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Auto merge of #85603 - ogoffart:fix-uninhabited-enum-branching-pass, r=wesleywiser

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Fix uninhabited enum branching pass

when the discriminant is taken with some projection.
This commit is contained in:
bors 2021-06-25 15:35:47 +00:00
commit f726dbe934
4 changed files with 305 additions and 7 deletions
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12
compiler/rustc_mir/src/transform/uninhabited_enum_branching.rs
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@ -24,6 +24,7 @@ fn get_discriminant_local(terminator: &TerminatorKind<'_>) -> Option<Local> {
/// discriminant is read from. Otherwise, returns None.
fn get_switched_on_type<'tcx>(
block_data: &BasicBlockData<'tcx>,
tcx: TyCtxt<'tcx>,
body: &Body<'tcx>,
) -> Option<Ty<'tcx>> {
let terminator = block_data.terminator();
@ -36,12 +37,9 @@ fn get_switched_on_type<'tcx>(
if let Some(StatementKind::Assign(box (l, Rvalue::Discriminant(place)))) = stmt_before_term
{
if l.as_local() == Some(local) {
if let Some(r_local) = place.as_local() {
let ty = body.local_decls[r_local].ty;
if ty.is_enum() {
return Some(ty);
}
let ty = place.ty(body, tcx).ty;
if ty.is_enum() {
return Some(ty);
}
}
}
@ -86,7 +84,7 @@ impl<'tcx> MirPass<'tcx> for UninhabitedEnumBranching {
trace!("processing block {:?}", bb);
let discriminant_ty =
if let Some(ty) = get_switched_on_type(&body.basic_blocks()[bb], body) {
if let Some(ty) = get_switched_on_type(&body.basic_blocks()[bb], tcx, body) {
ty
} else {
continue;