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clarify comment on Deref promotion

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This commit is contained in:
Ralf Jung 2022-12-01 16:41:49 +01:00
parent 8a09420ac4
commit b7f2b1cd5c
1 changed files with 4 additions and 4 deletions
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8
compiler/rustc_const_eval/src/transform/promote_consts.rs
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@ -318,14 +318,14 @@ impl<'tcx> Validator<'_, 'tcx> {
match elem { match elem {
ProjectionElem::Deref => { ProjectionElem::Deref => {
let mut promotable = false; let mut promotable = false;
// When a static is used by-value, that gets desugared to `*STATIC_ADDR`,
// and we need to be able to promote this. So check if this deref matches
// that specific pattern.
// We need to make sure this is a `Deref` of a local with no further projections. // We need to make sure this is a `Deref` of a local with no further projections.
// Discussion can be found at // Discussion can be found at
// https://github.com/rust-lang/rust/pull/74945#discussion_r463063247 // https://github.com/rust-lang/rust/pull/74945#discussion_r463063247
if let Some(local) = place_base.as_local() { if let Some(local) = place_base.as_local() {
// This is a special treatment for cases like *&STATIC where STATIC is a
// global static variable.
// This pattern is generated only when global static variables are directly
// accessed and is qualified for promotion safely.
if let TempState::Defined { location, .. } = self.temps[local] { if let TempState::Defined { location, .. } = self.temps[local] {
let def_stmt = self.body[location.block] let def_stmt = self.body[location.block]
.statements .statements