Remove some ImplSource candidates

Author: compiler-errors

compiler/rustc_middle/src/traits/mod.rs

@@ -662,10 +662,10 @@ pub enum ImplSource<'tcx, N> {
     Object(ImplSourceObjectData<'tcx, N>),
 
     /// Successful resolution for a builtin trait.
-    Builtin(ImplSourceBuiltinData<N>),
+    Builtin(Vec<N>),
 
     /// ImplSource for trait upcasting coercion
-    TraitUpcasting(ImplSourceTraitUpcastingData<'tcx, N>),
+    TraitUpcasting(ImplSourceTraitUpcastingData<N>),
 
     /// ImplSource automatically generated for a closure. The `DefId` is the ID
     /// of the closure expression. This is an `ImplSource::UserDefined` in spirit, but the
@@ -692,8 +692,7 @@ impl<'tcx, N> ImplSource<'tcx, N> {
     pub fn nested_obligations(self) -> Vec<N> {
         match self {
             ImplSource::UserDefined(i) => i.nested,
-            ImplSource::Param(n, _) => n,
-            ImplSource::Builtin(i) => i.nested,
+            ImplSource::Param(n, _) | ImplSource::Builtin(n) => n,
             ImplSource::AutoImpl(d) => d.nested,
             ImplSource::Closure(c) => c.nested,
             ImplSource::Generator(c) => c.nested,
@@ -709,8 +708,7 @@ impl<'tcx, N> ImplSource<'tcx, N> {
     pub fn borrow_nested_obligations(&self) -> &[N] {
         match self {
             ImplSource::UserDefined(i) => &i.nested,
-            ImplSource::Param(n, _) => n,
-            ImplSource::Builtin(i) => &i.nested,
+            ImplSource::Param(n, _) | ImplSource::Builtin(n) => n,
             ImplSource::AutoImpl(d) => &d.nested,
             ImplSource::Closure(c) => &c.nested,
             ImplSource::Generator(c) => &c.nested,
@@ -726,8 +724,7 @@ impl<'tcx, N> ImplSource<'tcx, N> {
     pub fn borrow_nested_obligations_mut(&mut self) -> &mut [N] {
         match self {
             ImplSource::UserDefined(i) => &mut i.nested,
-            ImplSource::Param(n, _) => n,
-            ImplSource::Builtin(i) => &mut i.nested,
+            ImplSource::Param(n, _) | ImplSource::Builtin(n) => n,
             ImplSource::AutoImpl(d) => &mut d.nested,
             ImplSource::Closure(c) => &mut c.nested,
             ImplSource::Generator(c) => &mut c.nested,
@@ -751,9 +748,7 @@ impl<'tcx, N> ImplSource<'tcx, N> {
                 nested: i.nested.into_iter().map(f).collect(),
             }),
             ImplSource::Param(n, ct) => ImplSource::Param(n.into_iter().map(f).collect(), ct),
-            ImplSource::Builtin(i) => ImplSource::Builtin(ImplSourceBuiltinData {
-                nested: i.nested.into_iter().map(f).collect(),
-            }),
+            ImplSource::Builtin(n) => ImplSource::Builtin(n.into_iter().map(f).collect()),
             ImplSource::Object(o) => ImplSource::Object(ImplSourceObjectData {
                 upcast_trait_ref: o.upcast_trait_ref,
                 vtable_base: o.vtable_base,
@@ -789,7 +784,6 @@ impl<'tcx, N> ImplSource<'tcx, N> {
             }),
             ImplSource::TraitUpcasting(d) => {
                 ImplSource::TraitUpcasting(ImplSourceTraitUpcastingData {
-                    upcast_trait_ref: d.upcast_trait_ref,
                     vtable_vptr_slot: d.vtable_vptr_slot,
                     nested: d.nested.into_iter().map(f).collect(),
                 })
@@ -860,10 +854,7 @@ pub struct ImplSourceAutoImplData<N> {
 
