Merging upstream version 1.67.1+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

4 files changed, 77 insertions, 51 deletions

diff --git a/compiler/rustc_middle/src/traits/mod.rs b/compiler/rustc_middle/src/traits/mod.rs
index e73d44bbb..143435cb2 100644
--- a/compiler/rustc_middle/src/traits/mod.rs
+++ b/compiler/rustc_middle/src/traits/mod.rs
@@ -203,13 +203,20 @@ pub struct UnifyReceiverContext<'tcx> {
     pub substs: SubstsRef<'tcx>,
 }
 
-#[derive(Clone, Debug, PartialEq, Eq, Hash, Lift, Default)]
+#[derive(Clone, PartialEq, Eq, Hash, Lift, Default)]
 pub struct InternedObligationCauseCode<'tcx> {
     /// `None` for `ObligationCauseCode::MiscObligation` (a common case, occurs ~60% of
     /// the time). `Some` otherwise.
     code: Option<Lrc<ObligationCauseCode<'tcx>>>,
 }
 
+impl<'tcx> std::fmt::Debug for InternedObligationCauseCode<'tcx> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let cause: &ObligationCauseCode<'_> = self;
+        cause.fmt(f)
+    }
+}
+
 impl<'tcx> ObligationCauseCode<'tcx> {
     #[inline(always)]
     fn into(self) -> InternedObligationCauseCode<'tcx> {
@@ -431,6 +438,8 @@ pub enum ObligationCauseCode<'tcx> {
     },
 
     AscribeUserTypeProvePredicate(Span),
+
+    RustCall,
 }
 
 /// The 'location' at which we try to perform HIR-based wf checking.
@@ -462,7 +471,7 @@ pub struct ImplDerivedObligationCause<'tcx> {
 }
 
 impl<'tcx> ObligationCauseCode<'tcx> {
-    // Return the base obligation, ignoring derived obligations.
+    /// Returns the base obligation, ignoring derived obligations.
     pub fn peel_derives(&self) -> &Self {
         let mut base_cause = self;
         while let Some((parent_code, _)) = base_cause.parent() {
@@ -567,9 +576,6 @@ pub enum SelectionError<'tcx> {
     /// Signaling that an error has already been emitted, to avoid
     /// multiple errors being shown.
     ErrorReporting,
-    /// Multiple applicable `impl`s where found. The `DefId`s correspond to
-    /// all the `impl`s' Items.
-    Ambiguous(Vec<DefId>),
 }
 
 /// When performing resolution, it is typically the case that there
@@ -645,15 +651,12 @@ pub enum ImplSource<'tcx, N> {
     /// Same as above, but for a function pointer type with the given signature.
     FnPointer(ImplSourceFnPointerData<'tcx, N>),
 
-    /// ImplSource for a builtin `DeterminantKind` trait implementation.
-    DiscriminantKind(ImplSourceDiscriminantKindData),
-
-    /// ImplSource for a builtin `Pointee` trait implementation.
-    Pointee(ImplSourcePointeeData),
-
     /// ImplSource automatically generated for a generator.
     Generator(ImplSourceGeneratorData<'tcx, N>),
 
+    /// ImplSource automatically generated for a generator backing an async future.
+    Future(ImplSourceFutureData<'tcx, N>),
+
     /// ImplSource for a trait alias.
     TraitAlias(ImplSourceTraitAliasData<'tcx, N>),
 
@@ -670,10 +673,9 @@ impl<'tcx, N> ImplSource<'tcx, N> {
             ImplSource::AutoImpl(d) => d.nested,
             ImplSource::Closure(c) => c.nested,
             ImplSource::Generator(c) => c.nested,
+            ImplSource::Future(c) => c.nested,
             ImplSource::Object(d) => d.nested,
             ImplSource::FnPointer(d) => d.nested,
-            ImplSource::DiscriminantKind(ImplSourceDiscriminantKindData)
-            | ImplSource::Pointee(ImplSourcePointeeData) => vec![],
             ImplSource::TraitAlias(d) => d.nested,
             ImplSource::TraitUpcasting(d) => d.nested,
             ImplSource::ConstDestruct(i) => i.nested,
@@ -688,10 +690,9 @@ impl<'tcx, N> ImplSource<'tcx, N> {
             ImplSource::AutoImpl(d) => &d.nested,
             ImplSource::Closure(c) => &c.nested,
             ImplSource::Generator(c) => &c.nested,
+            ImplSource::Future(c) => &c.nested,
             ImplSource::Object(d) => &d.nested,
             ImplSource::FnPointer(d) => &d.nested,
-            ImplSource::DiscriminantKind(ImplSourceDiscriminantKindData)
-            | ImplSource::Pointee(ImplSourcePointeeData) => &[],
             ImplSource::TraitAlias(d) => &d.nested,
             ImplSource::TraitUpcasting(d) => &d.nested,
             ImplSource::ConstDestruct(i) => &i.nested,
@@ -731,16 +732,15 @@ impl<'tcx, N> ImplSource<'tcx, N> {
                 substs: c.substs,
                 nested: c.nested.into_iter().map(f).collect(),
             }),
+            ImplSource::Future(c) => ImplSource::Future(ImplSourceFutureData {
+                generator_def_id: c.generator_def_id,
+                substs: c.substs,
+                nested: c.nested.into_iter().map(f).collect(),
+            }),
             ImplSource::FnPointer(p) => ImplSource::FnPointer(ImplSourceFnPointerData {
                 fn_ty: p.fn_ty,
                 nested: p.nested.into_iter().map(f).collect(),
             }),
-            ImplSource::DiscriminantKind(ImplSourceDiscriminantKindData) => {
-                ImplSource::DiscriminantKind(ImplSourceDiscriminantKindData)
-            }
-            ImplSource::Pointee(ImplSourcePointeeData) => {
-                ImplSource::Pointee(ImplSourcePointeeData)
-            }
             ImplSource::TraitAlias(d) => ImplSource::TraitAlias(ImplSourceTraitAliasData {
                 alias_def_id: d.alias_def_id,
                 substs: d.substs,
@@ -792,6 +792,16 @@ pub struct ImplSourceGeneratorData<'tcx, N> {
 
