[clang] [webkit.UncountedLambdaCapturesChecker] Treat a call to lambda function via a variable as safe. (PR #135688)

[Ryosuke Niwa via cfe-commits]

https://github.com/rniwa updated https://github.com/llvm/llvm-project/pull/135688

>From 41992e5ffb43f7db7704b93c7ad5fe2135e86e26 Mon Sep 17 00:00:00 2001
From: Ryosuke Niwa <rniwa at webkit.org>
Date: Mon, 14 Apr 2025 15:12:10 -0700
Subject: [PATCH 1/2] [webkit.UncountedLambdaCapturesChecker] Treat a call to
 lambda function via a variable as safe.

This PR makes the checker ignore a function call to lambda via a local variable.
---
 .../Checkers/WebKit/RawPtrRefLambdaCapturesChecker.cpp    | 2 --
 .../Checkers/WebKit/uncounted-lambda-captures.cpp         | 8 ++++++++
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/clang/lib/StaticAnalyzer/Checkers/WebKit/RawPtrRefLambdaCapturesChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/WebKit/RawPtrRefLambdaCapturesChecker.cpp
index da403d591a2e2..0a658b59ad8c5 100644
--- a/clang/lib/StaticAnalyzer/Checkers/WebKit/RawPtrRefLambdaCapturesChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/WebKit/RawPtrRefLambdaCapturesChecker.cpp
@@ -263,8 +263,6 @@ class RawPtrRefLambdaCapturesChecker
           return;
         DeclRefExprsToIgnore.insert(ArgRef);
         LambdasToIgnore.insert(L);
-        Checker->visitLambdaExpr(L, shouldCheckThis() && !hasProtectedThis(L),
-                                 ClsType, /* ignoreParamVarDecl */ true);
       }
 
       bool hasProtectedThis(LambdaExpr *L) {
diff --git a/clang/test/Analysis/Checkers/WebKit/uncounted-lambda-captures.cpp b/clang/test/Analysis/Checkers/WebKit/uncounted-lambda-captures.cpp
index 36135973e78c0..cc3d27bbc1375 100644
--- a/clang/test/Analysis/Checkers/WebKit/uncounted-lambda-captures.cpp
+++ b/clang/test/Analysis/Checkers/WebKit/uncounted-lambda-captures.cpp
@@ -372,6 +372,14 @@ void trivial_lambda() {
   trivial_lambda();
 }
 
+bool call_lambda_var_decl() {
+  RefCountable* ref_countable = make_obj();
+  auto lambda = [&]() -> bool {
+    return ref_countable->next();
+  };
+  return lambda();
+}
+
 void lambda_with_args(RefCountable* obj) {
   auto trivial_lambda = [&](int v) {
     obj->method();

>From fb8444e38f55152265c09405ae9075d27617c1de Mon Sep 17 00:00:00 2001
From: Ryosuke Niwa <rniwa at webkit.org>
Date: Thu, 24 Apr 2025 15:20:04 -0700
Subject: [PATCH 2/2] Add a test case for capture by value

---
 .../Analysis/Checkers/WebKit/uncounted-lambda-captures.cpp | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/clang/test/Analysis/Checkers/WebKit/uncounted-lambda-captures.cpp b/clang/test/Analysis/Checkers/WebKit/uncounted-lambda-captures.cpp
index cc3d27bbc1375..daa15d55aee5a 100644
--- a/clang/test/Analysis/Checkers/WebKit/uncounted-lambda-captures.cpp
+++ b/clang/test/Analysis/Checkers/WebKit/uncounted-lambda-captures.cpp
@@ -374,10 +374,13 @@ void trivial_lambda() {
 
 bool call_lambda_var_decl() {
   RefCountable* ref_countable = make_obj();
-  auto lambda = [&]() -> bool {
+  auto lambda1 = [&]() -> bool {
     return ref_countable->next();
   };
-  return lambda();
+  auto lambda2 = [=]() -> bool {
+    return ref_countable->next();
+  };
+  return lambda1() && lambda2();
 }
 
 void lambda_with_args(RefCountable* obj) {