On 08/11/2014 07:12 PM, Peter A. Bigot wrote:
On 08/11/2014 02:02 PM, Peter A. Bigot wrote:
The program below built on the target with the MACHINE=beaglebone
gcc-4.9.1 compiler from Yocto/OpenEmbedded poky master produces this
error:
beaglebone[52]$ g++ -std=c++1y -pthread test.cc && ./a.out
starting
joining
pure virtual method called
terminate called without an active exception
Aborted (core dumped)
When the program is recompiled with the defines for
__GCC_HAVE_SYNC_COMPARE_AND_SWAP_X enabled as suggested at
https://groups.google.com/d/msg/automatak-dnp3/Jisp_zGhd5I/ck_Cj6nO8joJ
it works:
beaglebone[53]$ g++ -std=c++1y -pthread test.cc && ./a.out
starting
joining
doit
done
Preliminary analysis confirms that the built-ins for those defines
are not being added by the compiler because it thinks the target
doesn't support those operations. Nonetheless, it doesn't use the
substitutes that are obviously available.
Can anybody recall anything about the way GCC is built under OE that
would explain this?
Not an OE problem. See:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62100
I'm testing a patch locally and awaiting GCC maintainer comment before
proposing it for OE.
The GNU folks objected to the workaround and suggested that the behavior
is evidence that libstdc++ was not built with the same ABI flags as the
compiler uses by default.
I built the release version of gcc 4.9.1 on the beaglebone and confirmed
that it works fine.
This is indeed an OE-Core bug.
I've just sent a series of cleanup patches to gcc that may make it
easier to detect differences. I've spent some time changing the
"obvious" things and have been unable to figure out where the
compilation is going wrong. I'm hoping somebody else can help out; as
C++11 becomes more prevalent the workaround recommended on stackoverflow
and other sites will continue to propagate, and it's not the right solution.
Peter
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