[webkit.UncountedLambdaCapturesChecker] Fix a nullptr deference. (#120702)

Added a nullptr check.

Author: rniwa

clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLambdaCapturesChecker.cpp

@@ -155,6 +155,8 @@ class UncountedLambdaCapturesChecker
         if (!Init)
           return nullptr;
         TempExpr = dyn_cast<CXXBindTemporaryExpr>(Init->IgnoreParenCasts());
+        if (!TempExpr)
+          return nullptr;
         return dyn_cast_or_null<LambdaExpr>(TempExpr->getSubExpr());
       }
 

clang/test/Analysis/Checkers/WebKit/uncounted-lambda-captures-find-lambda-crash.cpp

@@ -0,0 +1,16 @@
+// RUN: %clang_analyze_cc1 -analyzer-checker=webkit.UncountedLambdaCapturesChecker -verify %s
+// expected-no-diagnostics
+
+struct Foo {
+  int x;
+  int y;
+  Foo(int x, int y) : x(x) , y(y) { }
+  ~Foo() { }
+};
+
+Foo bar(const Foo&);
+void foo() {
+  int x = 7;
+  int y = 5;
+  bar(Foo(x, y));
+}