[analyzer] pr38072: Suppress an assertion failure for eliding the same destructor twice due to the default argument problem.

[NoQ]

Summary

@alexfh provided an example that demonstrates that elided copy constructors may get agglutinated due to improper control flow when default arguments are involved.

Suppress the assertion failure for now. Proper support is still an open problem.

[NoQ]

lib/StaticAnalyzer/Core/ExprEngine.cpp

434–435

Same problem here.

[alexfh]

FTR, this is http://llvm.org/PR38072

[george.karpenkov]

LGTM with a nit.

test/Analysis/temporaries.cpp

472

// no-crash?

lib/StaticAnalyzer/Core/ExprEngine.cpp

ExprEngine::createTemporaryRegionIfNeeded(ProgramStateRef State,
   return State;
 }
 
 ProgramStateRef
 ExprEngine::addObjectUnderConstruction(ProgramStateRef State,
                                        const ConstructionContextItem &Item,
                                        const LocationContext *LC, SVal V) {
   ConstructedObjectKey Key(Item, LC->getStackFrame());
   // FIXME: Currently the state might already contain the marker due to
   // incorrect handling of temporaries bound to default parameters.
   assert(!State->get<ObjectsUnderConstruction>(Key) ||
          Key.getItem().getKind() ==
              ConstructionContextItem::TemporaryDestructorKind);
   return State->set<ObjectsUnderConstruction>(Key, V);
 }
 
 Optional<SVal>
 ExprEngine::getObjectUnderConstruction(ProgramStateRef State,
ExprEngine::finishObjectConstruction(ProgramStateRef State,
   assert(State->contains<ObjectsUnderConstruction>(Key));
   return State->remove<ObjectsUnderConstruction>(Key);
 }
 
 ProgramStateRef ExprEngine::elideDestructor(ProgramStateRef State,
                                             const CXXBindTemporaryExpr *BTE,
                                             const LocationContext *LC) {
   ConstructedObjectKey Key({BTE, /*IsElided=*/true}, LC);
-  assert(!State->contains<ObjectsUnderConstruction>(Key));
+  // FIXME: Currently the state might already contain the marker due to
+  // incorrect handling of temporaries bound to default parameters.
   return State->set<ObjectsUnderConstruction>(Key, UnknownVal());
 }
 
 ProgramStateRef
 ExprEngine::cleanupElidedDestructor(ProgramStateRef State,
                                     const CXXBindTemporaryExpr *BTE,
                                     const LocationContext *LC) {
   ConstructedObjectKey Key({BTE, /*IsElided=*/true}, LC);

test/Analysis/temporaries.cpp

#if __cplusplus >= 201103L
   CtorWithNoReturnDtor returnNoReturnDtor() {
     return {1}; // no-crash
   }
 #endif
 
 #endif // TEMPORARY_DTORS
 }
 
+namespace default_param_elided_destructors {
+struct a {
+  ~a();
+};
+struct F {
+  a d;
+  F(char *, a = a());
+};
+void g() {
+  char h[1];
+  for (int i = 0;;)
+    F j(i ? j : h);
+}
+} // namespace default_param_elided_destructors
+
 void testStaticMaterializeTemporaryExpr() {
   static const Trivial &ref = getTrivial();
   clang_analyzer_eval(ref.value == 42); // expected-warning{{TRUE}}
 
   static const Trivial &directRef = Trivial(42);
   clang_analyzer_eval(directRef.value == 42); // expected-warning{{TRUE}}
 
 #if __has_feature(cxx_thread_local)