rerevert

This reverts commit e551a366a0.

src/Init/Core.lean

@@ -837,9 +837,6 @@ instance : Trans Iff Iff Iff where
 theorem Eq.comm {a b : α} : a = b ↔ b = a := Iff.intro Eq.symm Eq.symm
 theorem eq_comm {a b : α} : a = b ↔ b = a := Eq.comm
 
-theorem HEq.comm {a : α} {b : β} : HEq a b ↔ HEq b a := Iff.intro HEq.symm HEq.symm
-theorem heq_comm {a : α} {b : β} : HEq a b ↔ HEq b a := HEq.comm
-
 @[symm] theorem Iff.symm (h : a ↔ b) : b ↔ a := Iff.intro h.mpr h.mp
 theorem Iff.comm: (a ↔ b) ↔ (b ↔ a) := Iff.intro Iff.symm Iff.symm
 theorem iff_comm : (a ↔ b) ↔ (b ↔ a) := Iff.comm

src/Init/Data/Array/Lemmas.lean

@@ -57,7 +57,9 @@ open Array
 
 /-! ### Lemmas about `List.toArray`. -/
 
-@[simp] theorem size_toArrayAux {a : List α} {b : Array α} :
+@[simp] theorem toArray_size (as : List α) : as.toArray.size = as.length := by simp [size]
+
+@[simp] theorem toArrayAux_size {a : List α} {b : Array α} :
     (a.toArrayAux b).size = b.size + a.length := by
   simp [size]
 
@@ -65,7 +67,6 @@ open Array
 
 @[deprecated toArray_toList (since := "2024-09-09")]
 abbrev toArray_data := @toArray_toList
-
 @[simp] theorem getElem_toArray {a : List α} {i : Nat} (h : i < a.toArray.size) :
     a.toArray[i] = a[i]'(by simpa using h) := rfl
 

src/Init/Data/BitVec/Lemmas.lean

@@ -927,10 +927,6 @@ theorem not_def {x : BitVec v} : ~~~x = allOnes v ^^^ x := rfl
   ext
   simp
 
-@[simp] theorem not_allOnes : ~~~ allOnes w = 0#w := by
-  ext
-  simp
-
 @[simp] theorem xor_allOnes {x : BitVec w} : x ^^^ allOnes w = ~~~ x := by
   ext i
   simp
@@ -1414,10 +1410,6 @@ theorem msb_append {x : BitVec w} {y : BitVec v} :
   rw [getLsbD_append]
   simpa using lt_of_getLsbD
 
-@[simp] theorem zero_append_zero : 0#v ++ 0#w = 0#(v + w) := by
-  ext
-  simp only [getLsbD_append, getLsbD_zero, Bool.cond_self]
-
 @[simp] theorem cast_append_right (h : w + v = w + v') (x : BitVec w) (y : BitVec v) :
     cast h (x ++ y) = x ++ cast (by omega) y := by
   ext
@@ -1663,10 +1655,6 @@ theorem getElem_concat (x : BitVec w) (b : Bool) (i : Nat) (h : i < w + 1) :
     (concat x a) ^^^ (concat y b) = concat (x ^^^ y) (a ^^ b) := by
   ext i; cases i using Fin.succRecOn <;> simp
 
-@[simp] theorem zero_concat_false : concat 0#w false = 0#(w + 1) := by
-  ext
-  simp [getLsbD_concat]
-
 /-! ### add -/
 
 theorem add_def {n} (x y : BitVec n) : x + y = .ofNat n (x.toNat + y.toNat) := rfl
@@ -2178,20 +2166,6 @@ theorem twoPow_zero {w : Nat} : twoPow w 0 = 1#w := by
 theorem getLsbD_one {w i : Nat} : (1#w).getLsbD i = (decide (0 < w) && decide (0 = i)) := by
   rw [← twoPow_zero, getLsbD_twoPow]
 
-@[simp] theorem true_cons_zero : cons true 0#w = twoPow (w + 1) w := by
-  ext
-  simp [getLsbD_cons]
-  omega
-
-@[simp] theorem false_cons_zero : cons false 0#w = 0#(w + 1) := by
-  ext
-  simp [getLsbD_cons]
-
-@[simp] theorem zero_concat_true : concat 0#w true = 1#(w + 1) := by
-  ext
-  simp [getLsbD_concat]
-  omega
-
 /- ### setWidth, setWidth, and bitwise operations -/
 
 /--

src/Init/Prelude.lean

@@ -754,10 +754,10 @@ infer the proof of `Nonempty α`.
 noncomputable def Classical.ofNonempty {α : Sort u} [Nonempty α] : α :=
   Classical.choice inferInstance
 
-instance {α : Sort u} {β : Sort v} [Nonempty β] : Nonempty (α → β) :=
+instance (α : Sort u) {β : Sort v} [Nonempty β] : Nonempty (α → β) :=
   Nonempty.intro fun _ => Classical.ofNonempty
 
-instance Pi.instNonempty {α : Sort u} {β : α → Sort v} [(a : α) → Nonempty (β a)] :
+instance Pi.instNonempty (α : Sort u) {β : α → Sort v} [(a : α) → Nonempty (β a)] :
     Nonempty ((a : α) → β a) :=
   Nonempty.intro fun _ => Classical.ofNonempty
 
@@ -767,7 +767,7 @@ instance : Inhabited (Sort u) where
 instance (α : Sort u) {β : Sort v} [Inhabited β] : Inhabited (α → β) where
   default := fun _ => default
 
-instance Pi.instInhabited {α : Sort u} {β : α → Sort v} [(a : α) → Inhabited (β a)] :
+instance Pi.instInhabited (α : Sort u) {β : α → Sort v} [(a : α) → Inhabited (β a)] :
     Inhabited ((a : α) → β a) where
   default := fun _ => default
 
@@ -2570,9 +2570,7 @@ structure Array (α : Type u) where
   /--
   Converts a `List α` into an `Array α`.
 
-  You can also use the synonym `List.toArray` when dot notation is convenient.
-
-  At runtime, this constructor is implemented by `List.toArrayImpl` and is O(n) in the length of the
+  At runtime, this constructor is implemented by `List.toArray` and is O(n) in the length of the
   list.
   -/
   mk ::