| Summary: | makeWeakPtr() on a derived class provides a bad pointer if CanMakeWeakPtr<> is not its first base class | ||
|---|---|---|---|
| Product: | WebKit | Reporter: | Simon Fraser (smfr) <simon.fraser> |
| Component: | Web Template Framework | Assignee: | Nobody <webkit-unassigned> |
| Status: | NEW --- | ||
| Severity: | Normal | CC: | cdumez, ggaren, jiewen_tan, koivisto, lforschler, sam, simon.fraser |
| Priority: | P2 | ||
| Version: | WebKit Nightly Build | ||
| Hardware: | Unspecified | ||
| OS: | Unspecified | ||
Related: https://bugs.webkit.org/show_bug.cgi?id=188799 https://bugs.webkit.org/show_bug.cgi?id=179405 This could probably be marked a dup of one of those. I'd like this to work soonish... A short-term workaround is to list ScrollableArea first in the inheritance hierarchy:
class RenderLayer final : public ScrollableArea, public RenderLayerNode {
Sadly that breaks some other casting I wanted to do (but may have to do differently). I'll try to fix WeakPtr at some point. |
I changed RenderLayer to: class RenderLayer final : public RenderLayerNode, public ScrollableArea { ... } where RenderLayerNode is a base class with virtual members and ScrollableArea is: class ScrollableArea : public CanMakeWeakPtr<ScrollableArea> { ... } This triggered crashes in code that referenced weak ptrs to RenderLayers. It seems that weak_reference_downcast() assumes that the pointers are reinterpret-castable, but that's not always true.