[analyzer] SmartPtrModeling: Fix a null dereference.

Don't crash when trying to model a call in which the callee is unknown
in compile time, eg. a pointer-to-member call.

Differential Revision: https://reviews.llvm.org/D61285

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@359530 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit 4ecb1e1)

Author: haoNoQ

lib/StaticAnalyzer/Checkers/SmartPtrModeling.cpp

@@ -39,7 +39,7 @@ bool SmartPtrModeling::isNullAfterMoveMethod(
   // TODO: Handle other methods, such as .get() or .release().
   // But once we do, we'd need a visitor to explain null dereferences
   // that are found via such modeling.
-  const auto *CD = dyn_cast<CXXConversionDecl>(Call->getDecl());
+  const auto *CD = dyn_cast_or_null<CXXConversionDecl>(Call->getDecl());
   return CD && CD->getConversionType()->isBooleanType();
 }
 

test/Analysis/smart-ptr.cpp

@@ -16,3 +16,13 @@ void derefAfterMove(std::unique_ptr<int> P) {
   // TODO: Report a null dereference (instead).
   *P.get() = 1; // expected-warning {{Method called on moved-from object 'P'}}
 }
+
+// Don't crash when attempting to model a call with unknown callee.
+namespace testUnknownCallee {
+struct S {
+  void foo();
+};
+void bar(S *s, void (S::*func)(void)) {
+  (s->*func)(); // no-crash
+}
+} // namespace testUnknownCallee