Bug#764510: gcc-4.9: gnucash segfaults when built with GCC 4.9

[Matthias Klose <doko@debian.org>]

Am 08.10.2014 um 19:32 schrieb Frédéric Brière:
> Package: gcc-4.9
> Version: 4.9.1-16
> Severity: important
> Control: affects -1 gnucash
> 
> [ I'm probably filing this under the wrong package/severity; please
> reassign/adjust as you see fit. ]
> 
> 
> The current version of gnucash (1:2.6.4-1) repeatably segfaults upon
> launch (and entering one value), which does not happen with the previous
> version (1:2.6.3-1).  See the attached file for a full backtrace with
> debug symbols.
> 
> After some testing, I found that the emergence of the bug does not come
> from gnucash, but GCC: compiling either version with 4.8 (as was the
> case with 1:2.6.3-1) works fine, while compiling with 4.9 (as was the
> case with 1:2.6.4-1) triggers the bug.
> 
> I'm not quite sure how to proceed from that point on; I suppose that the
> bug itself could very well be in gnucash (or glib2.0, or gtk+2.0) with
> gcc/g++ 4.9 merely exposing it.  Trying to bisect all four at the same
> time seems like such a daunting task beyond my expertise, so any
> guidance would be welcome.

are there any suspicious compiler warnings? maybe fix these first.

please try to build gnucash with -O1 or -O0 and see if it works. If yes, build
half of the object files with -O2 (the default) and with -O0.  Then try to
reduce the files built with -O0.  Once you have identified one file, continue
using the optimize attribute to lower the optimization level for a function
until you have identified the misbuilt function.

or if you have an idea from looking at the backtrace, maybe start with this file.