
     (all : Array Name) (brecOnName : Name) : MetaM Unit := do
   let brecOnGoName := brecOnName.str "go"
   let brecOnEqName := brecOnName.str "eq"

src/Lean/Meta/Constructions/SparseCasesOn.lean

@@ -15,7 +15,7 @@ import Lean.Meta.Transform
 namespace Lean.Meta
 
 
-private structure SparseCasesOnKey where
+structure SparseCasesOnKey where
   indName : Name
   ctors   : Array Name
   -- When this is created in a private context and thus may contain private references, we must
@@ -23,7 +23,7 @@ private structure SparseCasesOnKey where
   isPrivate : Bool
 deriving BEq, Hashable
 
-private builtin_initialize sparseCasesOnCacheExt : EnvExtension (PHashMap SparseCasesOnKey Name) ←
+builtin_initialize sparseCasesOnCacheExt : EnvExtension (PHashMap SparseCasesOnKey Name) ←
   registerEnvExtension (pure {}) (asyncMode := .local)  -- mere cache, keep it local
 
 /-- Information necessary to recognize and split on sparse casesOn (in particular in MatchEqs) -/
@@ -34,7 +34,7 @@ public structure SparseCasesOnInfo where
   insterestingCtors : Array Name
 deriving Inhabited
 
-private builtin_initialize sparseCasesOnInfoExt : MapDeclarationExtension SparseCasesOnInfo ←
+builtin_initialize sparseCasesOnInfoExt : MapDeclarationExtension SparseCasesOnInfo ←
   mkMapDeclarationExtension (exportEntriesFn := fun env s =>
     let all := s.toArray
     -- Do not export for non-exposed defs at exported/server levels

src/Lean/Meta/Constructions/SparseCasesOnEq.lean

@@ -83,7 +83,7 @@ where
           value := val
         })
 
-private def isName (env : Environment) (n : Name) : Bool :=
+def isName (env : Environment) (n : Name) : Bool :=
   if let .str p "else_eq" := n then
     (getSparseCasesOnInfoCore env p).isSome
   else

src/Lean/Meta/CtorIdxHInj.lean

@@ -16,7 +16,7 @@ def hinjSuffix := "hinj"
 public def mkCtorIdxHInjTheoremNameFor (indName : Name) : Name :=
   (mkCtorIdxName indName).str hinjSuffix
 
-private partial def mkHInjectiveTheorem? (thmName : Name) (indVal : InductiveVal) : MetaM TheoremVal := do
+partial def mkHInjectiveTheorem? (thmName : Name) (indVal : InductiveVal) : MetaM TheoremVal := do
   let us := indVal.levelParams.map mkLevelParam
   let thmType ←
     forallBoundedTelescope indVal.type (indVal.numParams + indVal.numIndices) fun xs1 _ => do

src/Lean/Meta/Match/AltTelescopes.lean

@@ -40,7 +40,7 @@ namespace Lean.Meta.Match
 
   This can be used to use the alternative of a match expression in its splitter.
 -/
-public partial def forallAltVarsTelescope (altType : Expr) (altInfo : AltParamInfo)
+partial def forallAltVarsTelescope (altType : Expr) (altInfo : AltParamInfo)
   (k : (patVars : Array Expr) → (args : Array Expr) → (mask : Array Bool) → (type : Expr) → MetaM α) : MetaM α := do
   assert! altInfo.numOverlaps = 0
   if altInfo.hasUnitThunk then
@@ -104,7 +104,7 @@ where
 
   This can be used to use the alternative of a match expression in its splitter.
 -/
-public partial def forallAltTelescope (altType : Expr) (altInfo : AltParamInfo) (numDiscrEqs : Nat)
+partial def forallAltTelescope (altType : Expr) (altInfo : AltParamInfo) (numDiscrEqs : Nat)
     (k : (ys : Array Expr) → (eqs : Array Expr) → (args : Array Expr) → (mask : Array Bool) → (type : Expr) → MetaM α)
     : MetaM α := do
   forallAltVarsTelescope altType altInfo fun ys args mask altType => do

src/Lean/Meta/Match/SolveOverlap.lean

@@ -21,7 +21,7 @@ We will eventually have to write more efficient proof automation for this module
 The new proof automation should exploit the structure of the generated goals and avoid general purpose tactics
 such as `contradiction`.
 -/
-private def _root_.Lean.MVarId.contradictionQuick (mvarId : MVarId) : MetaM Bool := do
+def _root_.Lean.MVarId.contradictionQuick (mvarId : MVarId) : MetaM Bool := do
   mvarId.withContext do
     let mut posMap : Std.HashMap Expr FVarId := {}
     let mut negMap : Std.HashMap Expr FVarId := {}

src/Lean/Meta/SplitSparseCasesOn.lean

@@ -16,7 +16,7 @@ import Lean.Meta.Tactic.Replace
 
 namespace Lean.Meta
 
-private def rewriteGoalUsingEq (goal : MVarId) (eq : Expr) (symm : Bool := false) : MetaM MVarId := do
+def rewriteGoalUsingEq (goal : MVarId) (eq : Expr) (symm : Bool := false) : MetaM MVarId := do
   let rewriteResult ← goal.rewrite (←goal.getType) eq symm
   goal.replaceTargetEq rewriteResult.eNew rewriteResult.eqProof
 

src/Lean/Meta/Sym/Simp/EvalGround.lean

@@ -383,7 +383,7 @@ When equal, uses `eq_self` (no kernel evaluation needed). When different, uses
 `mkStringLitNeProof` which finds the first differing character position and proves
 inequality via `congrArg (List.get?Internal · i)`.
 -/
-private def evalStringEq (a b : Expr) : SimpM Result := do
+def evalStringEq (a b : Expr) : SimpM Result := do
   let some va := getStringValue? a | return .rfl
   let some vb := getStringValue? b | return .rfl
   if va = vb then

src/Lean/Meta/Sym/Simp/SimpM.lean

@@ -172,7 +172,7 @@ inductive Result where
 Pre-computed `.rfl` results to avoid dynamic memory allocation.
 Each combination of `done` and `contextDependent` maps to a compile-time constant.
 -/
-public def mkRflResult (done : Bool := false) (contextDependent : Bool := false) : Result :=
+def mkRflResult (done : Bool := false) (contextDependent : Bool := false) : Result :=
   match done, contextDependent with
   | false, false => .rfl
   | false, true  => .rfl false true
@@ -180,15 +180,15 @@ public def mkRflResult (done : Bool := false) (contextDependent : Bool := false)
   | true,  true  => .rfl true true
 
 /-- Like `mkRflResult` with `done := false`. -/
-public def mkRflResultCD (contextDependent : Bool) : Result :=
+def mkRflResultCD (contextDependent : Bool) : Result :=
   if contextDependent then .rfl false true else .rfl
 
 /-- Returns `true` if this result depends on the local context (e.g., hypotheses). -/
-public abbrev Result.isContextDependent : Result → Bool
+abbrev Result.isContextDependent : Result → Bool
   | .rfl _ cd | .step _ _ _ cd => cd
 
 /-- Marks a result as context-dependent. -/
-public def Result.withContextDependent : Result → Result
+def Result.withContextDependent : Result → Result
   | .rfl done _ => .rfl done true
   | .step e h done _ => .step e h done true
 

src/Lean/Meta/Sym/SymM.lean

@@ -66,7 +66,7 @@ This is used during pattern matching and structural definitional equality tests
 to identify arguments that can be skipped or handled specially
 (e.g., instance arguments can be synthesized, proof arguments can be inferred).
 -/
-public structure ProofInstArgInfo where
+structure ProofInstArgInfo where
   /-- `true` if this argument is a proof (its type is a `Prop`). -/
   isProof    : Bool
   /-- `true` if this argument is a type class instance. -/
@@ -78,7 +78,7 @@ Information about a function symbol. It stores which argument positions are proo
 enabling optimizations during pattern matching and structural definitional equality tests
 such as skipping proof arguments or deferring instance synthesis.
 -/
-public structure ProofInstInfo where
+structure ProofInstInfo where
   /-- Information about each argument position. -/
   argsInfo : Array ProofInstArgInfo
   deriving Inhabited

src/Lean/Meta/Tactic/Cbv/BuiltinCbvSimprocs/Array.lean

@@ -17,7 +17,7 @@ import Init.GetElem
 namespace Lean.Meta.Tactic.Cbv
 
 /-- Extract elements from an array literal (`Array.mk` applied to a list literal). -/
-private def getArrayLitElems? (e : Expr) : Option <| Array Expr :=
+def getArrayLitElems? (e : Expr) : Option <| Array Expr :=
   match_expr e with
   | Array.mk _ as => getListLitElems as
   | _ => none

src/Lean/Meta/Tactic/Cleanup.lean

@@ -12,7 +12,7 @@ import Lean.Meta.Tactic.Util
 
 namespace Lean.Meta
 
-private partial def cleanupCore (mvarId : MVarId) (toPreserve : Array FVarId) (indirectProps : Bool) : MetaM MVarId := do
+partial def cleanupCore (mvarId : MVarId) (toPreserve : Array FVarId) (indirectProps : Bool) : MetaM MVarId := do
   mvarId.withContext do
     mvarId.checkNotAssigned `cleanup
     let used ← collectUsed |>.run' (false, {})

src/Lean/Meta/Tactic/Simp/SimpTheorems.lean

@@ -50,6 +50,18 @@ register_builtin_option debug.tactic.simp.checkDefEqAttr : Bool := {
     of the `defeq` attribute, and warn if it was. Note that this is a costly check."
 }
 
+register_builtin_option warning.simp.varHead : Bool := {
+  defValue := false
+  descr := "If true, warns when the head symbol of the left-hand side of a `@[simp]` theorem \
+    is a variable. Such lemmas are tried on every simp step, which can be slow."
+}
+
+register_builtin_option warning.simp.otherHead : Bool := {
+  defValue := true
+  descr := "If true, warns when the left-hand side of a `@[simp]` theorem is headed by a \
+    `.other` key in the discrimination tree (e.g. a lambda expression). Such lemmas can cause slowdowns."
+}
+
 /--
 An `Origin` is an identifier for simp theorems which indicates roughly
 what action the user took which lead to this theorem existing in the simp set.
@@ -359,12 +371,27 @@ private def checkTypeIsProp (type : Expr) : MetaM Unit :=
   unless (← isProp type) do
     throwError "Invalid simp theorem: Expected a proposition, but found{indentExpr type}"
 
-private def mkSimpTheoremKeys (type : Expr) (noIndexAtArgs : Bool) : MetaM (Array SimpTheoremKey × Bool) := do
+private def mkSimpTheoremKeys (type : Expr) (noIndexAtArgs : Bool) (checkLhs : Bool := false) : MetaM (Array SimpTheoremKey × Bool) := do
   withNewMCtxDepth do
     let (_, _, type) ← forallMetaTelescopeReducing type
     let type ← whnfR type
     match type.eq? with
-    | some (_, lhs, rhs) => pure (← DiscrTree.mkPath lhs noIndexAtArgs, ← isPerm lhs rhs)
+    | some (_, lhs, rhs) =>
+      let keys ← DiscrTree.mkPath lhs noIndexAtArgs
+      if checkLhs then
+        if warning.simp.varHead.get (← getOptions) && keys[0]? == some .star then
+          logWarning m!"Left-hand side of simp theorem has a variable as head symbol. \
+            This means the theorem will be tried on every simp step, which can be expensive. \
+            This may be acceptable for `local` or `scoped` simp lemmas.\n\
+            Use `set_option warning.simp.varHead false` to disable this warning."
+        if warning.simp.otherHead.get (← getOptions) && keys[0]? == some .other then
+          logWarning m!"Left-hand side of simp theorem is headed by a `.other` key in the \
+            discrimination tree (e.g. because it is a lambda expression). \
+            This theorem will be tried against all expressions that also have a `.other` key as head, \
+            which can cause slowdowns. \
+            This may be acceptable for `local` or `scoped` simp lemmas.\n\
+            Use `set_option warning.simp.otherHead false` to disable this warning."
+      pure (keys, ← isPerm lhs rhs)
     | none => throwError "Unexpected kind of simp theorem{indentExpr type}"
 
 register_builtin_option simp.rfl.checkTransparency: Bool := {
@@ -373,10 +400,10 @@ register_builtin_option simp.rfl.checkTransparency: Bool := {
 }
 
 private def mkSimpTheoremCore (origin : Origin) (e : Expr) (levelParams : Array Name) (proof : Expr)
-    (post : Bool) (prio : Nat) (noIndexAtArgs : Bool) : MetaM SimpTheorem := do
+    (post : Bool) (prio : Nat) (noIndexAtArgs : Bool) (checkLhs : Bool := false): MetaM SimpTheorem := do
   assert! origin != .fvar ⟨.anonymous⟩
   let type ← instantiateMVars (← inferType e)
-  let (keys, perm) ← mkSimpTheoremKeys type noIndexAtArgs
+  let (keys, perm) ← mkSimpTheoremKeys type noIndexAtArgs checkLhs
   let rfl ← isRflProof proof
   if rfl && simp.rfl.checkTransparency.get (← getOptions) then
     forallTelescopeReducing type fun _ type => do
@@ -399,7 +426,7 @@ Creates a `SimpTheorem` from a global theorem.
 Because some theorems lead to multiple `SimpTheorems` (in particular conjunctions), returns an array.
 -/
 def mkSimpTheoremFromConst (declName : Name) (post := true) (inv := false)
-    (prio : Nat := eval_prio default) : MetaM (Array SimpTheorem) := do
+    (prio : Nat := eval_prio default) (checkLhs : Bool := false) : MetaM (Array SimpTheorem) := do
   let cinfo ← getConstVal declName
   let us := cinfo.levelParams.map mkLevelParam
   let origin := .decl declName post inv
@@ -413,10 +440,10 @@ def mkSimpTheoremFromConst (declName : Name) (post := true) (inv := false)
         let auxName ← mkAuxLemma (kind? := `_simp) cinfo.levelParams type val (inferRfl := true)
           (forceExpose := true)  -- These kinds of theorems are small and `to_additive` may need to
                                  -- unfold them.
-        r := r.push <| (← do mkSimpTheoremCore origin (mkConst auxName us) #[] (mkConst auxName) post prio (noIndexAtArgs := false))
+        r := r.push <| (← do mkSimpTheoremCore origin (mkConst auxName us) #[] (mkConst auxName) post prio (noIndexAtArgs := false) (checkLhs := checkLhs))
       return r
     else
-      return #[← withoutExporting do mkSimpTheoremCore origin (mkConst declName us) #[] (mkConst declName) post prio (noIndexAtArgs := false)]
+      return #[← withoutExporting do mkSimpTheoremCore origin (mkConst declName us) #[] (mkConst declName) post prio (noIndexAtArgs := false) (checkLhs := checkLhs)]
 
 def SimpTheorem.getValue (simpThm : SimpTheorem) : MetaM Expr := do
   if simpThm.proof.isConst && simpThm.levelParams.isEmpty then
@@ -670,7 +697,7 @@ def SimpExtension.getTheorems (ext : SimpExtension) : CoreM SimpTheorems :=
 Adds a simp theorem to a simp extension
 -/
 def addSimpTheorem (ext : SimpExtension) (declName : Name) (post : Bool) (inv : Bool) (attrKind : AttributeKind) (prio : Nat) : MetaM Unit := do
-  let simpThms ← withExporting (isExporting := attrKind != .local && !isPrivateName declName) do mkSimpTheoremFromConst declName post inv prio
+  let simpThms ← withExporting (isExporting := attrKind != .local && !isPrivateName declName) do mkSimpTheoremFromConst declName post inv prio (checkLhs := true)
   for simpThm in simpThms do
     ext.add (SimpEntry.thm simpThm) attrKind
 

src/Lean/Meta/WrapInstance.lean

@@ -88,21 +88,6 @@ builtin_initialize registerTraceClass `Meta.wrapInstance
 
 open Meta
 
-/--
-Rebuild a type application with fresh synthetic metavariables for instance-implicit arguments.
-Non-instance-implicit arguments are assigned from the original application's arguments.
-If the function is over-applied, extra arguments are preserved.
--/
-public def abstractInstImplicitArgs (type : Expr) : MetaM Expr := do
-  let fn := type.getAppFn
-  let args := type.getAppArgs
-  let (mvars, bis, _) ← forallMetaTelescope (← inferType fn)
-  for i in [:mvars.size] do
-    unless bis[i]!.isInstImplicit do
-      mvars[i]!.mvarId!.assign args[i]!
-  let args := mvars ++ args.drop mvars.size
-  instantiateMVars (mkAppN fn args)
-
 partial def getFieldOrigin (structName field : Name) : MetaM (Name × StructureFieldInfo) := do
   let env ← getEnv
   for parent in getStructureParentInfo env structName do

src/Lean/Parser/Command.lean

@@ -342,10 +342,11 @@ namespace InternalSyntax
   This command is for internal use only. It is intended for macros that implicitly introduce new
   scopes, such as `expandInCmd` and `expandNamespacedDeclaration`. It allows local attributes to remain
   accessible beyond those implicit scopes, even though they would normally be hidden from the user.
+  The numeric argument specifies how many scope levels to mark as non-delimiting.
   -/
-  scoped syntax (name := end_local_scope) "end_local_scope" : command
+  scoped syntax (name := end_local_scope) "end_local_scope" num : command
 
-  def endLocalScopeSyntax : Command := Unhygienic.run `(end_local_scope)
+  def endLocalScopeSyntax (depth : Nat) : Command := Unhygienic.run `(end_local_scope $(Syntax.mkNumLit (toString depth)))
 end InternalSyntax
 
 /-- Declares one or more typed variables, or modifies whether already-declared variables are

src/Lean/Parser/Term.lean

@@ -50,17 +50,17 @@ def versoCommentBodyFn : ParserFn := fun c s =>
     rawFn (Doc.Parser.ignoreFn <| chFn '-' >> chFn '/') (trailingWs := true) c s
   else s
 
-public def versoCommentBody : Parser where
+def versoCommentBody : Parser where
   fn := fun c s => nodeFn `Lean.Parser.Command.versoCommentBody versoCommentBodyFn c s
 
 
 @[combinator_parenthesizer versoCommentBody, expose]
-public def versoCommentBody.parenthesizer := PrettyPrinter.Parenthesizer.visitToken
+def versoCommentBody.parenthesizer := PrettyPrinter.Parenthesizer.visitToken
 
 open PrettyPrinter Formatter in
 open Syntax.MonadTraverser in
 @[combinator_formatter versoCommentBody, expose]
-public def versoCommentBody.formatter : PrettyPrinter.Formatter := do
+def versoCommentBody.formatter : PrettyPrinter.Formatter := do
   visitArgs $ do
     visitAtom `«-/»
     goLeft

src/Lean/ScopedEnvExtension.lean

@@ -144,13 +144,18 @@ def ScopedEnvExtension.popScope (ext : ScopedEnvExtension α β σ) (env : Envir
     | _      :: state₂ :: stack => { s with stateStack := state₂ :: stack }
     | _ => s
 
-/-- Modifies `delimitsLocal` flag to `false` to turn off delimiting of local entries.
+/-- Modifies `delimitsLocal` flag to `false` on the top `depth` entries of the state stack,
+to turn off delimiting of local entries across multiple implicit scope levels
+(e.g. those introduced by compound `namespace A.B.C` expansions).
 -/
-def ScopedEnvExtension.setDelimitsLocal (ext : ScopedEnvExtension α β σ) (env : Environment)  : Environment :=
+def ScopedEnvExtension.setDelimitsLocal (ext : ScopedEnvExtension α β σ) (env : Environment) (depth : Nat) : Environment :=
   ext.ext.modifyState (asyncMode := .local) env fun s =>
-    match s.stateStack with
-    | [] => s
-    | state :: stack => {s with stateStack := {state with delimitsLocal := false} :: stack}
+    {s with stateStack := go depth s.stateStack}
+where
+  go : Nat → List (State σ) → List (State σ)
+    | 0, stack => stack
+    | _, [] => []
+    | n + 1, state :: stack => {state with delimitsLocal := false} :: go n stack
 
 def ScopedEnvExtension.addEntry (ext : ScopedEnvExtension α β σ) (env : Environment) (b : β) : Environment :=
   ext.ext.addEntry env (Entry.global b)
@@ -226,11 +231,12 @@ def popScope [Monad m] [MonadEnv m] [MonadLiftT (ST IO.RealWorld) m] : m Unit :=
   for ext in (← scopedEnvExtensionsRef.get) do
     modifyEnv ext.popScope
 
-/-- Used to implement `end_local_scope` command, that disables delimiting local entries of ScopedEnvExtension in a current scope.
+/-- Used to implement `end_local_scope` command, that disables delimiting local entries of ScopedEnvExtension
+across `depth` scope levels.
 -/
-def setDelimitsLocal [Monad m] [MonadEnv m] [MonadLiftT (ST IO.RealWorld) m] : m Unit := do
+def setDelimitsLocal [Monad m] [MonadEnv m] [MonadLiftT (ST IO.RealWorld) m] (depth : Nat) : m Unit := do
   for ext in (← scopedEnvExtensionsRef.get) do
-    modifyEnv (ext.setDelimitsLocal ·)
+    modifyEnv (ext.setDelimitsLocal · depth)
 
 def activateScoped [Monad m] [MonadEnv m] [MonadLiftT (ST IO.RealWorld) m] (namespaceName : Name) : m Unit := do
   for ext in (← scopedEnvExtensionsRef.get) do

src/Lean/Setup.lean

@@ -35,7 +35,7 @@ structure Import where
 
 -- TODO: move further up into `Init` by using simpler representation for `imports`
 @[extern "lean_idbg_client_loop"]
-public opaque Idbg.idbgClientLoop {α : Type} [Nonempty α]
+opaque Idbg.idbgClientLoop {α : Type} [Nonempty α]
   (siteId : String) (imports : Array Import) (apply : α → String) : IO Unit
 
 instance : Coe Name Import := ⟨({module := ·})⟩
@@ -130,7 +130,7 @@ The type of module package identifiers.
 This is a {name}`String` that is used to disambiguate native symbol prefixes between
 different packages (and different versions of the same package).
 -/
-public abbrev PkgId := String
+abbrev PkgId := String
 
