[clang] d5a2638 - [webkit.UncountedLambdaCapturesChecker] Fix a bug that the checker didn't take the object pointer into account. (#125662)

[via cfe-commits]

Author: Ryosuke Niwa
Date: 2025-02-04T21:51:16-08:00
New Revision: d5a2638ae98746d9382231a0f04b11a5415b5e8e

URL: https://github.com/llvm/llvm-project/commit/d5a2638ae98746d9382231a0f04b11a5415b5e8e
DIFF: https://github.com/llvm/llvm-project/commit/d5a2638ae98746d9382231a0f04b11a5415b5e8e.diff

LOG: [webkit.UncountedLambdaCapturesChecker] Fix a bug that the checker didn't take the object pointer into account. (#125662)

When a callee is a method call (e.g. calling a lambda), we need to skip
the object pointer to match the parameter list with the call arguments.
This manifests as a bug that the checker erroneously generate a warning
for a lambda capture (L1) which is passed to a no-escape argument of
another lambda (L2).

Added: 
    

Modified: 
    clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLambdaCapturesChecker.cpp
    clang/test/Analysis/Checkers/WebKit/uncounted-lambda-captures.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLambdaCapturesChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLambdaCapturesChecker.cpp
index a57499d52acd0c..53ef423bd82e7e 100644
--- a/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLambdaCapturesChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLambdaCapturesChecker.cpp
@@ -109,8 +109,10 @@ class UncountedLambdaCapturesChecker
       bool VisitCallExpr(CallExpr *CE) override {
         checkCalleeLambda(CE);
         if (auto *Callee = CE->getDirectCallee()) {
-          bool TreatAllArgsAsNoEscape = shouldTreatAllArgAsNoEscape(Callee);
           unsigned ArgIndex = 0;
+          if (auto *CXXCallee = dyn_cast<CXXMethodDecl>(Callee))
+            ArgIndex = CXXCallee->isInstance();
+          bool TreatAllArgsAsNoEscape = shouldTreatAllArgAsNoEscape(Callee);
           for (auto *Param : Callee->parameters()) {
             if (ArgIndex >= CE->getNumArgs())
               return true;

diff  --git a/clang/test/Analysis/Checkers/WebKit/uncounted-lambda-captures.cpp b/clang/test/Analysis/Checkers/WebKit/uncounted-lambda-captures.cpp
index 2173245bc7af3e..2a1a164557cdbe 100644
--- a/clang/test/Analysis/Checkers/WebKit/uncounted-lambda-captures.cpp
+++ b/clang/test/Analysis/Checkers/WebKit/uncounted-lambda-captures.cpp
@@ -252,13 +252,22 @@ struct RefCountableWithLambdaCapturingThis {
     call(lambda);
   }
 
-  void method_captures_this_with_guardian_refPtr() {
+  void method_captures_this_with_guardian_refptr() {
     auto lambda = [this, protectedThis = RefPtr { &*this }]() {
       nonTrivial();
     };
     call(lambda);
   }
 
+  void forEach(const WTF::Function<void(RefCountable&)>&);
+  void method_captures_this_with_lambda_with_no_escape() {
+    auto run = [&]([[clang::noescape]] const WTF::Function<void(RefCountable&)>& func) {
+      forEach(func);
+    };
+    run([&](RefCountable&) {
+      nonTrivial();
+    });
+  }
 };
 
 struct NonRefCountableWithLambdaCapturingThis {