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

Add a missing nullptr check to declProtectsThis.

Author: rniwa

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;
@@ -276,9 +278,10 @@ class UncountedLambdaCapturesChecker
           }
           if (auto *UO = dyn_cast<UnaryOperator>(Arg)) {
             auto OpCode = UO->getOpcode();
-            if (OpCode == UO_Deref || OpCode == UO_AddrOf)
+            if (OpCode == UO_Deref || OpCode == UO_AddrOf) {
               Arg = UO->getSubExpr()->IgnoreParenCasts();
-            continue;
+              continue;
+            }
           }
           break;
         } while (Arg);

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*();
+  bool 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@-1{{Captured raw-pointer 'this' to ref-counted type or CheckedPtr-capable type is unsafe [webkit.UncountedLambdaCapturesChecker]}}
+      bar([this, foo = *baz, foo2 = !baz](auto&&) {
+        // expected-warning@-1{{Captured raw-pointer 'this' to ref-counted type or CheckedPtr-capable type is unsafe [webkit.UncountedLambdaCapturesChecker]}}
+        someFunction();
+      });
+    });
+  }
+};