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supplement for the missing or incomplete comments

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Ding Xiang Fei 2022-09-05 14:24:13 +08:00
parent af591ebe4d
commit 34f0c4502f
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GPG Key ID: 3CD748647EEF6359
2 changed files with 13 additions and 2 deletions
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5
compiler/rustc_mir_build/src/build/block.rs
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@ -119,10 +119,13 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
} => {
let ignores_expr_result = matches!(pattern.kind, PatKind::Wild);
this.block_context.push(BlockFrame::Statement { ignores_expr_result });
// Lower the `else` block first because its parent scope is actually
// enclosing the rest of the `let .. else ..` parts.
let else_block_span = this.thir[*else_block].span;
// This place is not really used because this destination place
// should never be used to take values at the end of the failure
// block.
let else_block_span = this.thir[*else_block].span;
let dummy_place = this.temp(this.tcx.types.never, else_block_span);
let failure_entry = this.cfg.start_new_block();
let failure_block;

10
compiler/rustc_typeck/src/check/region.rs
View File

@ -128,16 +128,24 @@ fn resolve_block<'tcx>(visitor: &mut RegionResolutionVisitor<'tcx>, blk: &'tcx h
match statement.kind {
hir::StmtKind::Local(hir::Local { els: Some(els), .. }) => {
// Let-else has a special lexical structure for variables.
// First we take a checkpoint of the current scope context here.
let mut prev_cx = visitor.cx;
visitor.enter_scope(Scope {
id: blk.hir_id.local_id,
data: ScopeData::Remainder(FirstStatementIndex::new(i)),
});
visitor.cx.var_parent = visitor.cx.parent;
visitor.visit_stmt(statement);
// We need to back out temporarily to the last enclosing scope
// for the `else` block, so that even the temporaries receiving
// extended lifetime will be dropped inside this block.
// We are visiting the `else` block in this order so that
// the sequence of visits agree with the order in the default
// `hir::intravisit` visitor.
mem::swap(&mut prev_cx, &mut visitor.cx);
// We need to back out temporarily and
visitor.visit_block(els);
// From now on, we continue normally.
visitor.cx = prev_cx;
}
hir::StmtKind::Local(..) | hir::StmtKind::Item(..) => {