On Aug 6, 2012, at 16:25 , Anna Zaks <[email protected]> wrote:
> +// Return a better dynamic type if one can be derived from the cast.
> +// Compare the current dynamic type of the region and the new type to which
> we
> +// are casting. If the new type is lower in the inheritance hierarchy, pick
> it.
> +const ObjCObjectPointerType *
> +DynamicTypePropagation::getBetterObjCType(const Expr *CastE,
> + CheckerContext &C) const {
> + const MemRegion *ToR = C.getSVal(CastE).getAsRegion();
> + assert(ToR);
> +
> + // Get the old and new types.
> + const ObjCObjectPointerType *NewTy =
> + CastE->getType()->getAs<ObjCObjectPointerType>();
> + if (!NewTy)
> + return 0;
> + QualType OldDTy = C.getState()->getDynamicTypeInfo(ToR).getType();
> + if (OldDTy.isNull()) {
> + return NewTy;
> + }
> + const ObjCObjectPointerType *OldTy =
> + OldDTy->getAs<ObjCObjectPointerType>();
> + if (!OldTy)
> + return 0;
> +
> + // Id the old type is 'id', the new one is more precise.
> + if (OldTy->isObjCIdType() && !NewTy->isObjCIdType())
> + return NewTy;
> +
> + // Return new if it's a subclass of old.
> + const ObjCInterfaceDecl *ToI = NewTy->getInterfaceDecl();
> + const ObjCInterfaceDecl *FromI = OldTy->getInterfaceDecl();
> + if (ToI && FromI && FromI->isSuperClassOf(ToI))
> + return NewTy;
> +
> + return 0;
> +}
Why is this here and not in addDynamicTypeInfo? (If there's a good reason
that's fine; it just seemed odd.)
> +// Casting to parent should not pessimize the dynamic type.
> ++ (void) testCastToParent {
> + id a = [[self alloc] init];
> + MyParent *p = a;
> + clang_analyzer_eval([p getZeroOverridden] == 0); //
> expected-warning{{TRUE}}
> +}
> +
> +// The type of parameter gets used.
> ++ (void)testTypeFromParam:(MyParent*) p {
> + clang_analyzer_eval([p getZero] == 0); // expected-warning{{TRUE}}
> +}
> +
> +// Test implisit cast.
> ++ (void) testCastFromId:(id) a {
> + MyParent *p = a;
> + clang_analyzer_eval([p getZero] == 0); // expected-warning{{TRUE}}
> }
Typo: "implisit".
This is also eventually the case where we should have a branch, since even if
'a' is a MyParent instance, the implementation of -getZero should have been
overridden. (With all the caveats about MyParent being declared in the main
source file, but also having subclasses.)
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