revert changes to ui test

Author: gaurikholkar

src/test/ui/lint/use_suggestion_json.stderr

@@ -2,7 +2,72 @@
   "message": "cannot find type `Iter` in this scope",
   "code": {
     "code": "E0412",
-    "explanation": null
+    "explanation": "
+The type name used is not in scope.
+
+Erroneous code examples:
+
+```compile_fail,E0412
+impl Something {} // error: type name `Something` is not in scope
+
+// or:
+
+trait Foo {
+    fn bar(N); // error: type name `N` is not in scope
+}
+
+// or:
+
+fn foo(x: T) {} // type name `T` is not in scope
+```
+
+To fix this error, please verify you didn't misspell the type name, you did
+declare it or imported it into the scope. Examples:
+
+```
+struct Something;
+
+impl Something {} // ok!
+
+// or:
+
+trait Foo {
+    type N;
+
+    fn bar(_: Self::N); // ok!
+}
+
+// or:
+
+fn foo<T>(x: T) {} // ok!
+```
+
+Another case that causes this error is when a type is imported into a parent
+module. To fix this, you can follow the suggestion and use File directly or
+`use super::File;` which will import the types from the parent namespace. An
+example that causes this error is below:
+
+```compile_fail,E0412
+use std::fs::File;
+
+mod foo {
+    fn some_function(f: File) {}
+}
+```
+
+```
+use std::fs::File;
+
+mod foo {
+    // either
+    use super::File;
+    // or
+    // use std::fs::File;
+    fn foo(f: File) {}
+}
+# fn main() {} // don't insert it for us; that'll break imports
+```
+"
   },
   "level": "error",
   "spans": [