Improve test

Author: jonas-schievink

src/test/ui/associated-types/defaults-specialization.rs

@@ -1,3 +1,5 @@
+//! Tests the interaction of associated type defaults and specialization.
+
 // compile-fail
 
 #![feature(associated_type_defaults, specialization)]
@@ -16,6 +18,13 @@ default impl<T> Tr for A<T> {
     //~^ ERROR method `make` has an incompatible type for trait
 }
 
+struct A2<T>(T);
+// ...same, but in the method body
+default impl<T> Tr for A2<T> {
+    fn make() -> Self::Ty { 0u8 }
+    //~^ ERROR mismatched types
+}
+
 struct B<T>(T);
 // Explicitly defaulting the type does the same.
 impl<T> Tr for B<T> {
@@ -25,6 +34,15 @@ impl<T> Tr for B<T> {
     //~^ ERROR method `make` has an incompatible type for trait
 }
 
+struct B2<T>(T);
+// ...same, but in the method body
+impl<T> Tr for B2<T> {
+    default type Ty = bool;
+
+    fn make() -> Self::Ty { true }
+    //~^ ERROR mismatched types
+}
+
 struct C<T>(T);
 // Only the method is defaulted, so this is fine.
 impl<T> Tr for C<T> {

src/test/ui/associated-types/defaults-specialization.stderr

@@ -1,5 +1,5 @@
 error[E0053]: method `make` has an incompatible type for trait
-  --> $DIR/defaults-specialization.rs:15:18
+  --> $DIR/defaults-specialization.rs:17:18
    |
 LL |     fn make() -> Self::Ty;
    |                  -------- type in trait
@@ -11,7 +11,7 @@ LL |     fn make() -> u8 { 0 }
               found type `fn() -> u8`
 
 error[E0053]: method `make` has an incompatible type for trait
-  --> $DIR/defaults-specialization.rs:24:18
+  --> $DIR/defaults-specialization.rs:33:18
    |
 LL |     fn make() -> Self::Ty;
    |                  -------- type in trait
@@ -22,6 +22,29 @@ LL |     fn make() -> bool { true }
    = note: expected type `fn() -> <B<T> as Tr>::Ty`
               found type `fn() -> bool`
 
-error: aborting due to 2 previous errors
+error[E0308]: mismatched types
+  --> $DIR/defaults-specialization.rs:24:29
+   |
+LL |     fn make() -> Self::Ty { 0u8 }
+   |                  --------   ^^^ expected associated type, found u8
+   |                  |
+   |                  expected `<A2<T> as Tr>::Ty` because of return type
+   |
+   = note: expected type `<A2<T> as Tr>::Ty`
+              found type `u8`
+
+error[E0308]: mismatched types
+  --> $DIR/defaults-specialization.rs:42:29
+   |
+LL |     fn make() -> Self::Ty { true }
+   |                  --------   ^^^^ expected associated type, found bool
+   |                  |
+   |                  expected `<B2<T> as Tr>::Ty` because of return type
+   |
+   = note: expected type `<B2<T> as Tr>::Ty`
+              found type `bool`
+
+error: aborting due to 4 previous errors
 
-For more information about this error, try `rustc --explain E0053`.
+Some errors have detailed explanations: E0053, E0308.
+For more information about an error, try `rustc --explain E0053`.