[clang] [webkit.UncountedLambdaCapturesChecker] Fix a crash in declProtectsThis (PR #127309)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Ryosuke Niwa (rniwa)

<details>
<summary>Changes</summary>

Add a missing nullptr check to declProtectsThis.

---
Full diff: https://github.com/llvm/llvm-project/pull/127309.diff


2 Files Affected:

- (modified) clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLambdaCapturesChecker.cpp (+2) 
- (added) clang/test/Analysis/Checkers/WebKit/uncounted-lambda-captures-decl-protects-this-crash.cpp (+38) 


``````````diff
diff --git a/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLambdaCapturesChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLambdaCapturesChecker.cpp
index 4ffdac5ca4873..aee43bdd983a0 100644
--- a/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLambdaCapturesChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLambdaCapturesChecker.cpp
@@ -267,6 +267,8 @@ class UncountedLambdaCapturesChecker
             auto OpCode = OpCE->getOperator();
             if (OpCode == OO_Star || OpCode == OO_Amp) {
               auto *Callee = OpCE->getDirectCallee();
+              if (!Callee)
+                return false;
               auto clsName = safeGetName(Callee->getParent());
               if (!isRefType(clsName) || !OpCE->getNumArgs())
                 return false;
diff --git a/clang/test/Analysis/Checkers/WebKit/uncounted-lambda-captures-decl-protects-this-crash.cpp b/clang/test/Analysis/Checkers/WebKit/uncounted-lambda-captures-decl-protects-this-crash.cpp
new file mode 100644
index 0000000000000..0d25c599ffb3e
--- /dev/null
+++ b/clang/test/Analysis/Checkers/WebKit/uncounted-lambda-captures-decl-protects-this-crash.cpp
@@ -0,0 +1,38 @@
+// RUN: %clang_analyze_cc1 -analyzer-checker=webkit.UncountedLambdaCapturesChecker -verify %s
+
+struct Foo {
+  int x;
+  int y;
+  Foo(int x, int y) : x(x) , y(y) { }
+};
+
+template <typename T>
+struct Baz {
+  void ref() const;
+  void deref() const;
+  Foo operator*();
+};
+
+inline Foo operator*(const Foo& a, const Foo& b);
+
+Baz<Foo> someFunction();
+template <typename CallbackType> void bar(CallbackType callback) {
+  auto baz = someFunction();
+  callback(baz);
+}
+
+struct Obj {
+  void ref() const;
+  void deref() const;
+
+  void foo(Foo foo) {
+    bar([this](auto baz) {
+      // expected-warning at -1{{Captured raw-pointer 'this' to ref-counted type or CheckedPtr-capable type is unsafe [webkit.UncountedLambdaCapturesChecker]}}
+      bar([this, foo = *baz](auto&&) {
+        // expected-warning at -1{{Captured raw-pointer 'this' to ref-counted type or CheckedPtr-capable type is unsafe [webkit.UncountedLambdaCapturesChecker]}}
+        someFunction();
+      });
+    });
+  }
+};
+

``````````

</details>


https://github.com/llvm/llvm-project/pull/127309