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Add a comparison between match *self and intrinsics::unreachable()

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David Tolnay 2023-07-16 15:33:29 -07:00
parent f441adc89a
commit 56633b3f51
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1 changed files with 3 additions and 2 deletions
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5
compiler/rustc_builtin_macros/src/deriving/generic/mod.rs
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@ -1149,8 +1149,9 @@ impl<'a> MethodDef<'a> {
let unify_fieldless_variants = let unify_fieldless_variants =
self.fieldless_variants_strategy == FieldlessVariantsStrategy::Unify; self.fieldless_variants_strategy == FieldlessVariantsStrategy::Unify;
// For zero-variant enum, this function body is unreachable. // For zero-variant enum, this function body is unreachable. Generate
// Generate `match *self {}`. // `match *self {}`. This produces machine code identical to `unsafe {
// core::intrinsics::unreachable() }` while being safe and stable.
if variants.is_empty() { if variants.is_empty() {
selflike_args.truncate(1); selflike_args.truncate(1);
let match_arg = cx.expr_deref(span, selflike_args.pop().unwrap()); let match_arg = cx.expr_deref(span, selflike_args.pop().unwrap());