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The ordinary lowering of thir::ExprKind::Let is unreachable #121892

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Merged
merged 1 commit into from
Mar 2, 2024
Merged

The ordinary lowering of thir::ExprKind::Let is unreachable #121892

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38 changes: 6 additions & 32 deletions compiler/rustc_mir_build/src/build/expr/into.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -109,38 +109,12 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
this.cfg.goto(else_blk, source_info, join_block);
join_block.unit()
}
ExprKind::Let { expr, ref pat } => {
let scope = this.local_scope();
let (true_block, false_block) = this.in_if_then_scope(scope, expr_span, |this| {
this.lower_let_expr(block, expr, pat, scope, None, expr_span, true)
});

this.cfg.push_assign_constant(
true_block,
source_info,
destination,
ConstOperand {
span: expr_span,
user_ty: None,
const_: Const::from_bool(this.tcx, true),
},
);

this.cfg.push_assign_constant(
false_block,
source_info,
destination,
ConstOperand {
span: expr_span,
user_ty: None,
const_: Const::from_bool(this.tcx, false),
},
);

let join_block = this.cfg.start_new_block();
this.cfg.goto(true_block, source_info, join_block);
this.cfg.goto(false_block, source_info, join_block);
join_block.unit()
ExprKind::Let { .. } => {
// After desugaring, `let` expressions should only appear inside `if`
// expressions or `match` guards, possibly nested within a let-chain.
// In both cases they are specifically handled by the lowerings of
// those expressions, so this case is currently unreachable.
span_bug!(expr_span, "unexpected let expression outside of if or match-guard");
}
ExprKind::NeverToAny { source } => {
let source_expr = &this.thir[source];
Expand Down