Add test for #49919

Author: JohnTitor

src/test/ui/issues/issue-49919.rs

@@ -0,0 +1,7 @@
+fn foo<'a, T: 'a>(t: T) -> Box<dyn Fn() -> &'a T + 'a> {
+    let foo: Box<dyn for <'c> Fn() -> &'c T> = Box::new(move || &t);
+    //~^ ERROR: binding for associated type
+    unimplemented!()
+}
+
+fn main() {}

src/test/ui/issues/issue-49919.stderr

@@ -0,0 +1,9 @@
+error[E0582]: binding for associated type `Output` references lifetime `'c`, which does not appear in the trait input types
+  --> $DIR/issue-49919.rs:2:39
+   |
+LL |     let foo: Box<dyn for <'c> Fn() -> &'c T> = Box::new(move || &t);
+   |                                       ^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0582`.