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Bug 3979

Summary: Failed to link with "multiple definition of `scalbln'" error on both MinGW and MinGW-w64 by CMake
Product: SDL Reporter: Vitaly Novichkov <admin>
Component: buildAssignee: Sam Lantinga <slouken>
Status: RESOLVED FIXED QA Contact: Sam Lantinga <slouken>
Severity: critical    
Priority: P2    
Version: HG 2.1   
Hardware: All   
OS: Windows (All)   

Description Vitaly Novichkov 2017-11-24 10:05:00 UTC 
Hello!

Once I ran build of my codecs collection on AppVeyor where my CMake script downloads latest SDL2 from HG repo, failed to link because of math functions conflict:

https://ci.appveyor.com/project/Wohlstand/audiocodecs/build/1.0.44
The revision is b94292eebb5c

There are both vanilla MinGW and MinGW-w64 are failed to build.


```
[100%] Linking C shared library libSDL2.dll
c:/mingw/bin/../lib/gcc/mingw32/5.3.0/../../../libmingwex.a(scalbn.o):(.text+0x0): multiple definition of `scalbln'
CMakeFiles\SDL2.dir/objects.a(s_scalbn.c.obj):C:/projects/audiocodecs/build-MinGW-Release-Win32/external/SDL2/src/SDL2HG/src/libm/s_scalbn.c:30: first defined here
collect2.exe: error: ld returned 1 exit status
CMakeFiles\SDL2.dir\build.make:3678: recipe for target 'libSDL2.dll' failed
mingw32-make.exe[5]: *** [libSDL2.dll] Error 1
CMakeFiles\Makefile2:140: recipe for target 'CMakeFiles/SDL2.dir/all' failed
mingw32-make.exe[4]: *** [CMakeFiles/SDL2.dir/all] Error 2
Makefile:128: recipe for target 'all' failed
mingw32-make.exe[3]: *** [all] Error 2
CMakeFiles\SDL2HG.dir\build.make:112: recipe for target 'external/SDL2/src/SDL2HG-stamp/SDL2HG-build' failed
mingw32-make.exe[2]: *** [external/SDL2/src/SDL2HG-stamp/SDL2HG-build] Error 2
CMakeFiles\Makefile2:66: recipe for target 'CMakeFiles/SDL2HG.dir/all' failed
mingw32-make.exe[1]: *** [CMakeFiles/SDL2HG.dir/all] Error 2
Makefile:128: recipe for target 'all' failed
mingw32-make.exe: *** [all] Error 2
```

Through autotools build on MinGW is fine.
Comment 1 Sam Lantinga 2017-11-24 11:01:24 UTC 
Fixed, thanks!
https://hg.libsdl.org/SDL/rev/0083f778ede4