Bug 96084 – There is no need to call "Document::removeFocusedNodeOfSubtree()" after calling "Document::prepareForDestruction()

• Component: DOM
• Status: UNCONFIRMED

[luowenping]

i'm fused by function" FrameLoader::clear(bool clearWindowProperties, bool clearScriptObjects, bool clearFrameView)", in this method
we have code like this:

    if (!m_frame->document()->inPageCache()) {
        m_frame->document()->cancelParsing();
        m_frame->document()->stopActiveDOMObjects();
        if (m_frame->document()->attached()) {
            m_frame->document()->prepareForDestruction();
            m_frame->document()->removeFocusedNodeOfSubtree(m_frame->document());
        }
    }

step 1:"Document::prepareForDestruction()" will call "Document::detach()", in detach() method, we will make m_focusedNode = 0;
void Document::prepareForDestruction()
{
    disconnectDescendantFrames();
    if (DOMWindow* window = this->domWindow())
        window->willDetachDocumentFromFrame();
    detach();
}

step2:"Document::removeFocusedNodeOfSubtree(Node* node, bool amongChildrenOnly)" will return first when m_focusedNode = 0;

void Document::removeFocusedNodeOfSubtree(Node* node, bool amongChildrenOnly)
{
    if (!m_focusedNode || this->inPageCache()) // If the document is in the page cache, then we don't need to clear out the focused node.
        return;
        
    bool nodeInSubtree = false;
    if (amongChildrenOnly)
        nodeInSubtree = m_focusedNode->isDescendantOf(node);
    else
        nodeInSubtree = (m_focusedNode == node) || m_focusedNode->isDescendantOf(node);
    
    if (nodeInSubtree)
        document()->focusedNodeRemoved();
}

step3: this means we has no deed to call "Document::removeFocusedNodeOfSubtree()" after call "Document::prepareForDestruction()"
may be , m_focusedNode will be set value in Document::detach().but This is real we want ?

[linyufei]

I am also confused with this issue:
void FrameLoader::clear(bool clearWindowProperties, bool clearScriptObjects, bool clearFrameView)
{
    m_frame->editor()->clear();

    if (!m_needsClear)
        return;
    m_needsClear = false;
    
    if (!m_frame->document()->inPageCache()) {
        m_frame->document()->cancelParsing();
        m_frame->document()->stopActiveDOMObjects();
        if (m_frame->document()->attached()) {
            m_frame->document()->willRemove();
            m_frame->document()->detach();
            
            m_frame->document()->removeFocusedNodeOfSubtree(m_frame->document());
        }
    }

since"m_frame->document()->detach()" will set the document's focusenode null
and "removeFocusedNodeOfSubtree" will return if the document's focusnode is null.

So the code in removeFocusedNodeOfSubtree will never be called.

And I wonder why will there be such a statement.

Anyone knows? Thank you!

[Ahmad Saleem]

[e-mail] - Is this something still required? Thanks!

[Alexey Proskuryakov]

This was never a bug report, and webkit-dev mailing list would have been more appropriate for this question. 

FrameLoader::clear has changed so much that it would take too much effort to see if this is still applicable in some way.