 #[derive(Clone, PartialEq, Eq, TyEncodable, TyDecodable, HashStable, Lift)]
 #[derive(TypeFoldable, TypeVisitable)]
-pub struct ImplSourceTraitUpcastingData<'tcx, N> {
-    /// `Foo` upcast to the obligation trait. This will be some supertrait of `Foo`.
-    pub upcast_trait_ref: ty::PolyTraitRef<'tcx>,
-
+pub struct ImplSourceTraitUpcastingData<N> {
     /// The vtable is formed by concatenating together the method lists of
     /// the base object trait and all supertraits, pointers to supertrait vtable will
     /// be provided when necessary; this is the position of `upcast_trait_ref`'s vtable
@@ -873,12 +864,6 @@ pub struct ImplSourceTraitUpcastingData<'tcx, N> {
     pub nested: Vec<N>,
 }
 
-#[derive(Clone, PartialEq, Eq, TyEncodable, TyDecodable, HashStable, Lift)]
-#[derive(TypeFoldable, TypeVisitable)]
-pub struct ImplSourceBuiltinData<N> {
-    pub nested: Vec<N>,
-}
-
 #[derive(PartialEq, Eq, Clone, TyEncodable, TyDecodable, HashStable, Lift)]
 #[derive(TypeFoldable, TypeVisitable)]
 pub struct ImplSourceObjectData<'tcx, N> {

compiler/rustc_middle/src/traits/structural_impls.rs

@@ -76,18 +76,12 @@ impl<'tcx, N: fmt::Debug> fmt::Debug for traits::ImplSourceClosureData<'tcx, N>
     }
 }
 
-impl<N: fmt::Debug> fmt::Debug for traits::ImplSourceBuiltinData<N> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "ImplSourceBuiltinData(nested={:?})", self.nested)
-    }
-}
-
-impl<'tcx, N: fmt::Debug> fmt::Debug for traits::ImplSourceTraitUpcastingData<'tcx, N> {
+impl<N: fmt::Debug> fmt::Debug for traits::ImplSourceTraitUpcastingData<N> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(
             f,
-            "ImplSourceTraitUpcastingData(upcast={:?}, vtable_vptr_slot={:?}, nested={:?})",
-            self.upcast_trait_ref, self.vtable_vptr_slot, self.nested
+            "ImplSourceTraitUpcastingData(vtable_vptr_slot={:?}, nested={:?})",
+            self.vtable_vptr_slot, self.nested
         )
     }
 }

compiler/rustc_trait_selection/src/traits/project.rs

@@ -30,7 +30,6 @@ use rustc_hir::lang_items::LangItem;
 use rustc_infer::infer::at::At;
 use rustc_infer::infer::resolve::OpportunisticRegionResolver;
 use rustc_infer::infer::DefineOpaqueTypes;
-use rustc_infer::traits::ImplSourceBuiltinData;
 use rustc_infer::traits::ObligationCauseCode;
 use rustc_middle::traits::select::OverflowError;
 use rustc_middle::ty::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
@@ -2106,7 +2105,7 @@ fn confirm_future_candidate<'cx, 'tcx>(
 fn confirm_builtin_candidate<'cx, 'tcx>(
     selcx: &mut SelectionContext<'cx, 'tcx>,
     obligation: &ProjectionTyObligation<'tcx>,
-    data: ImplSourceBuiltinData<PredicateObligation<'tcx>>,
+    data: Vec<PredicateObligation<'tcx>>,
 ) -> Progress<'tcx> {
     let tcx = selcx.tcx();
     let self_ty = obligation.predicate.self_ty();
@@ -2154,7 +2153,7 @@ fn confirm_builtin_candidate<'cx, 'tcx>(
 
     confirm_param_env_candidate(selcx, obligation, ty::Binder::dummy(predicate), false)
         .with_addl_obligations(obligations)
-        .with_addl_obligations(data.nested)
+        .with_addl_obligations(data)
 }
 