 /-- A module's setup information as described by a JSON file. -/
 structure ModuleSetup where

src/Lean/Widget/Diff.lean

@@ -22,7 +22,7 @@ open Server Std Lean SubExpr
 
 NOTE: in the future we may add other tags.
   -/
-private inductive ExprDiffTag where
+inductive ExprDiffTag where
   | change
   | delete
   | insert

src/Std/Internal/Http.lean

@@ -7,3 +7,4 @@ module
 
 prelude
 public import Std.Internal.Http.Data
+public import Std.Internal.Http.Protocol.H1

src/Std/Internal/Http/Data/Headers/Basic.lean

@@ -6,6 +6,7 @@ Authors: Sofia Rodrigues
 module
 
 prelude
+public import Std.Internal.Http.Data.URI
 public import Std.Internal.Http.Data.Headers.Name
 public import Std.Internal.Http.Data.Headers.Value
 public import Std.Internal.Parsec.Basic
@@ -215,4 +216,89 @@ def serialize (connection : Connection) : Header.Name × Header.Value :=
 
 instance : Header Connection := ⟨parse, serialize⟩
 
-end Std.Http.Header.Connection
+end Connection
+
+/--
+The `Host` header.
+
+Represents the authority component of a URI:
+  host [ ":" port ]
+
+Reference: https://www.rfc-editor.org/rfc/rfc9110.html#name-host-and-authority
+-/
+structure Host where
+  /--
+  Host name (reg-name, IPv4, or IPv6 literal).
+  -/
+  host : URI.Host
+
+  /--
+  Optional port.
+  -/
+  port : URI.Port
+deriving Repr, BEq
+
+namespace Host
+
+/--
+Parses a `Host` header value.
+-/
+def parse (v : Value) : Option Host :=
+  let parsed := (Std.Http.URI.Parser.parseHostHeader <* Std.Internal.Parsec.eof).run v.value.toUTF8
+  match parsed with
+  | .ok ⟨host, port⟩ => some ⟨host, port⟩
+  | .error _ => none
+
+/--
+Serializes a `Host` header back to a name and a value.
+-/
+def serialize (host : Host) : Header.Name × Header.Value :=
+  let value := match host.port with
+    | .value port => Header.Value.ofString! s!"{host.host}:{port}"
+    | .empty => Header.Value.ofString! s!"{host.host}:"
+    | .omitted => Header.Value.ofString! <| toString host.host
+
+  (.mk "host", value)
+
+instance : Header Host := ⟨parse, serialize⟩
+
+end Host
+
+/--
+The `Expect` header.
+
+Represents an expectation token.
+The only standardized expectation is `100-continue`.
+
+Reference: https://www.rfc-editor.org/rfc/rfc9110.html#name-expect
+-/
+structure Expect where
+deriving Repr, BEq
+
+namespace Expect
+
+/--
+Parses an `Expect` header.
+
+Succeeds only if the value is exactly `100-continue`
+(case-insensitive, trimmed).
+-/
+def parse (v : Value) : Option Expect :=
+  let normalized := v.value.trimAscii.toString.toLower
+
+  if normalized == "100-continue" then
+    some ⟨⟩
+  else
+    none
+
+/--
+Serializes an `Expect` header.
+-/
+def serialize (_ : Expect) : Header.Name × Header.Value :=
+  (Header.Name.expect, Value.ofString! "100-continue")
+
+instance : Header Expect := ⟨parse, serialize⟩
+
+end Expect
+
+end Std.Http.Header

src/Std/Internal/Http/Data/URI/Parser.lean

@@ -52,13 +52,13 @@ private def parseScheme (config : URI.Config) : Parser URI.Scheme := do
   if config.maxSchemeLength = 0 then
     fail "scheme length limit is 0 (no scheme allowed)"
 
-  let first ← takeWhileUpTo1 isAlphaByte 1
-  let rest ← takeWhileUpTo
+  let first : UInt8 ← satisfy isAlphaByte
+  let rest ← takeWhileAtMost
     (fun c =>
       isAlphaNum c ∨
       c = '+'.toUInt8 ∨ c = '-'.toUInt8 ∨ c = '.'.toUInt8)
     (config.maxSchemeLength - 1)
-  let schemeBytes := first.toByteArray ++ rest.toByteArray
+  let schemeBytes := ByteArray.empty.push first ++ rest.toByteArray
   let str := String.fromUTF8! schemeBytes |>.toLower
 
   if h : URI.IsValidScheme str then
@@ -68,7 +68,7 @@ private def parseScheme (config : URI.Config) : Parser URI.Scheme := do
 
 -- port = 1*DIGIT
 private def parsePortNumber : Parser UInt16 := do
-  let portBytes ← takeWhileUpTo1 isDigitByte 5
+  let portBytes ← takeWhileAtMost isDigitByte 5
 
   let portStr := String.fromUTF8! portBytes.toByteArray
 
@@ -82,7 +82,7 @@ private def parsePortNumber : Parser UInt16 := do
 
 -- userinfo = *( unreserved / pct-encoded / sub-delims / ":" )
 private def parseUserInfo (config : URI.Config) : Parser URI.UserInfo := do
-  let userBytesName ← takeWhileUpTo
+  let userBytesName ← takeWhileAtMost
     (fun x =>
       x ≠ ':'.toUInt8 ∧
       (isUserInfoChar x ∨ x = '%'.toUInt8))
@@ -94,7 +94,7 @@ private def parseUserInfo (config : URI.Config) : Parser URI.UserInfo := do
   let userPassEncoded ← if ← peekIs (· == ':'.toUInt8) then
       skip
 
-      let userBytesPass ← takeWhileUpTo
+      let userBytesPass ← takeWhileAtMost
         (fun x => isUserInfoChar x ∨ x = '%'.toUInt8)
         config.maxUserInfoLength
 
@@ -113,7 +113,7 @@ private def parseUserInfo (config : URI.Config) : Parser URI.UserInfo := do
 private def parseIPv6 : Parser Net.IPv6Addr := do
   skipByte '['.toUInt8
 
-  let result ← takeWhileUpTo1
+  let result ← takeWhile1AtMost
     (fun x => x = ':'.toUInt8 ∨ x = '.'.toUInt8 ∨ isHexDigitByte x)
     256
 
@@ -127,7 +127,7 @@ private def parseIPv6 : Parser Net.IPv6Addr := do
 
 -- IPv4address = dec-octet "." dec-octet "." dec-octet "." dec-octet
 private def parseIPv4 : Parser Net.IPv4Addr := do
-  let result ← takeWhileUpTo1
+  let result ← takeWhile1AtMost
     (fun x => x = '.'.toUInt8 ∨ isDigitByte x)
     256
 
@@ -148,8 +148,8 @@ private def parseHost (config : URI.Config) : Parser URI.Host := do
       if let some ipv4 ← tryOpt parseIPv4 then
         return .ipv4 ipv4
 
-    -- We intentionally parse DNS names here (not full RFC 3986 reg-name).
-    let some str := String.fromUTF8? (← takeWhileUpTo1
+    -- It needs to be a legal DNS label, so it differs from reg-name.
+    let some str := String.fromUTF8? (← takeWhile1AtMost
       (fun x => isAlphaNum x ∨ x = '-'.toUInt8 ∨ x = '.'.toUInt8)
       config.maxHostLength).toByteArray
       | fail s!"invalid host"
@@ -187,7 +187,7 @@ private def parseAuthority (config : URI.Config) : Parser URI.Authority := do
 
 -- segment = *pchar
 private def parseSegment (config : URI.Config) : Parser ByteSlice := do
-  takeWhileUpTo (fun c => isPChar c ∨ c = '%'.toUInt8) config.maxSegmentLength
+  takeWhileAtMost (fun c => isPChar c ∨ c = '%'.toUInt8) config.maxSegmentLength
 
 /-
 path = path-abempty ; begins with "/" or is empty
@@ -272,7 +272,7 @@ def parsePath (config : URI.Config) (forceAbsolute : Bool) (allowEmpty : Bool) :
 -- query = *( pchar / "/" / "?" )
 private def parseQuery (config : URI.Config) : Parser URI.Query := do
   let queryBytes ←
-    takeWhileUpTo (fun c => isQueryChar c ∨ c = '%'.toUInt8) config.maxQueryLength
+    takeWhileAtMost (fun c => isQueryChar c ∨ c = '%'.toUInt8) config.maxQueryLength
 
   let some queryStr := String.fromUTF8? queryBytes.toByteArray
     | fail "invalid query string"
@@ -304,7 +304,7 @@ private def parseQuery (config : URI.Config) : Parser URI.Query := do
 --  fragment = *( pchar / "/" / "?" )
 private def parseFragment (config : URI.Config) : Parser URI.EncodedFragment := do
   let fragmentBytes ←
-    takeWhileUpTo (fun c => isFragmentChar c ∨ c = '%'.toUInt8) config.maxFragmentLength
+    takeWhileAtMost (fun c => isFragmentChar c ∨ c = '%'.toUInt8) config.maxFragmentLength
 
   let some fragmentStr := URI.EncodedFragment.ofByteArray? fragmentBytes.toByteArray
     | fail "invalid percent encoding in fragment"
@@ -328,7 +328,7 @@ Parses a URI (Uniform Resource Identifier).
 URI = scheme ":" hier-part [ "?" query ] [ "#" fragment ]
 hier-part = "//" authority path-abempty / path-absolute / path-rootless / path-empty
 -/
-public def parseURI (config : URI.Config := {}) : Parser URI := do
+def parseURI (config : URI.Config := {}) : Parser URI := do
   let scheme ← parseScheme config
   skipByte ':'.toUInt8
 
@@ -347,7 +347,7 @@ public def parseURI (config : URI.Config := {}) : Parser URI := do
 /--
 Parses a request target with combined parsing and validation.
 -/
-public def parseRequestTarget (config : URI.Config := {}) : Parser RequestTarget :=
+def parseRequestTarget (config : URI.Config := {}) : Parser RequestTarget :=
   asterisk <|> origin <|> absoluteHttp <|> authority <|> absolute
 where
   -- The asterisk form
@@ -406,7 +406,7 @@ where
 /--
 Parses an HTTP `Host` header value.
 -/
-public def parseHostHeader (config : URI.Config := {}) : Parser (URI.Host × URI.Port) := do
+def parseHostHeader (config : URI.Config := {}) : Parser (URI.Host × URI.Port) := do
   let host ← parseHost config
 
   let port : URI.Port ←

src/Std/Internal/Http/Protocol/H1/Config.lean

@@ -0,0 +1,134 @@
+/-
+Copyright (c) 2025 Lean FRO, LLC. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Sofia Rodrigues
+-/
+module
+
+prelude
+public import Std.Internal.Http.Data
+public import Std.Internal.Http.Internal
+
+public section
+
+/-!
+# HTTP/1.1 Configuration
+
+This module defines the configuration options for HTTP/1.1 protocol processing,
+including connection limits, header constraints, and various size limits.
+-/
+
+namespace Std.Http.Protocol.H1
+
+set_option linter.all true
+
+open Std Internal Parsec ByteArray
+open Internal
+
+/--
+Connection limits and parser bounds configuration.
+-/
+structure Config where
+  /--
+  Maximum number of requests (server) or responses (client) per connection.
+  -/
+  maxMessages : Nat := 100
+
+  /--
+  Maximum number of headers allowed per message.
+  -/
+  maxHeaders : Nat := 100
+
+  /--
+  Maximum aggregate byte size of all header field lines in a single message
+  (name + value bytes plus 4 bytes per line for `: ` and `\r\n`). Default: 64 KiB.
+  -/
+  maxHeaderBytes : Nat := 65536
+
+  /--
+  Whether to enable keep-alive connections by default.
+  -/
+  enableKeepAlive : Bool := true
+
+  /--
+  The `Server` header value injected into outgoing responses (receiving mode) or the
+  `User-Agent` header value injected into outgoing requests (sending mode).
+  `none` suppresses the header entirely.
+  -/
+  agentName : Option Header.Value := none
+
+  /--
+  Maximum length of request URI (default: 8192 bytes).
+  -/
+  maxUriLength : Nat := 8192
+
+  /--
+  Maximum number of bytes consumed while parsing request/status start-lines (default: 8192 bytes).
+  -/
+  maxStartLineLength : Nat := 8192
+
+  /--
+  Maximum length of header field name (default: 256 bytes).
+  -/
+  maxHeaderNameLength : Nat := 256
+
+  /--
+  Maximum length of header field value (default: 8192 bytes).
+  -/
+  maxHeaderValueLength : Nat := 8192
+
+  /--
+  Maximum number of spaces in delimiter sequences (default: 16).
+  -/
+  maxSpaceSequence : Nat := 16
+
+  /--
+  Maximum number of leading empty lines (bare CRLF) to skip before a request-line
+  (RFC 9112 §2.2 robustness). Default: 8.
+  -/
+  maxLeadingEmptyLines : Nat := 8
+
+  /--
+  Maximum number of extensions on a single chunk-size line (default: 16).
+  -/
+  maxChunkExtensions : Nat := 16
+
+  /--
+  Maximum length of chunk extension name (default: 256 bytes).
+  -/
+  maxChunkExtNameLength : Nat := 256
+
+  /--
+  Maximum length of chunk extension value (default: 256 bytes).
+  -/
+  maxChunkExtValueLength : Nat := 256
+
+  /--
+  Maximum number of bytes consumed while parsing one chunk-size line with extensions (default: 8192 bytes).
+  -/
+  maxChunkLineLength : Nat := 8192
+
+  /--
+  Maximum allowed chunk payload size in bytes (default: 8 MiB).
+  -/
+  maxChunkSize : Nat := 8 * 1024 * 1024
+
+  /--
+  Maximum allowed total body size per message in bytes (default: 64 MiB).
+  This limit applies across all body framing modes. For chunked transfer encoding,
+  chunk-size lines (including extensions) and the trailer section also count toward
+  this limit, so the total wire bytes consumed by the body cannot exceed this value.
+  -/
+  maxBodySize : Nat := 64 * 1024 * 1024
+
+  /--
+  Maximum length of reason phrase (default: 512 bytes).
+  -/
+  maxReasonPhraseLength : Nat := 512
+
+  /--
+  Maximum number of trailer headers (default: 20).
+  -/
+  maxTrailerHeaders : Nat := 20
+
+end Std.Http.Protocol.H1

src/Std/Internal/Http/Protocol/H1/Error.lean

@@ -0,0 +1,110 @@
+/-
+Copyright (c) 2025 Lean FRO, LLC. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Sofia Rodrigues
+-/
+module
+
+prelude
+public import Std.Time
+public import Std.Internal.Http.Data
+public import Std.Internal.Http.Internal
+public import Std.Internal.Http.Protocol.H1.Parser
+public import Std.Internal.Http.Protocol.H1.Config
+public import Std.Internal.Http.Protocol.H1.Message
+
+public section
+
+/-!
+# HTTP/1.1 Errors
+
+This module defines the error types for HTTP/1.1 protocol processing,
+including parsing errors, timeout errors, and connection errors.
+-/
+
+namespace Std.Http.Protocol.H1
+
+set_option linter.all true
+
+/--
+Specific HTTP processing errors with detailed information.
+-/
+inductive Error
+  /--
+  Malformed start line (request-line or status-line).
+  -/
+  | invalidStatusLine
+
+  /--
+  Invalid or malformed header.
+  -/
+  | invalidHeader
+
+  /--
+  Request timeout occurred.
+  -/
+  | timeout
+
+  /--
+  Request entity too large.
+  -/
+  | entityTooLarge
+
+  /--
+  Request URI is too long.
+  -/
+  | uriTooLong
+
+  /--
+  Unsupported HTTP version.
+  -/
+  | unsupportedVersion
+
+  /--
+  Invalid chunk encoding.
+  -/
+  | invalidChunk
+
+  /--
+  Connection closed.
+  -/
+  | connectionClosed
+
+  /--
+  Bad request or response message.
+  -/
+  | badMessage
+
+  /--
+  The number of header fields in the message exceeds the configured limit.
+  Maps to HTTP 431 Request Header Fields Too Large.
+  -/
+  | tooManyHeaders
+
+  /--
+  The aggregate byte size of all header fields exceeds the configured limit.
+  Maps to HTTP 431 Request Header Fields Too Large.
+  -/
+  | headersTooLarge
+
+  /--
+  Generic error with message.
+  -/
+  | other (message : String)
+deriving Repr, BEq
+
+instance : ToString Error where
+  toString
+  | .invalidStatusLine => "Invalid status line"
+  | .invalidHeader => "Invalid header"
+  | .timeout => "Timeout"
+  | .entityTooLarge => "Entity too large"
+  | .uriTooLong => "URI too long"
+  | .unsupportedVersion => "Unsupported version"
+  | .invalidChunk => "Invalid chunk"
+  | .connectionClosed => "Connection closed"
+  | .badMessage => "Bad message"
+  | .tooManyHeaders => "Too many headers"
+  | .headersTooLarge => "Headers too large"
+  | .other msg => s!"Other error: {msg}"
+

src/Std/Internal/Http/Protocol/H1/Event.lean

@@ -0,0 +1,73 @@
+/-
+Copyright (c) 2025 Lean FRO, LLC. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Sofia Rodrigues
+-/
+module
+
+prelude
+public import Std.Time
+public import Std.Internal.Http.Data
+public import Std.Internal.Http.Internal
+public import Std.Internal.Http.Protocol.H1.Parser
+public import Std.Internal.Http.Protocol.H1.Config
+public import Std.Internal.Http.Protocol.H1.Message
+public import Std.Internal.Http.Protocol.H1.Error
+
+public section
+
+/-!
+# HTTP/1.1 Events
+
+This module defines the events that can occur during HTTP/1.1 message processing,
+including header completion and control/error signals.
+-/
+
+namespace Std.Http.Protocol.H1
+
+set_option linter.all true
+
+/--
+Events emitted during HTTP message processing.
+-/
+inductive Event (dir : Direction)
+  /--
+  Indicates that all headers have been successfully parsed.
+  -/
+  | endHeaders (head : Message.Head dir)
+
+  /--
+  Signals that additional input data is required to continue processing.
+  -/
+  | needMoreData (size : Option Nat)
+
+  /--
+  Indicates a failure during parsing or processing.
+  -/
+  | failed (err : Error)
+
+  /--
+  Requests that the connection be closed.
+  -/
+  | close
+
+  /--
+  The body should be closed.
+  -/
+  | closeBody
+
+  /--
+  Indicates that a response is required.
+  -/
+  | needAnswer
+
+  /--
+  Indicates readiness to process the next message.
+  -/
+  | next
+
+  /--
+  Signals that an `Expect: 100-continue` decision is pending.
+  -/
+  | «continue»
+deriving Inhabited, Repr

src/Std/Internal/Http/Protocol/H1/Message.lean

@@ -0,0 +1,139 @@
+/-
+Copyright (c) 2025 Lean FRO, LLC. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Sofia Rodrigues
+-/
+module
+
+prelude
+import Init.Data.Array
+public import Std.Internal.Http.Data
+
+public section
+
+/-!
+# Message
+
+This module provides types and operations for HTTP/1.1 messages, centered around the `Direction`
+type which models the server's role in message exchange: `Direction.receiving` for parsing incoming
+requests from clients, and `Direction.sending` for generating outgoing responses to clients.
+The `Message.Head` type is parameterized by `Direction` and resolves to `Request.Head` or
+`Response.Head` accordingly, enabling generic code that works uniformly across both phases
+while exposing common operations such as headers, version, and `shouldKeepAlive`
+-/
+
+namespace Std.Http.Protocol.H1
+
+set_option linter.all true
+
+/--
+Direction of message flow from the server's perspective.
+-/
+inductive Direction
+  /--
+  Receiving and parsing incoming requests from clients.
+  -/
+  | receiving
+
+  /--
+  Client perspective: writing outgoing requests and reading incoming responses.
+  -/
+  | sending
+deriving BEq
+
+/--
+Inverts the message direction.
+-/
+@[expose]
+abbrev Direction.swap : Direction → Direction
+  | .receiving => .sending
+  | .sending => .receiving
+
+/--
+Gets the message head type based on direction.
+-/
+@[expose]
+def Message.Head : Direction → Type
+  | .receiving => Request.Head
+  | .sending => Response.Head
+
+/--
+Gets the headers of a `Message`.
+-/
+def Message.Head.headers (m : Message.Head dir) : Headers :=
+  match dir with
+  | .receiving => Request.Head.headers m
+  | .sending => Response.Head.headers m
+
+/--
+Gets the version of a `Message`.
+-/
+def Message.Head.version (m : Message.Head dir) : Version :=
+  match dir with
+  | .receiving => Request.Head.version m
+  | .sending => Response.Head.version m
+
+/--
+Determines the message body size based on the `Content-Length` header and the `Transfer-Encoding` (chunked) flag.
+-/
+def Message.Head.getSize (message : Message.Head dir) (allowEOFBody : Bool) : Option Body.Length :=
+  let contentLength := message.headers.getAll? .contentLength
+
+  match message.headers.getAll? .transferEncoding with
+  | none =>
+      match contentLength with
+      | some #[cl] => .fixed <$> cl.value.toNat?
+      | some _ => none -- To avoid request smuggling with malformed/multiple content-length headers.
+      | none => if allowEOFBody then some (.fixed 0) else none
+
+  -- Single transfer-encoding header.
+  | some #[header] =>
+    let te := Header.TransferEncoding.parse header
+
+    match Header.TransferEncoding.isChunked <$> te, contentLength with
+    | some true, none =>
+        -- HTTP/1.0 does not define chunked transfer encoding (RFC 2068 §19.4.6).
+        -- A server MUST NOT use chunked with an HTTP/1.0 peer; likewise, an
+        -- HTTP/1.0 request carrying Transfer-Encoding: chunked is malformed.
+        if message.version == .v10 then none else some .chunked
+    | _, _ => none -- To avoid request smuggling when TE and CL are mixed.
+
+  -- We disallow multiple transfer-encoding headers.
+  | some _ => none
+/--
+Checks whether the message indicates that the connection should be kept alive.
+-/
+def Message.Head.shouldKeepAlive (message : Message.Head dir) : Bool :=
+  let tokens? : Option (Array String) :=
+    match message.headers.getAll? .connection with
+    | none => some #[]
+    | some values =>
+        values.foldl (fun acc raw => do
+          let acc ← acc
+          let parsed ← Header.Connection.parse raw
+          pure (acc ++ parsed.tokens)
+        ) (some #[])
+
+  match tokens? with
+  | none => false
+  | some tokens =>
+      if message.version == .v11 then
+        !tokens.any (· == "close")
+      else
+        tokens.any (· == "keep-alive")
+
+instance : Repr (Message.Head dir) :=
+  match dir with
+  | .receiving => inferInstanceAs (Repr Request.Head)
+  | .sending => inferInstanceAs (Repr Response.Head)
+
+instance : Internal.Encode .v11 (Message.Head dir) :=
+  match dir with
+  | .receiving => inferInstanceAs (Internal.Encode .v11 Request.Head)
+  | .sending => inferInstanceAs (Internal.Encode .v11 Response.Head)
+
+instance : EmptyCollection (Message.Head dir) where
+  emptyCollection :=
+    match dir with
+    | .receiving => { method := .get, version := .v11 }
+    | .sending => {}

