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rustc_mir: also promote interior borrows, not just whole temps.

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This commit is contained in:
Eduard-Mihai Burtescu 2018-05-10 12:06:51 +03:00
parent b9af400a46
commit d79dee0b62
2 changed files with 43 additions and 2 deletions
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15
src/librustc_mir/transform/qualify_consts.rs
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@ -737,10 +737,21 @@ impl<'a, 'tcx> Visitor<'tcx> for Qualifier<'a, 'tcx, 'tcx> {
// We might have a candidate for promotion.
let candidate = Candidate::Ref(location);
if self.can_promote() {
// We can only promote direct borrows of temps.
// We can only promote interior borrows of non-drop temps.
let mut place = place;
while let Place::Projection(ref proj) = *place {
if proj.elem == ProjectionElem::Deref {
break;
}
place = &proj.base;
}
if let Place::Local(local) = *place {
if self.mir.local_kind(local) == LocalKind::Temp {
self.promotion_candidates.push(candidate);
if let Some(qualif) = self.temp_qualif[local] {
if !qualif.intersects(Qualif::NEEDS_DROP) {
self.promotion_candidates.push(candidate);
}
}
}
}
}