diff options
Diffstat (limited to 'compiler/rustc_trait_selection/src/traits/codegen.rs')
-rw-r--r-- | compiler/rustc_trait_selection/src/traits/codegen.rs | 89 |
1 files changed, 50 insertions, 39 deletions
diff --git a/compiler/rustc_trait_selection/src/traits/codegen.rs b/compiler/rustc_trait_selection/src/traits/codegen.rs index 08adbcbd4..8a62bf015 100644 --- a/compiler/rustc_trait_selection/src/traits/codegen.rs +++ b/compiler/rustc_trait_selection/src/traits/codegen.rs @@ -4,10 +4,12 @@ // general routines. use crate::infer::{DefiningAnchor, TyCtxtInferExt}; +use crate::traits::error_reporting::TypeErrCtxtExt; use crate::traits::{ ImplSource, Obligation, ObligationCause, SelectionContext, TraitEngine, TraitEngineExt, Unimplemented, }; +use rustc_infer::traits::FulfillmentErrorCode; use rustc_middle::traits::CodegenObligationError; use rustc_middle::ty::{self, TyCtxt}; @@ -27,52 +29,61 @@ pub fn codegen_select_candidate<'tcx>( // Do the initial selection for the obligation. This yields the // shallow result we are looking for -- that is, what specific impl. - let mut infcx_builder = - tcx.infer_ctxt().ignoring_regions().with_opaque_type_inference(DefiningAnchor::Bubble); - infcx_builder.enter(|infcx| { - //~^ HACK `Bubble` is required for - // this test to pass: type-alias-impl-trait/assoc-projection-ice.rs - let mut selcx = SelectionContext::new(&infcx); + let infcx = tcx + .infer_ctxt() + .ignoring_regions() + .with_opaque_type_inference(DefiningAnchor::Bubble) + .build(); + //~^ HACK `Bubble` is required for + // this test to pass: type-alias-impl-trait/assoc-projection-ice.rs + let mut selcx = SelectionContext::new(&infcx); - let obligation_cause = ObligationCause::dummy(); - let obligation = - Obligation::new(obligation_cause, param_env, trait_ref.to_poly_trait_predicate()); + let obligation_cause = ObligationCause::dummy(); + let obligation = + Obligation::new(obligation_cause, param_env, trait_ref.to_poly_trait_predicate()); - let selection = match selcx.select(&obligation) { - Ok(Some(selection)) => selection, - Ok(None) => return Err(CodegenObligationError::Ambiguity), - Err(Unimplemented) => return Err(CodegenObligationError::Unimplemented), - Err(e) => { - bug!("Encountered error `{:?}` selecting `{:?}` during codegen", e, trait_ref) - } - }; + let selection = match selcx.select(&obligation) { + Ok(Some(selection)) => selection, + Ok(None) => return Err(CodegenObligationError::Ambiguity), + Err(Unimplemented) => return Err(CodegenObligationError::Unimplemented), + Err(e) => { + bug!("Encountered error `{:?}` selecting `{:?}` during codegen", e, trait_ref) + } + }; - debug!(?selection); + debug!(?selection); - // Currently, we use a fulfillment context to completely resolve - // all nested obligations. This is because they can inform the - // inference of the impl's type parameters. - let mut fulfill_cx = <dyn TraitEngine<'tcx>>::new(tcx); - let impl_source = selection.map(|predicate| { - fulfill_cx.register_predicate_obligation(&infcx, predicate); - }); + // Currently, we use a fulfillment context to completely resolve + // all nested obligations. This is because they can inform the + // inference of the impl's type parameters. + let mut fulfill_cx = <dyn TraitEngine<'tcx>>::new(tcx); + let impl_source = selection.map(|predicate| { + fulfill_cx.register_predicate_obligation(&infcx, predicate); + }); - // In principle, we only need to do this so long as `impl_source` - // contains unbound type parameters. It could be a slight - // optimization to stop iterating early. - let errors = fulfill_cx.select_all_or_error(&infcx); - if !errors.is_empty() { - return Err(CodegenObligationError::FulfillmentError); + // In principle, we only need to do this so long as `impl_source` + // contains unbound type parameters. It could be a slight + // optimization to stop iterating early. + let errors = fulfill_cx.select_all_or_error(&infcx); + if !errors.is_empty() { + // `rustc_monomorphize::collector` assumes there are no type errors. + // Cycle errors are the only post-monomorphization errors possible; emit them now so + // `rustc_ty_utils::resolve_associated_item` doesn't return `None` post-monomorphization. + for err in errors { + if let FulfillmentErrorCode::CodeCycle(cycle) = err.code { + infcx.err_ctxt().report_overflow_error_cycle(&cycle); + } } + return Err(CodegenObligationError::FulfillmentError); + } - let impl_source = infcx.resolve_vars_if_possible(impl_source); - let impl_source = infcx.tcx.erase_regions(impl_source); + let impl_source = infcx.resolve_vars_if_possible(impl_source); + let impl_source = infcx.tcx.erase_regions(impl_source); - // Opaque types may have gotten their hidden types constrained, but we can ignore them safely - // as they will get constrained elsewhere, too. - // (ouz-a) This is required for `type-alias-impl-trait/assoc-projection-ice.rs` to pass - let _ = infcx.inner.borrow_mut().opaque_type_storage.take_opaque_types(); + // Opaque types may have gotten their hidden types constrained, but we can ignore them safely + // as they will get constrained elsewhere, too. + // (ouz-a) This is required for `type-alias-impl-trait/assoc-projection-ice.rs` to pass + let _ = infcx.inner.borrow_mut().opaque_type_storage.take_opaque_types(); - Ok(&*tcx.arena.alloc(impl_source)) - }) + Ok(&*tcx.arena.alloc(impl_source)) } |