bjoernager/rust
bjoernager/rust
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use abstract consts when unifying ConstKind::Unevaluated

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This commit is contained in:
Bastian Kauschke 2020-09-10 18:48:18 +02:00
parent d327fa112b
commit c3a772f55f
8 changed files with 96 additions and 10 deletions
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22
compiler/rustc_trait_selection/src/traits/const_evaluatable.rs
View file

@ -269,7 +269,27 @@ pub(super) fn mir_abstract_const<'tcx>(
}
}
pub fn try_unify<'tcx>(tcx: TyCtxt<'tcx>, a: AbstractConst<'tcx>, b: AbstractConst<'tcx>) -> bool {
pub(super) fn try_unify_abstract_consts<'tcx>(
tcx: TyCtxt<'tcx>,
((a, a_substs), (b, b_substs)): (
(ty::WithOptConstParam<DefId>, SubstsRef<'tcx>),
(ty::WithOptConstParam<DefId>, SubstsRef<'tcx>),
),
) -> bool {
if let Some(a) = AbstractConst::new(tcx, a, a_substs) {
if let Some(b) = AbstractConst::new(tcx, b, b_substs) {
return try_unify(tcx, a, b);
}
}
false
}
pub(super) fn try_unify<'tcx>(
tcx: TyCtxt<'tcx>,
a: AbstractConst<'tcx>,
b: AbstractConst<'tcx>,
) -> bool {
match (a.root(), b.root()) {
(Node::Leaf(a_ct), Node::Leaf(b_ct)) => {
let a_ct = a_ct.subst(tcx, a.substs);

19
compiler/rustc_trait_selection/src/traits/fulfill.rs
View file

@ -476,6 +476,25 @@ impl<'a, 'b, 'tcx> ObligationProcessor for FulfillProcessor<'a, 'b, 'tcx> {
ty::PredicateAtom::ConstEquate(c1, c2) => {
debug!("equating consts: c1={:?} c2={:?}", c1, c2);
if self.selcx.tcx().features().const_evaluatable_checked {
// 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:
if let (
ty::ConstKind::Unevaluated(a_def, a_substs, None),
ty::ConstKind::Unevaluated(b_def, b_substs, None),
) = (c1.val, c2.val)
{
if self
.selcx
.tcx()
.try_unify_abstract_consts(((a_def, a_substs), (b_def, b_substs)))
{
return ProcessResult::Changed(vec![]);
}
}
}
let stalled_on = &mut pending_obligation.stalled_on;

1
compiler/rustc_trait_selection/src/traits/mod.rs
View file

@ -566,6 +566,7 @@ pub fn provide(providers: &mut ty::query::Providers) {
ty::WithOptConstParam { did, const_param_did: Some(param_did) },
)
},
try_unify_abstract_consts: const_evaluatable::try_unify_abstract_consts,
..*providers
};
}