 #[derive(Clone, PartialEq, Eq, TyEncodable, TyDecodable, HashStable, Lift)]
 #[derive(TypeFoldable, TypeVisitable)]
+pub struct ImplSourceFutureData<'tcx, N> {
+    pub generator_def_id: DefId,
+    pub substs: SubstsRef<'tcx>,
+    /// Nested obligations. This can be non-empty if the generator
+    /// signature contains associated types.
+    pub nested: Vec<N>,
+}
+
+#[derive(Clone, PartialEq, Eq, TyEncodable, TyDecodable, HashStable, Lift)]
+#[derive(TypeFoldable, TypeVisitable)]
 pub struct ImplSourceClosureData<'tcx, N> {
     pub closure_def_id: DefId,
     pub substs: SubstsRef<'tcx>,
@@ -850,13 +860,6 @@ pub struct ImplSourceFnPointerData<'tcx, N> {
     pub nested: Vec<N>,
 }
 
-// FIXME(@lcnr): This should be  refactored and merged with other builtin vtables.
-#[derive(Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)]
-pub struct ImplSourceDiscriminantKindData;
-
-#[derive(Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)]
-pub struct ImplSourcePointeeData;
-
 #[derive(Clone, PartialEq, Eq, TyEncodable, TyDecodable, HashStable, Lift)]
 #[derive(TypeFoldable, TypeVisitable)]
 pub struct ImplSourceConstDestructData<N> {
@@ -918,10 +921,13 @@ impl ObjectSafetyViolation {
             }
             ObjectSafetyViolation::Method(
                 name,
-                MethodViolationCode::ReferencesImplTraitInTrait,
+                MethodViolationCode::ReferencesImplTraitInTrait(_),
                 _,
             ) => format!("method `{}` references an `impl Trait` type in its return type", name)
                 .into(),
+            ObjectSafetyViolation::Method(name, MethodViolationCode::AsyncFn, _) => {
+                format!("method `{}` is `async`", name).into()
+            }
             ObjectSafetyViolation::Method(
                 name,
                 MethodViolationCode::WhereClauseReferencesSelf,
@@ -1029,7 +1035,10 @@ pub enum MethodViolationCode {
     ReferencesSelfOutput,
 
     /// e.g., `fn foo(&self) -> impl Sized`
-    ReferencesImplTraitInTrait,
+    ReferencesImplTraitInTrait(Span),
+
+    /// e.g., `async fn foo(&self)`
+    AsyncFn,
 
     /// e.g., `fn foo(&self) where Self: Clone`
     WhereClauseReferencesSelf,
diff --git a/compiler/rustc_middle/src/traits/select.rs b/compiler/rustc_middle/src/traits/select.rs
index 85ead3171..ec69864c9 100644
--- a/compiler/rustc_middle/src/traits/select.rs
+++ b/compiler/rustc_middle/src/traits/select.rs
@@ -105,6 +105,12 @@ pub type EvaluationCache<'tcx> = Cache<
 /// parameter environment.
 #[derive(PartialEq, Eq, Debug, Clone, TypeFoldable, TypeVisitable)]
 pub enum SelectionCandidate<'tcx> {
+    /// A builtin implementation for some specific traits, used in cases
+    /// where we cannot rely an ordinary library implementations.
+    ///
+    /// The most notable examples are `sized`, `Copy` and `Clone`. This is also
+    /// used for the `DiscriminantKind` and `Pointee` trait, both of which have
+    /// an associated type.
     BuiltinCandidate {
         /// `false` if there are no *further* obligations.
         has_nested: bool,
@@ -131,18 +137,16 @@ pub enum SelectionCandidate<'tcx> {
     /// generated for a generator.
     GeneratorCandidate,
 
