[analyzer]FieldRegion in getStaticSize should return size of pointee type

[jcsxky]

Summary

In getStaticSize, case of FieldRegionKind should return size of pointee type of the member. In the following example:

struct B {
	int x;
	int y;
	int z;
};

class A{
public:
	void foo(){
		m++;
	}
private:
	B *m;
};

getDynamicElementCount of m region, if getDynamicExtent return the pointer size, getDynamicElementCount returns 0 in 64bit architecture(since pointer size is 8 while size of pointee type is 12). Use pointee type instead, it will return 1.

[donat.nagy]

Please add a testcase that demonstrates this issue (fails when your change in MemRegion.cpp isn't added) and shows that your commit fixes it.

[jcsxky]

In D159412#4636813, @donat.nagy wrote:

Please add a testcase that demonstrates this issue (fails when your change in MemRegion.cpp isn't added) and shows that your commit fixes it.

Thanks for your advice. We use this api in our own project and miss some cases which leads the incorrect result. I will abandon this patch later.

clang/lib/StaticAnalyzer/Core/MemRegion.cpp

case MemRegion::ObjCStringRegionKind: {
     return getElementExtent(Ty, SVB);
   }
   case MemRegion::FieldRegionKind: {
     // Force callers to deal with bitfields explicitly.
     if (cast<FieldRegion>(SR)->getDecl()->isBitField())
       return UnknownVal();
 
     QualType Ty = cast<TypedValueRegion>(SR)->getDesugaredValueType(Ctx);
+    if (Ty->isPointerType()) {
+      QualType PointeeTy = Ty->getPointeeType();
+      if(!PointeeTy->isIncompleteType() && PointeeTy->isObjectType()){
+        Ty = PointeeTy;
+      }
+    }
     const DefinedOrUnknownSVal Size = getElementExtent(Ty, SVB);
 
     // We currently don't model flexible array members (FAMs), which are:
     //  - int array[]; of IncompleteArrayType
     //  - int array[0]; of ConstantArrayType with size 0
     //  - int array[1]; of ConstantArrayType with size 1
     // https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
     const auto isFlexibleArrayMemberCandidate =