src/Std/Internal/Http/Protocol/H1/Parser.lean

@@ -0,0 +1,548 @@
+/-
+Copyright (c) 2025 Lean FRO, LLC. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Sofia Rodrigues
+-/
+module
+
+prelude
+public import Std.Internal.Parsec
+public import Std.Internal.Http.Data
+public import Std.Internal.Parsec.ByteArray
+public import Std.Internal.Http.Protocol.H1.Config
+
+/-!
+This module defines parsers for HTTP/1.1 request and response lines, headers, and body framing. The
+reference used is https://httpwg.org/specs/rfc9112.html.
+-/
+
+namespace Std.Http.Protocol.H1
+
+open Std Internal Parsec ByteArray Internal Internal.Char
+
+set_option linter.all true
+
+/--
+Checks if a byte may appear inside a field value.
+
+This parser enforces strict ASCII-only field values and allows only `field-content`
+(`HTAB / SP / VCHAR`).
+-/
+@[inline]
+def isFieldVChar (c : UInt8) : Bool :=
+  fieldContent (Char.ofUInt8 c)
+
+/--
+Checks if a byte may appear unescaped inside a quoted-string value.
+
+Allows `HTAB / SP / %x21 / %x23-5B / %x5D-7E` (strict ASCII-only; no obs-text).
+-/
+@[inline]
+def isQdText (c : UInt8) : Bool :=
+  qdtext (Char.ofUInt8 c)
+
+/--
+Checks if a byte is optional whitespace (`OWS = SP / HTAB`, RFC 9110 §5.6.3).
+-/
+@[inline]
+def isOwsByte (c : UInt8) : Bool :=
+  ows (Char.ofUInt8 c)
+
+-- Parser blocks
+
+/--
+Repeatedly applies `parser` until it returns `none` or the `maxCount` limit is
+exceeded. Returns the collected results as an array.
+-/
+partial def manyItems {α : Type} (parser : Parser (Option α)) (maxCount : Nat) : Parser (Array α) := do
+  let rec go (acc : Array α) : Parser (Array α) := do
+    let step ← optional <| attempt do
+      match ← parser with
+      | none => fail "end of items"
+      | some x => return x
+
+    match step with
+    | none =>
+      return acc
+    | some x =>
+      let acc := acc.push x
+
+      if acc.size > maxCount then
+        fail s!"too many items: {acc.size} > {maxCount}"
+
+      go acc
+  go #[]
+
+
+/--
+Lifts an `Option` into the parser monad, failing with a generic message if the value is `none`.
+-/
+def liftOption (x : Option α) : Parser α :=
+  if let some res := x then
+    return res
+  else
+    fail "expected value but got none"
+
+/--
+Parses an HTTP token (RFC 9110 §5.6.2): one or more token characters, up to `limit` bytes.
+Fails if the input starts with a non-token character or is empty.
+-/
+@[inline]
+def parseToken (limit : Nat) : Parser ByteSlice :=
+  takeWhileUpTo1 (fun c => tchar (Char.ofUInt8 c)) limit
+
+/--
+Parses a line terminator.
+-/
+@[inline]
+def crlf : Parser Unit := do
+  skipBytes "\r\n".toUTF8
+
+/--
+Consumes and ignores empty lines (`CRLF`) that appear before a request-line.
+
+https://httpwg.org/specs/rfc9112.html#rfc.section.2.2:
+
+"In the interest of robustness, a server that is expecting to receive and parse a request-line SHOULD
+ignore at least one empty line (CRLF) received prior to the request-line."
+-/
+def skipLeadingRequestEmptyLines (limits : H1.Config) : Parser Unit := do
+  let mut count := 0
+  while (← peekWhen? (· == '\r'.toUInt8)).isSome do
+    if count >= limits.maxLeadingEmptyLines then
+      fail "too many leading empty lines"
+    crlf
+    count := count + 1
+
+/--
+Parses a single space (SP, 0x20).
+-/
+@[inline]
+def sp : Parser Unit :=
+  skipByte ' '.toUInt8
+
+/--
+Parses optional whitespace (OWS = *(SP / HTAB), RFC 9110 §5.6.3), bounded by
+`limits.maxSpaceSequence`. Fails if more whitespace follows the limit, so oversized
+padding is rejected rather than silently truncated.
+-/
+@[inline]
+def ows (limits : H1.Config) : Parser Unit := do
+  discard <| takeWhileUpTo isOwsByte limits.maxSpaceSequence
+
+  if (← peekWhen? isOwsByte) |>.isSome then
+    fail "invalid space sequence"
+  else
+    pure ()
+
+/--
+Parses a single ASCII hex digit and returns its numeric value (`0`–`15`).
+-/
+def hexDigit : Parser UInt8 := do
+  let b ← any
+  if isHexDigitByte b then
+    if b ≥ '0'.toUInt8 && b ≤ '9'.toUInt8 then return b - '0'.toUInt8
+    else if b ≥ 'A'.toUInt8 && b ≤ 'F'.toUInt8 then return b - 'A'.toUInt8 + 10
+    else return b - 'a'.toUInt8 + 10
+  else fail s!"invalid hex digit {Char.ofUInt8 b |>.quote}"
+
+/--
+Parses a hexadecimal integer (one or more hex digits, up to 16 digits).
+Used for chunk-size lines in chunked transfer encoding.
+-/
+partial def hex : Parser Nat := do
+  let rec go (acc : Nat) (count : Nat) : Parser Nat := do
+    match ← optional (attempt hexDigit) with
+    | some d =>
+        if count + 1 > 16 then
+          fail "chunk size too large"
+        else
+          go (acc * 16 + d.toNat) (count + 1)
+    | none =>
+        if count = 0 then
+          -- Preserve EOF as incremental chunk-size parsing can request more data.
+          -- For non-EOF invalid bytes, keep the specific parse failure.
+          let _ ← peek!
+          fail "expected hex digit"
+        else
+          return acc
+  go 0 0
+
+-- Actual parsers
+
+/--
+Parses `HTTP-version = HTTP-name "/" DIGIT "." DIGIT` and returns the major and
+minor version numbers as a pair.
+-/
+def parseHttpVersionNumber : Parser (Nat × Nat) := do
+  skipBytes "HTTP/".toUTF8
+  let major ← digit
+  skipByte '.'.toUInt8
+  let minor ← digit
+  pure ((major.toNat - 48), (minor.toNat - 48))
+
+/--
+Parses an HTTP version string and returns the corresponding `Version` value.
+Fails if the version is not recognized by `Version.ofNumber?`.
+-/
+def parseHttpVersion : Parser Version := do
+  let (major, minor) ← parseHttpVersionNumber
+  liftOption <| Version.ofNumber? major minor
+
+/-
+method         = token
+
+Every branch is wrapped in `attempt` so that `<|>` always backtracks on
+failure, even after consuming bytes. This is strictly necessary only for the
+P-group (POST / PUT / PATCH) which share a common first byte, but wrapping
+all alternatives keeps the parser defensively correct if new methods are
+added in the future.
+-/
+def parseMethod : Parser Method :=
+  (attempt <| skipBytes "GET".toUTF8 <&> fun _ => Method.get)
+  <|> (attempt <| skipBytes "HEAD".toUTF8 <&> fun _ => Method.head)
+  <|> (attempt <| skipBytes "DELETE".toUTF8 <&> fun _ => Method.delete)
+  <|> (attempt <| skipBytes "TRACE".toUTF8 <&> fun _ => Method.trace)
+  <|> (attempt <| skipBytes "ACL".toUTF8 <&> fun _ => Method.acl)
+  <|> (attempt <| skipBytes "QUERY".toUTF8 <&> fun _ => Method.query)
+  <|> (attempt <| skipBytes "SEARCH".toUTF8 <&> fun _ => Method.search)
+  <|> (attempt <| skipBytes "BASELINE-CONTROL".toUTF8 <&> fun _ => Method.baselineControl)
+  <|> (attempt <| skipBytes "BIND".toUTF8 <&> fun _ => Method.bind)
+  <|> (attempt <| skipBytes "CONNECT".toUTF8 <&> fun _ => Method.connect)
+  <|> (attempt <| skipBytes "CHECKIN".toUTF8 <&> fun _ => Method.checkin)
+  <|> (attempt <| skipBytes "CHECKOUT".toUTF8 <&> fun _ => Method.checkout)
+  <|> (attempt <| skipBytes "COPY".toUTF8 <&> fun _ => Method.copy)
+  <|> (attempt <| skipBytes "LABEL".toUTF8 <&> fun _ => Method.label)
+  <|> (attempt <| skipBytes "LINK".toUTF8 <&> fun _ => Method.link)
+  <|> (attempt <| skipBytes "LOCK".toUTF8 <&> fun _ => Method.lock)
+  <|> (attempt <| skipBytes "MERGE".toUTF8 <&> fun _ => Method.merge)
+  <|> (attempt <| skipBytes "MKACTIVITY".toUTF8 <&> fun _ => Method.mkactivity)
+  <|> (attempt <| skipBytes "MKCALENDAR".toUTF8 <&> fun _ => Method.mkcalendar)
+  <|> (attempt <| skipBytes "MKCOL".toUTF8 <&> fun _ => Method.mkcol)
+  <|> (attempt <| skipBytes "MKREDIRECTREF".toUTF8 <&> fun _ => Method.mkredirectref)
+  <|> (attempt <| skipBytes "MKWORKSPACE".toUTF8 <&> fun _ => Method.mkworkspace)
+  <|> (attempt <| skipBytes "MOVE".toUTF8 <&> fun _ => Method.move)
+  <|> (attempt <| skipBytes "OPTIONS".toUTF8 <&> fun _ => Method.options)
+  <|> (attempt <| skipBytes "ORDERPATCH".toUTF8 <&> fun _ => Method.orderpatch)
+  <|> (attempt <| skipBytes "POST".toUTF8 <&> fun _ => Method.post)
+  <|> (attempt <| skipBytes "PUT".toUTF8 <&> fun _ => Method.put)
+  <|> (attempt <| skipBytes "PATCH".toUTF8 <&> fun _ => Method.patch)
+  <|> (attempt <| skipBytes "PRI".toUTF8 <&> fun _ => Method.pri)
+  <|> (attempt <| skipBytes "PROPFIND".toUTF8 <&> fun _ => Method.propfind)
+  <|> (attempt <| skipBytes "PROPPATCH".toUTF8 <&> fun _ => Method.proppatch)
+  <|> (attempt <| skipBytes "REBIND".toUTF8 <&> fun _ => Method.rebind)
+  <|> (attempt <| skipBytes "REPORT".toUTF8 <&> fun _ => Method.report)
+  <|> (attempt <| skipBytes "UNBIND".toUTF8 <&> fun _ => Method.unbind)
+  <|> (attempt <| skipBytes "UNCHECKOUT".toUTF8 <&> fun _ => Method.uncheckout)
+  <|> (attempt <| skipBytes "UNLINK".toUTF8 <&> fun _ => Method.unlink)
+  <|> (attempt <| skipBytes "UNLOCK".toUTF8 <&> fun _ => Method.unlock)
+  <|> (attempt <| skipBytes "UPDATEREDIRECTREF".toUTF8 <&> fun _ => Method.updateredirectref)
+  <|> (attempt <| skipBytes "UPDATE".toUTF8 <&> fun _ => Method.update)
+  <|> (attempt <| skipBytes "VERSION-CONTROL".toUTF8 <&> fun _ => Method.versionControl)
+  <|> (parseToken 64 *> fail "unrecognized method")
+
+/--
+Parses a request-target URI, up to `limits.maxUriLength` bytes.
+Fails with `"uri too long"` if the target exceeds the configured limit.
+-/
+def parseURI (limits : H1.Config) : Parser ByteArray := do
+  let uri ← takeUntilUpTo (· == ' '.toUInt8) limits.maxUriLength
+  if uri.size == limits.maxUriLength then
+    if (← peekWhen? (· != ' '.toUInt8)) |>.isSome then
+      fail "uri too long"
+
+  return uri.toByteArray
+
+/--
+Shared core for request-line parsing: parses `request-target SP HTTP-version CRLF`
+and returns the `RequestTarget` together with the raw major/minor version numbers.
+
+Both `parseRequestLine` and `parseRequestLineRawVersion` call this after consuming
+the method token, keeping URI validation and version parsing in one place.
+-/
+def parseRequestLineBody (limits : H1.Config) : Parser (RequestTarget × Nat × Nat) := do
+  let rawUri ← parseURI limits <* sp
+  let uri ← match (Std.Http.URI.Parser.parseRequestTarget <* eof).run rawUri with
+  | .ok res => pure res
+  | .error res => fail res
+  let versionPair ← parseHttpVersionNumber <* crlf
+  return (uri, versionPair)
+
+/--
+Parses a request line and returns a fully-typed `Request.Head`.
+`request-line = method SP request-target SP HTTP-version`
+-/
+public def parseRequestLine (limits : H1.Config) : Parser Request.Head := do
+  skipLeadingRequestEmptyLines limits
+  let method ← parseMethod <* sp
+  let (uri, (major, minor)) ← parseRequestLineBody limits
+  if major == 1 ∧ minor == 1 then
+    return ⟨method, .v11, uri, .empty⟩
+  else if major == 1 ∧ minor == 0 then
+    return ⟨method, .v10, uri, .empty⟩
+  else
+    fail "unsupported HTTP version"
+
+/--
+Parses a request line and returns the recognized HTTP method and version when available.
+
+request-line = method SP request-target SP HTTP-version
+-/
+public def parseRequestLineRawVersion (limits : H1.Config) : Parser (Method × RequestTarget × Option Version) := do
+  skipLeadingRequestEmptyLines limits
+  let method ← parseMethod <* sp
+  let (uri, (major, minor)) ← parseRequestLineBody limits
+  return (method, uri, Version.ofNumber? major minor)
+
+/--
+Parses a single header field line.
+
+`field-line = field-name ":" OWS field-value OWS`
+-/
+def parseFieldLine (limits : H1.Config) : Parser (String × String) := do
+  let name ← parseToken limits.maxHeaderNameLength
+  let value ← skipByte ':'.toUInt8 *> ows limits *> optional (takeWhileUpTo isFieldVChar limits.maxHeaderValueLength) <* ows limits
+
+  let name ← liftOption <| String.fromUTF8? name.toByteArray
+  let value ← liftOption <| String.fromUTF8? <| value.map (·.toByteArray) |>.getD .empty
+  let value := value.trimAsciiEnd.toString
+
+  return (name, value)
+
+/--
+Parses a single header field line, or returns `none` when it sees the blank line that
+terminates the header section.
+
+```
+field-line = field-name ":" OWS field-value OWS CRLF
+```
+-/
+public def parseSingleHeader (limits : H1.Config) : Parser (Option (String × String)) := do
+  let next ← peek?
+  if next == some '\r'.toUInt8 ∨ next == some '\n'.toUInt8 then
+    crlf
+    pure none
+  else
+    some <$> (parseFieldLine limits <* crlf)
+
+/--
+Parses a backslash-escaped character inside a quoted-string.
+
+`quoted-pair = "\" ( HTAB / SP / VCHAR )` — strict ASCII-only (no obs-text).
+-/
+def parseQuotedPair : Parser UInt8 := do
+  skipByte '\\'.toUInt8
+  let b ← any
+
+  if quotedPairChar (Char.ofUInt8 b) then
+    return b
+  else
+    fail s!"invalid quoted-pair byte: {Char.ofUInt8 b |>.quote}"
+
+/--
+Parses a quoted-string value, unescaping quoted-pairs.
+
+`quoted-string = DQUOTE *( qdtext / quoted-pair ) DQUOTE`
+-/
+partial def parseQuotedString (maxLength : Nat) : Parser String := do
+  skipByte '"'.toUInt8
+
+  let rec loop (buf : ByteArray) (length : Nat) : Parser ByteArray := do
+    let b ← any
+
+    if b == '"'.toUInt8 then
+      return buf
+    else if b == '\\'.toUInt8 then
+      let next ← any
+      if quotedPairChar (Char.ofUInt8 next)
+        then
+          let length := length + 1
+          if length > maxLength then
+            fail "quoted-string too long"
+          else
+            loop (buf.push next) length
+        else fail s!"invalid quoted-pair byte: {Char.ofUInt8 next |>.quote}"
+    else if isQdText b then
+      let length := length + 1
+      if length > maxLength then
+        fail "quoted-string too long"
+      else
+        loop (buf.push b) length
+    else
+      fail s!"invalid qdtext byte: {Char.ofUInt8 b |>.quote}"
+
+  liftOption <| String.fromUTF8? (← loop .empty 0)
+
+-- chunk-ext = *( BWS ";" BWS chunk-ext-name [ BWS "=" BWS chunk-ext-val] )
+def parseChunkExt (limits : H1.Config) : Parser (Chunk.ExtensionName × Option Chunk.ExtensionValue) := do
+  ows limits *> skipByte ';'.toUInt8 *> ows limits
+  let name ← (liftOption =<< String.fromUTF8? <$> ByteSlice.toByteArray <$> parseToken limits.maxChunkExtNameLength) <* ows limits
+
+  let some name := Chunk.ExtensionName.ofString? name
+    | fail "invalid extension name"
+
+  if (← peekWhen? (· == '='.toUInt8)) |>.isSome then
+    -- RFC 9112 §7.1.1: BWS is allowed around "=".
+    -- The `<* ows limits` after the name already consumed any trailing whitespace,
+    -- so these ows calls are no-ops in practice, but kept for explicit grammar correspondence.
+    ows limits *> skipByte '='.toUInt8 *> ows limits
+    let value ← ows limits *> (parseQuotedString limits.maxChunkExtValueLength <|> liftOption =<< (String.fromUTF8? <$> ByteSlice.toByteArray <$> parseToken limits.maxChunkExtValueLength))
+
+    let some value := Chunk.ExtensionValue.ofString? value
+      | fail "invalid extension value"
+
+    return (name, some value)
+
+  return (name, none)
+
+/--
+Parses the size and extensions of a chunk.
+-/
+public def parseChunkSize (limits : H1.Config) : Parser (Nat × Array (Chunk.ExtensionName × Option Chunk.ExtensionValue)) := do
+  let size ← hex
+  let ext ← manyItems (optional (attempt (parseChunkExt limits))) limits.maxChunkExtensions
+  crlf
+  return (size, ext)
+
+/--
+Result of parsing partial or complete information.
+-/
+public inductive TakeResult
+  | complete (data : ByteSlice)
+  | incomplete (data : ByteSlice) (remaining : Nat)
+
+/--
+Parses a single chunk in chunked transfer encoding.
+-/
+public def parseChunkPartial (limits : H1.Config) : Parser (Option (Nat × Array (Chunk.ExtensionName × Option Chunk.ExtensionValue) × ByteSlice)) := do
+  let (size, ext) ← parseChunkSize limits
+  if size == 0 then
+    return none
+  else
+    let data ← take size
+    return some ⟨size, ext, data⟩
+
+/--
+Parses fixed-size data that can be incomplete.
+-/
+public def parseFixedSizeData (size : Nat) : Parser TakeResult := fun it =>
+  if it.remainingBytes = 0 then
+    .error it .eof
+  else if it.remainingBytes < size then
+    .success (it.forward it.remainingBytes) (.incomplete it.array[it.idx...(it.idx+it.remainingBytes)] (size - it.remainingBytes))
+  else
+    .success (it.forward size) (.complete (it.array[it.idx...(it.idx+size)]))
+
+/--
+Parses fixed-size chunk data that can be incomplete.
+-/
+public def parseChunkSizedData (size : Nat) : Parser TakeResult := do
+  match ← parseFixedSizeData size with
+  | .complete data => crlf *> return .complete data
+  | .incomplete data res => return .incomplete data res
+
+/--
+Returns `true` if `name` (compared case-insensitively) is a field that MUST NOT appear in HTTP/1.1
+trailer sections per RFC 9112 §6.5. Forbidden fields are those required for message framing
+(`content-length`, `transfer-encoding`), routing (`host`), or connection management (`connection`).
+-/
+def isForbiddenTrailerField (name : String) : Bool :=
+  let n := name.toLower
+  n == "content-length" || n == "transfer-encoding" || n == "host" ||
+  n == "connection" || n == "expect" || n == "te" ||
+  n == "authorization" || n == "max-forwards" || n == "cache-control" ||
+  n == "content-encoding" || n == "upgrade" || n == "trailer"
+
+/--
+Parses a trailer header (used after a chunked body), rejecting forbidden field names per RFC 9112
+§6.5. Fields used for message framing (`content-length`, `transfer-encoding`), routing (`host`),
+or connection management (`connection`, `te`, `upgrade`) are rejected to prevent trailer injection
+attacks where a downstream proxy might re-interpret them.
+-/
+def parseTrailerHeader (limits : H1.Config) : Parser (Option (String × String)) := do
+  let result ← parseSingleHeader limits
+  if let some (name, _) := result then
+    if isForbiddenTrailerField name then
+      fail s!"forbidden trailer field: {name}"
+  return result
+
+/--
+Parses trailer headers after a chunked body and returns them as an array of name-value pairs.
+
+This is exposed for callers that need the trailer values directly (e.g. clients). The
+internal protocol machine uses `parseLastChunkBody` instead, which discards trailer values.
+-/
+public def parseTrailers (limits : H1.Config) : Parser (Array (String × String)) := do
+  let trailers ← manyItems (parseTrailerHeader limits) limits.maxTrailerHeaders
+  crlf
+  return trailers
+
+/--
+Returns `true` if `c` is a valid reason-phrase byte (`HTAB / SP / VCHAR`, strict ASCII-only).
+-/
+@[inline]
+def isReasonPhraseByte (c : UInt8) : Bool :=
+  fieldContent (Char.ofUInt8 c)
+
+/--
+Parses a reason phrase (text after status code).
+
+Allows only `HTAB / SP / VCHAR` bytes (strict ASCII-only).
+-/
+def parseReasonPhrase (limits : H1.Config) : Parser String := do
+  let bytes ← takeWhileUpTo isReasonPhraseByte limits.maxReasonPhraseLength
+  liftOption <| String.fromUTF8? bytes.toByteArray
+
+/--
+Parses a status-code (3 decimal digits), the following reason phrase, and the
+terminating CRLF; returns a typed `Status`.
+-/
+def parseStatusCode (limits : H1.Config) : Parser Status := do
+  let d1 ← digit
+  let d2 ← digit
+  let d3 ← digit
+  let code := (d1.toNat - 48) * 100 + (d2.toNat - 48) * 10 + (d3.toNat - 48)
+  sp
+  let phrase ← parseReasonPhrase limits <* crlf
+
+  if h : IsValidReasonPhrase phrase then
+    if let some status := Status.ofCode (some ⟨phrase, h⟩) code.toUInt16 then
+      return status
+
+  fail "invalid status code"
+
+/--
+Parses a status line and returns a fully-typed `Response.Head`.
+`status-line = HTTP-version SP status-code SP [ reason-phrase ]`
+Accepts only HTTP/1.1. For parsing where the version may be unrecognized and must be
+mapped to an error event, use `parseStatusLineRawVersion`.
+-/
+public def parseStatusLine (limits : H1.Config) : Parser Response.Head := do
+  let (major, minor) ← parseHttpVersionNumber <* sp
+  let status ← parseStatusCode limits
+  if major == 1 ∧ minor == 1 then
+    return { status, version := .v11, headers := .empty }
+  else if major == 1 ∧ minor == 0 then
+    return { status, version := .v10, headers := .empty }
+  else
+    fail "unsupported HTTP version"
+
+/--
+Parses a status line and returns the status code plus recognized HTTP version when available.
+Consumes and discards the reason phrase.
+
+status-line = HTTP-version SP status-code SP [ reason-phrase ] CRLF
+-/
+public def parseStatusLineRawVersion (limits : H1.Config) : Parser (Status × Option Version) := do
+  let (major, minor) ← parseHttpVersionNumber <* sp
+  let status ← parseStatusCode limits
+  return (status, Version.ofNumber? major minor)
+
+/--
+Parses the trailer section that follows the last chunk size line (`0\r\n`).
+-/
+public def parseLastChunkBody (limits : H1.Config) : Parser Unit := do
+  discard <| manyItems (parseTrailerHeader limits) limits.maxTrailerHeaders
+  crlf
+
+end Std.Http.Protocol.H1