 fn confirm_fn_pointer_candidate<'cx, 'tcx>(

compiler/rustc_trait_selection/src/traits/select/confirmation.rs

@@ -27,12 +27,11 @@ use crate::traits::vtable::{
 };
 use crate::traits::{
     BuiltinDerivedObligation, ImplDerivedObligation, ImplDerivedObligationCause, ImplSource,
-    ImplSourceAutoImplData, ImplSourceBuiltinData, ImplSourceClosureData,
-    ImplSourceConstDestructData, ImplSourceFnPointerData, ImplSourceFutureData,
-    ImplSourceGeneratorData, ImplSourceObjectData, ImplSourceTraitAliasData,
-    ImplSourceTraitUpcastingData, ImplSourceUserDefinedData, Normalized, Obligation,
-    ObligationCause, OutputTypeParameterMismatch, PredicateObligation, Selection, SelectionError,
-    TraitNotObjectSafe, TraitObligation, Unimplemented,
+    ImplSourceAutoImplData, ImplSourceClosureData, ImplSourceConstDestructData,
+    ImplSourceFnPointerData, ImplSourceFutureData, ImplSourceGeneratorData, ImplSourceObjectData,
+    ImplSourceTraitAliasData, ImplSourceTraitUpcastingData, ImplSourceUserDefinedData, Normalized,
+    Obligation, ObligationCause, OutputTypeParameterMismatch, PredicateObligation, Selection,
+    SelectionError, TraitNotObjectSafe, TraitObligation, Unimplemented,
 };
 
 use super::BuiltinImplConditions;
@@ -114,7 +113,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 // This indicates something like `Trait + Send: Send`. In this case, we know that
                 // this holds because that's what the object type is telling us, and there's really
                 // no additional obligations to prove and no types in particular to unify, etc.
-                ImplSource::Param(Vec::new(), ty::BoundConstness::NotConst)
+                ImplSource::Builtin(Vec::new())
             }
 
             BuiltinUnsizeCandidate => {
@@ -244,7 +243,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         &mut self,
         obligation: &TraitObligation<'tcx>,
         has_nested: bool,
-    ) -> ImplSourceBuiltinData<PredicateObligation<'tcx>> {
+    ) -> Vec<PredicateObligation<'tcx>> {
         debug!(?obligation, ?has_nested, "confirm_builtin_candidate");
 
         let lang_items = self.tcx().lang_items();
@@ -277,14 +276,14 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
         debug!(?obligations);
 
-        ImplSourceBuiltinData { nested: obligations }
+        obligations
     }
 
     #[instrument(level = "debug", skip(self))]
     fn confirm_transmutability_candidate(
         &mut self,
         obligation: &TraitObligation<'tcx>,
-    ) -> Result<ImplSourceBuiltinData<PredicateObligation<'tcx>>, SelectionError<'tcx>> {
+    ) -> Result<Vec<PredicateObligation<'tcx>>, SelectionError<'tcx>> {
         use rustc_transmute::{Answer, Condition};
         #[instrument(level = "debug", skip(tcx, obligation, predicate))]
         fn flatten_answer_tree<'tcx>(
@@ -369,7 +368,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         };
 
         debug!(?fully_flattened);
-        Ok(ImplSourceBuiltinData { nested: fully_flattened })
+        Ok(fully_flattened)
     }
 
     /// This handles the case where an `auto trait Foo` impl is being used.
@@ -912,8 +911,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         &mut self,
         obligation: &TraitObligation<'tcx>,
         idx: usize,
-    ) -> Result<ImplSourceTraitUpcastingData<'tcx, PredicateObligation<'tcx>>, SelectionError<'tcx>>
-    {
+    ) -> Result<ImplSourceTraitUpcastingData<PredicateObligation<'tcx>>, SelectionError<'tcx>> {
         let tcx = self.tcx();
 
         // `assemble_candidates_for_unsizing` should ensure there are no late-bound
@@ -1010,13 +1008,13 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         let vtable_vptr_slot =
             prepare_vtable_segments(tcx, source_trait_ref, vtable_segment_callback).unwrap();
 
-        Ok(ImplSourceTraitUpcastingData { upcast_trait_ref, vtable_vptr_slot, nested })
+        Ok(ImplSourceTraitUpcastingData { vtable_vptr_slot, nested })
     }
 
     fn confirm_builtin_unsize_candidate(
         &mut self,
         obligation: &TraitObligation<'tcx>,
-    ) -> Result<ImplSourceBuiltinData<PredicateObligation<'tcx>>, SelectionError<'tcx>> {
+    ) -> Result<Vec<PredicateObligation<'tcx>>, SelectionError<'tcx>> {
         let tcx = self.tcx();
 
         // `assemble_candidates_for_unsizing` should ensure there are no late-bound
@@ -1217,7 +1215,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             _ => bug!("source: {source}, target: {target}"),
         };
 
-        Ok(ImplSourceBuiltinData { nested })
+        Ok(nested)
     }
 
     fn confirm_const_destruct_candidate(