bjoernager/rust
bjoernager/rust
1
Fork 0
Code Issues Pull requests Activity

Add AliasKind::Weak for type aliases.

Browse source 
Only use it when the type alias contains an opaque type.

Also does wf-checking on such type aliases.
This commit is contained in:
Oli Scherer 2023-03-07 12:03:11 +00:00
parent 4fdd07fe88
commit f3b7dd6388
86 changed files with 474 additions and 199 deletions
Download patch file Download diff file Expand all files Collapse all files

27
compiler/rustc_trait_selection/src/traits/project.rs
View file

@ -31,6 +31,7 @@ use rustc_infer::infer::at::At;
use rustc_infer::infer::resolve::OpportunisticRegionResolver;
use rustc_infer::infer::DefineOpaqueTypes;
use rustc_infer::traits::ImplSourceBuiltinData;
use rustc_infer::traits::ObligationCauseCode;
use rustc_middle::traits::select::OverflowError;
use rustc_middle::ty::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
use rustc_middle::ty::visit::{MaxUniverse, TypeVisitable, TypeVisitableExt};
@ -621,6 +622,30 @@ impl<'a, 'b, 'tcx> TypeFolder<TyCtxt<'tcx>> for AssocTypeNormalizer<'a, 'b, 'tcx
);
normalized_ty
}
ty::Weak => {
let infcx = self.selcx.infcx;
self.obligations.extend(
infcx
.tcx
.predicates_of(data.def_id)
.instantiate_own(infcx.tcx, data.substs)
.map(|(mut predicate, span)| {
if data.has_escaping_bound_vars() {
(predicate, ..) = BoundVarReplacer::replace_bound_vars(
infcx,
&mut self.universes,
predicate,
);
}
let mut cause = self.cause.clone();
cause.map_code(|code| {
ObligationCauseCode::TypeAlias(code, span, data.def_id)
});
Obligation::new(infcx.tcx, cause, self.param_env, predicate)
}),
);
infcx.tcx.type_of(data.def_id).subst(infcx.tcx, data.substs).fold_with(self)
}
ty::Inherent if !data.has_escaping_bound_vars() => {
// This branch is *mostly* just an optimization: when we don't
@ -1545,7 +1570,7 @@ fn assemble_candidates_from_trait_def<'cx, 'tcx>(
// Check whether the self-type is itself a projection.
// If so, extract what we know from the trait and try to come up with a good answer.
let bounds = match *obligation.predicate.self_ty().kind() {
// Excluding IATs here as they don't have meaningful item bounds.
// Excluding IATs and type aliases here as they don't have meaningful item bounds.
ty::Alias(ty::Projection | ty::Opaque, ref data) => {
tcx.item_bounds(data.def_id).subst(tcx, data.substs)
}