]> git.lizzy.rs Git - rust.git/blobdiff - compiler/rustc_trait_selection/src/traits/select/confirmation.rs
Add bound_explicit_item_bounds and bound_item_bounds
[rust.git] / compiler / rustc_trait_selection / src / traits / select / confirmation.rs
index df760a166e82c52945bb80786aa3a96d80bd768e..b9025c98fe7b71a421e3c9804d6c4df8aa6a1db1 100644 (file)
 use rustc_index::bit_set::GrowableBitSet;
 use rustc_infer::infer::InferOk;
 use rustc_infer::infer::LateBoundRegionConversionTime::HigherRankedType;
-use rustc_middle::ty::subst::{GenericArg, GenericArgKind, Subst, SubstsRef};
-use rustc_middle::ty::{self, Ty};
+use rustc_middle::ty::subst::{GenericArg, GenericArgKind, InternalSubsts, Subst, SubstsRef};
+use rustc_middle::ty::{self, EarlyBinder, GenericParamDefKind, Ty};
 use rustc_middle::ty::{ToPolyTraitRef, ToPredicate};
 use rustc_span::def_id::DefId;
 
 use crate::traits::project::{normalize_with_depth, normalize_with_depth_to};
 use crate::traits::select::TraitObligationExt;
-use crate::traits::util;
-use crate::traits::util::{closure_trait_ref_and_return_type, predicate_for_trait_def};
-use crate::traits::ImplSource;
-use crate::traits::Normalized;
-use crate::traits::OutputTypeParameterMismatch;
-use crate::traits::Selection;
-use crate::traits::TraitNotObjectSafe;
-use crate::traits::VtblSegment;
-use crate::traits::{BuiltinDerivedObligation, ImplDerivedObligation};
+use crate::traits::util::{self, closure_trait_ref_and_return_type, predicate_for_trait_def};
 use crate::traits::{
-    ImplSourceAutoImplData, ImplSourceBuiltinData, ImplSourceClosureData,
-    ImplSourceConstDestructData, ImplSourceDiscriminantKindData, ImplSourceFnPointerData,
-    ImplSourceGeneratorData, ImplSourceObjectData, ImplSourcePointeeData, ImplSourceTraitAliasData,
-    ImplSourceTraitUpcastingData, ImplSourceUserDefinedData,
+    BuiltinDerivedObligation, DerivedObligationCause, ImplDerivedObligation,
+    ImplDerivedObligationCause, ImplSource, ImplSourceAutoImplData, ImplSourceBuiltinData,
+    ImplSourceClosureData, ImplSourceConstDestructData, ImplSourceDiscriminantKindData,
+    ImplSourceFnPointerData, ImplSourceGeneratorData, ImplSourceObjectData, ImplSourcePointeeData,
+    ImplSourceTraitAliasData, ImplSourceTraitUpcastingData, ImplSourceUserDefinedData, Normalized,
+    ObjectCastObligation, Obligation, ObligationCause, OutputTypeParameterMismatch,
+    PredicateObligation, Selection, SelectionError, TraitNotObjectSafe, TraitObligation,
+    Unimplemented, VtblSegment,
 };
-use crate::traits::{ObjectCastObligation, PredicateObligation, TraitObligation};
-use crate::traits::{Obligation, ObligationCause};
-use crate::traits::{SelectionError, Unimplemented};
 
 use super::BuiltinImplConditions;
 use super::SelectionCandidate::{self, *};
@@ -181,7 +174,8 @@ fn confirm_projection_candidate(
                 _ => bug!("projection candidate for unexpected type: {:?}", placeholder_self_ty),
             };
 
-            let candidate_predicate = tcx.item_bounds(def_id)[idx].subst(tcx, substs);
+            let candidate_predicate =
+                tcx.bound_item_bounds(def_id).map_bound(|i| i[idx]).subst(tcx, substs);
             let candidate = candidate_predicate
                 .to_opt_poly_trait_pred()
                 .expect("projection candidate is not a trait predicate")
@@ -321,28 +315,29 @@ fn vtable_auto_impl(
         debug!(?nested, "vtable_auto_impl");
         ensure_sufficient_stack(|| {
             let cause = obligation.derived_cause(BuiltinDerivedObligation);
-            let mut obligations = self.collect_predicates_for_types(
-                obligation.param_env,
-                cause,
-                obligation.recursion_depth + 1,
-                trait_def_id,
-                nested,
-            );
 
             let trait_obligations: Vec<PredicateObligation<'_>> =
                 self.infcx.commit_unconditionally(|_| {
                     let poly_trait_ref = obligation.predicate.to_poly_trait_ref();
                     let trait_ref = self.infcx.replace_bound_vars_with_placeholders(poly_trait_ref);
-                    let cause = obligation.derived_cause(ImplDerivedObligation);
                     self.impl_or_trait_obligations(
-                        cause,
+                        &cause,
                         obligation.recursion_depth + 1,
                         obligation.param_env,
                         trait_def_id,
                         &trait_ref.substs,
+                        obligation.predicate,
                     )
                 });
 
