delete this dangerous in duchain? [was: Crash in duchaintest]

[Andreas Pakulat]

On 30.01.09 20:41:41, Andreas Pakulat wrote:
> Hi,
> 
> happens when executing duchaintest, apparently in the
> spezializedTemplateTest().
> 
> The crash is actually inside the assembler code for the return call in the
> TopDUContext::deleting() method. No idea what might be going on, maybe I
> can talk Frerich (our assembler guru) into doing some debugging with me
> next week...
> 
>         kdevplatformlanguage.dll!KDevelop::TopDUContext::deleting()  Zeile
> 1314 + 0x6 Bytes        C++
>         kdevplatformlanguage.dll!KDevelop::DUContext::~DUContext()  Zeile
> 559 + 0x8 Bytes C++
>         kdev4cppduchain.dll!Cpp::CppDUContext<KDevelop::DUContext>::~CppDUContext<KDevelop::DUContext>()
> Zeile 601 + 0x2d Bytes  C++
>         kdev4cppduchain.dll!Cpp::CppDUContext<KDevelop::DUContext>::`scalar
> deleting destructor'()  + 0x16 Bytes    C++
>         kdevplatformlanguage.dll!KDevelop::TopDUContextDynamicData::~TopDUContextDynamicData()
> Zeile 127 + 0x30 Bytes  C++
>         kdevplatformlanguage.dll!KDevelop::TopDUContextDynamicData::`scalar
> deleting destructor'()  + 0x16 Bytes    C++
>         kdevplatformlanguage.dll!KDevelop::TopDUContext::deleteSelf()
> Zeile 897 + 0x1c Bytes  C++
>         kdevplatformlanguage.dll!KDevelop::DUChainPrivate::removeDocumentChainFromMemory(KDevelop::TopDUContext
> * context=0x050811c0)  Zeile 332        C++
>         kdevplatformlanguage.dll!KDevelop::DUChain::removeDocumentChain(KDevelop::TopDUContext
> * context=0x050811c0)  Zeile 870        C++
> >       duchaintest.exe!release(KDevelop::TopDUContext * top=0x050811c0)
> >       Zeile 82 + 0x1d Bytes   C++
>         duchaintest.exe!TestDUChain::testSpecializedTemplates()  Zeile 2289
> + 0x9 Bytes     C++

Hitting this with openprojectpage.h now outside the test. I'm wondering
wether accessing m_dynamicData is actually a good idea at this point. After
all, ~DUContext is being called from ~TopDUContextDynamicData, hence
m_dynamicData might already have been deleted or is now inaccessible.

In particular I'm seeing a delete this _before_ deleting the dynamic data
and local attribute in ~TopDUContext. Now, you may call me a C++ newbie,
but that really doesn't look right, in particular accessing members of an
already-deleted object. It seems msvc puts member variable pointers onto
bogus adresses when deleting an object, as m_dynamicData value is 0xdddddd.

Moving the delete this to the end of the method fixes the crash here, but
is this "safe"? Was there a special intent for that delete call?

Andreas

> Andreas
> 
> -- 
> Keep emotionally active.  Cater to your favorite neurosis.
> 
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