Build fails on GCC 10

[Gaelan]

GCC 10 contains a breaking change: it defaults to -fno-common, which requires globals to be declared in exactly one C file, and referenced elsewhere with extern. This causes openal-soft to fail to build with a linker error:

ld: CMakeFiles/OpenAL.dir/Alc/ALu.c.o:(.rodata+0x3bf60): multiple definition of `FuMa2N3DScale'; CMakeFiles/OpenAL.dir/Alc/ALc.c.o:(.rodata+0xf40): first defined here
ld: CMakeFiles/OpenAL.dir/Alc/ALu.c.o:(.rodata+0x3bfa0): multiple definition of `SN3D2N3DScale'; CMakeFiles/OpenAL.dir/Alc/ALc.c.o:(.rodata+0xf80): first defined here
ld: CMakeFiles/OpenAL.dir/Alc/ALu.c.o:(.rodata+0x3bfe0): multiple definition of `N3D2N3DScale'; CMakeFiles/OpenAL.dir/Alc/ALc.c.o:(.rodata+0xfc0): first defined here
ld: CMakeFiles/OpenAL.dir/Alc/bformatdec.c.o:(.rodata+0x2e0): multiple definition of `SN3D2N3DScale'; CMakeFiles/OpenAL.dir/Alc/ALc.c.o:(.rodata+0xf80): first defined here
ld: CMakeFiles/OpenAL.dir/Alc/bformatdec.c.o:(.rodata+0x320): multiple definition of `N3D2N3DScale'; CMakeFiles/OpenAL.dir/Alc/ALc.c.o:(.rodata+0xfc0): first defined here
ld: CMakeFiles/OpenAL.dir/Alc/bformatdec.c.o:(.rodata+0x2a0): multiple definition of `FuMa2N3DScale'; CMakeFiles/OpenAL.dir/Alc/ALc.c.o:(.rodata+0xf40): first defined here
ld: CMakeFiles/OpenAL.dir/Alc/panning.c.o:(.rodata+0x1360): multiple definition of `FuMa2N3DScale'; CMakeFiles/OpenAL.dir/Alc/ALc.c.o:(.rodata+0xf40): first defined here
ld: CMakeFiles/OpenAL.dir/Alc/panning.c.o:(.rodata+0x13e0): multiple definition of `N3D2N3DScale'; CMakeFiles/OpenAL.dir/Alc/ALc.c.o:(.rodata+0xfc0): first defined here
ld: CMakeFiles/OpenAL.dir/Alc/panning.c.o:(.rodata+0x13a0): multiple definition of `SN3D2N3DScale'; CMakeFiles/OpenAL.dir/Alc/ALc.c.o:(.rodata+0xf80): first defined here
collect2: error: ld returned 1 exit status

This could be fixed by declaring globals in exactly one place as noted above, or by explicitly passing -fcommon to gcc.

[kcat]

How is it supposed to work for global constexpr values/arrays? Inline variables are a C++17 feature, but it should be possible to have global constexpr variables in C++14.

[Gaelan]

I'm afraid I know very little about C++, so I can't be of much help here.

…

On Jan 20, 2021, at 10:31 PM, kcat ***@***.***> wrote: How is it supposed to work for global constexpr values/arrays? Inline variables are a C++17 feature, but it should be possible to have global constexpr variables in C++14. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#519 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABCJTBUBODPJC26RQ3TDAILS27C3VANCNFSM4WMI37MA>.

[kcat]

Fixed with commit 20f5e7c.