Deduplicate implied supertraits for pretty printing

Author: compiler-errors

compiler/rustc_middle/src/ty/print/pretty.rs

@@ -1293,6 +1293,19 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
         // FIXME(eddyb) avoid printing twice (needed to ensure
         // that the auto traits are sorted *and* printed via cx).
         let mut auto_traits: Vec<_> = predicates.auto_traits().collect();
+        let principal_super_traits: FxHashSet<_> = predicates
+            .principal()
+            .into_iter()
+            .flat_map(|principal| {
+                supertraits_for_pretty_printing(
+                    self.tcx(),
+                    principal.with_self_ty(self.tcx(), self.tcx().types.trait_object_dummy_self),
+                )
+                .map(|trait_ref| trait_ref.def_id())
+            })
+            .collect();
+
+        auto_traits.retain(|def_id| !principal_super_traits.contains(def_id));
 
         // The auto traits come ordered by `DefPathHash`. While
         // `DefPathHash` is *stable* in the sense that it depends on

tests/ui/coherence/coherence-impl-trait-for-marker-trait-negative.stderr

@@ -1,40 +1,40 @@
-error[E0371]: the object type `(dyn Object + Marker1 + Marker2 + 'static)` automatically implements the trait `Marker1`
+error[E0371]: the object type `(dyn Object + Marker2 + 'static)` automatically implements the trait `Marker1`
   --> $DIR/coherence-impl-trait-for-marker-trait-negative.rs:15:1
    |
 LL | impl !Marker1 for dyn Object + Marker2 {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `(dyn Object + Marker1 + Marker2 + 'static)` automatically implements trait `Marker1`
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `(dyn Object + Marker2 + 'static)` automatically implements trait `Marker1`
 
-error[E0371]: the object type `(dyn Object + Marker1 + Marker2 + 'static)` automatically implements the trait `Marker1`
+error[E0371]: the object type `(dyn Object + Marker2 + 'static)` automatically implements the trait `Marker1`
   --> $DIR/coherence-impl-trait-for-marker-trait-negative.rs:15:1
    |
 LL | impl !Marker1 for dyn Object + Marker2 {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `(dyn Object + Marker1 + Marker2 + 'static)` automatically implements trait `Marker1`
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `(dyn Object + Marker2 + 'static)` automatically implements trait `Marker1`
    |
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
-error[E0321]: traits with a default impl, like `Marker1`, cannot be implemented for trait object `(dyn Object + Marker1 + Marker2 + 'static)`
+error[E0321]: traits with a default impl, like `Marker1`, cannot be implemented for trait object `(dyn Object + Marker2 + 'static)`
   --> $DIR/coherence-impl-trait-for-marker-trait-negative.rs:15:1
    |
 LL | impl !Marker1 for dyn Object + Marker2 {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: a trait object implements `Marker1` if and only if `Marker1` is one of the trait object's trait bounds
 
-error[E0371]: the object type `(dyn Object + Marker1 + Marker2 + 'static)` automatically implements the trait `Marker2`
+error[E0371]: the object type `(dyn Object + Marker2 + 'static)` automatically implements the trait `Marker2`
   --> $DIR/coherence-impl-trait-for-marker-trait-negative.rs:21:1
    |
 LL | impl !Marker2 for dyn Object + Marker2 {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `(dyn Object + Marker1 + Marker2 + 'static)` automatically implements trait `Marker2`
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `(dyn Object + Marker2 + 'static)` automatically implements trait `Marker2`
 
-error[E0321]: traits with a default impl, like `Marker2`, cannot be implemented for trait object `(dyn Object + Marker1 + Marker2 + 'static)`
+error[E0321]: traits with a default impl, like `Marker2`, cannot be implemented for trait object `(dyn Object + Marker2 + 'static)`
   --> $DIR/coherence-impl-trait-for-marker-trait-negative.rs:21:1
    |
 LL | impl !Marker2 for dyn Object + Marker2 {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: a trait object implements `Marker2` if and only if `Marker2` is one of the trait object's trait bounds
 
-error[E0321]: traits with a default impl, like `Marker2`, cannot be implemented for trait object `(dyn Object + Marker1 + 'static)`
+error[E0321]: traits with a default impl, like `Marker2`, cannot be implemented for trait object `(dyn Object + 'static)`
   --> $DIR/coherence-impl-trait-for-marker-trait-negative.rs:29:1
    |
 LL | impl !Marker2 for dyn Object {}
@@ -53,13 +53,13 @@ LL | impl !Send for dyn Marker2 {}
    |
    = note: define and implement a trait or new type instead
 
