Simplify some impl source candidates

6 files changed, 18 insertions, 81 deletions

diff --git a/compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs b/compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs
index 1da20579021..a2d23425f3b 100644
--- a/compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs
+++ b/compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs
@@ -172,7 +172,7 @@ impl Qualif for NeedsNonConstDrop {
 
         if !matches!(
             impl_src,
-            ImplSource::ConstDestruct(_) | ImplSource::Param(_, ty::BoundConstness::ConstIfConst)
+            ImplSource::Builtin(_) | ImplSource::Param(_, ty::BoundConstness::ConstIfConst)
         ) {
             // If our const destruct candidate is not ConstDestruct or implied by the param env,
             // then it's bad
diff --git a/compiler/rustc_middle/src/traits/mod.rs b/compiler/rustc_middle/src/traits/mod.rs
index a9d85ca506c..adc63aa6add 100644
--- a/compiler/rustc_middle/src/traits/mod.rs
+++ b/compiler/rustc_middle/src/traits/mod.rs
@@ -646,12 +646,6 @@ pub enum ImplSource<'tcx, N> {
     /// ImplSource identifying a particular impl.
     UserDefined(ImplSourceUserDefinedData<'tcx, N>),
 
-    /// ImplSource for auto trait implementations.
-    /// This carries the information and nested obligations with regards
-    /// to an auto implementation for a trait `Trait`. The nested obligations
-    /// ensure the trait implementation holds for all the constituent types.
-    AutoImpl(ImplSourceAutoImplData<N>),
-
     /// Successful resolution to an obligation provided by the caller
     /// for some type parameter. The `Vec<N>` represents the
     /// obligations incurred from normalizing the where-clause (if
@@ -683,9 +677,6 @@ pub enum ImplSource<'tcx, N> {
 
     /// ImplSource for a trait alias.
     TraitAlias(ImplSourceTraitAliasData<'tcx, N>),
-
-    /// ImplSource for a `const Drop` implementation.
-    ConstDestruct(ImplSourceConstDestructData<N>),
 }
 
 impl<'tcx, N> ImplSource<'tcx, N> {
@@ -693,7 +684,6 @@ impl<'tcx, N> ImplSource<'tcx, N> {
         match self {
             ImplSource::UserDefined(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,
             ImplSource::Future(c) => c.nested,
@@ -701,7 +691,6 @@ impl<'tcx, N> ImplSource<'tcx, N> {
             ImplSource::FnPointer(d) => d.nested,
             ImplSource::TraitAlias(d) => d.nested,
             ImplSource::TraitUpcasting(d) => d.nested,
-            ImplSource::ConstDestruct(i) => i.nested,
         }
     }
 
@@ -709,7 +698,6 @@ impl<'tcx, N> ImplSource<'tcx, N> {
         match self {
             ImplSource::UserDefined(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,
             ImplSource::Future(c) => &c.nested,
@@ -717,7 +705,6 @@ impl<'tcx, N> ImplSource<'tcx, N> {
             ImplSource::FnPointer(d) => &d.nested,
             ImplSource::TraitAlias(d) => &d.nested,
             ImplSource::TraitUpcasting(d) => &d.nested,
-            ImplSource::ConstDestruct(i) => &i.nested,
         }
     }
 
@@ -725,7 +712,6 @@ impl<'tcx, N> ImplSource<'tcx, N> {
         match self {
             ImplSource::UserDefined(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,
             ImplSource::Future(c) => &mut c.nested,
@@ -733,7 +719,6 @@ impl<'tcx, N> ImplSource<'tcx, N> {
             ImplSource::FnPointer(d) => &mut d.nested,
             ImplSource::TraitAlias(d) => &mut d.nested,
             ImplSource::TraitUpcasting(d) => &mut d.nested,
-            ImplSource::ConstDestruct(i) => &mut i.nested,
         }
     }
 
@@ -754,10 +739,6 @@ impl<'tcx, N> ImplSource<'tcx, N> {
                 vtable_base: o.vtable_base,
                 nested: o.nested.into_iter().map(f).collect(),
             }),
-            ImplSource::AutoImpl(d) => ImplSource::AutoImpl(ImplSourceAutoImplData {
-                trait_def_id: d.trait_def_id,
-                nested: d.nested.into_iter().map(f).collect(),
-            }),
             ImplSource::Closure(c) => ImplSource::Closure(ImplSourceClosureData {
                 closure_def_id: c.closure_def_id,
                 substs: c.substs,
@@ -788,11 +769,6 @@ impl<'tcx, N> ImplSource<'tcx, N> {
                     nested: d.nested.into_iter().map(f).collect(),
                 })
             }
-            ImplSource::ConstDestruct(i) => {
-                ImplSource::ConstDestruct(ImplSourceConstDestructData {
-                    nested: i.nested.into_iter().map(f).collect(),
-                })
-            }
         }
     }
 }
@@ -847,13 +823,6 @@ pub struct ImplSourceClosureData<'tcx, N> {
 
