Skip mutable diagnostics on synthetic bindings

crates/ide-diagnostics/src/handlers/mutability_errors.rs

@@ -1091,6 +1091,19 @@ fn main() {
       //^^^^^ 💡 weak: variable does not need to be mutable
     f(x);
 }
+"#,
+        );
+    }
+
+    #[test]
+    fn regression_15099() {
+        check_diagnostics(
+            r#"
+//- minicore: iterator, range
+fn f() {
+    loop {}
+    for _ in 0..2 {}
+}
 "#,
         );
     }