diff options
Diffstat (limited to '')
| -rw-r--r-- | compiler/rustc_ty_utils/src/instance.rs | 192 |
1 files changed, 31 insertions, 161 deletions
diff --git a/compiler/rustc_ty_utils/src/instance.rs b/compiler/rustc_ty_utils/src/instance.rs index bd1d568cd..6436713b3 100644 --- a/compiler/rustc_ty_utils/src/instance.rs +++ b/compiler/rustc_ty_utils/src/instance.rs @@ -3,115 +3,11 @@ use rustc_hir::def_id::{DefId, LocalDefId}; use rustc_infer::infer::TyCtxtInferExt; use rustc_middle::traits::CodegenObligationError; use rustc_middle::ty::subst::SubstsRef; -use rustc_middle::ty::{ - self, Binder, Instance, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitor, -}; -use rustc_span::{sym, DUMMY_SP}; +use rustc_middle::ty::{self, Instance, TyCtxt, TypeVisitable}; +use rustc_span::sym; use rustc_trait_selection::traits; use traits::{translate_substs, Reveal}; -use rustc_data_structures::sso::SsoHashSet; -use std::collections::btree_map::Entry; -use std::collections::BTreeMap; -use std::ops::ControlFlow; - -use tracing::debug; - -// FIXME(#86795): `BoundVarsCollector` here should **NOT** be used -// outside of `resolve_associated_item`. It's just to address #64494, -// #83765, and #85848 which are creating bound types/regions that lose -// their `Binder` *unintentionally*. -// It's ideal to remove `BoundVarsCollector` and just use -// `ty::Binder::*` methods but we use this stopgap until we figure out -// the "real" fix. -struct BoundVarsCollector<'tcx> { - binder_index: ty::DebruijnIndex, - vars: BTreeMap<u32, ty::BoundVariableKind>, - // We may encounter the same variable at different levels of binding, so - // this can't just be `Ty` - visited: SsoHashSet<(ty::DebruijnIndex, Ty<'tcx>)>, -} - -impl<'tcx> BoundVarsCollector<'tcx> { - fn new() -> Self { - BoundVarsCollector { - binder_index: ty::INNERMOST, - vars: BTreeMap::new(), - visited: SsoHashSet::default(), - } - } - - fn into_vars(self, tcx: TyCtxt<'tcx>) -> &'tcx ty::List<ty::BoundVariableKind> { - let max = self.vars.iter().map(|(k, _)| *k).max().unwrap_or(0); - for i in 0..max { - if let None = self.vars.get(&i) { - panic!("Unknown variable: {:?}", i); - } - } - - tcx.mk_bound_variable_kinds(self.vars.into_iter().map(|(_, v)| v)) - } -} - -impl<'tcx> TypeVisitor<'tcx> for BoundVarsCollector<'tcx> { - type BreakTy = (); - - fn visit_binder<T: TypeVisitable<'tcx>>( - &mut self, - t: &Binder<'tcx, T>, - ) -> ControlFlow<Self::BreakTy> { - self.binder_index.shift_in(1); - let result = t.super_visit_with(self); - self.binder_index.shift_out(1); - result - } - - fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> { - if t.outer_exclusive_binder() < self.binder_index - || !self.visited.insert((self.binder_index, t)) - { - return ControlFlow::CONTINUE; - } - match *t.kind() { - ty::Bound(debruijn, bound_ty) if debruijn == self.binder_index => { - match self.vars.entry(bound_ty.var.as_u32()) { - Entry::Vacant(entry) => { - entry.insert(ty::BoundVariableKind::Ty(bound_ty.kind)); - } - Entry::Occupied(entry) => match entry.get() { - ty::BoundVariableKind::Ty(_) => {} - _ => bug!("Conflicting bound vars"), - }, - } - } - - _ => (), - }; - - t.super_visit_with(self) - } - - fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> { - match *r { - ty::ReLateBound(index, br) if index == self.binder_index => { - match self.vars.entry(br.var.as_u32()) { - Entry::Vacant(entry) => { - entry.insert(ty::BoundVariableKind::Region(br.kind)); - } - Entry::Occupied(entry) => match entry.get() { - ty::BoundVariableKind::Region(_) => {} - _ => bug!("Conflicting bound vars"), - }, - } - } - - _ => (), - }; - - r.super_visit_with(self) - } -} - fn resolve_instance<'tcx>( tcx: TyCtxt<'tcx>, key: ty::ParamEnvAnd<'tcx, (DefId, SubstsRef<'tcx>)>, @@ -203,19 +99,14 @@ fn resolve_associated_item<'tcx>( let trait_ref = ty::TraitRef::from_method(tcx, trait_id, rcvr_substs); - // See FIXME on `BoundVarsCollector`. - let mut bound_vars_collector = BoundVarsCollector::new(); - trait_ref.visit_with(&mut bound_vars_collector); - let trait_binder = ty::Binder::bind_with_vars(trait_ref, bound_vars_collector.into_vars(tcx)); - let vtbl = match tcx.codegen_fulfill_obligation((param_env, trait_binder)) { + let vtbl = match tcx.codegen_select_candidate((param_env, ty::Binder::dummy(trait_ref))) { Ok(vtbl) => vtbl, Err(CodegenObligationError::Ambiguity) => { let reported = tcx.sess.delay_span_bug( tcx.def_span(trait_item_id), &format!