+            let mut obligations = self.collect_predicates_for_types(
+                obligation.param_env,
+                cause,
+                obligation.recursion_depth + 1,
+                trait_def_id,
+                nested,
+            );
+
             // Adds the predicates from the trait.  Note that this contains a `Self: Trait`
             // predicate as usual.  It won't have any effect since auto traits are coinductive.
             obligations.extend(trait_obligations);
@@ -365,14 +360,14 @@ fn confirm_impl_candidate(
         self.infcx.commit_unconditionally(|_| {
             let substs = self.rematch_impl(impl_def_id, obligation);
             debug!(?substs, "impl substs");
-            let cause = obligation.derived_cause(ImplDerivedObligation);
             ensure_sufficient_stack(|| {
                 self.vtable_impl(
                     impl_def_id,
                     substs,
-                    cause,
+                    &obligation.cause,
                     obligation.recursion_depth + 1,
                     obligation.param_env,
+                    obligation.predicate,
                 )
             })
         })
@@ -382,9 +377,10 @@ fn vtable_impl(
         &mut self,
         impl_def_id: DefId,
         substs: Normalized<'tcx, SubstsRef<'tcx>>,
-        cause: ObligationCause<'tcx>,
+        cause: &ObligationCause<'tcx>,
         recursion_depth: usize,
         param_env: ty::ParamEnv<'tcx>,
+        parent_trait_pred: ty::Binder<'tcx, ty::TraitPredicate<'tcx>>,
     ) -> ImplSourceUserDefinedData<'tcx, PredicateObligation<'tcx>> {
         debug!(?impl_def_id, ?substs, ?recursion_depth, "vtable_impl");
 
@@ -394,6 +390,7 @@ fn vtable_impl(
             param_env,
             impl_def_id,
             &substs.value,
+            parent_trait_pred,
         );
 
         debug!(?impl_obligations, "vtable_impl");
@@ -491,18 +488,81 @@ fn confirm_object_candidate(
             .collect();
 
         for assoc_type in assoc_types {
-            if !tcx.generics_of(assoc_type).params.is_empty() {
+            let defs: &ty::Generics = tcx.generics_of(assoc_type);
+
+            if !defs.params.is_empty() && !tcx.features().generic_associated_types_extended {
                 tcx.sess.delay_span_bug(
                     obligation.cause.span,
                     "GATs in trait object shouldn't have been considered",
                 );
                 return Err(SelectionError::Unimplemented);
             }
+
             // This maybe belongs in wf, but that can't (doesn't) handle
             // higher-ranked things.
             // Prevent, e.g., `dyn Iterator<Item = str>`.
-            for bound in self.tcx().item_bounds(assoc_type) {
-                let subst_bound = bound.subst(tcx, trait_predicate.trait_ref.substs);
+            for bound in self.tcx().bound_item_bounds(assoc_type).transpose_iter() {
+                let subst_bound =
+                    if defs.count() == 0 {
+                        bound.subst(tcx, trait_predicate.trait_ref.substs)
+                    } else {
+                        let mut substs = smallvec::SmallVec::with_capacity(defs.count());
+                        substs.extend(trait_predicate.trait_ref.substs.iter());
+                        let mut bound_vars: smallvec::SmallVec<[ty::BoundVariableKind; 8]> =
+                            smallvec::SmallVec::with_capacity(
+                                bound.0.kind().bound_vars().len() + defs.count(),
+                            );
+                        bound_vars.extend(bound.0.kind().bound_vars().into_iter());
+                        InternalSubsts::fill_single(&mut substs, defs, &mut |param, _| match param
+                            .kind
+                        {
+                            GenericParamDefKind::Type { .. } => {
+                                let kind = ty::BoundTyKind::Param(param.name);
+                                let bound_var = ty::BoundVariableKind::Ty(kind);
+                                bound_vars.push(bound_var);
+                                tcx.mk_ty(ty::Bound(
+                                    ty::INNERMOST,
+                                    ty::BoundTy {
+                                        var: ty::BoundVar::from_usize(bound_vars.len() - 1),
+                                        kind,
+                                    },
+                                ))
+                                .into()
+                            }
+                            GenericParamDefKind::Lifetime => {
+                                let kind = ty::BoundRegionKind::BrNamed(param.def_id, param.name);
+                                let bound_var = ty::BoundVariableKind::Region(kind);
+                                bound_vars.push(bound_var);
+                                tcx.mk_region(ty::ReLateBound(
+                                    ty::INNERMOST,
+                                    ty::BoundRegion {
+                                        var: ty::BoundVar::from_usize(bound_vars.len() - 1),
+                                        kind,
+                                    },
+                                ))
+                                .into()
+                            }
+                            GenericParamDefKind::Const { .. } => {
+                                let bound_var = ty::BoundVariableKind::Const;
+                                bound_vars.push(bound_var);
+                                tcx.mk_const(ty::ConstS {
+                                    ty: tcx.type_of(param.def_id),
+                                    val: ty::ConstKind::Bound(
+                                        ty::INNERMOST,
+                                        ty::BoundVar::from_usize(bound_vars.len() - 1),
+                                    ),
+                                })
+                                .into()
+                            }
+                        });
+                        let bound_vars = tcx.mk_bound_variable_kinds(bound_vars.into_iter());
+                        let assoc_ty_substs = tcx.intern_substs(&substs);
+
+                        let bound_vars = tcx.mk_bound_variable_kinds(bound_vars.into_iter());
+                        let bound =
+                            EarlyBinder(bound.0.kind().skip_binder()).subst(tcx, assoc_ty_substs);
+                        tcx.mk_predicate(ty::Binder::bind_with_vars(bound, bound_vars))
+                    };
                 let normalized_bound = normalize_with_depth_to(
                     self,
                     obligation.param_env,
@@ -566,11 +626,12 @@ fn confirm_trait_alias_candidate(
             let substs = trait_ref.substs;
 
