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https://issues.apache.org/jira/browse/XERCESC-2088?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15991345#comment-15991345
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Alberto Massari commented on XERCESC-2088:
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This is a cast required by the fact that each implementation class derives only
from the interface class, and includes the implementation of the basic methods
from DOMNode by embedding a DOMNodeImpl instance. This instance is always the
first member of the implementation class, so actually it doesn't matter that
the method does a cast to DOMElementImpl, as any other class would be just
fine. If the compiler doesn't accept a C-style cast, maybe a
reinterpret_cast<DOMElementImpl*> could work
> Bad casting from DOMTextImpl to DOMElementImpl
> ----------------------------------------------
>
> Key: XERCESC-2088
> URL: https://issues.apache.org/jira/browse/XERCESC-2088
> Project: Xerces-C++
> Issue Type: Bug
> Components: DOM
> Affects Versions: 3.1.1, 3.1.2, 3.1.3, 3.1.4
> Environment: ubuntu 16.04 LTS, Intel(R) Core(TM) i7-6700 CPU @
> 3.40GHz, 16GB
> Reporter: Yuseok Jeon
> Attachments: Actual_result.txt, relationship_tree.jpeg
>
>
> Hi all,
> Our recently developed type confusion detection tool reports a type_confusion
> error in the "xercesc/dom/imple/DOMCasts.hpp"
> xercesc/dom/imple/DOMCasts.hpp, line 146
> static inline DOMNodeImpl *castToNodeImpl(const DOMNode *p)
> {
> DOMElementImpl *pE = (DOMElementImpl *)p;
> return &(pE->fNode);
> }
> p is pointing to the object allocated as DOMTextImpl, and it is casted into
> DOMElementImpl. However, since DOMElementImpl is not a subobject of
> DOMTextImpl, it is violating C++ standard rules 5.2.9/11 (down casting is
> undefined if the object that the pointer to be casted points to is not a
> suboject of down casting type) and causes undefined behaviors.
> There are similar type-confusion cases as below links.
> - (libstdc++) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60734
> - (Firefox) https://bugzilla.mozilla.org/show_bug.cgi?id=1074280
> I attached a actual type confusion report and object relationship
> information.
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