[clang] [alpha.webkit.UncountedCallArgsChecker] Treat an explicit construction of Ref from a Ref return value safe. (PR #130911)

[Ryosuke Niwa via cfe-commits]

https://github.com/rniwa created https://github.com/llvm/llvm-project/pull/130911

Fix a bug that an explicit construction of Ref out of a Ref return value would not be treated as safe. It is definitely safe albit redundant.

>From 6eefb934996532201cc3f137931e3cb140bf25c1 Mon Sep 17 00:00:00 2001
From: Ryosuke Niwa <rniwa at webkit.org>
Date: Wed, 12 Mar 2025 00:11:14 -0700
Subject: [PATCH] [alpha.webkit.UncountedCallArgsChecker] Treat an explicit
 construction of Ref from a Ref return value safe.

Fix a bug that an explicit construction of Ref out of a Ref return value would not be treated as safe.
It is definitely safe albit redundant.
---
 clang/lib/StaticAnalyzer/Checkers/WebKit/ASTUtils.cpp | 2 ++
 clang/test/Analysis/Checkers/WebKit/call-args.cpp     | 7 +++++++
 2 files changed, 9 insertions(+)

diff --git a/clang/lib/StaticAnalyzer/Checkers/WebKit/ASTUtils.cpp b/clang/lib/StaticAnalyzer/Checkers/WebKit/ASTUtils.cpp
index 5e67cb29d08e4..1d9e8a468e899 100644
--- a/clang/lib/StaticAnalyzer/Checkers/WebKit/ASTUtils.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/WebKit/ASTUtils.cpp
@@ -70,6 +70,8 @@ bool tryToFindPtrOrigin(
           if (isCtorOfSafePtr(ConversionFunc))
             return callback(E, true);
         }
+        if (isa<CXXFunctionalCastExpr>(E) && isSafePtrType(cast->getType()))
+          return callback(E, true);
       }
       // FIXME: This can give false "origin" that would lead to false negatives
       // in checkers. See https://reviews.llvm.org/D37023 for reference.
diff --git a/clang/test/Analysis/Checkers/WebKit/call-args.cpp b/clang/test/Analysis/Checkers/WebKit/call-args.cpp
index e7afd9798da3e..0d53df6a2052f 100644
--- a/clang/test/Analysis/Checkers/WebKit/call-args.cpp
+++ b/clang/test/Analysis/Checkers/WebKit/call-args.cpp
@@ -407,6 +407,13 @@ namespace call_with_explicit_temporary_obj {
   void baz() {
     bar<int>();
   }
+
+  class Foo {
+    Ref<RefCountable> ensure();
+    void foo() {
+      Ref { ensure() }->method();
+    }
+  };
 }
 
 namespace call_with_explicit_construct {