diff options
Diffstat (limited to 'compiler/rustc_hir_analysis/src/astconv/mod.rs')
| -rw-r--r-- | compiler/rustc_hir_analysis/src/astconv/mod.rs | 61 |
1 files changed, 35 insertions, 26 deletions
diff --git a/compiler/rustc_hir_analysis/src/astconv/mod.rs b/compiler/rustc_hir_analysis/src/astconv/mod.rs index c199b9da6fe..e50e4800621 100644 --- a/compiler/rustc_hir_analysis/src/astconv/mod.rs +++ b/compiler/rustc_hir_analysis/src/astconv/mod.rs @@ -2378,6 +2378,10 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { return Ok(None); } + // + // Select applicable inherent associated type candidates modulo regions. + // + // In contexts that have no inference context, just make a new one. // We do need a local variable to store it, though. let infcx_; @@ -2390,7 +2394,9 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { } }; - let param_env = tcx.param_env(block.owner.to_def_id()); + // FIXME(inherent_associated_types): Acquiring the ParamEnv this early leads to cycle errors + // when inside of an ADT (#108491) or where clause. + let param_env = tcx.param_env(block.owner); let cause = ObligationCause::misc(span, block.owner.def_id); let mut fulfillment_errors = Vec::new(); @@ -2398,6 +2404,8 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { let universe = infcx.create_next_universe(); // Regions are not considered during selection. + // FIXME(non_lifetime_binders): Here we are "truncating" or "flattening" the universes + // of type and const binders. Is that correct in the selection phase? See also #109505. let self_ty = tcx.replace_escaping_bound_vars_uncached( self_ty, FnMutDelegate { @@ -2413,41 +2421,40 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { candidates .iter() - .filter_map(|&(impl_, (assoc_item, def_scope))| { + .copied() + .filter(|&(impl_, _)| { infcx.probe(|_| { let ocx = ObligationCtxt::new_in_snapshot(&infcx); - let impl_ty = tcx.type_of(impl_); let impl_substs = infcx.fresh_item_substs(impl_); - let impl_ty = impl_ty.subst(tcx, impl_substs); + let impl_ty = tcx.type_of(impl_).subst(tcx, impl_substs); let impl_ty = ocx.normalize(&cause, param_env, impl_ty); - // Check that the Self-types can be related. - // FIXME(fmease): Should we use `eq` here? - ocx.sup(&ObligationCause::dummy(), param_env, impl_ty, self_ty).ok()?; + // Check that the self types can be related. + // FIXME(inherent_associated_types): Should we use `eq` here? Method probing uses + // `sup` for this situtation, too. What for? To constrain inference variables? + if ocx.sup(&ObligationCause::dummy(), param_env, impl_ty, self_ty).is_err() + { + return false; + } // Check whether the impl imposes obligations we have to worry about. - let impl_bounds = tcx.predicates_of(impl_); - let impl_bounds = impl_bounds.instantiate(tcx, impl_substs); - + let impl_bounds = tcx.predicates_of(impl_).instantiate(tcx, impl_substs); let impl_bounds = ocx.normalize(&cause, param_env, impl_bounds); - let impl_obligations = traits::predicates_for_generics( |_, _| cause.clone(), param_env, impl_bounds, ); - ocx.register_obligations(impl_obligations); let mut errors = ocx.select_where_possible(); if !errors.is_empty() { fulfillment_errors.append(&mut errors); - return None; + return false; } - // FIXME(fmease): Unsolved vars can escape this InferCtxt snapshot. - Some((assoc_item, def_scope, infcx.resolve_vars_if_possible(impl_substs))) + true }) }) .collect() @@ -2456,24 +2463,26 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { if applicable_candidates.len() > 1 { return Err(self.complain_about_ambiguous_inherent_assoc_type( name, - applicable_candidates.into_iter().map(|(candidate, ..)| candidate).collect(), + applicable_candidates.into_iter().map(|(_, (candidate, _))| candidate).collect(), span, )); } - if let Some((assoc_item, def_scope, impl_substs)) = applicable_candidates.pop() { + if let Some((impl_, (assoc_item, def_scope))) = applicable_candidates.pop() { self.check_assoc_ty(assoc_item, name, def_scope, block, span); - // FIXME(inherent_associated_types): To fully *confirm* the *probed* candidate, we still - // need to relate the Self-type with fresh item substs & register region obligations for - // regionck to prove/disprove. - - let item_substs = - self.create_substs_for_associated_item(span, assoc_item, segment, impl_substs); + // FIXME(fmease): Currently creating throwaway `parent_substs` to please + // `create_substs_for_associated_item`. Modify the latter instead (or sth. similar) to + // not require the parent substs logic. + let parent_substs = InternalSubsts::identity_for_item(tcx, impl_); + let substs = + self.create_substs_for_associated_item(span, assoc_item, segment, parent_substs); + let substs = tcx.mk_substs_from_iter( + std::iter::once(ty::GenericArg::from(self_ty)) + .chain(substs.into_iter().skip(parent_substs.len())), + ); - // FIXME(fmease, #106722): Check if the bounds on the parameters of the - // associated type hold, if any. - let ty = tcx.type_of(assoc_item).subst(tcx, item_substs); + let ty = tcx.mk_alias(ty::Inherent, tcx.mk_alias_ty(assoc_item, substs)); return Ok(Some((ty, assoc_item))); } |