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rustc_trans: support ZST indexing involving uninhabited types.

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This commit is contained in:
Eduard-Mihai Burtescu 2017-12-26 03:20:35 +02:00
parent 269827ced9
commit 57bb8ab832
2 changed files with 50 additions and 3 deletions
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19
src/librustc_trans/mir/operand.rs
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@ -267,9 +267,22 @@ impl<'a, 'tcx> MirContext<'a, 'tcx> {
// Moves out of scalar and scalar pair fields are trivial.
if let &mir::Place::Projection(ref proj) = place {
if let mir::ProjectionElem::Field(ref f, _) = proj.elem {
if let Some(o) = self.maybe_trans_consume_direct(bcx, &proj.base) {
return Some(o.extract_field(bcx, f.index()));
if let Some(o) = self.maybe_trans_consume_direct(bcx, &proj.base) {
match proj.elem {
mir::ProjectionElem::Field(ref f, _) => {
return Some(o.extract_field(bcx, f.index()));
}
mir::ProjectionElem::Index(_) |
mir::ProjectionElem::ConstantIndex { .. } => {
// ZSTs don't require any actual memory access.
// FIXME(eddyb) deduplicate this with the identical
// checks in `trans_consume` and `extract_field`.
let elem = o.layout.field(bcx.ccx, 0);
if elem.is_zst() {
return Some(OperandRef::new_zst(bcx.ccx, elem));
}
}
_ => {}
}
}
}