Fix scoping for let-else.

Author: cjgillot

compiler/rustc_mir_build/src/build/block.rs

@@ -221,27 +221,37 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
 
  let init = &this.thir[*initializer];
  let initializer_span = init.span;
- this.declare_bindings(
- visibility_scope,
- remainder_span,
- pattern,
- ArmHasGuard(false),
- Some((None, initializer_span)),
- );
- this.visit_primary_bindings(
- pattern,
- UserTypeProjections::none(),
- &mut |this, _, _, _, node, span, _, _| {
- this.storage_live_binding(block, node, span, OutsideGuard, true);
- this.schedule_drop_for_binding(node, span, OutsideGuard);
- },
- );
  let failure = unpack!(
  block = this.in_opt_scope(
  opt_destruction_scope.map(|de| (de, source_info)),
  |this| {
  let scope = (*init_scope, source_info);
  this.in_scope(scope, *lint_level, |this| {
+ this.declare_bindings(
+ visibility_scope,
+ remainder_span,
+ pattern,
+ ArmHasGuard(false),
+ Some((None, initializer_span)),
+ );
+ this.visit_primary_bindings(
+ pattern,
+ UserTypeProjections::none(),
+ &mut |this, _, _, _, node, span, _, _| {
+ this.storage_live_binding(
+ block,
+ node,
+ span,
+ OutsideGuard,
+ true,
+ );
+ this.schedule_drop_for_binding(
+ node,
+ span,
+ OutsideGuard,
+ );
+ },
+ );
  this.ast_let_else(
  block,
  init,
@@ -306,7 +316,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
  ArmHasGuard(false),
  Some((None, initializer_span)),
  );
- this.expr_into_pattern(block, &pattern, init) // irrefutable pattern
+ this.expr_into_pattern(block, &pattern, init)
+ // irrefutable pattern
  })
  },
  )