[SDL2] MSVC weird ARM64 link error ?

[sezero]

This wasn't happening before. See:
https://github.com/libsdl-org/SDL/actions/runs/15802295971/job/44542260352

LINK Pass 1: command "C:\PROGRA~1\MICROS~2\2022\ENTERP~1\VC\Tools\MSVC\1444~1.352\bin\Hostx64\arm64\link.exe /nologo @CMakeFiles\SDL2.rsp /out:SDL2.dll /implib:SDL2.lib /pdb:SDL2.pdb /dll /version:2.33 -DEBUG /debug /INCREMENTAL /NODEFAULTLIB /MANIFEST /MANIFESTFILE:CMakeFiles\SDL2.dir/intermediate.manifest CMakeFiles\SDL2.dir/manifest.res" failed (exit code 1120) with the following output:
   Creating library SDL2.lib and object SDL2.exp
SDL_atomic.c.obj : error LNK2019: unresolved external symbol _InterlockedCompareExchange referenced in function SDL_AtomicCAS_REAL
SDL_malloc.c.obj : error LNK2001: unresolved external symbol _InterlockedCompareExchange
SDL_syssem.c.obj : error LNK2001: unresolved external symbol _InterlockedCompareExchange
SDL_atomic.c.obj : error LNK2019: unresolved external symbol _InterlockedCompareExchangePointer referenced in function SDL_AtomicCASPtr_REAL
SDL_atomic.c.obj : error LNK2019: unresolved external symbol _InterlockedExchange referenced in function SDL_AtomicSet_REAL
SDL_malloc.c.obj : error LNK2001: unresolved external symbol _InterlockedExchange
SDL_atomic.c.obj : error LNK2019: unresolved external symbol _InterlockedExchangeAdd referenced in function SDL_AtomicAdd_REAL
SDL_atomic.c.obj : error LNK2019: unresolved external symbol _InterlockedExchangePointer referenced in function SDL_AtomicSetPtr_REAL
SDL_atomic.c.obj : error LNK2019: unresolved external symbol _InterlockedOr referenced in function SDL_AtomicGet_REAL
SDL_spinlock.c.obj : error LNK2019: unresolved external symbol _InterlockedExchange_acq referenced in function SDL_AtomicTryLock_REAL
SDL_spinlock.c.obj : error LNK2019: unresolved external symbol _InterlockedExchange_rel referenced in function SDL_AtomicUnlock_REAL
SDL_syssem.c.obj : error LNK2019: unresolved external symbol _InterlockedDecrement referenced in function SDL_SemWaitTimeout_kern
SDL_syssem.c.obj : error LNK2019: unresolved external symbol _InterlockedIncrement referenced in function SDL_SemPost_atom
SDL2.dll : fatal error LNK1120: 10 unresolved externals

[sezero]

Is this related? https://devblogs.microsoft.com/cppblog/introducing-the-forceinterlockedfunctions-switch-for-arm64/

[sezero]

It seems to happen with MSVC 19.44.35209.0, but not with 19.43.34808.0 as in my fork.

It doesn't happen with SDL3, either...

[madebr]

I think SDL2 is failng because it is -DSDL_LIBC=OFF, whereas SDL3 is -DSDL_LIBC=ON.

Is this related? https://devblogs.microsoft.com/cppblog/introducing-the-forceinterlockedfunctions-switch-for-arm64/

I'm sure this is related. The missing symbols are _InterlockedCompareExchange, not __imp_InterlockedCompareExchange@12.

So it looks like SDL should compile with /forceInterlockedFunctions on arm64 when SDL_LIBC is disabled.

[sezero]

You have a patch?

[madebr]

You have a patch?

Not yet. Will create one asap.

[sezero]

I tried sezero@66867a7 and the flag is added to compilation, but linkage still seems to fail: https://github.com/sezero/SDL/actions/runs/16133662443/job/45525800038

[mmozeiko]

The flag needs to be set to opposite value, disabled, with - symbol at the end. So interlocked functions are NOT forced (instead inline code will be generated):

/forceInterlockedFunctions-

[sezero]

The flag needs to be set to opposite value, disabled, with - symbol at the end. So interlocked functions are NOT forced (instead inline code will be generated):

Sigh. Face palm...

Thanks!

[sezero]

Fixed by #13340