-error[E0321]: cross-crate traits with a default impl, like `Send`, can only be implemented for a struct/enum type, not `(dyn Object + Marker1 + 'static)`
+error[E0321]: cross-crate traits with a default impl, like `Send`, can only be implemented for a struct/enum type, not `(dyn Object + 'static)`
   --> $DIR/coherence-impl-trait-for-marker-trait-negative.rs:30:1
    |
 LL | impl !Send for dyn Object {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^ can't implement cross-crate trait with a default impl for non-struct/enum type
 
-error[E0321]: cross-crate traits with a default impl, like `Send`, can only be implemented for a struct/enum type, not `(dyn Object + Marker1 + Marker2 + 'static)`
+error[E0321]: cross-crate traits with a default impl, like `Send`, can only be implemented for a struct/enum type, not `(dyn Object + Marker2 + 'static)`
   --> $DIR/coherence-impl-trait-for-marker-trait-negative.rs:31:1
    |
 LL | impl !Send for dyn Object + Marker2 {}

tests/ui/coherence/coherence-impl-trait-for-marker-trait-positive.stderr

@@ -1,40 +1,40 @@
-error[E0371]: the object type `(dyn Object + Marker1 + Marker2 + 'static)` automatically implements the trait `Marker1`
+error[E0371]: the object type `(dyn Object + Marker2 + 'static)` automatically implements the trait `Marker1`
   --> $DIR/coherence-impl-trait-for-marker-trait-positive.rs:15:1
    |
 LL | impl Marker1 for dyn Object + Marker2 {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `(dyn Object + Marker1 + Marker2 + 'static)` automatically implements trait `Marker1`
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `(dyn Object + Marker2 + 'static)` automatically implements trait `Marker1`
 
-error[E0371]: the object type `(dyn Object + Marker1 + Marker2 + 'static)` automatically implements the trait `Marker1`
+error[E0371]: the object type `(dyn Object + Marker2 + 'static)` automatically implements the trait `Marker1`
   --> $DIR/coherence-impl-trait-for-marker-trait-positive.rs:15:1
    |
 LL | impl Marker1 for dyn Object + Marker2 {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `(dyn Object + Marker1 + Marker2 + 'static)` automatically implements trait `Marker1`
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `(dyn Object + Marker2 + 'static)` automatically implements trait `Marker1`
    |
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
-error[E0321]: traits with a default impl, like `Marker1`, cannot be implemented for trait object `(dyn Object + Marker1 + Marker2 + 'static)`
+error[E0321]: traits with a default impl, like `Marker1`, cannot be implemented for trait object `(dyn Object + Marker2 + 'static)`
   --> $DIR/coherence-impl-trait-for-marker-trait-positive.rs:15:1
    |
 LL | impl Marker1 for dyn Object + Marker2 {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: a trait object implements `Marker1` if and only if `Marker1` is one of the trait object's trait bounds
 
-error[E0371]: the object type `(dyn Object + Marker1 + Marker2 + 'static)` automatically implements the trait `Marker2`
+error[E0371]: the object type `(dyn Object + Marker2 + 'static)` automatically implements the trait `Marker2`
   --> $DIR/coherence-impl-trait-for-marker-trait-positive.rs:20:1
    |
 LL | impl Marker2 for dyn Object + Marker2 {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `(dyn Object + Marker1 + Marker2 + 'static)` automatically implements trait `Marker2`
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `(dyn Object + Marker2 + 'static)` automatically implements trait `Marker2`
 
-error[E0321]: traits with a default impl, like `Marker2`, cannot be implemented for trait object `(dyn Object + Marker1 + Marker2 + 'static)`
+error[E0321]: traits with a default impl, like `Marker2`, cannot be implemented for trait object `(dyn Object + Marker2 + 'static)`
   --> $DIR/coherence-impl-trait-for-marker-trait-positive.rs:20:1
    |
 LL | impl Marker2 for dyn Object + Marker2 {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: a trait object implements `Marker2` if and only if `Marker2` is one of the trait object's trait bounds
 
-error[E0321]: traits with a default impl, like `Marker2`, cannot be implemented for trait object `(dyn Object + Marker1 + 'static)`
+error[E0321]: traits with a default impl, like `Marker2`, cannot be implemented for trait object `(dyn Object + 'static)`
   --> $DIR/coherence-impl-trait-for-marker-trait-positive.rs:28:1
    |
 LL | impl Marker2 for dyn Object {}
@@ -53,13 +53,13 @@ LL | unsafe impl Send for dyn Marker2 {}
    |
    = note: define and implement a trait or new type instead
 
