feat: rename tactic byCases => by_cases

RELEASES.md

@@ -27,3 +27,5 @@ theorem dep_congr [DecidableEq ι] {p : ι → Set α} [∀ i, Inhabited (p i)]
 * [Relax auto-implicit restrictions](https://github.com/leanprover/lean4/pull/1011). The command `set_option relaxedAutoImplicit false` disables the relaxations.
 
 * `contradiction` tactic now closes the goal if there is a `False.elim` application in the target.
+
+* Renamed tatic `byCases` => `by_cases` (motivation: enforcing naming convention).

src/Init/Classical.lean

@@ -125,7 +125,7 @@ theorem byCases {p q : Prop} (hpq : p → q) (hnpq : ¬p → q) : q :=
 theorem byContradiction {p : Prop} (h : ¬p → False) : p :=
   Decidable.byContradiction (dec := propDecidable _) h
 
-macro "byCases" h:ident ":" e:term : tactic =>
+macro "by_cases" h:ident ":" e:term : tactic =>
   `(cases em $e:term with
     | inl $h:ident => _
     | inr $h:ident => _)

tests/lean/run/ac_expr.lean

@@ -105,7 +105,7 @@ where
       | var i =>
         cases a with
         | var j =>
-          byCases h : i > j
+          by_cases h : i > j
           focus
             simp [sort.swap, h]
             match h:sort.swap (var j) b with
@@ -123,7 +123,7 @@ where
     | var j =>
       cases e₁ with
       | var i =>
-        byCases h : i > j
+        by_cases h : i > j
         focus simp [sort.swap, h, denote, Context.comm]
         focus simp [sort.swap, h]
       | _ => rfl

tests/lean/run/specialize2.lean

@@ -1,7 +1,7 @@
 example : (p → q → False) ↔ (¬ p ∨ ¬ q) := by
   apply Iff.intro
   . intro h
-    byCases hp:p <;> byCases hq:q
+    by_cases hp:p <;> by_cases hq:q
     . specialize h hp hq; contradiction
     . exact Or.inr hq
     . exact Or.inl hp