src/Std/Internal/Http/Protocol/H1/Reader.lean

@@ -0,0 +1,319 @@
+/-
+Copyright (c) 2025 Lean FRO, LLC. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Sofia Rodrigues
+-/
+module
+
+prelude
+public import Std.Time
+public import Std.Internal.Http.Data
+public import Std.Internal.Http.Internal
+public import Std.Internal.Http.Protocol.H1.Parser
+public import Std.Internal.Http.Protocol.H1.Config
+public import Std.Internal.Http.Protocol.H1.Message
+public import Std.Internal.Http.Protocol.H1.Error
+
+public section
+
+/-!
+# HTTP/1.1 Reader
+
+This module defines the reader state machine for parsing incoming HTTP/1.1 messages.
+It tracks the parsing state including start line, headers, and body handling for
+both fixed-length and chunked transfer encodings.
+-/
+
+namespace Std.Http.Protocol.H1
+
+set_option linter.all true
+
+/--
+The body-framing sub-state of the `Reader` state machine.
+-/
+inductive Reader.BodyState where
+  /--
+  Parse fixed-length body bytes, tracking the number of bytes remaining.
+  -/
+  | fixed (remaining : Nat)
+
+  /--
+  Parse the next chunk-size line in chunked transfer encoding.
+  -/
+  | chunkedSize
+
+  /--
+  Parse chunk data for the current chunk.
+  -/
+  | chunkedBody (ext : Array (Chunk.ExtensionName × Option Chunk.ExtensionValue)) (remaining : Nat)
+
+  /--
+  Parse body bytes until EOF (connection close).
+  -/
+  | closeDelimited
+deriving Inhabited, Repr, BEq
+
+/--
+The state of the `Reader` state machine.
+-/
+inductive Reader.State (dir : Direction) : Type
+  /--
+  Initial state waiting for HTTP start line.
+  -/
+  | needStartLine : State dir
+
+  /--
+  State waiting for HTTP headers, tracking number of headers parsed.
+  -/
+  | needHeader : Nat → State dir
+
+  /--
+  Unified body-reading state.
+  -/
+  | readBody : Reader.BodyState → State dir
+
+  /--
+  Paused waiting for a `canContinue` decision, carrying the next state.
+  -/
+  | continue : State dir → State dir
+
+  /--
+  State waiting to be able to read new data.
+  -/
+  | pending : State dir
+
+  /--
+  State that it completed a single request or response and can go to the next one
+  -/
+  | complete
+
+  /--
+  State that it has completed and cannot process more data.
+  -/
+  | closed
+
+  /--
+  The input is malformed.
+  -/
+  | failed (error : Error) : State dir
+deriving Inhabited, Repr, BEq
+
+/--
+Manages the reading state of the HTTP parsing and processing machine.
+-/
+structure Reader (dir : Direction) where
+  /--
+  The current state of the machine.
+  -/
+  state : Reader.State dir := match dir with | .receiving => .needStartLine | .sending => .pending
+
+  /--
+  The input byte array.
+  -/
+  input : ByteArray.Iterator := ByteArray.emptyWithCapacity 4096 |>.iter
+
+  /--
+  The incoming message head.
+  -/
+  messageHead : Message.Head dir := {}
+
+  /--
+  Count of messages that this connection has already parsed.
+  -/
+  messageCount : Nat := 0
+
+  /--
+  Number of body bytes read for the current message.
+  -/
+  bodyBytesRead : Nat := 0
+
+  /--
+  Number of header bytes accumulated for the current message.
+  Counts name + value bytes plus 4 bytes per line for `: ` and `\r\n`.
+  -/
+  headerBytesRead : Nat := 0
+
+  /--
+  Set when no further input bytes will arrive (the remote end has closed the connection).
+  -/
+  noMoreInput : Bool := false
+
+namespace Reader
+
+/--
+Checks if the reader is in a closed state and cannot process more messages.
+-/
+@[inline]
+def isClosed (reader : Reader dir) : Bool :=
+  match reader.state with
+  | .closed => true
+  | _ => false
+
+/--
+Checks if the reader has completed parsing the current message.
+-/
+@[inline]
+def isComplete (reader : Reader dir) : Bool :=
+  match reader.state with
+  | .complete => true
+  | _ => false
+
+/--
+Checks if the reader has encountered an error.
+-/
+@[inline]
+def hasFailed (reader : Reader dir) : Bool :=
+  match reader.state with
+  | .failed _ => true
+  | _ => false
+
+/--
+Feeds new data into the reader's input buffer.
+If the current input is exhausted, replaces it; otherwise compacts the buffer
+by discarding already-parsed bytes before appending.
+-/
+@[inline]
+def feed (data : ByteArray) (reader : Reader dir) : Reader dir :=
+  { reader with input :=
+    if reader.input.atEnd
+      then data.iter
+      else (reader.input.array.extract reader.input.pos reader.input.array.size ++ data).iter }
+
+/--
+Replaces the reader's input iterator with a new one.
+-/
+@[inline]
+def setInput (input : ByteArray.Iterator) (reader : Reader dir) : Reader dir :=
+  { reader with input }
+
+/--
+Updates the message head being constructed.
+-/
+@[inline]
+def setMessageHead (messageHead : Message.Head dir) (reader : Reader dir) : Reader dir :=
+  { reader with messageHead }
+
+/--
+Adds a header to the current message head.
+-/
+@[inline]
+def addHeader (name : Header.Name) (value : Header.Value) (reader : Reader dir) : Reader dir :=
+  match dir with
+  | .sending | .receiving => { reader with messageHead := { reader.messageHead with headers := reader.messageHead.headers.insert name value } }
+
+/--
+Closes the reader, transitioning to the closed state.
+-/
+@[inline]
+def close (reader : Reader dir) : Reader dir :=
+  { reader with state := .closed, noMoreInput := true }
+
+/--
+Marks the current message as complete and prepares for the next message.
+-/
+@[inline]
+def markComplete (reader : Reader dir) : Reader dir :=
+  { reader with
+    state := .complete
+    messageCount := reader.messageCount + 1 }
+
+/--
+Transitions the reader to a failed state with the given error.
+-/
+@[inline]
+def fail (error : Error) (reader : Reader dir) : Reader dir :=
+  { reader with state := .failed error }
+
+/--
+Resets the reader to parse a new message on the same connection.
+-/
+@[inline]
+def reset (reader : Reader dir) : Reader dir :=
+  { reader with
+    state := .needStartLine
+    bodyBytesRead := 0
+    headerBytesRead := 0
+    messageHead := {} }
+
+/--
+Checks if more input is needed to continue parsing.
+-/
+@[inline]
+def needsMoreInput (reader : Reader dir) : Bool :=
+  reader.input.atEnd && !reader.noMoreInput &&
+  match reader.state with
+  | .complete | .closed | .failed _ | .«continue» _ => false
+  | _ => true
+
+/--
+Returns the current parse error if the reader has failed.
+-/
+@[inline]
+def getError (reader : Reader dir) : Option Error :=
+  match reader.state with
+  | .failed err => some err
+  | _ => none
+
+/--
+Gets the number of bytes remaining in the input buffer.
+-/
+@[inline]
+def remainingBytes (reader : Reader dir) : Nat :=
+  reader.input.array.size - reader.input.pos
+
+/--
+Advances the input iterator by n bytes.
+-/
+@[inline]
+def advance (n : Nat) (reader : Reader dir) : Reader dir :=
+  { reader with input := reader.input.forward n }
+
+/--
+Transitions to the state for reading headers.
+-/
+@[inline]
+def startHeaders (reader : Reader dir) : Reader dir :=
+  { reader with state := .needHeader 0, bodyBytesRead := 0, headerBytesRead := 0 }
+
+/--
+Adds body bytes parsed for the current message.
+-/
+@[inline]
+def addBodyBytes (n : Nat) (reader : Reader dir) : Reader dir :=
+  { reader with bodyBytesRead := reader.bodyBytesRead + n }
+
+/--
+Adds header bytes accumulated for the current message.
+-/
+@[inline]
+def addHeaderBytes (n : Nat) (reader : Reader dir) : Reader dir :=
+  { reader with headerBytesRead := reader.headerBytesRead + n }
+
+/--
+Transitions to the state for reading a fixed-length body.
+-/
+@[inline]
+def startFixedBody (size : Nat) (reader : Reader dir) : Reader dir :=
+  { reader with state := .readBody (.fixed size) }
+
+/--
+Transitions to the state for reading chunked transfer encoding.
+-/
+@[inline]
+def startChunkedBody (reader : Reader dir) : Reader dir :=
+  { reader with state := .readBody .chunkedSize }
+
+/--
+Marks that no more input will be provided (connection closed).
+-/
+@[inline]
+def markNoMoreInput (reader : Reader dir) : Reader dir :=
+  { reader with noMoreInput := true }
+
+/--
+Checks if the connection should be kept alive for the next message.
+-/
+def shouldKeepAlive (reader : Reader dir) : Bool :=
+  reader.messageHead.shouldKeepAlive
+
+end Reader

src/Std/Internal/Http/Protocol/H1/Writer.lean

@@ -0,0 +1,280 @@
+/-
+Copyright (c) 2025 Lean FRO, LLC. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Sofia Rodrigues
+-/
+module
+
+prelude
+public import Std.Time
+public import Std.Internal.Http.Data
+public import Std.Internal.Http.Internal
+public import Std.Internal.Http.Protocol.H1.Parser
+public import Std.Internal.Http.Protocol.H1.Config
+public import Std.Internal.Http.Protocol.H1.Message
+public import Std.Internal.Http.Protocol.H1.Error
+
+public section
+
+/-!
+# HTTP/1.1 Writer
+
+This module defines the writer state machine for generating outgoing HTTP/1.1 messages.
+It handles encoding headers and body content for both fixed-length and chunked
+transfer encodings.
+-/
+
+namespace Std.Http.Protocol.H1
+
+set_option linter.all true
+
+open Internal
+
+/--
+The state of the `Writer` state machine.
+-/
+inductive Writer.State
+  /--
+  Initial state before any outgoing message has been prepared.
+  -/
+  | pending
+
+  /--
+  Waiting for the application to provide the outgoing message head via `send`.
+  -/
+  | waitingHeaders
+
+  /--
+  The message head has been provided; waiting for `shouldFlush` to become true before
+  serializing headers to output.
+  -/
+  | waitingForFlush
+
+  /--
+  Writing the body output (either fixed-length or chunked).
+  -/
+  | writingBody (mode : Body.Length)
+
+  /--
+  Completed writing a single message and ready to begin the next one.
+  -/
+  | complete
+
+  /--
+  Closed; no further data can be written.
+  -/
+  | closed
+deriving Inhabited, Repr, BEq
+
+/--
+Manages the writing state of the HTTP generating and writing machine.
+-/
+structure Writer (dir : Direction) where
+  /--
+  Body chunks supplied by the user, accumulated before being flushed to output.
+  -/
+  userData : Array Chunk := .empty
+
+  /--
+  All the data produced by the writer, ready to be sent to the socket.
+  -/
+  outputData : ChunkedBuffer := .empty
+
+  /--
+  The state of the writer machine.
+  -/
+  state : Writer.State := match dir with | .receiving => .pending | .sending => .waitingHeaders
+
+  /--
+  When the user specifies the exact body size upfront, `Content-Length` framing is
+  used instead of chunked transfer encoding.
+  -/
+  knownSize : Option Body.Length := none
+
+  /--
+  The outgoing message that will be written to the output.
+  -/
+  messageHead : Message.Head dir.swap := {}
+
+  /--
+  Whether the user has called `send` to provide the outgoing message head.
+  -/
+  sentMessage : Bool := false
+
+  /--
+  Set when the user has finished sending body data, allowing fixed-size framing
+  to be determined upfront.
+  -/
+  userClosedBody : Bool := false
+
+  /--
+  When `true`, body bytes are intentionally omitted from the wire for this message
+  (e.g. HEAD responses), while headers/framing metadata may still describe the
+  hypothetical representation.
+  -/
+  omitBody : Bool := false
+
+  /--
+  Running total of bytes across all `userData` chunks, maintained incrementally
+  to avoid an O(n) fold on every fixed-length write step.
+  -/
+  userDataBytes : Nat := 0
+
+namespace Writer
+
+/--
+Returns `true` when no more user body data will arrive: either the user called
+`closeBody`, or the writer has already transitioned to `complete` or `closed`.
+
+Note: this does **not** mean the wire is ready to accept new bytes — a `closed`
+writer cannot send anything. Use this to decide whether to flush pending body
+data rather than to check writability.
+-/
+@[inline]
+def noMoreUserData {dir} (writer : Writer dir) : Bool :=
+  match writer.state with
+  | .closed | .complete => true
+  | _ => writer.userClosedBody
+
+/--
+Checks if the writer is closed (cannot process more data).
+-/
+@[inline]
+def isClosed (writer : Writer dir) : Bool :=
+  match writer.state with
+  | .closed => true
+  | _ => false
+
+/--
+Checks if the writer has completed processing a request.
+-/
+@[inline]
+def isComplete (writer : Writer dir) : Bool :=
+  match writer.state with
+  | .complete => true
+  | _ => false
+
+/--
+Checks if the writer can accept more data from the user.
+-/
+@[inline]
+def canAcceptData (writer : Writer dir) : Bool :=
+  match writer.state with
+  | .waitingHeaders => true
+  | .waitingForFlush => true
+  | .writingBody _ => !writer.userClosedBody
+  | _ => false
+
+/--
+Marks the body as closed, indicating no more user data will be added.
+-/
+@[inline]
+def closeBody (writer : Writer dir) : Writer dir :=
+  { writer with userClosedBody := true }
+
+/--
+Determines the transfer encoding mode based on explicit setting, body closure state, or defaults to chunked.
+-/
+def determineTransferMode (writer : Writer dir) : Body.Length :=
+  if let some mode := writer.knownSize then
+    mode
+  else if writer.userClosedBody then
+    .fixed writer.userDataBytes
+  else
+    .chunked
+
+/--
+Adds user data chunks to the writer's buffer if the writer can accept data.
+-/
+@[inline]
+def addUserData (data : Array Chunk) (writer : Writer dir) : Writer dir :=
+  if writer.canAcceptData then
+    let extraBytes := data.foldl (fun acc c => acc + c.data.size) 0
+    { writer with userData := writer.userData ++ data, userDataBytes := writer.userDataBytes + extraBytes }
+  else
+    writer
+
+/--
+Writes accumulated user data to output using fixed-size encoding.
+-/
+def writeFixedBody (writer : Writer dir) (limitSize : Nat) : Writer dir × Nat :=
+  if writer.userData.size = 0 then
+    (writer, limitSize)
+  else
+    let (chunks, pending, totalSize) := writer.userData.foldl (fun (state : Array ByteArray × Array Chunk × Nat) chunk =>
+      let (acc, pending, size) := state
+      if size >= limitSize then
+        (acc, pending.push chunk, size)
+      else
+        let remaining := limitSize - size
+        let takeSize := min chunk.data.size remaining
+        let dataPart := chunk.data.extract 0 takeSize
+        let acc := if takeSize = 0 then acc else acc.push dataPart
+        let size := size + takeSize
+        if takeSize < chunk.data.size then
+          let pendingChunk : Chunk := { chunk with data := chunk.data.extract takeSize chunk.data.size }
+          (acc, pending.push pendingChunk, size)
+        else
+          (acc, pending, size)
+    ) (#[], #[], 0)
+    let outputData := writer.outputData.append (ChunkedBuffer.ofArray chunks)
+    let remaining := limitSize - totalSize
+    ({ writer with userData := pending, outputData, userDataBytes := writer.userDataBytes - totalSize }, remaining)
+
+/--
+Writes accumulated user data to output using chunked transfer encoding.
+-/
+def writeChunkedBody (writer : Writer dir) : Writer dir :=
+  if writer.userData.size = 0 then
+    writer
+  else
+    let data := writer.userData
+    { writer with userData := #[], userDataBytes := 0, outputData := data.foldl (Encode.encode .v11) writer.outputData }
+
+/--
+Writes the final chunk terminator (0\r\n\r\n) and transitions to complete state.
+-/
+def writeFinalChunk (writer : Writer dir) : Writer dir :=
+  let writer := writer.writeChunkedBody
+  { writer with
+    outputData := writer.outputData.write "0\r\n\r\n".toUTF8
+    state := .complete
+  }
+
+/--
+Extracts all accumulated output data and returns it with a cleared output buffer.
+-/
+@[inline]
+def takeOutput (writer : Writer dir) : Option (Writer dir × ByteArray) :=
+  let output := writer.outputData.toByteArray
+  some ({ writer with outputData := ChunkedBuffer.empty }, output)
+
+/--
+Updates the writer's state machine to a new state.
+-/
+@[inline]
+def setState (state : Writer.State) (writer : Writer dir) : Writer dir :=
+  { writer with state }
+
+/--
+Writes the message headers to the output buffer.
+-/
+private def writeHeaders (messageHead : Message.Head dir.swap) (writer : Writer dir) : Writer dir :=
+  { writer with outputData := Internal.Encode.encode (v := .v11) writer.outputData messageHead }
+
+/--
+Checks if the connection should be kept alive based on the Connection header.
+-/
+def shouldKeepAlive (writer : Writer dir) : Bool :=
+  writer.messageHead.headers.get? .connection
+  |>.map (fun v => v.value.toLower != "close")
+  |>.getD true
+
+/--
+Closes the writer, transitioning to the closed state.
+-/
+@[inline]
+def close (writer : Writer dir) : Writer dir :=
+  { writer with state := .closed }
+
+end Writer

src/Std/Internal/Parsec/ByteArray.lean

@@ -44,8 +44,15 @@ protected def Parser.run (p : Parser α) (arr : ByteArray) : Except String α :=
 Parse a single byte equal to `b`, fails if different.
 -/
 @[inline]
-def pbyte (b : UInt8) : Parser UInt8 := attempt do
-  if (← any) = b then pure b else fail s!"expected: '{b}'"
+def pbyte (b : UInt8) : Parser UInt8 := fun it =>
+  if h : it.hasNext then
+    let got := it.curr' h
+    if got = b then
+      .success (it.next' h) got
+    else
+      .error it (.other s!"expected: '{b}'")
+  else
+    .error it .eof
 
 /--
 Skip a single byte equal to `b`, fails if different.
@@ -57,16 +64,29 @@ def skipByte (b : UInt8) : Parser Unit :=
 /--
 Skip a sequence of bytes equal to the given `ByteArray`.
 -/
-def skipBytes (arr : ByteArray) : Parser Unit := do
-  for b in arr do
-    skipByte b
+def skipBytes (arr : ByteArray) : Parser Unit := fun it =>
+  let rec go (idx : Nat) (it : ByteArray.Iterator) : ParseResult Unit ByteArray.Iterator :=
+    if h : idx < arr.size then
+      if hnext : it.hasNext then
+        let got := it.curr' hnext
+        let want := arr[idx]
+        if got = want then
+          go (idx + 1) (it.next' hnext)
+        else
+          .error it (.other s!"expected byte {want}, got {got}")
+      else
+        .error it .eof
+    else
+      .success it ()
+  go 0 it
 