-error[E0321]: cross-crate traits with a default impl, like `Send`, can only be implemented for a struct/enum type, not `(dyn Object + Marker1 + 'static)`
+error[E0321]: cross-crate traits with a default impl, like `Send`, can only be implemented for a struct/enum type, not `(dyn Object + 'static)`
   --> $DIR/coherence-impl-trait-for-marker-trait-positive.rs:29:1
    |
 LL | unsafe impl Send for dyn Object {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ can't implement cross-crate trait with a default impl for non-struct/enum type
 
-error[E0321]: cross-crate traits with a default impl, like `Send`, can only be implemented for a struct/enum type, not `(dyn Object + Marker1 + Marker2 + 'static)`
+error[E0321]: cross-crate traits with a default impl, like `Send`, can only be implemented for a struct/enum type, not `(dyn Object + Marker2 + 'static)`
   --> $DIR/coherence-impl-trait-for-marker-trait-positive.rs:30:1
    |
 LL | unsafe impl Send for dyn Object + Marker2 {}

tests/ui/traits/trait-upcasting/subtrait-method.rs

@@ -51,17 +51,17 @@ fn main() {
 
     let bar: &dyn Bar = baz;
     bar.c();
-    //~^ ERROR no method named `c` found for reference `&dyn Bar + Send + Sync` in the current scope [E0599]
+    //~^ ERROR no method named `c` found for reference `&dyn Bar` in the current scope [E0599]
 
     let foo: &dyn Foo = baz;
     foo.b();
-    //~^ ERROR no method named `b` found for reference `&dyn Foo + Send + Sync` in the current scope [E0599]
+    //~^ ERROR no method named `b` found for reference `&dyn Foo` in the current scope [E0599]
     foo.c();
-    //~^ ERROR no method named `c` found for reference `&dyn Foo + Send + Sync` in the current scope [E0599]
+    //~^ ERROR no method named `c` found for reference `&dyn Foo` in the current scope [E0599]
 
     let foo: &dyn Foo = bar;
     foo.b();
-    //~^ ERROR no method named `b` found for reference `&dyn Foo + Send + Sync` in the current scope [E0599]
+    //~^ ERROR no method named `b` found for reference `&dyn Foo` in the current scope [E0599]
     foo.c();
-    //~^ ERROR no method named `c` found for reference `&dyn Foo + Send + Sync` in the current scope [E0599]
+    //~^ ERROR no method named `c` found for reference `&dyn Foo` in the current scope [E0599]
 }

tests/ui/traits/trait-upcasting/subtrait-method.stderr

@@ -1,4 +1,4 @@
-error[E0599]: no method named `c` found for reference `&dyn Bar + Send + Sync` in the current scope
+error[E0599]: no method named `c` found for reference `&dyn Bar` in the current scope
   --> $DIR/subtrait-method.rs:53:9
    |
 LL |     bar.c();
@@ -11,7 +11,7 @@ note: `Baz` defines an item `c`, perhaps you need to implement it
 LL | trait Baz: Bar {
    | ^^^^^^^^^^^^^^
 
-error[E0599]: no method named `b` found for reference `&dyn Foo + Send + Sync` in the current scope
+error[E0599]: no method named `b` found for reference `&dyn Foo` in the current scope
   --> $DIR/subtrait-method.rs:57:9
    |
 LL |     foo.b();
@@ -24,7 +24,7 @@ note: `Bar` defines an item `b`, perhaps you need to implement it
 LL | trait Bar: Foo {
    | ^^^^^^^^^^^^^^
 
-error[E0599]: no method named `c` found for reference `&dyn Foo + Send + Sync` in the current scope
+error[E0599]: no method named `c` found for reference `&dyn Foo` in the current scope
   --> $DIR/subtrait-method.rs:59:9
    |
 LL |     foo.c();
@@ -37,7 +37,7 @@ note: `Baz` defines an item `c`, perhaps you need to implement it
 LL | trait Baz: Bar {
    | ^^^^^^^^^^^^^^
 
-error[E0599]: no method named `b` found for reference `&dyn Foo + Send + Sync` in the current scope
+error[E0599]: no method named `b` found for reference `&dyn Foo` in the current scope
   --> $DIR/subtrait-method.rs:63:9
    |
 LL |     foo.b();
@@ -50,7 +50,7 @@ note: `Bar` defines an item `b`, perhaps you need to implement it
 LL | trait Bar: Foo {
    | ^^^^^^^^^^^^^^
 
-error[E0599]: no method named `c` found for reference `&dyn Foo + Send + Sync` in the current scope
+error[E0599]: no method named `c` found for reference `&dyn Foo` in the current scope
   --> $DIR/subtrait-method.rs:65:9
    |
 LL |     foo.c();