Document MacCall special case in Parser::parse_arm

rust-lang · May 11, 2024 · 728e117 · 728e117
1 parent 9dbe33d
commit 728e117
Showing 1 changed file with 11 additions and 0 deletions.
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
@@ -3182,6 +3182,17 @@ impl<'a> Parser<'a> {
  })?;
 
  let require_comma = match expr.kind {
+ // Special case: braced macro calls require comma in a match
+ // arm, even though they do not require semicolon in a
+ // statement.
+ //
+ // m! {} // okay without semicolon
+ //
+ // match ... {
+ // _ => m! {}, // requires comma
+ // _ => ...
+ // }
+ //
  ExprKind::MacCall(_) => true,
  _ => classify::expr_requires_semi_to_be_stmt(&expr),
  } && this.token != token::CloseDelim(Delimiter::Brace);