feat: add tactic macro unhygienic <tactic-seq>

src/Init/Notation.lean

@@ -310,6 +310,8 @@ macro_rules | `(tactic| trivial) => `(tactic| contradiction)
 macro_rules | `(tactic| trivial) => `(tactic| apply True.intro)
 macro_rules | `(tactic| trivial) => `(tactic| apply And.intro <;> trivial)
 
+macro "unhygienic " t:tacticSeq : tactic => `(set_option tactic.hygienic false in $t:tacticSeq)
+
 end Tactic
 
 namespace Attr

tests/lean/hygienicIntro.lean

@@ -45,3 +45,8 @@ example {p q : Prop} (h₁ : p → q) (h₂ : p ∨ q) : q := by
 match h₂ with
 | Or.inl _ => apply h₁; assumption
 | Or.inr h => exact h
+
+example {p q : Prop} (h₁ : p → q) (h₂ : p ∨ q) : q := by unhygienic
+  cases h₂
+  { apply h₁; exact h } -- hygiene is disabled
+  exact h