[Analyzer] Fix an assertion caused by r250237 (PR25392)

[seaneveson]

Summary

Fix an assertion which occurs when getCXXThisVal() returns an Unknown SVal and the Analyzer tries to get the corresponding memory region.

This assertion was reported in PR25392. The test case from this Bugzilla has been added.

Regards,
Sean Eveson
SN Systems - Sony Computer Entertainment Group

[seaneveson]

Fix an assertion which occurs when getCXXThisVal() returns an Unknown SVal and the Analyzer tries to get the corresponding memory region.

This assertion was reported in PR25392. The test case from this Bugzilla has been added.

(Forgot to add cfe-commits when creating the review).

[dcoughlin]

Hi Sean, I just committed a slightly different fix that I already had prepared (r252506). That fix also handles the case when the ThisVal is a loc that can't be converted to a memory region.

Thanks for looking into this and my apologies for the duplication of effort!

[seaneveson]

Fixed by r252506. Thanks Devin.

lib/StaticAnalyzer/Core/CallEvent.cpp

   SVal ThisVal = getCXXThisVal();
   Values.push_back(ThisVal);
 
+  if (ThisVal.isUnknown())
+    return;
+
   // Don't invalidate if the method is const and there are no mutable fields.
   if (const CXXMethodDecl *D = cast_or_null<CXXMethodDecl>(getDecl())) {
     if (!D->isConst())

test/Analysis/const-method-call.cpp

     s2().f(0);
 }
 
+// --- PR25392 --- //
+
+struct x0;
+template <typename> struct x1 {
+  typedef x0 x2;
+};
+
+template <typename x3, typename x4 = x3> struct x5 {
+public:
+  typename x1<x4>::x2 operator[](int) {} // expected-warning {{control reaches end of non-void function}}
+};
+
+struct x0 {
+public:
+  template <typename> void x6() const;
+  x5<int> x7;
+} x8;
+
+void x9() {
+  x8.x7[0].x6<x5<int> >(); // expected-note {{in instantiation of member function 'x5<int, int>::operator[]' requested here}}
+}
+
 // FIXME
 // When there is a circular reference to an object and a const method is called
 // the object is not invalidated because TK_PreserveContents has already been