+    /// Implementation of a `Future` trait by one of the generator types
+    /// generated for an async construct.
+    FutureCandidate,
+
     /// Implementation of a `Fn`-family trait by one of the anonymous
     /// types generated for a fn pointer type (e.g., `fn(int) -> int`)
     FnPointerCandidate {
         is_const: bool,
     },
 
-    /// Builtin implementation of `DiscriminantKind`.
-    DiscriminantKindCandidate,
-
-    /// Builtin implementation of `Pointee`.
-    PointeeCandidate,
-
     TraitAliasCandidate,
 
     /// Matching `dyn Trait` with a supertrait of `Trait`. The index is the
diff --git a/compiler/rustc_middle/src/traits/specialization_graph.rs b/compiler/rustc_middle/src/traits/specialization_graph.rs
index 0a2819fee..cccedc9ec 100644
--- a/compiler/rustc_middle/src/traits/specialization_graph.rs
+++ b/compiler/rustc_middle/src/traits/specialization_graph.rs
@@ -1,3 +1,4 @@
+use crate::error::StrictCoherenceNeedsNegativeCoherence;
 use crate::ty::fast_reject::SimplifiedType;
 use crate::ty::visit::TypeVisitable;
 use crate::ty::{self, TyCtxt};
@@ -65,9 +66,21 @@ impl OverlapMode {
 
         if with_negative_coherence {
             if strict_coherence { OverlapMode::Strict } else { OverlapMode::WithNegative }
-        } else if strict_coherence {
-            bug!("To use strict_coherence you need to set with_negative_coherence feature flag");
         } else {
+            if strict_coherence {
+                let attr_span = trait_id
+                    .as_local()
+                    .into_iter()
+                    .flat_map(|local_def_id| {
+                        tcx.hir().attrs(tcx.hir().local_def_id_to_hir_id(local_def_id))
+                    })
+                    .find(|attr| attr.has_name(sym::rustc_strict_coherence))
+                    .map(|attr| attr.span);
+                tcx.sess.emit_err(StrictCoherenceNeedsNegativeCoherence {
+                    span: tcx.def_span(trait_id),
+                    attr_span,
+                });
+            }
             OverlapMode::Stable
         }
     }
@@ -249,7 +262,7 @@ pub fn ancestors<'tcx>(
 
     if let Some(reported) = specialization_graph.has_errored {
         Err(reported)
-    } else if let Some(reported) = tcx.type_of(start_from_impl).error_reported() {
+    } else if let Err(reported) = tcx.type_of(start_from_impl).error_reported() {
         Err(reported)
     } else {
         Ok(Ancestors {
diff --git a/compiler/rustc_middle/src/traits/structural_impls.rs b/compiler/rustc_middle/src/traits/structural_impls.rs
index 7fbd57ac7..6acb7745d 100644
--- a/compiler/rustc_middle/src/traits/structural_impls.rs
+++ b/compiler/rustc_middle/src/traits/structural_impls.rs
@@ -15,11 +15,9 @@ impl<'tcx, N: fmt::Debug> fmt::Debug for traits::ImplSource<'tcx, N> {
 
             super::ImplSource::Generator(ref d) => write!(f, "{:?}", d),
 
-            super::ImplSource::FnPointer(ref d) => write!(f, "({:?})", d),
-
-            super::ImplSource::DiscriminantKind(ref d) => write!(f, "{:?}", d),
+            super::ImplSource::Future(ref d) => write!(f, "{:?}", d),
 
-            super::ImplSource::Pointee(ref d) => write!(f, "{:?}", d),
+            super::ImplSource::FnPointer(ref d) => write!(f, "({:?})", d),
 
             super::ImplSource::Object(ref d) => write!(f, "{:?}", d),
 
@@ -58,6 +56,16 @@ impl<'tcx, N: fmt::Debug> fmt::Debug for traits::ImplSourceGeneratorData<'tcx, N
     }
 }
 
+impl<'tcx, N: fmt::Debug> fmt::Debug for traits::ImplSourceFutureData<'tcx, N> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(
+            f,
+            "ImplSourceFutureData(generator_def_id={:?}, substs={:?}, nested={:?})",
+            self.generator_def_id, self.substs, self.nested
+        )
+    }
+}
+
 impl<'tcx, N: fmt::Debug> fmt::Debug for traits::ImplSourceClosureData<'tcx, N> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(
@@ -125,11 +133,3 @@ impl<N: fmt::Debug> fmt::Debug for traits::ImplSourceConstDestructData<N> {
         write!(f, "ImplSourceConstDestructData(nested={:?})", self.nested)
     }
 }
-
-///////////////////////////////////////////////////////////////////////////
-// Lift implementations
-
-TrivialTypeTraversalAndLiftImpls! {
-    super::ImplSourceDiscriminantKindData,
-    super::ImplSourcePointeeData,
-}