diff options
Diffstat (limited to 'compiler/rustc_trait_selection/src/traits/specialize/mod.rs')
-rw-r--r-- | compiler/rustc_trait_selection/src/traits/specialize/mod.rs | 71 |
1 files changed, 52 insertions, 19 deletions
diff --git a/compiler/rustc_trait_selection/src/traits/specialize/mod.rs b/compiler/rustc_trait_selection/src/traits/specialize/mod.rs index 8546bbe52dc..9a4b72013b8 100644 --- a/compiler/rustc_trait_selection/src/traits/specialize/mod.rs +++ b/compiler/rustc_trait_selection/src/traits/specialize/mod.rs @@ -83,6 +83,30 @@ pub fn translate_substs<'tcx>( source_substs: SubstsRef<'tcx>, target_node: specialization_graph::Node, ) -> SubstsRef<'tcx> { + translate_substs_with_cause( + infcx, + param_env, + source_impl, + source_substs, + target_node, + |_, _| ObligationCause::dummy(), + ) +} + +/// Like [translate_substs], but obligations from the parent implementation +/// are registered with the provided `ObligationCause`. +/// +/// This is for reporting *region* errors from those bounds. Type errors should +/// not happen because the specialization graph already checks for those, and +/// will result in an ICE. +pub fn translate_substs_with_cause<'tcx>( + infcx: &InferCtxt<'tcx>, + param_env: ty::ParamEnv<'tcx>, + source_impl: DefId, + source_substs: SubstsRef<'tcx>, + target_node: specialization_graph::Node, + cause: impl Fn(usize, Span) -> ObligationCause<'tcx>, +) -> SubstsRef<'tcx> { debug!( "translate_substs({:?}, {:?}, {:?}, {:?})", param_env, source_impl, source_substs, target_node @@ -99,14 +123,13 @@ 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, cause) + .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 +176,12 @@ 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, |_, _| { + ObligationCause::dummy() + }) + .is_ok() } /// Attempt to fulfill all obligations of `target_impl` after unification with @@ -178,23 +193,41 @@ fn fulfill_implication<'tcx>( infcx: &InferCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>, source_trait_ref: ty::TraitRef<'tcx>, + source_impl: DefId, target_impl: DefId, + error_cause: impl Fn(usize, Span) -> ObligationCause<'tcx>, ) -> Result<SubstsRef<'tcx>, ()> { debug!( "fulfill_implication({:?}, trait_ref={:?} |- {:?} applies)", 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); let target_substs = infcx.fresh_substs_for_item(DUMMY_SP, target_impl); let (target_trait, obligations) = - util::impl_subject_and_oblig(selcx, param_env, target_impl, target_substs); + util::impl_subject_and_oblig(selcx, param_env, target_impl, target_substs, error_cause); // 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 {:?}", @@ -373,7 +406,7 @@ fn report_conflicting_impls<'tcx>( } None => format!("conflicting implementation in crate `{}`", cname), }; - err.note(&msg); + err.note(msg); } } |