             let trait_obligations = self.impl_or_trait_obligations(
-                obligation.cause.clone(),
+                &obligation.cause,
                 obligation.recursion_depth,
                 obligation.param_env,
                 trait_def_id,
                 &substs,
+                obligation.predicate,
             );
 
             debug!(?trait_def_id, ?trait_obligations, "trait alias obligations");
@@ -653,9 +714,9 @@ fn confirm_closure_candidate(
     /// and we desugared it so that the type of the expression is
     /// `Closure`, and `Closure` expects `i32` as argument. Then it
     /// is "as if" the compiler generated this impl:
-    ///
-    ///     impl Fn(i32) for Closure { ... }
-    ///
+    /// ```ignore (illustrative)
+    /// impl Fn(i32) for Closure { ... }
+    /// ```
     /// Now imagine our obligation is `Closure: Fn(usize)`. So far
     /// we have matched the self type `Closure`. At this point we'll
     /// compare the `i32` to `usize` and generate an error.
@@ -946,10 +1007,10 @@ fn confirm_builtin_unsize_candidate(
                 // The last field of the structure has to exist and contain type/const parameters.
                 let (tail_field, prefix_fields) =
                     def.non_enum_variant().fields.split_last().ok_or(Unimplemented)?;
-                let tail_field_ty = tcx.type_of(tail_field.did);
+                let tail_field_ty = tcx.bound_type_of(tail_field.did);
 
                 let mut unsizing_params = GrowableBitSet::new_empty();
-                for arg in tail_field_ty.walk() {
+                for arg in tail_field_ty.0.walk() {
                     if let Some(i) = maybe_unsizing_param_idx(arg) {
                         unsizing_params.insert(i);
                     }
@@ -1047,13 +1108,6 @@ fn confirm_const_destruct_candidate(
         }
 
         let drop_trait = self.tcx().require_lang_item(LangItem::Drop, None);
-        // FIXME: remove if statement below when beta is bumped
-        #[cfg(bootstrap)]
-        {}
-
-        if obligation.predicate.skip_binder().def_id() == drop_trait {
-            return Ok(ImplSourceConstDestructData { nested: vec![] });
-        }
 
         let tcx = self.tcx();
         let self_ty = self.infcx.shallow_resolve(obligation.self_ty());
@@ -1073,14 +1127,30 @@ fn confirm_const_destruct_candidate(
                 });
                 let substs = self.rematch_impl(impl_def_id, &new_obligation);
                 debug!(?substs, "impl substs");
-                let cause = obligation.derived_cause(ImplDerivedObligation);
+
+                let derived = DerivedObligationCause {
+                    parent_trait_pred: obligation.predicate,
+                    parent_code: obligation.cause.clone_code(),
+                };
+                let derived_code = ImplDerivedObligation(Box::new(ImplDerivedObligationCause {
+                    derived,
+                    impl_def_id,
+                    span: obligation.cause.span,
+                }));
+
+                let cause = ObligationCause::new(
+                    obligation.cause.span,
+                    obligation.cause.body_id,
+                    derived_code,
+                );
                 ensure_sufficient_stack(|| {
                     self.vtable_impl(
                         impl_def_id,
                         substs,
-                        cause,
+                        &cause,
                         new_obligation.recursion_depth + 1,
                         new_obligation.param_env,
+                        obligation.predicate,
                     )
                 })
             });