Add test

Author: estebank

tests/ui/resolve/use-self-in-inner-fn.rs

@@ -7,9 +7,30 @@ impl A {
         //~^ ERROR can't use `Self` from outer item
         //~| NOTE use of `Self` from outer item
         //~| NOTE `Self` used in this inner function
-        //~| NOTE refer to the type directly here instead
+        //~| HELP refer to the type directly here instead
         }
     }
 }
 
+enum MyEnum {}
+
+impl MyEnum {
+//~^ NOTE `Self` type implicitly declared here, by this `impl`
+    fn do_something(result: impl FnOnce()) {
+        result();
+    }
+
+    fn do_something_extra() {
+        fn inner() {
+        //~^ NOTE `Self` used in this inner function
+            Self::do_something(move || {});
+            //~^ ERROR can't use `Self` from outer item
+            //~| NOTE use of `Self` from outer item
+            //~| HELP refer to the type directly here instead
+            MyEnum::do_something(move || {});
+        }
+        inner();
+    }
+}
+
 fn main() {}

tests/ui/resolve/use-self-in-inner-fn.stderr

@@ -15,6 +15,24 @@ LL -         fn peach(this: &Self) {
 LL +         fn peach(this: &A) {
    |
 
-error: aborting due to 1 previous error
+error[E0401]: can't use `Self` from outer item
+  --> $DIR/use-self-in-inner-fn.rs:26:13
+   |
+LL | impl MyEnum {
+   | ---- `Self` type implicitly declared here, by this `impl`
+...
+LL |         fn inner() {
+   |            ----- `Self` used in this inner function
+LL |
+LL |             Self::do_something(move || {});
+   |             ^^^^^^^^^^^^^^^^^^ use of `Self` from outer item
+   |
+help: refer to the type directly here instead
+   |
+LL -             Self::do_something(move || {});
+LL +             MyEnum(move || {});
+   |
+
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0401`.