 /--
 Parse a string by matching its UTF-8 bytes, returns the string on success.
 -/
 @[inline]
 def pstring (s : String) : Parser String := do
-  skipBytes s.toUTF8
+  let utf8 := s.toUTF8
+  skipBytes utf8
   return s
 
 /--
@@ -193,19 +213,47 @@ def take (n : Nat) : Parser ByteSlice := fun it =>
   else
     .success (it.forward n) (it.array[it.idx...(it.idx+n)])
 
+/--
+Scans while `pred` is satisfied. Returns `(count, iterator, hitEof)`.
+-/
+private partial def scanWhile (pred : UInt8 → Bool) (count : Nat) (iter : ByteArray.Iterator) :
+    Nat × ByteArray.Iterator × Bool :=
+  if h : iter.hasNext then
+    if pred (iter.curr' h) then
+      scanWhile pred (count + 1) (iter.next' h)
+    else
+      (count, iter, false)
+  else
+    (count, iter, true)
+
+/--
+Scans while `pred` is satisfied, bounded by `limit`.
+Returns `(count, iterator, hitEof)`.
+-/
+private partial def scanWhileUpTo (pred : UInt8 → Bool) (limit : Nat) (count : Nat)
+    (iter : ByteArray.Iterator) : Nat × ByteArray.Iterator × Bool :=
+  if count ≥ limit then
+    (count, iter, false)
+  else if h : iter.hasNext then
+    if pred (iter.curr' h) then
+      scanWhileUpTo pred limit (count + 1) (iter.next' h)
+    else
+      (count, iter, false)
+  else
+    (count, iter, true)
+
 /--
 Parses while a predicate is satisfied.
+Fails with `.eof` if input ends while the predicate still holds.
 -/
 @[inline]
 partial def takeWhile (pred : UInt8 → Bool) : Parser ByteSlice :=
   fun it =>
-    let rec findEnd (count : Nat) (iter : ByteArray.Iterator) : Nat × ByteArray.Iterator :=
-      if ¬iter.hasNext then (count, iter)
-      else if pred iter.curr then findEnd (count + 1) iter.next
-      else (count, iter)
-
-    let (length, newIt) := findEnd 0 it
-    .success newIt (it.array[it.idx...(it.idx + length)])
+    let (length, newIt, hitEof) := scanWhile pred 0 it
+    if hitEof then
+      .error newIt .eof
+    else
+      .success newIt (it.array[it.idx...(it.idx + length)])
 
 /--
 Parses until a predicate is satisfied (exclusive).
@@ -216,16 +264,16 @@ def takeUntil (pred : UInt8 → Bool) : Parser ByteSlice :=
 
 /--
 Skips while a predicate is satisfied.
+Fails with `.eof` if input ends while the predicate still holds.
 -/
 @[inline]
 partial def skipWhile (pred : UInt8 → Bool) : Parser Unit :=
   fun it =>
-    let rec findEnd (count : Nat) (iter : ByteArray.Iterator) : ByteArray.Iterator :=
-      if ¬iter.hasNext then iter
-      else if pred iter.curr then findEnd (count + 1) iter.next
-      else iter
-
-    .success (findEnd 0 it) ()
+    let (_, newIt, hitEof) := scanWhile pred 0 it
+    if hitEof then
+      .error newIt .eof
+    else
+      .success newIt ()
 
 /--
 Skips until a predicate is satisfied.
@@ -236,34 +284,31 @@ def skipUntil (pred : UInt8 → Bool) : Parser Unit :=
 
 /--
 Parses while a predicate is satisfied, up to a given limit.
+Fails with `.eof` if input ends before stopping or reaching the limit.
 -/
 @[inline]
 partial def takeWhileUpTo (pred : UInt8 → Bool) (limit : Nat) : Parser ByteSlice :=
   fun it =>
-    let rec findEnd (count : Nat) (iter : ByteArray.Iterator) : Nat × ByteArray.Iterator :=
-      if count ≥ limit then (count, iter)
-      else if ¬iter.hasNext then (count, iter)
-      else if pred iter.curr then findEnd (count + 1) iter.next
-      else (count, iter)
+    let (length, newIt, hitEof) := scanWhileUpTo pred limit 0 it
 
-    let (length, newIt) := findEnd 0 it
-    .success newIt (it.array[it.idx...(it.idx + length)])
+    if hitEof then
+      .error newIt .eof
+    else
+      .success newIt (it.array[it.idx...(it.idx + length)])
 
 /--
 Parses while a predicate is satisfied, up to a given limit, requiring at least one byte.
+Fails with `.eof` if input ends before stopping or reaching the limit.
 -/
 @[inline]
 def takeWhileUpTo1 (pred : UInt8 → Bool) (limit : Nat) : Parser ByteSlice :=
   fun it =>
-    let rec findEnd (count : Nat) (iter : ByteArray.Iterator) : Nat × ByteArray.Iterator :=
-      if count ≥ limit then (count, iter)
-      else if ¬iter.hasNext then (count, iter)
-      else if pred iter.curr then findEnd (count + 1) iter.next
-      else (count, iter)
+    let (length, newIt, hitEof) := scanWhileUpTo pred limit 0 it
 
-    let (length, newIt) := findEnd 0 it
-    if length = 0 then
-      .error it (if newIt.atEnd then .eof else .other "expected at least one char")
+    if hitEof then
+      .error newIt .eof
+    else if length = 0 then
+      .error it (.other "expected at least one char")
     else
       .success newIt (it.array[it.idx...(it.idx + length)])
 
@@ -274,19 +319,42 @@ Parses until a predicate is satisfied (exclusive), up to a given limit.
 def takeUntilUpTo (pred : UInt8 → Bool) (limit : Nat) : Parser ByteSlice :=
   takeWhileUpTo (fun b => ¬pred b) limit
 
+/--
+Parses while a predicate is satisfied, consuming at most `limit` bytes.
+Unlike `takeWhileUpTo`, succeeds even if input ends before the predicate stops holding.
+-/
+@[inline]
+def takeWhileAtMost (pred : UInt8 → Bool) (limit : Nat) : Parser ByteSlice :=
+  fun it =>
+    let (length, newIt, _) := scanWhileUpTo pred limit 0 it
+    .success newIt (it.array[it.idx...(it.idx + length)])
+
+/--
+Parses while a predicate is satisfied, consuming at most `limit` bytes, requiring at least one.
+Unlike `takeWhileUpTo1`, succeeds even if input ends before the predicate stops holding.
+-/
+@[inline]
+def takeWhile1AtMost (pred : UInt8 → Bool) (limit : Nat) : Parser ByteSlice :=
+  fun it =>
+    let (length, newIt, _) := scanWhileUpTo pred limit 0 it
+    if length = 0 then
+      .error it (.other "expected at least one char")
+    else
+      .success newIt (it.array[it.idx...(it.idx + length)])
+
 /--
 Skips while a predicate is satisfied, up to a given limit.
+Fails with `.eof` if input ends before stopping or reaching the limit.
 -/
 @[inline]
 partial def skipWhileUpTo (pred : UInt8 → Bool) (limit : Nat) : Parser Unit :=
   fun it =>
-    let rec findEnd (count : Nat) (iter : ByteArray.Iterator) : ByteArray.Iterator :=
-      if count ≥ limit then iter
-      else if ¬iter.hasNext then iter
-      else if pred iter.curr then findEnd (count + 1) iter.next
-      else iter
+    let (_, newIt, hitEof) := scanWhileUpTo pred limit 0 it
 
-    .success (findEnd 0 it) ()
+    if hitEof then
+      .error newIt .eof
+    else
+      .success newIt ()
 
 /--
 Skips until a predicate is satisfied, up to a given limit.

src/include/lean/lean.h

@@ -325,6 +325,55 @@ LEAN_EXPORT LEAN_NORETURN void lean_internal_panic(char const * msg);
 LEAN_EXPORT LEAN_NORETURN void lean_internal_panic_out_of_memory(void);
 LEAN_EXPORT LEAN_NORETURN void lean_internal_panic_unreachable(void);
 LEAN_EXPORT LEAN_NORETURN void lean_internal_panic_rc_overflow(void);
+LEAN_EXPORT LEAN_NORETURN void lean_internal_panic_overflow(void);
+
+static inline bool lean_usize_mul_would_overflow(size_t a, size_t b) {
+#if defined(__GNUC__) || defined(__clang__)
+    size_t r;
+    return __builtin_mul_overflow(a, b, &r);
+#else
+    return a != 0 && b > SIZE_MAX / a;
+#endif
+}
+
+static inline bool lean_usize_add_would_overflow(size_t a, size_t b) {
+#if defined(__GNUC__) || defined(__clang__)
+    size_t r;
+    return __builtin_add_overflow(a, b, &r);
+#else
+    return a > SIZE_MAX - b;
+#endif
+}
+
+static inline size_t lean_usize_mul_checked(size_t a, size_t b) {
+#if defined(__GNUC__) || defined(__clang__)
+    size_t r;
+    if (LEAN_UNLIKELY(__builtin_mul_overflow(a, b, &r))) {
+        lean_internal_panic_overflow();
+    }
+    return r;
+#else
+    if (a != 0 && b > SIZE_MAX / a) {
+        lean_internal_panic_overflow();
+    }
+    return a * b;
+#endif
+}
+
+static inline size_t lean_usize_add_checked(size_t a, size_t b) {
+#if defined(__GNUC__) || defined(__clang__)
+    size_t r;
+    if (LEAN_UNLIKELY(__builtin_add_overflow(a, b, &r))) {
+        lean_internal_panic_overflow();
+    }
+    return r;
+#else
+    if (a > SIZE_MAX - b) {
+        lean_internal_panic_overflow();
+    }
+    return a + b;
+#endif
+}
 
 static inline size_t lean_align(size_t v, size_t a) {
     return (v / a)*a + a * (v % a != 0);
@@ -617,7 +666,7 @@ static inline uint8_t * lean_ctor_scalar_cptr(lean_object * o) {
 
 static inline lean_object * lean_alloc_ctor(unsigned tag, unsigned num_objs, unsigned scalar_sz) {
     assert(tag <= LeanMaxCtorTag && num_objs < LEAN_MAX_CTOR_FIELDS && scalar_sz < LEAN_MAX_CTOR_SCALARS_SIZE);
-    lean_object * o = lean_alloc_ctor_memory(sizeof(lean_ctor_object) + sizeof(void*)*num_objs + scalar_sz);
+    lean_object * o = lean_alloc_ctor_memory(lean_usize_add_checked(lean_usize_add_checked(sizeof(lean_ctor_object), lean_usize_mul_checked(sizeof(void*), num_objs)), scalar_sz));
     lean_set_st_header(o, tag, num_objs);
     return o;
 }
@@ -727,7 +776,7 @@ static inline lean_object ** lean_closure_arg_cptr(lean_object * o) { return lea
 static inline lean_obj_res lean_alloc_closure(void * fun, unsigned arity, unsigned num_fixed) {
     assert(arity > 0);
     assert(num_fixed < arity);
-    lean_closure_object * o = (lean_closure_object*)lean_alloc_object(sizeof(lean_closure_object) + sizeof(void*)*num_fixed);
+    lean_closure_object * o = (lean_closure_object*)lean_alloc_object(lean_usize_add_checked(sizeof(lean_closure_object), lean_usize_mul_checked(sizeof(void*), num_fixed)));
     lean_set_st_header((lean_object*)o, LeanClosure, 0);
     o->m_fun = fun;
     o->m_arity = arity;
@@ -773,7 +822,7 @@ LEAN_EXPORT lean_object* lean_apply_m(lean_object* f, unsigned n, lean_object**
 
 /* Arrays of objects (low level API) */
 static inline lean_obj_res lean_alloc_array(size_t size, size_t capacity) {
-    lean_array_object * o = (lean_array_object*)lean_alloc_object(sizeof(lean_array_object) + sizeof(void*)*capacity);
+    lean_array_object * o = (lean_array_object*)lean_alloc_object(lean_usize_add_checked(sizeof(lean_array_object), lean_usize_mul_checked(sizeof(void*), capacity)));
     lean_set_st_header((lean_object*)o, LeanArray, 0);
     o->m_size = size;
     o->m_capacity = capacity;
@@ -950,8 +999,18 @@ LEAN_EXPORT lean_object * lean_mk_array(lean_obj_arg n, lean_obj_arg v);
 
 /* Array of scalars */
 
+static inline bool lean_alloc_sarray_would_overflow(unsigned elem_size, size_t capacity) {
+    if (lean_usize_mul_would_overflow(elem_size, capacity)) {
+        return true;
+    }
+    if (lean_usize_add_would_overflow(sizeof(lean_sarray_object), elem_size * capacity)) {
+        return true;
+    }
+    return false;
+}
+
 static inline lean_obj_res lean_alloc_sarray(unsigned elem_size, size_t size, size_t capacity) {
-    lean_sarray_object * o = (lean_sarray_object*)lean_alloc_object(sizeof(lean_sarray_object) + elem_size*capacity);
+    lean_sarray_object * o = (lean_sarray_object*)lean_alloc_object(lean_usize_add_checked(sizeof(lean_sarray_object), lean_usize_mul_checked(elem_size, capacity)));
     lean_set_st_header((lean_object*)o, LeanScalarArray, elem_size);
     o->m_size = size;
     o->m_capacity = capacity;
@@ -1113,7 +1172,7 @@ static inline lean_obj_res lean_float_array_set(lean_obj_arg a, b_lean_obj_arg i
 /* Strings */
 
 static inline lean_obj_res lean_alloc_string(size_t size, size_t capacity, size_t len) {
-    lean_string_object * o = (lean_string_object*)lean_alloc_object(sizeof(lean_string_object) + capacity);
+    lean_string_object * o = (lean_string_object*)lean_alloc_object(lean_usize_add_checked(sizeof(lean_string_object), capacity));
     lean_set_st_header((lean_object*)o, LeanString, 0);
     o->m_size = size;
     o->m_capacity = capacity;

src/lake/Lake/Build/Actions.lean

@@ -136,7 +136,7 @@ public def compileStaticLib
   let args := args.push libFile.toString ++ (← mkArgs libFile <| oFiles.map toString)
   proc {cmd := ar.toString, args}
 
-private def getMacOSXDeploymentEnv : BaseIO (Array (String × Option String)) := do
+def getMacOSXDeploymentEnv : BaseIO (Array (String × Option String)) := do
   -- It is difficult to identify the correct minor version here, leading to linking warnings like:
   -- `ld64.lld: warning: /usr/lib/system/libsystem_kernel.dylib has version 13.5.0, which is newer than target minimum of 13.0.0`
   -- In order to suppress these we set the MACOSX_DEPLOYMENT_TARGET variable into the far future.

src/lake/Lake/Build/Common.lean

@@ -126,7 +126,7 @@ public def BuildMetadata.parse (contents : String) : Except String BuildMetadata
 public def BuildMetadata.ofFetch (inputHash : Hash) (outputs : Json) : BuildMetadata :=
   {depHash := inputHash, outputs? := outputs, synthetic := true, inputs := #[], log := {}}
 
-private partial def serializeInputs (inputs : Array BuildTrace) : Array (String × Json) :=
+partial def serializeInputs (inputs : Array BuildTrace) : Array (String × Json) :=
   inputs.foldl (init := {}) fun r trace =>
     let val :=
       if trace.inputs.isEmpty then
@@ -135,7 +135,7 @@ private partial def serializeInputs (inputs : Array BuildTrace) : Array (String
         toJson (serializeInputs trace.inputs)
     r.push (trace.caption, val)
 
-private def BuildMetadata.ofBuildCore
+def BuildMetadata.ofBuildCore
   (depTrace : BuildTrace) (outputs : Json) (log : Log)
 : BuildMetadata where
   inputs := serializeInputs depTrace.inputs
@@ -210,7 +210,7 @@ deriving DecidableEq
 @[inline] public def OutputStatus.isCacheable (status : OutputStatus) : Bool :=
   status != .mtimeUpToDate
 
-@[specialize] private def checkHashUpToDate'
+@[specialize] def checkHashUpToDate'
   [CheckExists ι] [GetMTime ι]
   (info : ι) (depTrace : BuildTrace) (depHash : Option Hash)
   (oldTrace := depTrace.mtime)
@@ -514,7 +514,7 @@ stored in the cached input-to-content mapping.
 
 **For internal use only.**
 -/
-@[specialize] private def getArtifactsUsingCache?
+@[specialize] def getArtifactsUsingCache?
   [ResolveOutputs α] (inputHash : Hash) (pkg : Package)
 : JobM (Option α) := do
   if let some out ← (← getLakeCache).readOutputs? pkg.cacheScope inputHash then
@@ -868,7 +868,7 @@ public def buildStaticLib
       compileStaticLib libFile oFiles (← getLeanAr) thin
     return art.path
 
-private def mkLinkObjArgs
+def mkLinkObjArgs
   (objs : Array FilePath) (libs : Array Dynlib) : Array String
 := Id.run do
   let mut args := #[]
@@ -884,7 +884,7 @@ private def mkLinkObjArgs
 Topologically sorts the library dependency tree by name.
 Libraries come *before* their dependencies.
 -/
-private partial def mkLinkOrder (libs : Array Dynlib) : JobM (Array Dynlib) := do
+partial def mkLinkOrder (libs : Array Dynlib) : JobM (Array Dynlib) := do
   let r := libs.foldlM (m := Except (Cycle String)) (init := ({}, #[])) fun (v, o) lib =>
     go lib [] v o
   match r with

src/lake/Lake/Build/Executable.lean

@@ -19,7 +19,7 @@ open System (FilePath)
 The build function definition for a Lean executable.
 -/
 
-private def LeanExe.recBuildExe (self : LeanExe) : FetchM (Job FilePath) :=
+def LeanExe.recBuildExe (self : LeanExe) : FetchM (Job FilePath) :=
   withRegisterJob s!"{self.name}:exe" <| withCurrPackage self.pkg do
   /-
   Remark: We must build the root before we fetch the transitive imports
@@ -56,7 +56,7 @@ private def LeanExe.recBuildExe (self : LeanExe) : FetchM (Job FilePath) :=
 public def LeanExe.exeFacetConfig : LeanExeFacetConfig exeFacet :=
   mkFacetJobConfig recBuildExe
 
-private def LeanExe.recBuildDefault (lib : LeanExe) : FetchM (Job FilePath) :=
+def LeanExe.recBuildDefault (lib : LeanExe) : FetchM (Job FilePath) :=
   lib.exe.fetch
 
 /-- The facet configuration for the builtin `ExternLib.dynlibFacet`. -/

src/lake/Lake/Build/ExternLib.lean

@@ -20,7 +20,7 @@ open System
 
 namespace Lake
 
-private def ExternLib.recBuildStatic (lib : ExternLib) : FetchM (Job FilePath) :=
+def ExternLib.recBuildStatic (lib : ExternLib) : FetchM (Job FilePath) :=
   withRegisterJob s!"{lib.staticTargetName.toString}:static" do
   lib.config.getPath <$> fetch (lib.pkg.target lib.staticTargetName)
 
@@ -53,7 +53,7 @@ public def buildLeanSharedLibOfStatic
       compileSharedLib dynlib args lean.cc
     return dynlib
 
-private def ExternLib.recBuildShared (lib : ExternLib) : FetchM (Job FilePath) :=
+def ExternLib.recBuildShared (lib : ExternLib) : FetchM (Job FilePath) :=
   withRegisterJob s!"{lib.staticTargetName.toString}:shared" do
   buildLeanSharedLibOfStatic (← lib.static.fetch) lib.linkArgs
 
@@ -74,7 +74,7 @@ def computeDynlibOfShared (sharedLibTarget : Job FilePath) : SpawnM (Job Dynlib)
     else
       error s!"shared library `{sharedLib}` has no file name"
 
-private def ExternLib.recComputeDynlib (lib : ExternLib) : FetchM (Job Dynlib) := do
+def ExternLib.recComputeDynlib (lib : ExternLib) : FetchM (Job Dynlib) := do
   withRegisterJob s!"{lib.staticTargetName.toString}:dynlib" do
   computeDynlibOfShared (← lib.shared.fetch)
 
@@ -82,7 +82,7 @@ private def ExternLib.recComputeDynlib (lib : ExternLib) : FetchM (Job Dynlib) :
 public def ExternLib.dynlibFacetConfig : ExternLibFacetConfig dynlibFacet :=
   mkFacetJobConfig recComputeDynlib
 
-private def ExternLib.recBuildDefault (lib : ExternLib) : FetchM (Job FilePath) :=
+def ExternLib.recBuildDefault (lib : ExternLib) : FetchM (Job FilePath) :=
   lib.static.fetch
 
 /-- The facet configuration for the builtin `ExternLib.dynlibFacet`. -/

src/lake/Lake/Build/Index.lean

@@ -26,7 +26,7 @@ open System (FilePath)
 namespace Lake
 
 /-- Recursive build function for anything in the Lake build index. -/
-private def recBuildWithIndex (info : BuildInfo) : FetchM (Job (BuildData info.key)) :=
+def recBuildWithIndex (info : BuildInfo) : FetchM (Job (BuildData info.key)) :=
   match info with
   | .target pkg target => do
     if let some decl := pkg.findTargetDecl? target then
@@ -55,7 +55,7 @@ private def recBuildWithIndex (info : BuildInfo) : FetchM (Job (BuildData info.k
       error s!"invalid target '{info}': unknown facet '{facet}'"
 
 /-- Recursive build function with memoization. -/
-private def recFetchWithIndex : (info : BuildInfo) → RecBuildM (Job (BuildData info.key)) :=
+def recFetchWithIndex : (info : BuildInfo) → RecBuildM (Job (BuildData info.key)) :=
  inline <| recFetchAcyclic (β := (Job <| BuildData ·.key)) BuildInfo.key recBuildWithIndex
 
