Suggest named lifetime in ADT with hrtb

src/test/ui/associated-types/associated-types-project-from-hrtb-in-struct.rs

@@ -7,18 +7,25 @@ pub trait Foo<T> {
     fn get(&self, t: T) -> Self::A;
 }
 
-struct SomeStruct<I : for<'x> Foo<&'x isize>> {
+struct SomeStruct<I: for<'x> Foo<&'x isize>> {
     field: I::A
     //~^ ERROR cannot extract an associated type from a higher-ranked trait bound in this context
 }
 
+enum SomeEnum<I: for<'x> Foo<&'x isize>> {
+    TupleVariant(I::A),
+    //~^ ERROR cannot extract an associated type from a higher-ranked trait bound in this context
+    StructVariant { field: I::A },
+    //~^ ERROR cannot extract an associated type from a higher-ranked trait bound in this context
+}
+
 // FIXME(eddyb) This one doesn't even compile because of the unsupported syntax.
 
 // struct AnotherStruct<I : for<'x> Foo<&'x isize>> {
 //     field: <I as for<'y> Foo<&'y isize>>::A
 // }
 
-struct YetAnotherStruct<'a, I : for<'x> Foo<&'x isize>> {
+struct YetAnotherStruct<'a, I: for<'x> Foo<&'x isize>> {
     field: <I as Foo<&'a isize>>::A
 }
 

src/test/ui/associated-types/associated-types-project-from-hrtb-in-struct.stderr

@@ -3,6 +3,38 @@ error[E0212]: cannot extract an associated type from a higher-ranked trait bound
    |
 LL |     field: I::A
    |            ^^^^
+   |
+help: use a fully qualified path with explicit lifetimes
+   |
+LL | struct SomeStruct<'a, I: for<'x> Foo<&'x isize>> {
+LL |     field: <I as Foo<&'a isize>>::A
+   |
 
-error: aborting due to previous error
+error[E0212]: cannot extract an associated type from a higher-ranked trait bound in this context
+  --> $DIR/associated-types-project-from-hrtb-in-struct.rs:16:18
+   |
+LL |     TupleVariant(I::A),
+   |                  ^^^^
+   |
+help: use a fully qualified path with explicit lifetimes
+   |
+LL | enum SomeEnum<'a, I: for<'x> Foo<&'x isize>> {
+LL |     TupleVariant(<I as Foo<&'a isize>>::A),
+   |
+
+error[E0212]: cannot extract an associated type from a higher-ranked trait bound in this context
+  --> $DIR/associated-types-project-from-hrtb-in-struct.rs:18:28
+   |
+LL |     StructVariant { field: I::A },
+   |                            ^^^^
+   |
+help: use a fully qualified path with explicit lifetimes
+   |
+LL | enum SomeEnum<'a, I: for<'x> Foo<&'x isize>> {
+LL |     TupleVariant(I::A),
+LL |
+LL |     StructVariant { field: <I as Foo<&'a isize>>::A },
+   |
+
+error: aborting due to 3 previous errors