Improve selection errors for `~const` trait bounds

[rust.git] / compiler / rustc_middle / src / traits / mod.rs

diff --git a/compiler/rustc_middle/src/traits/mod.rs b/compiler/rustc_middle/src/traits/mod.rs
index de5beffb5c54180f34413836f32769a64523360d..1123cab807651b29a4024f5b86c31c3bb01697d1 100644 (file)
--- a/compiler/rustc_middle/src/traits/mod.rs
+++ b/compiler/rustc_middle/src/traits/mod.rs
@@ -402,7 +402,7 @@ pub fn peel_derives(&self) -> &Self {
 
 // `ObligationCauseCode` is used a lot. Make sure it doesn't unintentionally get bigger.
 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
-static_assert_size!(ObligationCauseCode<'_>, 40);
+static_assert_size!(ObligationCauseCode<'_>, 48);
 
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
 pub enum StatementAsExpression {
@@ -440,11 +440,11 @@ pub struct IfExpressionCause {
 
 #[derive(Clone, Debug, PartialEq, Eq, Hash, Lift)]
 pub struct DerivedObligationCause<'tcx> {
-    /// The trait reference of the parent obligation that led to the
+    /// The trait predicate of the parent obligation that led to the
     /// current obligation. Note that only trait obligations lead to
-    /// derived obligations, so we just store the trait reference here
+    /// derived obligations, so we just store the trait predicate here
     /// directly.
-    pub parent_trait_ref: ty::PolyTraitRef<'tcx>,
+    pub parent_trait_pred: ty::PolyTraitPredicate<'tcx>,
 
     /// The parent trait had this cause.
     pub parent_code: Lrc<ObligationCauseCode<'tcx>>,
@@ -566,7 +566,7 @@ pub enum ImplSource<'tcx, N> {
     TraitAlias(ImplSourceTraitAliasData<'tcx, N>),
 
     /// ImplSource for a `const Drop` implementation.
-    ConstDrop(ImplSourceConstDropData),
+    ConstDrop(ImplSourceConstDropData<N>),
 }
 
 impl<'tcx, N> ImplSource<'tcx, N> {
@@ -581,10 +581,10 @@ pub fn nested_obligations(self) -> Vec<N> {
             ImplSource::Object(d) => d.nested,
             ImplSource::FnPointer(d) => d.nested,
             ImplSource::DiscriminantKind(ImplSourceDiscriminantKindData)
-            | ImplSource::Pointee(ImplSourcePointeeData)
-            | ImplSource::ConstDrop(ImplSourceConstDropData) => Vec::new(),
+            | ImplSource::Pointee(ImplSourcePointeeData) => Vec::new(),
             ImplSource::TraitAlias(d) => d.nested,
             ImplSource::TraitUpcasting(d) => d.nested,
+            ImplSource::ConstDrop(i) => i.nested,
         }
     }
 
@@ -599,10 +599,10 @@ pub fn borrow_nested_obligations(&self) -> &[N] {
             ImplSource::Object(d) => &d.nested,
             ImplSource::FnPointer(d) => &d.nested,
             ImplSource::DiscriminantKind(ImplSourceDiscriminantKindData)
-            | ImplSource::Pointee(ImplSourcePointeeData)
-            | ImplSource::ConstDrop(ImplSourceConstDropData) => &[],
+            | ImplSource::Pointee(ImplSourcePointeeData) => &[],
             ImplSource::TraitAlias(d) => &d.nested,
             ImplSource::TraitUpcasting(d) => &d.nested,
+            ImplSource::ConstDrop(i) => &i.nested,
         }
     }
 
@@ -661,9 +661,9 @@ pub fn map<M, F>(self, f: F) -> ImplSource<'tcx, M>
                     nested: d.nested.into_iter().map(f).collect(),
                 })
             }
-            ImplSource::ConstDrop(ImplSourceConstDropData) => {
-                ImplSource::ConstDrop(ImplSourceConstDropData)
-            }
+            ImplSource::ConstDrop(i) => ImplSource::ConstDrop(ImplSourceConstDropData {
+                nested: i.nested.into_iter().map(f).collect(),
+            }),
         }
     }
 }
@@ -755,8 +755,10 @@ pub struct ImplSourceFnPointerData<'tcx, N> {
 #[derive(Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)]
 pub struct ImplSourcePointeeData;
 
-#[derive(Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)]
-pub struct ImplSourceConstDropData;
+#[derive(Clone, PartialEq, Eq, TyEncodable, TyDecodable, HashStable, TypeFoldable, Lift)]
+pub struct ImplSourceConstDropData<N> {
+    pub nested: Vec<N>,
+}
 
 #[derive(Clone, PartialEq, Eq, TyEncodable, TyDecodable, HashStable, TypeFoldable, Lift)]
 pub struct ImplSourceTraitAliasData<'tcx, N> {