 #[derive(Clone, PartialEq, Eq, TyEncodable, TyDecodable, HashStable, Lift)]
 #[derive(TypeFoldable, TypeVisitable)]
-pub struct ImplSourceAutoImplData<N> {
-    pub trait_def_id: DefId,
-    pub nested: Vec<N>,
-}
-
-#[derive(Clone, PartialEq, Eq, TyEncodable, TyDecodable, HashStable, Lift)]
-#[derive(TypeFoldable, TypeVisitable)]
 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
@@ -888,12 +857,6 @@ pub struct ImplSourceFnPointerData<'tcx, N> {
 
 #[derive(Clone, PartialEq, Eq, TyEncodable, TyDecodable, HashStable, Lift)]
 #[derive(TypeFoldable, TypeVisitable)]
-pub struct ImplSourceConstDestructData<N> {
-    pub nested: Vec<N>,
-}
-
-#[derive(Clone, PartialEq, Eq, TyEncodable, TyDecodable, HashStable, Lift)]
-#[derive(TypeFoldable, TypeVisitable)]
 pub struct ImplSourceTraitAliasData<'tcx, N> {
     pub alias_def_id: DefId,
     pub substs: SubstsRef<'tcx>,
diff --git a/compiler/rustc_middle/src/traits/structural_impls.rs b/compiler/rustc_middle/src/traits/structural_impls.rs
index 311d3d1f1e8..9cc732acefa 100644
--- a/compiler/rustc_middle/src/traits/structural_impls.rs
+++ b/compiler/rustc_middle/src/traits/structural_impls.rs
@@ -9,8 +9,6 @@ impl<'tcx, N: fmt::Debug> fmt::Debug for traits::ImplSource<'tcx, N> {
         match *self {
             super::ImplSource::UserDefined(ref v) => write!(f, "{:?}", v),
 
-            super::ImplSource::AutoImpl(ref t) => write!(f, "{:?}", t),
-
             super::ImplSource::Closure(ref d) => write!(f, "{:?}", d),
 
             super::ImplSource::Generator(ref d) => write!(f, "{:?}", d),
@@ -30,8 +28,6 @@ impl<'tcx, N: fmt::Debug> fmt::Debug for traits::ImplSource<'tcx, N> {
             super::ImplSource::TraitAlias(ref d) => write!(f, "{:?}", d),
 
             super::ImplSource::TraitUpcasting(ref d) => write!(f, "{:?}", d),
-
-            super::ImplSource::ConstDestruct(ref d) => write!(f, "{:?}", d),
         }
     }
 }
@@ -86,16 +82,6 @@ impl<N: fmt::Debug> fmt::Debug for traits::ImplSourceTraitUpcastingData<N> {
     }
 }
 
-impl<N: fmt::Debug> fmt::Debug for traits::ImplSourceAutoImplData<N> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(
-            f,
-            "ImplSourceAutoImplData(trait_def_id={:?}, nested={:?})",
-            self.trait_def_id, self.nested
-        )
-    }
-}
-
 impl<'tcx, N: fmt::Debug> fmt::Debug for traits::ImplSourceObjectData<'tcx, N> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(
@@ -121,9 +107,3 @@ impl<'tcx, N: fmt::Debug> fmt::Debug for traits::ImplSourceTraitAliasData<'tcx,
         )
     }
 }
-
-impl<N: fmt::Debug> fmt::Debug for traits::ImplSourceConstDestructData<N> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "ImplSourceConstDestructData(nested={:?})", self.nested)
-    }
-}
diff --git a/compiler/rustc_trait_selection/src/traits/project.rs b/compiler/rustc_trait_selection/src/traits/project.rs
index dd2bd45c07d..f82885252b7 100644
--- a/compiler/rustc_trait_selection/src/traits/project.rs
+++ b/compiler/rustc_trait_selection/src/traits/project.rs
@@ -1929,9 +1929,7 @@ fn assemble_candidates_from_impls<'cx, 'tcx>(
                 // why we special case object types.
                 false
             }
-            super::ImplSource::AutoImpl(..)
-            | super::ImplSource::TraitUpcasting(_)
-            | super::ImplSource::ConstDestruct(_) => {
+            | super::ImplSource::TraitUpcasting(_) => {
                 // These traits have no associated types.
                 selcx.tcx().sess.delay_span_bug(
                     obligation.cause.span,
@@ -2001,11 +1999,9 @@ fn confirm_select_candidate<'cx, 'tcx>(
         super::ImplSource::FnPointer(data) => confirm_fn_pointer_candidate(selcx, obligation, data),
         super::ImplSource::Builtin(data) => confirm_builtin_candidate(selcx, obligation, data),
         super::ImplSource::Object(_)
-        | super::ImplSource::AutoImpl(..)
         | super::ImplSource::Param(..)
         | super::ImplSource::TraitUpcasting(_)
-        | super::ImplSource::TraitAlias(..)
-        | super::ImplSource::ConstDestruct(_) => {
+        | super::ImplSource::TraitAlias(..) => {
             // we don't create Select candidates with this kind of resolution
             span_bug!(
                 obligation.cause.span,
diff --git a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
index 277367fe275..ea451a3736e 100644
--- a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
@@ -27,11 +27,11 @@ use crate::traits::vtable::{
 };
 use crate::traits::{
     BuiltinDerivedObligation, ImplDerivedObligation, ImplDerivedObligationCause, ImplSource,
-    ImplSourceAutoImplData, ImplSourceClosureData, ImplSourceConstDestructData,
-    ImplSourceFnPointerData, ImplSourceFutureData, ImplSourceGeneratorData, ImplSourceObjectData,
-    ImplSourceTraitAliasData, ImplSourceTraitUpcastingData, ImplSourceUserDefinedData, Normalized,
-    Obligation, ObligationCause, OutputTypeParameterMismatch, PredicateObligation, Selection,
-    SelectionError, TraitNotObjectSafe, TraitObligation, Unimplemented,
+    ImplSourceClosureData, ImplSourceFnPointerData, ImplSourceFutureData, ImplSourceGeneratorData,
+    ImplSourceObjectData, ImplSourceTraitAliasData, ImplSourceTraitUpcastingData,
+    ImplSourceUserDefinedData, Normalized, Obligation, ObligationCause,
+    OutputTypeParameterMismatch, PredicateObligation, Selection, SelectionError,
+    TraitNotObjectSafe, TraitObligation, Unimplemented,
 };
 