( - "encountered ambiguity selecting `{:?}` during codegen, presuming due to \ + "encountered ambiguity selecting `{trait_ref:?}` during codegen, presuming due to \ overflow or prior type error", - trait_binder ), ); return Err(reported); @@ -243,19 +134,17 @@ fn resolve_associated_item<'tcx>( .unwrap_or_else(|| { bug!("{:?} not found in {:?}", trait_item_id, impl_data.impl_def_id); }); - - let substs = tcx.infer_ctxt().enter(|infcx| { - let param_env = param_env.with_reveal_all_normalized(tcx); - let substs = rcvr_substs.rebase_onto(tcx, trait_def_id, impl_data.substs); - let substs = translate_substs( - &infcx, - param_env, - impl_data.impl_def_id, - substs, - leaf_def.defining_node, - ); - infcx.tcx.erase_regions(substs) - }); + let infcx = tcx.infer_ctxt().build(); + let param_env = param_env.with_reveal_all_normalized(tcx); + let substs = rcvr_substs.rebase_onto(tcx, trait_def_id, impl_data.substs); + let substs = translate_substs( + &infcx, + param_env, + impl_data.impl_def_id, + substs, + leaf_def.defining_node, + ); + let substs = infcx.tcx.erase_regions(substs); // Since this is a trait item, we need to see if the item is either a trait default item // or a specialization because we can't resolve those unless we can `Reveal::All`. @@ -280,9 +169,13 @@ fn resolve_associated_item<'tcx>( return Ok(None); } - // If the item does not have a value, then we cannot return an instance. + // Any final impl is required to define all associated items. if !leaf_def.item.defaultness(tcx).has_value() { - return Ok(None); + let guard = tcx.sess.delay_span_bug( + tcx.def_span(leaf_def.item.def_id), + "missing value for assoc item in impl", + ); + return Err(guard); } let substs = tcx.erase_regions(substs); @@ -291,40 +184,14 @@ fn resolve_associated_item<'tcx>( // a `trait` to an associated `const` definition in an `impl`, where // the definition in the `impl` has the wrong type (for which an // error has already been/will be emitted elsewhere). - // - // NB: this may be expensive, we try to skip it in all the cases where - // we know the error would've been caught (e.g. in an upstream crate). - // - // A better approach might be to just introduce a query (returning - // `Result<(), ErrorGuaranteed>`) for the check that `rustc_typeck` - // performs (i.e. that the definition's type in the `impl` matches - // the declaration in the `trait`), so that we can cheaply check - // here if it failed, instead of approximating it. if leaf_def.item.kind == ty::AssocKind::Const && trait_item_id != leaf_def.item.def_id - && leaf_def.item.def_id.is_local() + && let Some(leaf_def_item) = leaf_def.item.def_id.as_local() { - let normalized_type_of = |def_id, substs| { - tcx.subst_and_normalize_erasing_regions(substs, param_env, tcx.type_of(def_id)) - }; - - let original_ty = normalized_type_of(trait_item_id, rcvr_substs); - let resolved_ty = normalized_type_of(leaf_def.item.def_id, substs); - - if original_ty != resolved_ty { - let msg = format!( - "Instance::resolve: inconsistent associated `const` type: \ - was `{}: {}` but resolved to `{}: {}`", - tcx.def_path_str_with_substs(trait_item_id, rcvr_substs), - original_ty, - tcx.def_path_str_with_substs(leaf_def.item.def_id, substs), - resolved_ty, - ); - let span = tcx.def_span(leaf_def.item.def_id); - let reported = tcx.sess.delay_span_bug(span, &msg); - - return Err(reported); - } + tcx.compare_assoc_const_impl_item_with_trait_item(( + leaf_def_item, + trait_item_id, + ))?; } Some(ty::Instance::new(leaf_def.item.def_id, substs)) @@ -369,10 +236,13 @@ fn resolve_associated_item<'tcx>( if name == sym::clone { let self_ty = trait_ref.self_ty(); - let is_copy = self_ty.is_copy_modulo_regions(tcx.at(DUMMY_SP), param_env); + let is_copy = self_ty.is_copy_modulo_regions(tcx, param_env); match self_ty.kind() { _ if is_copy => (), - ty::Closure(..) | ty::Tuple(..) => {} + ty::Generator(..) + | ty::GeneratorWitness(..) + | ty::Closure(..) + | ty::Tuple(..) => {} _ => return Ok(None), }; 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