bjoernager/rust
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Normalize consistently for specializations

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This commit is contained in:
Matthew Jasper 2023-05-05 15:50:17 +01:00
parent bd928a0b5e
commit fafe9e71d5
4 changed files with 104 additions and 17 deletions
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39
compiler/rustc_trait_selection/src/traits/specialize/mod.rs
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@ -99,14 +99,13 @@ pub fn translate_substs<'tcx>(
return source_substs;
}
fulfill_implication(infcx, param_env, source_trait_ref, target_impl).unwrap_or_else(
|()| {
fulfill_implication(infcx, param_env, source_trait_ref, source_impl, target_impl)
.unwrap_or_else(|()| {
bug!(
"When translating substitutions from {source_impl:?} to {target_impl:?}, \
the expected specialization failed to hold"
)
},
)
})
}
specialization_graph::Node::Trait(..) => source_trait_ref.substs,
};
@ -153,20 +152,9 @@ pub(super) fn specializes(tcx: TyCtxt<'_>, (impl1_def_id, impl2_def_id): (DefId,
// Create an infcx, taking the predicates of impl1 as assumptions:
let infcx = tcx.infer_ctxt().build();
let impl1_trait_ref =
match traits::fully_normalize(&infcx, ObligationCause::dummy(), penv, impl1_trait_ref) {
Ok(impl1_trait_ref) => impl1_trait_ref,
Err(_errors) => {
tcx.sess.delay_span_bug(
tcx.def_span(impl1_def_id),
format!("failed to fully normalize {impl1_trait_ref}"),
);
impl1_trait_ref
}
};
// Attempt to prove that impl2 applies, given all of the above.
fulfill_implication(&infcx, penv, impl1_trait_ref, impl2_def_id).is_ok()
fulfill_implication(&infcx, penv, impl1_trait_ref, impl1_def_id, impl2_def_id).is_ok()
}
/// Attempt to fulfill all obligations of `target_impl` after unification with
@ -178,6 +166,7 @@ fn fulfill_implication<'tcx>(
infcx: &InferCtxt<'tcx>,
param_env: ty::ParamEnv<'tcx>,
source_trait_ref: ty::TraitRef<'tcx>,
source_impl: DefId,
target_impl: DefId,
) -> Result<SubstsRef<'tcx>, ()> {
debug!(
@ -185,6 +174,22 @@ fn fulfill_implication<'tcx>(
param_env, source_trait_ref, target_impl
);
let source_trait_ref = match traits::fully_normalize(
&infcx,
ObligationCause::dummy(),
param_env,
source_trait_ref,
) {
Ok(source_trait_ref) => source_trait_ref,
Err(_errors) => {
infcx.tcx.sess.delay_span_bug(
infcx.tcx.def_span(source_impl),
format!("failed to fully normalize {source_trait_ref}"),
);
source_trait_ref
}
};
let source_trait = ImplSubject::Trait(source_trait_ref);
let selcx = &mut SelectionContext::new(&infcx);
@ -194,7 +199,7 @@ fn fulfill_implication<'tcx>(
// do the impls unify? If not, no specialization.
let Ok(InferOk { obligations: more_obligations, .. }) =
infcx.at(&ObligationCause::dummy(), param_env, ).eq(DefineOpaqueTypes::No,source_trait, target_trait)
infcx.at(&ObligationCause::dummy(), param_env).eq(DefineOpaqueTypes::No, source_trait, target_trait)
else {
debug!(
"fulfill_implication: {:?} does not unify with {:?}",