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Compilation fails with gcc-10 #216

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yarda opened this issue Feb 10, 2020 · 0 comments
Open

Compilation fails with gcc-10 #216

yarda opened this issue Feb 10, 2020 · 0 comments

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@yarda
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@yarda yarda commented Feb 10, 2020

/usr/bin/ld: mausezahn/cdp.o:/builddir/build/BUILD/netsniff-ng-0.6.6/staging/mz.h:498: multiple definition of `tx'; mausezahn/automops.o:/builddir/build/BUILD/netsniff-ng-0.6.6/staging/mz.h:498: first defined here
/usr/bin/ld: mausezahn/cdp.o:/builddir/build/BUILD/netsniff-ng-0.6.6/staging/mz.h:288: multiple definition of `mz_start'; mausezahn/automops.o:/builddir/build/BUILD/netsniff-ng-0.6.6/staging/mz.h:288: first defined here
/usr/bin/ld: mausezahn/cdp.o:/builddir/build/BUILD/netsniff-ng-0.6.6/staging/mz.h:287: multiple definition of `total_d'; mausezahn/automops.o:/builddir/build/BUILD/netsniff-ng-0.6.6/staging/mz.h:287: first defined here
/usr/bin/ld: mausezahn/cdp.o:/builddir/build/BUILD/netsniff-ng-0.6.6/staging/mz.h:280: multiple definition of `verbose'; mausezahn/automops.o:/builddir/build/BUILD/netsniff-ng-0.6.6/staging/mz.h:280: first defined here
/usr/bin/ld: mausezahn/cdp.o:/builddir/build/BUILD/netsniff-ng-0.6.6/staging/mz.h:279: multiple definition of `quiet'; mausezahn/automops.o:/builddir/build/BUILD/netsniff-ng-0.6.6/staging/mz.h:279: first defined here
/usr/bin/ld: mausezahn/cdp.o:/builddir/build/BUILD/netsniff-ng-0.6.6/staging/mops.h:691: multiple definition of `mp_head'; mausezahn/automops.o:/builddir/build/BUILD/netsniff-ng-0.6.6/staging/mops.h:691: first defined here
/usr/bin/ld: mausezahn/cdp.o:/builddir/build/BUILD/netsniff-ng-0.6.6/staging/mops.h:249: multiple definition of `amp_head'; mausezahn/automops.o:/builddir/build/BUILD/netsniff-ng-0.6.6/staging/mops.h:249: first defined here
/usr/bin/ld: mausezahn/cdp.o:/builddir/build/BUILD/netsniff-ng-0.6.6/staging/mops.h:118: multiple definition of `max_frame_s'; mausezahn/automops.o:/builddir/build/BUILD/netsniff-ng-0.6.6/staging/mops.h:118: first defined here
...

This is caused by a change in GCC 10 defaults from -fcommon to -fno-common [1]:

GCC now defaults to -fno-common. As a result, global variable accesses are more efficient on various targets. In C, global variables with multiple tentative definitions now result in linker errors. With -fcommon such definitions are silently merged during linking.

If compiled with -fcommon it builds OK. The better solution is to fix the code to define the variables just once.

[1] https://gcc.gnu.org/gcc-10/changes.html

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