 /--

src/lake/Lake/Build/InputFile.lean

@@ -21,7 +21,7 @@ namespace Lake
 
 /-! ## Input File -/
 
-private def InputFile.recFetch (t : InputFile) : FetchM (Job FilePath) :=
+def InputFile.recFetch (t : InputFile) : FetchM (Job FilePath) :=
   withRegisterJob s!"{t.name}" do
   inputFile t.path t.text
 
@@ -39,7 +39,7 @@ public def InputFile.initFacetConfigs : DNameMap (KFacetConfig InputFile.facetKi
 
 /-! ## Input Directory -/
 
-private def InputDir.recFetch (t : InputDir) : FetchM (Job (Array FilePath)) :=
+def InputDir.recFetch (t : InputDir) : FetchM (Job (Array FilePath)) :=
   withRegisterJob s!"{t.name}" do
   inputDir t.path t.text t.filter
 

src/lake/Lake/Build/Job/Basic.lean

@@ -191,7 +191,7 @@ end Job
 /-- A Lake job task with an opaque value in `Type`. -/
 public abbrev OpaqueJobTask := JobTask Opaque
 
-@[inline] private unsafe def JobTask.toOpaqueImpl (self : JobTask α) : OpaqueJobTask :=
+@[inline] unsafe def JobTask.toOpaqueImpl (self : JobTask α) : OpaqueJobTask :=
   unsafeCast self
 
 /-- Forget the value of a job task. Implemented as a no-op cast. -/

src/lake/Lake/Build/Job/Monad.lean

@@ -275,7 +275,7 @@ public def collectList (jobs : List (Job α)) (traceCaption := "<collection>") :
 public def collectArray (jobs : Array (Job α)) (traceCaption := "<collection>") : Job (Array α) :=
   jobs.foldl (zipWith (sync := true) Array.push) (traceRoot (Array.mkEmpty jobs.size) traceCaption)
 
-private instance : Nonempty ({α : Type u} → [Nonempty α] → α) := ⟨Classical.ofNonempty⟩
+instance : Nonempty ({α : Type u} → [Nonempty α] → α) := ⟨Classical.ofNonempty⟩
 
 /-- Merge an `Vector` of jobs into one, collecting their outputs into an `Array`. -/
 public def collectVector {α : Type u} [Nonempty α] (jobs : Vector (Job α) n) (traceCaption := "<collection>") : Job (Vector α n) :=

src/lake/Lake/Build/Library.lean

@@ -33,7 +33,7 @@ private structure ModuleCollection where
 Collect the local modules of a library.
 That is, the modules from `getModuleArray` plus their local transitive imports.
 -/
-private partial def LeanLib.recCollectLocalModules
+partial def LeanLib.recCollectLocalModules
   (self : LeanLib) : FetchM (Job (Array Module))
 := ensureJob do
   let mut col : ModuleCollection := {}
@@ -59,10 +59,10 @@ where
     return col
 
 /-- The `LibraryFacetConfig` for the builtin `modulesFacet`. -/
-private def LeanLib.modulesFacetConfig : LibraryFacetConfig modulesFacet :=
+def LeanLib.modulesFacetConfig : LibraryFacetConfig modulesFacet :=
   mkFacetJobConfig LeanLib.recCollectLocalModules (buildable := false)
 
-private def LeanLib.recBuildLean
+def LeanLib.recBuildLean
   (self : LeanLib) : FetchM (Job Unit)
 := do
   let mods ← (← self.modules.fetch).await
@@ -73,7 +73,7 @@ private def LeanLib.recBuildLean
 public def LeanLib.leanArtsFacetConfig : LibraryFacetConfig leanArtsFacet :=
   mkFacetJobConfig LeanLib.recBuildLean
 
-@[specialize] private def LeanLib.recBuildStatic
+@[specialize] def LeanLib.recBuildStatic
   (self : LeanLib) (shouldExport : Bool) : FetchM (Job FilePath)
 := do
   let suffix :=
@@ -123,7 +123,7 @@ public def LeanLib.staticExportFacetConfig : LibraryFacetConfig staticExportFace
 
 /-! ## Build Shared Lib -/
 
-private def LeanLib.recBuildShared (self : LeanLib) : FetchM (Job Dynlib) := do
+def LeanLib.recBuildShared (self : LeanLib) : FetchM (Job Dynlib) := do
   withRegisterJob s!"{self.name}:shared" <| withCurrPackage self.pkg do
   let mods ← (← self.modules.fetch).await
   let objJobs ← mods.flatMapM fun mod =>
@@ -158,7 +158,7 @@ public def LeanLib.sharedFacetConfig : LibraryFacetConfig sharedFacet :=
 
 /--
 Build extra target dependencies of the library (e.g., `extraDepTargets`, `needs`). -/
-private def LeanLib.recBuildExtraDepTargets (self : LeanLib) : FetchM (Job Unit) := do
+def LeanLib.recBuildExtraDepTargets (self : LeanLib) : FetchM (Job Unit) := do
   let mut job := Job.nil s!"{self.pkg.baseName}/{self.name}:extraDep"
   job := job.mix (← self.pkg.extraDep.fetch)
   for target in self.extraDepTargets do
@@ -172,7 +172,7 @@ public def LeanLib.extraDepFacetConfig : LibraryFacetConfig extraDepFacet :=
   mkFacetJobConfig LeanLib.recBuildExtraDepTargets
 
 /-- Build the default facets for the library. -/
-private def LeanLib.recBuildDefaultFacets (self : LeanLib) : FetchM (Job Unit) := do
+def LeanLib.recBuildDefaultFacets (self : LeanLib) : FetchM (Job Unit) := do
   Job.mixArray <$> self.defaultFacets.mapM fun facet => do
     let job ← (self.facetCore facet).fetch
     return job.toOpaque

src/lake/Lake/Build/Module.lean

@@ -27,7 +27,7 @@ Build function definitions for a module's builtin facets.
 -/
 
 /-- Parse the header of a Lean file from its source. -/
-private def Module.recFetchInput (mod : Module) : FetchM (Job ModuleInput) := Job.async do
+def Module.recFetchInput (mod : Module) : FetchM (Job ModuleInput) := Job.async do
   let path := mod.leanFile
   let contents ← IO.FS.readFile path
   let trace := {caption := path.toString, mtime := ← getMTime path, hash := .ofText contents}
@@ -52,7 +52,7 @@ public def Module.headerFacetConfig : ModuleFacetConfig headerFacet :=
     return (← mod.input.fetch).map (sync := true) (·.header)
 
 /-- Compute an `Array` of a module's direct local imports from its header. -/
-private def Module.recParseImports (mod : Module) : FetchM (Job (Array Module)) := do
+def Module.recParseImports (mod : Module) : FetchM (Job (Array Module)) := do
   (← mod.input.fetch).mapM (sync := true) fun input => do
     let mods := input.imports.foldl (init := OrdModuleSet.empty) fun set imp =>
       match imp.module? with | some mod => set.insert mod | none => set
@@ -62,12 +62,12 @@ private def Module.recParseImports (mod : Module) : FetchM (Job (Array Module))
 public def Module.importsFacetConfig : ModuleFacetConfig importsFacet :=
   mkFacetJobConfig recParseImports (buildable := false)
 
-private structure ModuleImportData where
+structure ModuleImportData where
   module : Module
   transImports : Job (Array Module)
   includeSelf : Bool
 
-@[inline] private def collectImportsAux
+@[inline] def collectImportsAux
   (fileName : String) (imports : Array Module)
   (f : Module → FetchM (Bool × Job (Array Module)))
 : FetchM (Job (Array Module)) := do
@@ -93,21 +93,21 @@ private structure ModuleImportData where
     | .ok impSet s => .ok impSet.toArray s
     | .error e s => .error e s
 
-private def computeTransImportsAux
+def computeTransImportsAux
   (fileName : String) (imports : Array Module)
 : FetchM (Job (Array Module)) := do
   collectImportsAux fileName imports fun imp =>
     (true, ·) <$> imp.transImports.fetch
 
 /-- Recursively compute a module's transitive imports. -/
-private def Module.recComputeTransImports (mod : Module) : FetchM (Job (Array Module)) := ensureJob do
+def Module.recComputeTransImports (mod : Module) : FetchM (Job (Array Module)) := ensureJob do
   inline <| computeTransImportsAux mod.relLeanFile.toString (← (← mod.imports.fetch).await)
 
 /-- The `ModuleFacetConfig` for the builtin `transImportsFacet`. -/
 public def Module.transImportsFacetConfig : ModuleFacetConfig transImportsFacet :=
   mkFacetJobConfig recComputeTransImports (buildable := false)
 
-private def computePrecompileImportsAux
+def computePrecompileImportsAux
   (fileName : String) (imports : Array Module)
 : FetchM (Job (Array Module)) := do
   collectImportsAux fileName imports fun imp =>
@@ -117,7 +117,7 @@ private def computePrecompileImportsAux
       (false, ·) <$> imp.precompileImports.fetch
 
 /-- Recursively compute a module's precompiled imports. -/
-private def Module.recComputePrecompileImports (mod : Module) : FetchM (Job (Array Module)) := ensureJob do
+def Module.recComputePrecompileImports (mod : Module) : FetchM (Job (Array Module)) := ensureJob do
   inline <| computePrecompileImportsAux mod.relLeanFile.toString (← (← mod.imports.fetch).await)
 
 /-- The `ModuleFacetConfig` for the builtin `precompileImportsFacet`. -/
@@ -129,7 +129,7 @@ Computes the transitive dynamic libraries of a module's imports.
 Modules from the same library are loaded individually, while modules
 from other libraries are loaded as part of the whole library.
 -/
-private def Module.fetchImportLibs
+def Module.fetchImportLibs
   (self : Module) (imps : Array Module) (compileSelf : Bool)
 : FetchM (Array (Job Dynlib)) := do
   let (_, jobs) ← imps.foldlM (init := (({} : NameSet), #[])) fun (libs, jobs) imp => do
@@ -149,7 +149,7 @@ private def Module.fetchImportLibs
 Fetches the library dynlibs of a list of non-local imports.
 Modules are loaded as part of their whole library.
 -/
-private def fetchImportLibs
+def fetchImportLibs
   (mods : Array Module) : FetchM (Job (Array Dynlib))
 := do
   let (_, jobs) ← mods.foldlM (init := (({} : NameSet), #[])) fun (libs, jobs) imp => do
@@ -166,7 +166,7 @@ private def fetchImportLibs
 Topologically sorts the library dependency tree by name.
 Libraries come *after* their dependencies.
 -/
-private partial def mkLoadOrder (libs : Array Dynlib) : FetchM (Array Dynlib) := do
+partial def mkLoadOrder (libs : Array Dynlib) : FetchM (Array Dynlib) := do
   let r := libs.foldlM (m := Except (Cycle String)) (init := ({}, #[])) fun (v, o) lib =>
     go lib [] v o
   match r with
@@ -185,12 +185,12 @@ where
     let o := o.push lib
     return (v, o)
 
-private structure ModuleDeps where
+structure ModuleDeps where
   dynlibs : Array Dynlib := #[]
   plugins : Array Dynlib := #[]
   deriving Inhabited, Repr
 
-private def computeModuleDeps
+def computeModuleDeps
   (impLibs : Array Dynlib) (externLibs : Array Dynlib)
   (dynlibs : Array Dynlib) (plugins : Array Dynlib)
 : FetchM ModuleDeps := do
@@ -219,7 +219,7 @@ private def computeModuleDeps
     plugins := plugins.push (← getLakeInstall).sharedDynlib
   return {dynlibs, plugins}
 
-private partial def fetchTransImportArts
+partial def fetchTransImportArts
   (directImports : Array ModuleImport) (directArts : NameMap ImportArtifacts) (nonModule : Bool)
 : FetchM (NameMap ImportArtifacts) := do
   let q ← directImports.foldlM (init := #[]) fun q imp => do
@@ -254,7 +254,7 @@ where
         else q
       else q
 
-private def ModuleImportInfo.nil (modName : Name) : ModuleImportInfo where
+def ModuleImportInfo.nil (modName : Name) : ModuleImportInfo where
   directArts := {}
   trace := .nil s!"imports"
   transTrace := .nil s!"{modName} transitive imports (public)"
@@ -262,7 +262,7 @@ private def ModuleImportInfo.nil (modName : Name) : ModuleImportInfo where
   allTransTrace := .nil s!"{modName} transitive imports (all)"
   legacyTransTrace := .nil s!"{modName} transitive imports (legacy)"
 
-private def ModuleExportInfo.disambiguationHash
+def ModuleExportInfo.disambiguationHash
   (self : ModuleExportInfo) (nonModule : Bool) (imp : Import)
 : Hash :=
   if nonModule then
@@ -274,7 +274,7 @@ private def ModuleExportInfo.disambiguationHash
   else
     self.transTrace.hash.mix self.artsTrace.hash
 
-private def ModuleImportInfo.addImport
+def ModuleImportInfo.addImport
   (info : ModuleImportInfo) (nonModule : Bool)
   (imp : Import) (expInfo : ModuleExportInfo)
 : ModuleImportInfo :=
@@ -351,14 +351,14 @@ private def ModuleImportInfo.addImport
   else
     info
 
-private def Package.discriminant (self : Package) :=
+def Package.discriminant (self : Package) :=
   if self.version == {} then
     self.prettyName
   else
     s!"{self.prettyName}@{self.version}"
 
 set_option linter.unusedVariables.funArgs false in
-private def fetchImportInfo
+def fetchImportInfo
   (fileName : String) (pkgName modName : Name) (header : ModuleHeader)
 : FetchM (Job ModuleImportInfo) := do
   let nonModule := !header.isModule
@@ -422,17 +422,17 @@ public def Module.importInfoFacetConfig : ModuleFacetConfig importInfoFacet :=
     let header ← (← mod.header.fetch).await
     fetchImportInfo mod.relLeanFile.toString mod.pkg.keyName mod.name header
 
-private def noServerOLeanError :=
+def noServerOLeanError :=
   "No server olean generated. Ensure the module system is enabled."
 
-private def noPrivateOLeanError :=
+def noPrivateOLeanError :=
   "No private olean generated. Ensure the module system is enabled."
 
-private def noIRError :=
+def noIRError :=
   "No `.ir` generated. Ensure the module system is enabled."
 
 /-- Computes the import artifacts and transitive import trace of a module's imports. -/
-private def Module.computeExportInfo (mod : Module) : FetchM (Job ModuleExportInfo) := do
+def Module.computeExportInfo (mod : Module) : FetchM (Job ModuleExportInfo) := do
   (← mod.leanArts.fetch).mapM (sync := true) fun arts => do
     let input ← (← mod.input.fetch).await
     let importInfo ← (← mod.importInfo.fetch).await
@@ -496,7 +496,7 @@ Recursively build a module's dependencies, including:
 * Shared libraries (e.g., `extern_lib` targets or precompiled modules)
 * `extraDepTargets` of its library
 -/
-private def Module.recFetchSetup (mod : Module) : FetchM (Job ModuleSetup) := ensureJob do
+def Module.recFetchSetup (mod : Module) : FetchM (Job ModuleSetup) := ensureJob do
   let extraDepJob ← mod.lib.extraDep.fetch
   let headerJob ← mod.header.fetch
 
@@ -660,7 +660,7 @@ def resolveModuleOutputs (out : CacheOutput) : JobM ModuleOutputs := do
 instance : ResolveOutputs ModuleOutputs := ⟨resolveModuleOutputs⟩
 
 /-- Save module build artifacts to the local Lake cache. -/
-private def Module.cacheOutputArtifacts
+def Module.cacheOutputArtifacts
   (mod : Module)  (isModule : Bool) (useLocalFile : Bool)
 : JobM ModuleOutputArtifacts := do
   return {
@@ -686,12 +686,12 @@ Some module build artifacts must be located in the build directory (e.g., ILeans
 This copies the required artifacts from the local Lake cache to the build directory and
 updates the data structure with the new paths.
 -/
-private def Module.restoreNeededArtifacts (mod : Module) (cached : ModuleOutputArtifacts) : JobM ModuleOutputArtifacts := do
+def Module.restoreNeededArtifacts (mod : Module) (cached : ModuleOutputArtifacts) : JobM ModuleOutputArtifacts := do
   return {cached with
     ilean := ← restoreArtifact mod.ileanFile cached.ilean
   }
 
-private def Module.restoreAllArtifacts (mod : Module) (cached : ModuleOutputArtifacts) : JobM ModuleOutputArtifacts := do
+def Module.restoreAllArtifacts (mod : Module) (cached : ModuleOutputArtifacts) : JobM ModuleOutputArtifacts := do
   return {cached with
     olean := ← restoreArtifact mod.oleanFile cached.olean
     oleanServer? := ← restoreSome mod.oleanServerFile cached.oleanServer?
@@ -745,7 +745,7 @@ public protected def Module.getMTime (self : Module) (isModule : Bool) : IO MTim
 @[deprecated Module.getMTime (since := "2025-03-04")]
 public instance : GetMTime Module := ⟨Module.getMTime (isModule := false)⟩
 
-private def ModuleOutputArtifacts.setMTime (self : ModuleOutputArtifacts) (mtime : MTime) : ModuleOutputArtifacts :=
+def ModuleOutputArtifacts.setMTime (self : ModuleOutputArtifacts) (mtime : MTime) : ModuleOutputArtifacts :=
   {self with
     olean := {self.olean with mtime}
     oleanServer? := self.oleanServer?.map ({· with mtime})
@@ -756,7 +756,7 @@ private def ModuleOutputArtifacts.setMTime (self : ModuleOutputArtifacts) (mtime
     bc? := self.bc?.map ({· with mtime})
   }
 
-private def Module.mkArtifacts (mod : Module) (srcFile : FilePath) (isModule : Bool) : ModuleArtifacts where
+def Module.mkArtifacts (mod : Module) (srcFile : FilePath) (isModule : Bool) : ModuleArtifacts where
   lean? := srcFile
   olean? := mod.oleanFile
   oleanServer? := if isModule then some mod.oleanServerFile else none
@@ -766,7 +766,7 @@ private def Module.mkArtifacts (mod : Module) (srcFile : FilePath) (isModule : B
   c? := mod.cFile
   bc? := if Lean.Internal.hasLLVMBackend () then some mod.bcFile else none
 
-private def Module.computeArtifacts (mod : Module) (isModule : Bool) : FetchM ModuleOutputArtifacts :=
+def Module.computeArtifacts (mod : Module) (isModule : Bool) : FetchM ModuleOutputArtifacts :=
   return {
     isModule
     olean := ← compute mod.oleanFile "olean"
@@ -829,7 +829,7 @@ def Module.unpackLtar (self : Module) (ltar : FilePath) : JobM Unit := do
   ]
   proc (quiet := true) {cmd := (← getLeantar).toString, args}
 
-private def Module.recBuildLtar (self : Module) : FetchM (Job FilePath) := do
+def Module.recBuildLtar (self : Module) : FetchM (Job FilePath) := do
   withRegisterJob s!"{self.name}:ltar" <| withCurrPackage self.pkg do
   (← self.leanArts.fetch).mapM fun arts => do
     let art ← arts.ltar?.getDM do
@@ -846,7 +846,7 @@ private def Module.recBuildLtar (self : Module) : FetchM (Job FilePath) := do
 public def Module.ltarFacetConfig : ModuleFacetConfig ltarFacet :=
   mkFacetJobConfig recBuildLtar
 
-private def Module.buildLean
+def Module.buildLean
   (mod : Module) (depTrace : BuildTrace) (srcFile : FilePath) (setup : ModuleSetup)
 : JobM ModuleOutputArtifacts := buildAction depTrace mod.traceFile do
   let args := mod.weakLeanArgs ++ mod.leanArgs
@@ -861,7 +861,7 @@ private def Module.buildLean
   mod.clearOutputHashes
   mod.computeArtifacts setup.isModule
 
-private def traceOptions (opts : LeanOptions) (caption := "opts") : BuildTrace :=
+def traceOptions (opts : LeanOptions) (caption := "opts") : BuildTrace :=
   opts.values.foldl (init := .nil caption) fun t n v =>
     let opt := s!"-D{n}={v.asCliFlagValue}"
     t.mix <| .ofHash (pureHash opt) opt
@@ -871,7 +871,7 @@ Recursively build a Lean module.
 Fetch its dependencies and then elaborate the Lean source file, producing
 all possible artifacts (e.g., `.olean`, `.ilean`, `.c`, `.bc`).
 -/
-private def Module.recBuildLean (mod : Module) : FetchM (Job ModuleOutputArtifacts) := do
+def Module.recBuildLean (mod : Module) : FetchM (Job ModuleOutputArtifacts) := do
   /-
   Remark: `withRegisterJob` must register `setupJob` to display module builds
   in the job monitor. However, it must also include the fetching of both jobs to
@@ -997,7 +997,7 @@ where
 public def Module.leanArtsFacetConfig : ModuleFacetConfig leanArtsFacet :=
   mkFacetJobConfig recBuildLean
 
-@[inline] private def Module.fetchOLeanCore
+@[inline] def Module.fetchOLeanCore
   (facet : String) (f : ModuleOutputArtifacts → Option Artifact) (errMsg : String) (mod : Module)
 : FetchM (Job FilePath) := do
   (← mod.leanArts.fetch).mapM (sync := true) fun arts => do
@@ -1080,7 +1080,7 @@ public def Module.bcFacetConfig : ModuleFacetConfig bcFacet :=
 Recursively build the module's object file from its C file produced by `lean`
 with `-DLEAN_EXPORTING` set, which exports Lean symbols defined within the C files.
 -/
-private def Module.recBuildLeanCToOExport (self : Module) : FetchM (Job FilePath) := do
+def Module.recBuildLeanCToOExport (self : Module) : FetchM (Job FilePath) := do
   let suffix := if (← getIsVerbose) then " (with exports)" else ""
   withRegisterJob s!"{self.name}:c.o{suffix}" <| withCurrPackage self.pkg do
   -- TODO: add option to pass a target triplet for cross compilation
@@ -1095,7 +1095,7 @@ public def Module.coExportFacetConfig : ModuleFacetConfig coExportFacet :=
 Recursively build the module's object file from its C file produced by `lean`.
 This version does not export any Lean symbols.
 -/
-private def Module.recBuildLeanCToONoExport (self : Module) : FetchM (Job FilePath) := do
+def Module.recBuildLeanCToONoExport (self : Module) : FetchM (Job FilePath) := do
   let suffix := if (← getIsVerbose) then " (without exports)" else ""
   withRegisterJob s!"{self.name}:c.o{suffix}" <| withCurrPackage self.pkg do
   -- TODO: add option to pass a target triplet for cross compilation
@@ -1111,7 +1111,7 @@ public def Module.coFacetConfig : ModuleFacetConfig coFacet :=
     if Platform.isWindows then mod.coNoExport.fetch else mod.coExport.fetch
 
 /-- Recursively build the module's object file from its bitcode file produced by `lean`. -/
-private def Module.recBuildLeanBcToO (self : Module) : FetchM (Job FilePath) := do
+def Module.recBuildLeanBcToO (self : Module) : FetchM (Job FilePath) := do
   withRegisterJob s!"{self.name}:bc.o" <| withCurrPackage self.pkg do
   -- TODO: add option to pass a target triplet for cross compilation
   buildLeanO self.bcoFile (← self.bc.fetch) self.weakLeancArgs self.leancArgs
@@ -1145,7 +1145,7 @@ public def Module.oFacetConfig : ModuleFacetConfig oFacet :=
 Recursively build the shared library of a module
 (e.g., for `--load-dynlib` or `--plugin`).
 -/
-private def Module.recBuildDynlib (mod : Module) : FetchM (Job Dynlib) :=
+def Module.recBuildDynlib (mod : Module) : FetchM (Job Dynlib) :=
   withRegisterJob s!"{mod.name}:dynlib" <| withCurrPackage mod.pkg do
   /-
   Fetch the module's object files.
@@ -1221,7 +1221,7 @@ building its imports and other dependencies. Used by `lake setup-file`.
 
