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Check projections are well-formed when using projection candidates

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This commit is contained in:
Matthew Jasper
2020-06-28 12:41:46 +01:00
parent 87f2f42dc2
commit b3057f4d5f
13 changed files with 278 additions and 30 deletions
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34
compiler/rustc_trait_selection/src/traits/select/confirmation.rs
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@@ -69,8 +69,8 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
}
ProjectionCandidate => {
self.confirm_projection_candidate(obligation);
Ok(ImplSource::Param(Vec::new()))
let obligations = self.confirm_projection_candidate(obligation);
Ok(ImplSource::Param(obligations))
}
ClosureCandidate => {
@@ -116,10 +116,34 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
}
}
fn confirm_projection_candidate(&mut self, obligation: &TraitObligation<'tcx>) {
fn confirm_projection_candidate(
&mut self,
obligation: &TraitObligation<'tcx>,
) -> Vec<PredicateObligation<'tcx>> {
self.infcx.commit_unconditionally(|_| {
let result = self.match_projection_obligation_against_definition_bounds(obligation);
assert!(result);
let candidate = self
.match_projection_obligation_against_definition_bounds(obligation)
.unwrap_or_else(|| bug!("Can't find selected projection candidate"));
let mut obligations = self
.infcx
.at(&obligation.cause, obligation.param_env)
.sup(obligation.predicate.to_poly_trait_ref(), candidate)
.map(|InferOk { obligations, .. }| obligations)
.unwrap_or_else(|_| {
bug!(
"Projection bound `{:?}` was applicable to `{:?}` but now is not",
candidate,
obligation
);
});
// Require that the projection is well-formed.
let self_ty = obligation.predicate.skip_binder().self_ty();
obligations.push(Obligation::new(
obligation.cause.clone(),
obligation.param_env,
ty::PredicateKind::WellFormed(self_ty.into()).to_predicate(self.tcx()),
));
obligations
})
}