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handle assoc consts in fulfill ConstEquate

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Boxy 2022-11-15 22:53:30 +00:00 • committed by kadmin
parent d75cd5c051
commit 0ae3c5c609
8 changed files with 90 additions and 176 deletions
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50
compiler/rustc_trait_selection/src/traits/fulfill.rs
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@ -457,41 +457,45 @@ impl<'a, 'tcx> ObligationProcessor for FulfillProcessor<'a, 'tcx> {
tcx.features().generic_const_exprs,
"`ConstEquate` without a feature gate: {c1:?} {c2:?}",
);
debug!(?c1, ?c2, "equating consts");
// FIXME: we probably should only try to unify abstract constants
// if the constants depend on generic parameters.
//
// Let's just see where this breaks :shrug:
match (c1.kind(), c2.kind()) {
(ty::ConstKind::Unevaluated(a), ty::ConstKind::Unevaluated(b)) => {
// FIXME: remove
use rustc_hir::def::DefKind;
if tcx.def_kind(a.def.did) == DefKind::AssocConst
|| tcx.def_kind(b.def.did) == DefKind::AssocConst
{
// Two different constants using generic parameters ~> error.
let expected_found = ExpectedFound::new(true, c1, c2);
return ProcessResult::Error(
FulfillmentErrorCode::CodeConstEquateError(
expected_found,
TypeError::ConstMismatch(expected_found),
),
);
}
{
let c1 =
if let Ok(Some(a)) = tcx.expand_abstract_consts(c1) { a } else { c1 };
let c2 =
if let Ok(Some(b)) = tcx.expand_abstract_consts(c2) { b } else { c2 };
debug!("equating consts:\nc1= {:?}\nc2= {:?}", c1, c2);
if let Ok(Some(a)) = tcx.expand_abstract_consts(c1)
&& let Ok(Some(b)) = tcx.expand_abstract_consts(c2)
&& a.ty() == b.ty()
&& let Ok(new_obligations) = infcx
use rustc_hir::def::DefKind;
use ty::ConstKind::Unevaluated;
match (c1.kind(), c2.kind()) {
(Unevaluated(a), Unevaluated(b))
if a.def.did == b.def.did
&& tcx.def_kind(a.def.did) == DefKind::AssocConst =>
{
if let Ok(new_obligations) = infcx
.at(&obligation.cause, obligation.param_env)
.eq(a, b)
.trace(c1, c2)
.eq(a.substs, b.substs)
{
return ProcessResult::Changed(mk_pending(
new_obligations.into_obligations(),
));
}
}
(_, Unevaluated(_)) | (Unevaluated(_), _) => (),
(_, _) => {
if let Ok(new_obligations) =
infcx.at(&obligation.cause, obligation.param_env).eq(c1, c2)
{
return ProcessResult::Changed(mk_pending(
new_obligations.into_obligations(),
));
}
}
}
_ => {}
}
let stalled_on = &mut pending_obligation.stalled_on;