[clang] [webkit.UncountedLambdaCapturesChecker] Recognize nested protectedThis pattern (PR #126443)

[Ryosuke Niwa via cfe-commits]

================
@@ -299,6 +300,29 @@ struct RefCountableWithLambdaCapturingThis {
       return obj->next();
     });
   }
+
+  void callAsyncNoescape([[clang::noescape]] WTF::Function<bool(RefCountable&)>&&);
+  void method_temp_lambda(RefCountable* obj) {
+    callAsyncNoescape([this, otherObj = RefPtr { obj }](auto& obj) {
+      return otherObj == &obj;
+    });
+  }
+
+  void method_nested_lambda() {
+    callAsync([this, protectedThis = Ref { *this }] {
+      callAsync([this, protectedThis = static_cast<const Ref<RefCountableWithLambdaCapturingThis>&&>(protectedThis)] {
+        nonTrivial();
+      });
+    });
+  }
+
+  void method_nested_lambda2() {
+    callAsync([this, protectedThis = RefPtr { this }] {
+      callAsync([this, protectedThis = static_cast<const Ref<RefCountableWithLambdaCapturingThis>&&>(*protectedThis)] {
+        nonTrivial();
+      });
+    });
+  }
----------------
rniwa wrote:

Oh, we have such a test case. See method_captures_this_unsafe around line 217 :)

https://github.com/llvm/llvm-project/pull/126443