[Interest] Porting to Qt5/macx-xcode Mountain Lion

Joshua Grauman jnfo-c at grauman.com
Thu Jan 24 23:21:06 CET 2013


Ok, I think I've found the root problem. QTextCodec::codecByName("UTF-8") 
is returning 0. It's a static function, so I'm lost as to why this would 
be. I didn't compile my own Qt, just downloaded the main Qt5.0.0-clang SDK 
from the qt-project website and installed. This is what is causing the 
segfault in QTextStream::readLine(). Any idea what could be causing 
codecByName not to find UTF-8? Thanks!

Josh

> I'm not sure I did this correctly, but it did give some more information.
> Now I can see that it is segfaulting on QTextCodec::toUnicode(), which
> incidentally, also segfaults in another program I have. So I think I can
> trace most (all?) my segfaults to this function. Thanks for any more help!
>
> Josh
>
> Program received signal EXC_BAD_ACCESS, Could not access memory.
> Reason: KERN_INVALID_ADDRESS at address: 0x0000000000000000
> 0x000000010195730e in QTextCodec::toUnicode ()
> (gdb) backtrace
> #0  0x000000010195730e in QTextCodec::toUnicode ()
> #1  0x0000000101a2bea7 in QTextStreamPrivate::fillReadBuffer ()
> #2  0x0000000101a2cb1a in QTextStreamPrivate::scan ()
> #3  0x0000000101a2e5aa in QTextStream::readLine ()
> #4  0x0000000100005e6d in main ()
>
>> On quinta-feira, 24 de janeiro de 2013 19.36.02, Andreas Pakulat wrote:
>>>> Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
>>>> 0   QtCore                              0x0000000100d6bb0b
>>>> QTextStreamPrivate::fillReadBuffer(long long) + 299
>>>> 1   QtCore                              0x0000000100d6c26f
>>>> QTextStreamPrivate::scan(QChar const**, int*, int,
>>>> QTextStreamPrivate::TokenDelimiter) + 143
>>>> 2   QtCore                              0x0000000100d6d5dd
>>>> QTextStream::readLine(long long) + 125
>>>> 3   com.yourcompany.trainer             0x0000000100005e59 main + 2825
>>>> 4   com.yourcompany.trainer             0x00000001000028d4 start + 52
>>>
>>> Hmm, unfortunately thats not enough, its apparently crashing within
>>> fillReadBuffer, but the line is not available. Presumably this is
>>> because you didn't configure Qt with -debug and hence only minimal
>>> debug information are available. So re-configuring and rebuilding Qt
>>> would most probably give a more helpful information.
>>
>> That's because it's an xcode / Mac OS X backtrace.
>>
>> Please give us a gdb backtrace, of the application when launched with
>> DYLD_IMAGE_SUFFIX=_debug. That should select the debugging version of QtCore.
>>
>>
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