Compiling error on Alpine Armv7 (multiple definition)

[DvaMishkiLapa]

Good afternoon, I encountered the following problem during compilation:

...
[ 98%] Building C object CMakeFiles/gish.dir/main.c.o
[100%] Linking C executable /home/thesame/GitProjects/gish/gish
/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/game/custom.c.o:(.bss+0x0): multiple definition of `fread2'; CMakeFiles/gish.dir/game/block.c.o:(.bss+0x0): first defined here
/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/game/custom.c.o:(.bss+0x4): multiple definition of `fwrite2'; CMakeFiles/gish.dir/game/block.c.o:(.bss+0x4): first defined here
/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/game/game.c.o:(.bss+0x0): multiple definition of `numofobjectrenders'; CMakeFiles/gish.dir/game/editor.c.o:(.bss+0x0): first defined here
/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/game/game.c.o:(.bss+0x4): multiple definition of `objectrender'; CMakeFiles/gish.dir/game/editor.c.o:(.bss+0x4): first defined here
/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/game/gametexture.c.o:(.bss+0x0): multiple definition of `fread2'; CMakeFiles/gish.dir/game/block.c.o:(.bss+0x0): first defined here
/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/game/gametexture.c.o:(.bss+0x4): multiple definition of `fwrite2'; CMakeFiles/gish.dir/game/block.c.o:(.bss+0x4): first defined here
/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/game/high.c.o:(.bss+0x0): multiple definition of `fread2'; CMakeFiles/gish.dir/game/block.c.o:(.bss+0x0): first defined here
/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/game/high.c.o:(.bss+0x4): multiple definition of `fwrite2'; CMakeFiles/gish.dir/game/block.c.o:(.bss+0x4): first defined here
/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/game/level.c.o:(.bss+0x0): multiple definition of `fread2'; CMakeFiles/gish.dir/game/block.c.o:(.bss+0x0): first defined here
/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/game/level.c.o:(.bss+0x4): multiple definition of `fwrite2'; CMakeFiles/gish.dir/game/block.c.o:(.bss+0x4): first defined here
/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/game/lighting.c.o:(.bss+0x0): multiple definition of `numofobjectrenders'; CMakeFiles/gish.dir/game/editor.c.o:(.bss+0x0): first defined here
/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/game/lighting.c.o:(.bss+0x4): multiple definition of `objectrender'; CMakeFiles/gish.dir/game/editor.c.o:(.bss+0x4): first defined here/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/game/music.c.o:(.bss+0x0): multiple definition of `fread2'; CMakeFiles/gish.dir/game/block.c.o:(.bss+0x0): first defined here
/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/game/music.c.o:(.bss+0x4): multiple definition of `fwrite2'; CMakeFiles/gish.dir/game/block.c.o:(.bss+0x4): first defined here
/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/game/player.c.o:(.bss+0x0): multiple definition of `fread2'; CMakeFiles/gish.dir/game/block.c.o:(.bss+0x0): first defined here
/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/game/player.c.o:(.bss+0x4): multiple definition of `fwrite2'; CMakeFiles/gish.dir/game/block.c.o:(.bss+0x4): first defined here
/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/game/prerender.c.o:(.bss+0x0): multiple definition of `numofobjectrenders'; CMakeFiles/gish.dir/game/editor.c.o:(.bss+0x0): first defined here
/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/game/prerender.c.o:(.bss+0x4): multiple definition of `objectrender'; CMakeFiles/gish.dir/game/editor.c.o:(.bss+0x4): first defined here
/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/game/render.c.o:(.bss+0x0): multiple definition of `numofobjectrenders'; CMakeFiles/gish.dir/game/editor.c.o:(.bss+0x0): first defined here
/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/game/render.c.o:(.bss+0x4): multiple definition of `objectrender'; CMakeFiles/gish.dir/game/editor.c.o:(.bss+0x4): first defined here
/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/game/replay.c.o:(.bss+0x0): multiple definition of `fread2'; CMakeFiles/gish.dir/game/block.c.o:(.bss+0x0): first defined here
/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/game/replay.c.o:(.bss+0x4): multiple definition of `fwrite2'; CMakeFiles/gish.dir/game/block.c.o:(.bss+0x4): first defined here
/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/sdl/endian.c.o:(.bss+0x0): multiple definition of `fread2'; CMakeFiles/gish.dir/game/block.c.o:(.bss+0x0): first defined here
/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/sdl/endian.c.o:(.bss+0x4): multiple definition of `fwrite2'; CMakeFiles/gish.dir/game/block.c.o:(.bss+0x4): first defined here
/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/sdl/file.c.o:(.bss+0x0): multiple definition of `fread2'; CMakeFiles/gish.dir/game/block.c.o:(.bss+0x0): first defined here
/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/sdl/file.c.o:(.bss+0x4): multiple definition of `fwrite2'; CMakeFiles/gish.dir/game/block.c.o:(.bss+0x4): first defined here
/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/video/texture.c.o:(.bss+0x0): multiple definition of `fread2'; CMakeFiles/gish.dir/game/block.c.o:(.bss+0x0): first defined here
/usr/lib/gcc/armv7-alpine-linux-musleabihf/13.1.1/../../../../armv7-alpine-linux-musleabihf/bin/ld: CMakeFiles/gish.dir/video/texture.c.o:(.bss+0x4): multiple definition of `fwrite2'; CMakeFiles/gish.dir/game/block.c.o:(.bss+0x4): first defined here
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/gish.dir/build.make:1001: /home/thesame/GitProjects/gish/gish] Error 1
make[1]: *** [CMakeFiles/Makefile2:83: CMakeFiles/gish.dir/all] Error 2
make: *** [Makefile:91: all] Error 2

More information:

$ ld -v
GNU ld (GNU Binutils) 2.40

$ uname -a
Linux nokia-n900 6.3.4 #1-postmarketOS SMP PREEMPT Sun May 28 18:31:00 UTC 2023 armv7l Linux

$ gcc --version
gcc (Alpine 13.1.1_git20230527) 13.1.1 20230527

[marcosCapistrano]

Same problem here on ubuntu

EDIT:
Fixed it by declaring fread2 and fwrite2 with extern keywords,
and in sdl/file.c, defining it at the top of the file, like so:

sdl/file.h
extern size_t (*fwrite2)(const void *, size_t, size_t, FILE *);
extern size_t (*fread2)(void *, size_t, size_t, FILE *);

sdl/file.c
size_t (*fwrite2)(const void *, size_t, size_t, FILE *);
size_t (*fread2)(void *, size_t, size_t, FILE *);

Other compilation errors will show up for other files, just do the same thing and it will work!