bjoernager/rust
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Don't go through TraitRef to relate projections

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This commit is contained in:
Matthew Jasper 2021-02-12 22:07:46 +00:00
parent 9bbd3e0f8e
commit 0bf1d73d22
3 changed files with 42 additions and 18 deletions
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20
compiler/rustc_trait_selection/src/traits/select/mod.rs
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@ -32,6 +32,7 @@ use rustc_errors::ErrorReported;
use rustc_hir as hir;
use rustc_hir::def_id::DefId;
use rustc_hir::Constness;
use rustc_infer::infer::LateBoundRegionConversionTime;
use rustc_middle::dep_graph::{DepKind, DepNodeIndex};
use rustc_middle::mir::interpret::ErrorHandled;
use rustc_middle::ty::fast_reject;
@ -1254,32 +1255,33 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
pub(super) fn match_projection_projections(
&mut self,
obligation: &ProjectionTyObligation<'tcx>,
obligation_trait_ref: &ty::TraitRef<'tcx>,
data: &PolyProjectionPredicate<'tcx>,
env_predicate: PolyProjectionPredicate<'tcx>,
potentially_unnormalized_candidates: bool,
) -> bool {
let mut nested_obligations = Vec::new();
let projection_ty = if potentially_unnormalized_candidates {
let (infer_predicate, _) = self.infcx.replace_bound_vars_with_fresh_vars(
obligation.cause.span,
LateBoundRegionConversionTime::HigherRankedType,
env_predicate,
);
let infer_projection = if potentially_unnormalized_candidates {
ensure_sufficient_stack(|| {
project::normalize_with_depth_to(
self,
obligation.param_env,
obligation.cause.clone(),
obligation.recursion_depth + 1,
data.map_bound(|data| data.projection_ty),
infer_predicate.projection_ty,
&mut nested_obligations,
)
})
} else {
data.map_bound(|data| data.projection_ty)
infer_predicate.projection_ty
};
// FIXME(generic_associated_types): Compare the whole projections
let data_poly_trait_ref = projection_ty.map_bound(|proj| proj.trait_ref(self.tcx()));
let obligation_poly_trait_ref = ty::Binder::dummy(*obligation_trait_ref);
self.infcx
.at(&obligation.cause, obligation.param_env)
.sup(obligation_poly_trait_ref, data_poly_trait_ref)
.sup(obligation.predicate, infer_projection)
.map_or(false, |InferOk { obligations, value: () }| {
self.evaluate_predicates_recursively(
TraitObligationStackList::empty(&ProvisionalEvaluationCache::default()),