[blfs-support] Problem with gcc-6 and qt--5.6
pierre.bechetoille at free.fr
Sat May 21 14:55:05 PDT 2016
Le 21/05/2016 23:07, Bruce Dubbs a écrit :
> Pierre Bechetoille wrote:
>> Following BLFS dev, I built latest KDE plasma and sddm with QT-5.6.0.
>> build was OK.
>> However starting sddm or kde plasma failed (segmentation fault).
>> Using gdb on sddm, I finally found the culprit: the crash occured in
>> QV4::ExecutionEngine::newArrayObject(int) () from
>> Googling the problem, I found this issue in Qt bugreports:
>> The description explains exactly what happens :
>> "Upcoming gcc-6 has much more aggressive dead-store elimination.
>> See: http://gcc.gnu.org/gcc-6/porting_to.html (-flifetime-dse section).
>> Due to undefined behavior in QV4::ExecutionEngine::newArrayObject(int)
>> this will lead to segfaults"
>> There is no patch currently available however, the author suggests
>> compiling Qt-5.6.0 with gcc-6 adding "-flifetime-dse=1" to
>> (addition in
>> And it works ! I now can start sddm / kde plasma without crash.
>> Hope this can help if anyone encounters the same problem.
> Sounds like we need a sed, but I do not see any QMAKE_CXXFLAGS
> settings in that qmake.conf file. Do we just need to add
> QMAKE_CXXFLAGS += -flifetime-dse=1
> to the end of the file?
> -- Bruce
Yes, it is what I did. But there are lot of .conf files in mkspecs
directory: maybe there is a more appropriate place (e.g.
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