 use super::BuiltinImplConditions;
@@ -71,7 +71,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
             AutoImplCandidate => {
                 let data = self.confirm_auto_impl_candidate(obligation);
-                ImplSource::AutoImpl(data)
+                ImplSource::Builtin(data)
             }
 
             ProjectionCandidate(idx, constness) => {
@@ -128,7 +128,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
             ConstDestructCandidate(def_id) => {
                 let data = self.confirm_const_destruct_candidate(obligation, def_id)?;
-                ImplSource::ConstDestruct(data)
+                ImplSource::Builtin(data)
             }
         };
 
@@ -379,7 +379,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     fn confirm_auto_impl_candidate(
         &mut self,
         obligation: &TraitObligation<'tcx>,
-    ) -> ImplSourceAutoImplData<PredicateObligation<'tcx>> {
+    ) -> Vec<PredicateObligation<'tcx>> {
         debug!(?obligation, "confirm_auto_impl_candidate");
 
         let self_ty = self.infcx.shallow_resolve(obligation.predicate.self_ty());
@@ -393,7 +393,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         obligation: &TraitObligation<'tcx>,
         trait_def_id: DefId,
         nested: ty::Binder<'tcx, Vec<Ty<'tcx>>>,
-    ) -> ImplSourceAutoImplData<PredicateObligation<'tcx>> {
+    ) -> Vec<PredicateObligation<'tcx>> {
         debug!(?nested, "vtable_auto_impl");
         ensure_sufficient_stack(|| {
             let cause = obligation.derived_cause(BuiltinDerivedObligation);
@@ -423,7 +423,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
             debug!(?obligations, "vtable_auto_impl");
 
-            ImplSourceAutoImplData { trait_def_id, nested: obligations }
+            obligations
         })
     }
 
@@ -1222,10 +1222,10 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         &mut self,
         obligation: &TraitObligation<'tcx>,
         impl_def_id: Option<DefId>,
-    ) -> Result<ImplSourceConstDestructData<PredicateObligation<'tcx>>, SelectionError<'tcx>> {
+    ) -> Result<Vec<PredicateObligation<'tcx>>, SelectionError<'tcx>> {
         // `~const Destruct` in a non-const environment is always trivially true, since our type is `Drop`
         if !obligation.is_const() {
-            return Ok(ImplSourceConstDestructData { nested: vec![] });
+            return Ok(vec![]);
         }
 
         let drop_trait = self.tcx().require_lang_item(LangItem::Drop, None);
@@ -1379,6 +1379,6 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             }
         }
 
-        Ok(ImplSourceConstDestructData { nested })
+        Ok(nested)
     }
 }
diff --git a/compiler/rustc_ty_utils/src/instance.rs b/compiler/rustc_ty_utils/src/instance.rs
index dd911239ac4..81ad883903f 100644
--- a/compiler/rustc_ty_utils/src/instance.rs
+++ b/compiler/rustc_ty_utils/src/instance.rs
@@ -312,11 +312,9 @@ fn resolve_associated_item<'tcx>(
                 None
             }
         }
-        traits::ImplSource::AutoImpl(..)
-        | traits::ImplSource::Param(..)
+        traits::ImplSource::Param(..)
         | traits::ImplSource::TraitAlias(..)
-        | traits::ImplSource::TraitUpcasting(_)
-        | traits::ImplSource::ConstDestruct(_) => None,
+        | traits::ImplSource::TraitUpcasting(_) => None,
     })
 }