Test generic arg suggestion inside nested item

tests/ui/generics/generic-type-less-params-with-defaults.rs

@@ -15,4 +15,13 @@ fn main() {
     let _x = (1..10).collect::<HashMap>();
     //~^ ERROR missing generics for struct `HashMap`
     //~| SUGGESTION <_, _>
+
+    ().extend::<[(); 0]>({
+        fn not_the_extend() {
+            let _: Vec;
+            //~^ ERROR missing generics for struct `Vec`
+            //~| SUGGESTION <T>
+        }
+        []
+    });
 }

tests/ui/generics/generic-type-less-params-with-defaults.stderr

@@ -30,6 +30,22 @@ help: add missing generic arguments
 LL |     let _x = (1..10).collect::<HashMap<_, _>>();
    |                                       ++++++
 
-error: aborting due to 2 previous errors
+error[E0107]: missing generics for struct `Vec`
+  --> $DIR/generic-type-less-params-with-defaults.rs:21:20
+   |
+LL |             let _: Vec;
+   |                    ^^^ expected at least 1 generic argument
+   |
+note: struct defined here, with at least 1 generic parameter: `T`
+  --> $DIR/generic-type-less-params-with-defaults.rs:5:8
+   |
+LL | struct Vec<T, A = Heap>(
+   |        ^^^ -
+help: add missing generic argument
+   |
+LL |             let _: Vec<T>;
+   |                       +++
+
+error: aborting due to 3 previous errors
 
 For more information about this error, try `rustc --explain E0107`.