 Due to its exclusive use as a top-level build, it does not construct a proper trace state.
 -/
-private def setupEditedModule
+def setupEditedModule
   (mod : Module) (header : ModuleHeader)
 : FetchM (Job ModuleSetup) := do
   let extraDepJob ← mod.lib.extraDep.fetch
@@ -1269,7 +1269,7 @@ to build the dependencies of the file and generate the data for `lean --setup`.
 
 Due to its exclusive use as a top-level build, it does not construct a proper trace state.
 -/
-private def setupExternalModule
+def setupExternalModule
   (fileName : String) (header : ModuleHeader) (leanOpts : LeanOptions)
 : FetchM (Job ModuleSetup) := do
   let root ← getRootPackage

src/lake/Lake/Build/Package.lean

@@ -25,7 +25,7 @@ namespace Lake
 open Lean (Name)
 
 /-- Fetch the package's direct dependencies. -/
-private def Package.recFetchDeps (self : Package) : FetchM (Job (Array Package)) := ensureJob do
+def Package.recFetchDeps (self : Package) : FetchM (Job (Array Package)) := ensureJob do
   (pure ·) <$> self.depConfigs.mapM fun cfg => do
     let some dep ← findPackageByName? cfg.name
       | error s!"{self.prettyName}: package not found for dependency '{cfg.name}' \
@@ -37,7 +37,7 @@ public def Package.depsFacetConfig : PackageFacetConfig depsFacet :=
   mkFacetJobConfig recFetchDeps (buildable := false)
 
 /-- Compute a topological ordering of the package's transitive dependencies. -/
-private def Package.recComputeTransDeps (self : Package) : FetchM (Job (Array Package)) := ensureJob do
+def Package.recComputeTransDeps (self : Package) : FetchM (Job (Array Package)) := ensureJob do
   (pure ·.toArray) <$> self.depConfigs.foldlM (init := OrdPackageSet.empty) fun deps cfg => do
     let some dep ← findPackageByName? cfg.name
       | error s!"{self.prettyName}: package not found for dependency '{cfg.name}' \
@@ -53,7 +53,7 @@ public def Package.transDepsFacetConfig : PackageFacetConfig transDepsFacet :=
 Tries to download and unpack the package's cached build archive
 (e.g., from Reservoir or GitHub).
 -/
-private def Package.fetchOptBuildCacheCore (self : Package) : FetchM (Job Bool) := do
+def Package.fetchOptBuildCacheCore (self : Package) : FetchM (Job Bool) := do
   if self.preferReleaseBuild then
     self.optGitHubRelease.fetch
   else
@@ -64,7 +64,7 @@ public def Package.optBuildCacheFacetConfig : PackageFacetConfig optBuildCacheFa
   mkFacetJobConfig (·.fetchOptBuildCacheCore)
 
 /-- Tries to download the package's build cache (if configured). -/
-private def Package.maybeFetchBuildCache (self : Package) : FetchM (Job Bool) := do
+def Package.maybeFetchBuildCache (self : Package) : FetchM (Job Bool) := do
   let shouldFetch :=
     (← getTryCache) &&
     !(← self.buildDir.pathExists) && -- do not automatically clobber prebuilt artifacts
@@ -77,7 +77,7 @@ private def Package.maybeFetchBuildCache (self : Package) : FetchM (Job Bool) :=
     return pure true
 
 @[inline]
-private def Package.optFacetDetails (self : Package) (facet : Name) : JobM String := do
+def Package.optFacetDetails (self : Package) (facet : Name) : JobM String := do
   if (← getIsVerbose) then
     return s!" (see '{self.baseName}:{Name.eraseHead facet}' for details)"
   else
@@ -87,7 +87,7 @@ private def Package.optFacetDetails (self : Package) (facet : Name) : JobM Strin
 Tries to download and unpack the package's cached build archive
 (e.g., from Reservoir or GitHub). Prints a warning on failure.
 -/
-private def Package.maybeFetchBuildCacheWithWarning (self : Package) := do
+def Package.maybeFetchBuildCacheWithWarning (self : Package) := do
   let job ← self.maybeFetchBuildCache
   job.mapM fun success => do
     unless success do
@@ -102,7 +102,7 @@ private def Package.maybeFetchBuildCacheWithWarning (self : Package) := do
 Build the `extraDepTargets` for the package.
 Also, if the package is a dependency, maybe fetch its build cache.
 -/
-private def Package.recBuildExtraDepTargets (self : Package) : FetchM (Job Unit) :=
+def Package.recBuildExtraDepTargets (self : Package) : FetchM (Job Unit) :=
   withRegisterJob s!"{self.baseName}:extraDep" do
   let mut job := Job.nil s!"@{self.baseName}:extraDep"
   -- Fetch build cache if this package is a dependency
@@ -118,7 +118,7 @@ public def Package.extraDepFacetConfig : PackageFacetConfig extraDepFacet :=
   mkFacetJobConfig Package.recBuildExtraDepTargets
 
 /-- Compute the package's Reservoir barrel URL. -/
-private def Package.getBarrelUrl (self : Package) : JobM String := do
+def Package.getBarrelUrl (self : Package) : JobM String := do
   if self.scope.isEmpty then
     error "package has no Reservoir scope"
   let repo := GitRepo.mk self.dir
@@ -132,7 +132,7 @@ private def Package.getBarrelUrl (self : Package) : JobM String := do
   return url
 
 /-- Compute the package's GitHub release URL. -/
-private def Package.getReleaseUrl (self : Package) : JobM String := do
+def Package.getReleaseUrl (self : Package) : JobM String := do
   let repo := GitRepo.mk self.dir
   let repoUrl? := self.releaseRepo? <|> self.remoteUrl?
   let some repoUrl := repoUrl? <|> (← repo.getFilteredRemoteUrl?)
@@ -144,7 +144,7 @@ private def Package.getReleaseUrl (self : Package) : JobM String := do
   return s!"{repoUrl}/releases/download/{tag}/{self.buildArchive}"
 
 /-- Tries to download and unpack a build archive for the package from a URL. -/
-private def Package.fetchBuildArchive
+def Package.fetchBuildArchive
   (self : Package) (url : String) (archiveFile : FilePath)
   (headers : Array String := #[])
 : JobM PUnit := do
@@ -157,7 +157,7 @@ private def Package.fetchBuildArchive
     untar archiveFile self.buildDir
 
 @[inline]
-private def Package.mkOptBuildArchiveFacetConfig
+def Package.mkOptBuildArchiveFacetConfig
   {facet : Name} (archiveFile : Package → FilePath)
   (getUrl : Package → JobM String) (headers : Array String := #[])
   [FamilyDef FacetOut facet Bool]
@@ -172,7 +172,7 @@ private def Package.mkOptBuildArchiveFacetConfig
     return false
 
 @[inline]
-private def Package.mkBuildArchiveFacetConfig
+def Package.mkBuildArchiveFacetConfig
   {facet : Name} (optFacet : Name) (what : String)
   [FamilyDef FacetOut facet Unit]
   [FamilyDef FacetOut optFacet Bool]

src/lake/Lake/Build/Run.lean

@@ -34,11 +34,11 @@ public def mkBuildContext (ws : Workspace) (config : BuildConfig) : BaseIO Build
   }
 
 /-- Unicode icons that make up the spinner in animation order. -/
-private def Monitor.spinnerFrames :=
+def Monitor.spinnerFrames :=
   #['⣾','⣷','⣯','⣟','⡿','⢿','⣻','⣽']
 
 /-- Context of the Lake build monitor. -/
-private structure MonitorContext where
+structure MonitorContext where
   jobs : JobQueue
   out : IO.FS.Stream
   outLv : LogLevel
@@ -55,7 +55,7 @@ private structure MonitorContext where
   .stream ctx.out ctx.outLv ctx.useAnsi
 
 /-- State of the Lake build monitor. -/
-private structure MonitorState where
+structure MonitorState where
   jobNo : Nat := 0
   totalJobs : Nat := 0
   wantsRebuild : Bool := false
@@ -65,9 +65,9 @@ private structure MonitorState where
   spinnerIdx : Fin Monitor.spinnerFrames.size := ⟨0, by decide⟩
 
 /-- Monad of the Lake build monitor. -/
-private abbrev MonitorM := ReaderT MonitorContext <| StateT MonitorState BaseIO
+abbrev MonitorM := ReaderT MonitorContext <| StateT MonitorState BaseIO
 
-@[inline] private def MonitorM.run
+@[inline] def MonitorM.run
   (ctx : MonitorContext) (s : MonitorState) (self : MonitorM α)
 : BaseIO (α × MonitorState) :=
   StateT.run (ReaderT.run self ctx) s
@@ -80,23 +80,23 @@ def Ansi.resetLine : String :=
   "\x1B[2K\r"
 
 /-- Like `IO.FS.Stream.flush`, but ignores errors. -/
-@[inline] private def flush (out : IO.FS.Stream) : BaseIO PUnit :=
+@[inline] def flush (out : IO.FS.Stream) : BaseIO PUnit :=
   out.flush |>.catchExceptions fun _ => pure ()
 
 /-- Like `IO.FS.Stream.putStr`, but panics on errors. -/
-@[inline] private def print! (out : IO.FS.Stream) (s : String) : BaseIO PUnit :=
+@[inline] def print! (out : IO.FS.Stream) (s : String) : BaseIO PUnit :=
   out.putStr s |>.catchExceptions fun e =>
     panic! s!"[{decl_name%} failed: {e}] {repr s}"
 
 namespace Monitor
 
-@[inline] private def print (s : String) : MonitorM PUnit := do
+@[inline] def print (s : String) : MonitorM PUnit := do
   print! (← read).out s
 
-@[inline] private nonrec def flush : MonitorM PUnit := do
+@[inline] nonrec def flush : MonitorM PUnit := do
   flush (← read).out
 
-private def renderProgress (running unfinished : Array OpaqueJob) (h : 0 < unfinished.size) : MonitorM PUnit := do
+def renderProgress (running unfinished : Array OpaqueJob) (h : 0 < unfinished.size) : MonitorM PUnit := do
   let {jobNo, totalJobs, ..} ← get
   let {useAnsi, showProgress, ..} ← read
   if showProgress ∧ useAnsi then
@@ -114,7 +114,7 @@ private def renderProgress (running unfinished : Array OpaqueJob) (h : 0 < unfin
     print s!"{resetCtrl}{spinnerIcon} [{jobNo}/{totalJobs}] {caption}"
     flush
 
-private def reportJob (job : OpaqueJob) : MonitorM PUnit := do
+def reportJob (job : OpaqueJob) : MonitorM PUnit := do
   let {jobNo, totalJobs, ..} ← get
   let {failLv, outLv, showOptional, out, useAnsi, showProgress, minAction, showTime, ..} ← read
   let {task, caption, optional, ..} := job
@@ -153,7 +153,7 @@ where
     else if ms > 1000 then s!"{(ms) / 1000}.{(ms+50) / 100 % 10}s"
     else s!"{ms}ms"
 
-private def poll (unfinished : Array OpaqueJob) : MonitorM (Array OpaqueJob × Array OpaqueJob) := do
+def poll (unfinished : Array OpaqueJob) : MonitorM (Array OpaqueJob × Array OpaqueJob) := do
   let newJobs ← (← read).jobs.modifyGet ((·, #[]))
   modify fun s => {s with totalJobs := s.totalJobs + newJobs.size}
   let pollJobs := fun (running, unfinished) job => do
@@ -169,7 +169,7 @@ private def poll (unfinished : Array OpaqueJob) : MonitorM (Array OpaqueJob × A
   let r ← unfinished.foldlM pollJobs (#[], #[])
   newJobs.foldlM pollJobs r
 
-private def sleep : MonitorM PUnit := do
+def sleep : MonitorM PUnit := do
   let now ← IO.monoMsNow
   let lastUpdate := (← get).lastUpdate
   let sleepTime : Nat := (← read).updateFrequency - (now - lastUpdate)
@@ -178,14 +178,14 @@ private def sleep : MonitorM PUnit := do
   let now ← IO.monoMsNow
   modify fun s => {s with lastUpdate := now}
 
-private  partial def loop (unfinished : Array OpaqueJob) : MonitorM PUnit := do
+ partial def loop (unfinished : Array OpaqueJob) : MonitorM PUnit := do
   let (running, unfinished) ← poll unfinished
   if h : 0 < unfinished.size then
     renderProgress running unfinished h
     sleep
     loop unfinished
 
-private def main (init : Array OpaqueJob) : MonitorM PUnit := do
+def main (init : Array OpaqueJob) : MonitorM PUnit := do
   loop init
   let resetCtrl ← modifyGet fun s => (s.resetCtrl, {s with resetCtrl := ""})
   unless resetCtrl.isEmpty do

src/lake/Lake/Build/Store.lean

@@ -32,7 +32,7 @@ public  abbrev BuildStore :=
 namespace BuildStore
 
 set_option linter.deprecated false in
-private def getModuleFacetJob? (facet : Name) [FamilyOut FacetOut facet α]
+def getModuleFacetJob? (facet : Name) [FamilyOut FacetOut facet α]
     (k : BuildKey) (v : Job (BuildData k)) : Option (Name × Job α) :=
   match k with
   | .moduleFacet m f
@@ -67,7 +67,7 @@ public def collectModuleFacetMap
       res := res.insert m job
   return res
 
-private def getPackageFacetJob? (facet : Name) [FamilyOut FacetOut facet α]
+def getPackageFacetJob? (facet : Name) [FamilyOut FacetOut facet α]
     (k : BuildKey) (v : Job (BuildData k)) : Option (Job α) :=
   match k with
   | .packageFacet p f =>
@@ -88,7 +88,7 @@ public def collectPackageFacetArray
       res := res.push job
   return res
 
-private def getTargetFacetJob? (facet : Name) [FamilyOut FacetOut facet α]
+def getTargetFacetJob? (facet : Name) [FamilyOut FacetOut facet α]
     (k : BuildKey) (v : Job (BuildData k)) : Option (Job α) :=
   match k with
   | .targetFacet _ _ f =>

src/lake/Lake/Build/Target/Fetch.lean

@@ -16,7 +16,7 @@ open Lean
 namespace Lake
 
 variable (defaultPkg : Package) (root : PartialBuildKey) in
-private def PartialBuildKey.fetchInCoreAux
+def PartialBuildKey.fetchInCoreAux
   (self : PartialBuildKey) (facetless : Bool := false)
 : FetchM ((key : BuildKey) × Job (BuildData key)) := do
   match self with
@@ -98,7 +98,7 @@ Fetches the target specified by this key, resolving gaps as needed.
   (·.2.toOpaque) <$> fetchInCore defaultPkg self
 
 variable (root : BuildKey) in
-private def BuildKey.fetchCore
+def BuildKey.fetchCore
   (self : BuildKey)
 : FetchM (Job (BuildData self)) :=
   match self with

src/lake/Lake/CLI/Build.lean

@@ -140,7 +140,7 @@ def resolveTargetInWorkspace
   else
     throw <| CliError.unknownTarget target
 
-private def resolveTargetLikeSpec
+def resolveTargetLikeSpec
   (ws : Workspace) (spec : String) (facet : Name) (isMaybePath explicit := false)
 : Except CliError (Array BuildSpec) := do
   match spec.split '/' |>.toList with
@@ -169,7 +169,7 @@ private def resolveTargetLikeSpec
     else
       throw <| CliError.invalidTargetSpec spec '/'
 
-private def resolveTargetBaseSpec
+def resolveTargetBaseSpec
   (ws : Workspace) (spec : String) (facet : Name)
 : EIO CliError (Array BuildSpec) := do
   if spec.startsWith "@" then

src/lake/Lake/CLI/Main.lean

@@ -391,14 +391,14 @@ def serviceNotFound (service : String) (configuredServices : Array CacheServiceC
     let msg := s!"{msg}; configured services:\n"
     configuredServices.foldl (· ++ s!"  {·.name}") msg
 
-@[inline] private def cacheToolchain (pkg : Package) (toolchain : CacheToolchain) : CacheToolchain :=
+@[inline] def cacheToolchain (pkg : Package) (toolchain : CacheToolchain) : CacheToolchain :=
   if pkg.fixedToolchain || pkg.bootstrap then .none else toolchain
 
-@[inline] private def cachePlatform (pkg : Package) (platform : CachePlatform) : CachePlatform :=
+@[inline] def cachePlatform (pkg : Package) (platform : CachePlatform) : CachePlatform :=
   if pkg.isPlatformIndependent then .none else platform
 
 -- since 2026-02-19
-private def endpointDeprecation : String :=
+def endpointDeprecation : String :=
    "configuring the cache service via environment variables is deprecated; use --service instead"
 
 protected def get : CliM PUnit := do

src/lake/Lake/CLI/Translate.lean

@@ -16,13 +16,13 @@ import Lake.Load.Lean.Elab
 namespace Lake
 open Toml Lean System PrettyPrinter
 
-private partial def descopeSyntax : Syntax → Syntax
+partial def descopeSyntax : Syntax → Syntax
 | .ident info rawVal val preresolved =>
   .ident info rawVal val.eraseMacroScopes preresolved
 | .node info k args => .node info k <| args.map descopeSyntax
 | stx => stx
 
-private def descopeTSyntax (stx : TSyntax k) : TSyntax k :=
+def descopeTSyntax (stx : TSyntax k) : TSyntax k :=
   ⟨descopeSyntax stx.raw⟩
 
 public def Package.mkConfigString (pkg : Package) (lang : ConfigLang) : LogIO String := do

src/lake/Lake/CLI/Translate/Toml.lean

@@ -23,7 +23,7 @@ open Lean System Toml
 
 /-! ## General Helpers -/
 
-private local instance : BEq FilePath where
+local instance : BEq FilePath where
   beq a b := a.normalize == b.normalize
 
 class EncodeField (σ : Type u) (name : Name) (α : Type u) where
@@ -69,7 +69,7 @@ public def Toml.encodeLeanOptions (opts : Array LeanOption) : Table :=
 public instance : ToToml (Array LeanOption) where
   toToml opts := .table .missing <| encodeLeanOptions opts
 
-@[inline] private def encodeSingleton? [ToToml? α] (name : Name) (a : α) : Option Value :=
+@[inline] def encodeSingleton? [ToToml? α] (name : Name) (a : α) : Option Value :=
   toToml? a |>.map fun v => toToml <| Table.empty.insert name v
 
 mutual
@@ -149,7 +149,7 @@ public instance : ToToml Dependency := ⟨(toToml ·.toToml)⟩
 
 /-! ## Package & Target Configuration Encoders -/
 
-private meta def genToToml
+meta def genToToml
   (cmds : Array Command)
   (tyName : Name) [info : ConfigInfo tyName]
   (exclude : Array Name := #[])

src/lake/Lake/Config/Cache.lean

@@ -97,7 +97,7 @@ public partial def parse
   else
     loop 2 {} (lfPos.next h)
 
-@[inline] private partial def loadCore
+@[inline] partial def loadCore
   (h : IO.FS.Handle) (fileName : String) (platformIndependent : Bool)
 : LogIO CacheMap := do
   let rec loop (i : Nat) (cache : CacheMap) := do
@@ -575,7 +575,7 @@ def uploadS3
   | .error e =>
     error s!"curl produced invalid JSON output: {e}; received:\n{out.stderr}"
 
-private structure CacheServiceImpl where
+structure CacheServiceImpl where
   mk ::
     name? : Option CacheServiceName := none
     /- S3 Bucket -/
@@ -641,11 +641,11 @@ namespace CacheService
 /-- The MIME type of a Lake/Reservoir artifact. -/
 public def artifactContentType : String := "application/vnd.reservoir.artifact"
 
-private def appendScope (endpoint : String) (scope : String) : String :=
+def appendScope (endpoint : String) (scope : String) : String :=
   scope.split '/' |>.fold (init := endpoint) fun s component =>
     uriEncode component.copy (s.push '/')
 
-private def s3ArtifactUrl (contentHash : Hash) (service : CacheService) (scope : CacheServiceScope) : String :=
+def s3ArtifactUrl (contentHash : Hash) (service : CacheService) (scope : CacheServiceScope) : String :=
   let endpoint :=
     match scope.impl with
     | .repo scope => appendScope service.impl.artifactEndpoint scope
@@ -687,27 +687,27 @@ public def uploadArtifact
 
 /-! ## Multi-Artifact Transfer -/
 
-private inductive TransferKind
+inductive TransferKind
   | get
   | put
   deriving DecidableEq
 
-private structure TransferInfo where
+structure TransferInfo where
   url : String
   path : FilePath
   descr : ArtifactDescr
 
-private structure TransferConfig where
+structure TransferConfig where
   kind : TransferKind
   scope : CacheServiceScope
   infos : Array TransferInfo
   key : String := ""
 
-private structure TransferState where
+structure TransferState where
   didError : Bool := false
   numSuccesses : Nat := 0
 
-private partial def monitorTransfer
+partial def monitorTransfer
   (cfg : TransferConfig) (h hOut : IO.FS.Handle) (s : TransferState)
 : LoggerIO TransferState := do
   let line ← h.getLine
@@ -781,7 +781,7 @@ where
     logError msg
     logVerbose s!"curl JSON: {line.trimAsciiEnd}"
 
-private def transferArtifacts
+def transferArtifacts
   (cfg : TransferConfig)
 : LoggerIO Unit := IO.FS.withTempFile fun h path => do
   let args ← id do
@@ -941,7 +941,7 @@ public def uploadArtifacts
 /-- The MIME type of a Lake/Reservoir input-to-output mappings for a Git revision. -/
 public def mapContentType : String := "application/vnd.reservoir.outputs+json-lines"
 
-private def s3RevisionUrl
+def s3RevisionUrl
   (rev : String) (service : CacheService) (scope : CacheServiceScope)
   (platform := CachePlatform.none) (toolchain := CacheToolchain.none)
 : String :=

src/lake/Lake/Config/Kinds.lean

@@ -78,7 +78,7 @@ as the facet kind for modules.
 Returns the facet kind for an Lake target namespace.
 Used by the `builtin_facet` macro.
 -/
-private def facetKindForNamespace (ns : Name) : Name :=
+def facetKindForNamespace (ns : Name) : Name :=
   match ns with
   | `Lake.Package => Package.facetKind
   | `Lake.Module => Module.facetKind

src/lake/Lake/Config/Meta.lean

@@ -38,7 +38,7 @@ scoped syntax (name := configDecl)
 instance : Coe Ident (TSyntax ``Term.structInstLVal) where
   coe stx := Unhygienic.run `(Term.structInstLVal| $stx:ident)
 
-private structure FieldView where
+structure FieldView where
   ref : Syntax
   mods : TSyntax ``Command.declModifiers := Unhygienic.run `(declModifiers|)
   id : Ident
@@ -48,7 +48,7 @@ private structure FieldView where
   decl? : Option (TSyntax ``structSimpleBinder) := none
   parent  : Bool := false
 
-private structure FieldMetadata where
+structure FieldMetadata where
   cmds : Array Command := #[]
   fields : Term := Unhygienic.run `(Array.empty)
 
@@ -56,7 +56,7 @@ private structure FieldMetadata where
 -- quotations and are called only by `macro`s, so we disable the option for them manually.
 set_option internal.parseQuotWithCurrentStage false
 
-private meta def mkConfigAuxDecls
+meta def mkConfigAuxDecls
   (vis? : Option (TSyntax ``visibility))
   (structId : Ident) (structArity : Nat) (structTy : Term) (views : Array FieldView)
 : MacroM (Array Command) := do
@@ -123,7 +123,7 @@ private meta def mkConfigAuxDecls
   let emptyInst ← `( $[$vis?:visibility]? instance $instId:ident : EmptyCollection $structTy := ⟨{}⟩)
   return data.cmds.push fieldsDef |>.push fieldsInst |>.push infoInst |>.push emptyInst
 
-private meta def mkFieldView (stx : TSyntax ``configField) : MacroM FieldView := withRef stx do
+meta def mkFieldView (stx : TSyntax ``configField) : MacroM FieldView := withRef stx do
   let `(configField|$mods:declModifiers $[$id? @]? $ids,* $bs* : $rty $[:= $val?]?) := stx
     | Macro.throwError "ill-formed configuration field declaration"
   let bvs ← expandBinders bs
@@ -137,7 +137,7 @@ private meta def mkFieldView (stx : TSyntax ``configField) : MacroM FieldView :=
   let decl ← `(structSimpleBinder|$mods:declModifiers $id : $type := $defVal)
   return {ref := stx, mods, id, ids, type, defVal, decl? := decl}
 
-private meta def mkParentFieldView (stx : TSyntax ``structParent) : MacroM FieldView := withRef stx do
+meta def mkParentFieldView (stx : TSyntax ``structParent) : MacroM FieldView := withRef stx do
   let `(structParent|$[$id? :]? $type) := stx
     | Macro.throwError "ill-formed parent"
   let id ← do

src/lake/Lake/Config/Pattern.lean

@@ -36,7 +36,7 @@ mutual
 A pattern. Matches some subset of the values of a type.
 May also include a declarative description.
 -/
-public structure Pattern (α : Type u) (β : Type v) where
+structure Pattern (α : Type u) (β : Type v) where
   /-- Returns whether the value matches the pattern. -/
   filter : α → Bool
    /-- An optional name for the filter. -/
@@ -49,7 +49,7 @@ public structure Pattern (α : Type u) (β : Type v) where
 An abstract declarative pattern.
 Augments another pattern description `β` with logical connectives.
 -/
-public inductive PatternDescr (α : Type u) (β : Type v)
+inductive PatternDescr (α : Type u) (β : Type v)
 /-- Matches a value that does not satisfy the pattern. -/
 | not (p : Pattern α β)
 /-- Matches a value that satisfies every pattern. Short-circuits. -/

src/lake/Lake/Load/Lean/Eval.lean

@@ -22,7 +22,7 @@ open System Lean
 namespace Lake
 
 /-- Unsafe implementation of `evalConstCheck`. -/
-private unsafe def unsafeEvalConstCheck
+unsafe def unsafeEvalConstCheck
   (env : Environment) (opts : Options) (α) [TypeName α] (const : Name)
 : Except String α :=
   match env.find? const with
@@ -44,12 +44,12 @@ Like `Lean.Environment.evalConstCheck`,
 but with plain universe-polymorphic `Except`.
 -/
 @[implemented_by unsafeEvalConstCheck]
-private opaque evalConstCheck
+opaque evalConstCheck
   (env : Environment) (opts : Options) (α : Type) [TypeName α] (const : Name)
 : Except String α
 
 /-- Construct a `DNameMap` from the declarations tagged with `attr`. -/
-private def mkDTagMap
+def mkDTagMap
   (env : Environment) (attr : OrderedTagAttribute)
   [Monad m] (f : (n : Name) → m (β n))
 : m (DNameMap β) :=
@@ -58,7 +58,7 @@ private def mkDTagMap
     return map.insert declName <| ← f declName
 
 /-- Construct a `NameMap` from the declarations tagged with `attr`. -/
-private def mkTagMap
+def mkTagMap
   (env : Environment) (attr : OrderedTagAttribute)
   [Monad m] (f : (n : Name) → m β)
 : m (NameMap β) :=
@@ -67,7 +67,7 @@ private def mkTagMap
     return map.insert declName <| ← f declName
 
 /-- Construct a `OrdNameMap` from the declarations tagged with `attr`. -/
-private def mkOrdTagMap
+def mkOrdTagMap
   (env : Environment) (attr : OrderedTagAttribute)
   [Monad m] (f : (n : Name) → m β)
 : m (OrdNameMap β) :=

src/lake/Lake/Load/Manifest.lean

@@ -55,7 +55,7 @@ That is, Lake ignores the `-` suffix.
 @[inline] public def Manifest.version : StdVer := {major := 1, minor := 2}
 
 /-- Manifest version `0.6.0` package entry. For backwards compatibility. -/
-private inductive PackageEntryV6
+inductive PackageEntryV6
 | path (name : Name) (opts : NameMap String) (inherited : Bool) (dir : FilePath)
 | git (name : Name) (opts : NameMap String) (inherited : Bool) (url : String) (rev : String)
     (inputRev? : Option String) (subDir? : Option FilePath)
@@ -166,7 +166,7 @@ public instance : FromJson PackageEntry := ⟨PackageEntry.fromJson?⟩
 @[inline] public def inDirectory (pkgDir : FilePath) (entry : PackageEntry) : PackageEntry :=
   {entry with src := match entry.src with | .path dir => .path (pkgDir / dir) | s => s}
 
-private def ofV6 : PackageEntryV6 → PackageEntry
+def ofV6 : PackageEntryV6 → PackageEntry
 | .path name _opts inherited dir =>
   {name, inherited, src := .path dir}
 | .git name _opts inherited url rev inputRev? subDir? =>
@@ -200,7 +200,7 @@ public protected def toJson (self : Manifest) : Json :=
 
 public instance : ToJson Manifest := ⟨Manifest.toJson⟩
 
-private def getVersion (obj : JsonObject) : Except String SemVerCore := do
+def getVersion (obj : JsonObject) : Except String SemVerCore := do
   let ver : Json ← obj.get "version" <|> obj.get "schemaVersion"
   let ver : SemVerCore ←
     match ver with
@@ -216,7 +216,7 @@ private def getVersion (obj : JsonObject) : Except String SemVerCore := do
   else
     return ver
 
-private def getPackages (ver : StdVer) (obj : JsonObject) : Except String (Array PackageEntry) := do
+def getPackages (ver : StdVer) (obj : JsonObject) : Except String (Array PackageEntry) := do
   if ver < {minor := 7} then
     (·.map PackageEntry.ofV6) <$> obj.getD "packages" #[]
   else

src/lake/Lake/Load/Resolve.lean

@@ -94,7 +94,7 @@ abbrev ResolveT m := DepStackT <| StateT Workspace m
 : m (α × Workspace) := x.run stack |>.run ws
 
 /-- Recursively run a `ResolveT` monad starting from the workspace's root. -/
-@[specialize] private def Workspace.runResolveT
+@[specialize] def Workspace.runResolveT
   [Monad m] [MonadError m] (ws : Workspace)
   (go : RecFetchFn Package PUnit (ResolveT m))
   (root := ws.root) (stack : DepStack  := {})
@@ -113,7 +113,7 @@ resolved in reverse order before recursing to the dependencies' dependencies.
 
 See `Workspace.updateAndMaterializeCore` for more details.
 -/
-@[inline] private def Workspace.resolveDepsCore
+@[inline] def Workspace.resolveDepsCore
   [Monad m] [MonadError m] [MonadLiftT LogIO m] (ws : Workspace)
   (resolve : Package → Dependency → Workspace → m MaterializedDep)
   (root : Package := ws.root) (stack : DepStack := {})
@@ -148,7 +148,7 @@ abbrev UpdateT := StateT (NameMap PackageEntry)
 Reuse manifest versions of root packages that should not be updated.
 Also, move the packages directory if its location has changed.
 -/
-private def reuseManifest
+def reuseManifest
   (ws : Workspace) (toUpdate : NameSet)
 : UpdateT LoggerIO PUnit := do
   let rootName := ws.root.prettyName
@@ -178,7 +178,7 @@ private def reuseManifest
     logWarning s!"{rootName}: ignoring previous manifest because it failed to load: {e}"
 
 /-- Add a package dependency's manifest entries to the update state. -/
-private def addDependencyEntries (dep : MaterializedDep) : UpdateT LoggerIO PUnit := do
+def addDependencyEntries (dep : MaterializedDep) : UpdateT LoggerIO PUnit := do
   match (← Manifest.load dep.manifestFile |>.toBaseIO) with
   | .ok manifest =>
     manifest.packages.forM fun entry => do
@@ -191,7 +191,7 @@ private def addDependencyEntries (dep : MaterializedDep) : UpdateT LoggerIO PUni
     logWarning s!"{dep.prettyName}: ignoring manifest because it failed to load: {e}"
 
 /-- Materialize a single dependency, updating it if desired. -/
-private def updateAndMaterializeDep
+def updateAndMaterializeDep
   (ws : Workspace) (pkg : Package) (dep : Dependency)
 : UpdateT LoggerIO MaterializedDep := do
   if let some entry ← fetch? dep.name then
@@ -218,7 +218,7 @@ Used, for instance, if the toolchain is updated and no Elan is detected.
 def restartCode : ExitCode := 4
 
 /-- The toolchain information of a package. -/
-private structure ToolchainCandidate where
+structure ToolchainCandidate where
   /-- The name of the package which provided the toolchain candidate. -/
   src : Name
   /-- The version of the toolchain candidate. -/
@@ -227,7 +227,7 @@ private structure ToolchainCandidate where
   fixed : Bool := false
 
 private structure ToolchainState where
-  /-- The name of dependency which provided the current candidate toolchain. -/
+  /-- The name of depedency which provided the current candidate toolchain. -/
   src : Name
   /-- The current candidate toolchain version (if any). -/
   tc? : Option ToolchainVer

src/lake/Lake/Load/Toml.lean

@@ -342,20 +342,20 @@ public instance : DecodeToml CacheServiceKind := ⟨CacheServiceKind.decodeToml
 public structure TomlFieldInfo (σ : Type) where
   decodeAndSet : Table → Value → σ → DecodeM σ
 
-private abbrev TomlFieldInfos (σ : Type) :=
+abbrev TomlFieldInfos (σ : Type) :=
   NameMap (TomlFieldInfo σ)
 
-private def TomlFieldInfos.empty : TomlFieldInfos σ := {}
+def TomlFieldInfos.empty : TomlFieldInfos σ := {}
 
-@[inline] private def TomlFieldInfos.insert
+@[inline] def TomlFieldInfos.insert
   (name : Name) [DecodeField σ name] (infos : TomlFieldInfos σ)
 : TomlFieldInfos σ :=
   NameMap.insert infos name ⟨decodeField name⟩
 
-private class ConfigTomlInfo (α : Type) where
+class ConfigTomlInfo (α : Type) where
   fieldInfos : TomlFieldInfos α
 
-private def decodeTomlConfig
+def decodeTomlConfig
   [EmptyCollection α] [ConfigTomlInfo α] (t : Table)
 : Toml.DecodeM α :=
   t.foldM (init := ∅) fun cfg key val => do
@@ -373,7 +373,7 @@ section
 -- we can't use `in` as it is parsed as a single command and so the option would not influence the
 -- parser.
 set_option internal.parseQuotWithCurrentStage false
-private meta def genDecodeToml
+meta def genDecodeToml
   (cmds : Array Command)
   (tyName : Name) [info : ConfigInfo tyName]
   (exclude : Array Name := {})
@@ -417,12 +417,12 @@ local macro "gen_toml_decoders%" : command => do
 
 gen_toml_decoders%
 
-private structure DecodeTargetState (pkg : Name) where
+structure DecodeTargetState (pkg : Name) where
   decls : Array (PConfigDecl pkg) := #[]
   map : DNameMap (NConfigDecl pkg) := {}
   exeRoots : Lean.NameMap Name := {}
 
-private def decodeTargetDecls
+def decodeTargetDecls
   (pkg : Name) (prettyName : String) (t : Table)
 : DecodeM (Array (PConfigDecl pkg) × DNameMap (NConfigDecl pkg)) := do
   let r : DecodeTargetState pkg := {}
@@ -505,7 +505,7 @@ public def loadTomlConfig (cfg : LoadConfig) : LogIO LakefileConfig := do
 /-! ## System Configuration Loader -/
 
 /-- Load the system Lake configuration from a TOML file. -/
-private def loadLakeConfigCore (path : FilePath) (lakeEnv : Lake.Env) : LogIO LoadedLakeConfig := do
+def loadLakeConfigCore (path : FilePath) (lakeEnv : Lake.Env) : LogIO LoadedLakeConfig := do
   let input ← IO.FS.readFile path
   let ictx := mkInputContext input path.toString
   match (← loadToml ictx |>.toBaseIO) with
@@ -564,7 +564,7 @@ private def loadLakeConfigCore (path : FilePath) (lakeEnv : Lake.Env) : LogIO Lo
   | .error log =>
     errorWithLog <| log.forM fun msg => do logError (← msg.toString)
 
-private def LoadedLakeConfig.mkDefault (lakeEnv : Lake.Env) : LoadedLakeConfig :=
+def LoadedLakeConfig.mkDefault (lakeEnv : Lake.Env) : LoadedLakeConfig :=
   let defaultService := .reservoirService lakeEnv.reservoirApiUrl
   let defaultServiceConfig := {name := "reservoir", kind := .reservoir, apiEndpoint := lakeEnv.reservoirApiUrl}
   {

src/lake/Lake/Util/Opaque.lean

@@ -9,7 +9,7 @@ prelude
 public import Init.Prelude
 import Init.Tactics
 
-private opaque POpaque.nonemptyType.{u} : NonemptyType.{u}
+opaque POpaque.nonemptyType.{u} : NonemptyType.{u}
 
 /-- An value of unknown type in a specific universe. -/
 public def POpaque : Type u := POpaque.nonemptyType.type

src/lake/Lake/Util/Version.lean

@@ -53,7 +53,7 @@ where
   termination_by p
 
 /-- Returns whether a version component is a wildcard. -/
-private def isWildVer (s : String.Slice) : Bool :=
+def isWildVer (s : String.Slice) : Bool :=
   let p := s.startPos
   if h : p ≠ s.endPos then
     if p.next h = s.endPos then
@@ -62,7 +62,7 @@ private def isWildVer (s : String.Slice) : Bool :=
     else false
   else false
 
-@[inline] private def parseVerNat (what : String) (s : String.Slice) : EStateM String σ Nat := do
+@[inline] def parseVerNat (what : String) (s : String.Slice) : EStateM String σ Nat := do
   let some v := s.toNat?
     | throw s!"invalid {what} version: expected numeral, got '{s.copy}'"
   return v
@@ -70,7 +70,7 @@ private def isWildVer (s : String.Slice) : Bool :=
 inductive VerComponent
 | none | wild | nat (n : Nat)
 
-private def parseVerComponent {σ} (what : String) (s? : Option String.Slice) : EStateM String σ VerComponent := do
+def parseVerComponent {σ} (what : String) (s? : Option String.Slice) : EStateM String σ VerComponent := do
     let some s := s?
       | return .none
     if isWildVer s then
@@ -103,14 +103,14 @@ where
       nextUntilWhitespace (p.next h)
   termination_by p
 
-private def parseSpecialDescr (s : String) : EStateM String s.Pos String := do
+def parseSpecialDescr (s : String) : EStateM String s.Pos String := do
   let some specialDescr ← parseSpecialDescr? s
     | return ""
   if specialDescr.isEmpty then
     throw "invalid version: '-' suffix cannot be empty"
   return specialDescr
 
-private def runVerParse
+def runVerParse
   (s : String) (x : (s : String) → EStateM String s.Pos α)
   (startPos := s.startPos) (endPos := s.endPos)
 : Except String α :=

src/runtime/compact.cpp

@@ -143,7 +143,7 @@ object * object_compactor::copy_object(object * o) {
 void object_compactor::insert_sarray(object * o) {
     size_t sz        = lean_sarray_size(o);
     unsigned elem_sz = lean_sarray_elem_size(o);
-    size_t obj_sz = sizeof(lean_sarray_object) + elem_sz*sz;
+    size_t obj_sz = lean_usize_add_checked(sizeof(lean_sarray_object), lean_usize_mul_checked(elem_sz, sz));
     lean_sarray_object * new_o = (lean_sarray_object*)alloc(obj_sz);
     lean_set_non_heap_header_for_big((lean_object*)new_o, LeanScalarArray, elem_sz);
     new_o->m_size     = sz;
@@ -155,7 +155,7 @@ void object_compactor::insert_sarray(object * o) {
 void object_compactor::insert_string(object * o) {
     size_t sz        = lean_string_size(o);
     size_t len       = lean_string_len(o);
-    size_t obj_sz = sizeof(lean_string_object) + sz;
+    size_t obj_sz = lean_usize_add_checked(sizeof(lean_string_object), sz);
     lean_string_object * new_o = (lean_string_object*)alloc(obj_sz);
     lean_set_non_heap_header_for_big((lean_object*)new_o, LeanString, 0);
     new_o->m_size     = sz;
@@ -214,7 +214,7 @@ bool object_compactor::insert_array(object * o) {
     }
     if (missing_children)
         return false;
-    size_t obj_sz = sizeof(lean_array_object) + sizeof(void*)*sz;
+    size_t obj_sz = lean_usize_add_checked(sizeof(lean_array_object), lean_usize_mul_checked(sizeof(void*), sz));
     lean_array_object * new_o = (lean_array_object*)alloc(obj_sz);
     lean_set_non_heap_header_for_big((lean_object*)new_o, LeanArray, 0);
     new_o->m_size     = sz;
@@ -274,8 +274,8 @@ bool object_compactor::insert_promise(object * o) {
 void object_compactor::insert_mpz(object * o) {
 #ifdef LEAN_USE_GMP
     size_t nlimbs = mpz_size(to_mpz(o)->m_value.m_val);
-    size_t data_sz = sizeof(mp_limb_t) * nlimbs;
-    size_t sz = sizeof(mpz_object) + data_sz;
+    size_t data_sz = lean_usize_mul_checked(sizeof(mp_limb_t), nlimbs);
+    size_t sz = lean_usize_add_checked(sizeof(mpz_object), data_sz);
     mpz_object * new_o = (mpz_object *)alloc(sz);
     memcpy(new_o, to_mpz(o), sizeof(mpz_object));
     lean_set_non_heap_header((lean_object*)new_o, sz, LeanMPZ, 0);
@@ -287,8 +287,8 @@ void object_compactor::insert_mpz(object * o) {
     m._mp_alloc = nlimbs;
     save(o, (lean_object*)new_o);
 #else
-    size_t data_sz = sizeof(mpn_digit) * to_mpz(o)->m_value.m_size;
-    size_t sz      = sizeof(mpz_object) + data_sz;
+    size_t data_sz = lean_usize_mul_checked(sizeof(mpn_digit), to_mpz(o)->m_value.m_size);
+    size_t sz      = lean_usize_add_checked(sizeof(mpz_object), data_sz);
     mpz_object * new_o = (mpz_object *)alloc(sz);
     // Manually copy the `mpz_object` to ensure `mpz` struct padding is left as
     // zero as prepared by `object_compactor::alloc`. `memcpy` would copy the