Re: Building GNUstep for Windows using Clang

[David Chisnall]

Hi,

On ELF platforms, there were some issues with the ld -r invocation that 
-base Additions did.  Can you try just adding the .m files from 
Additions directly to the -base project and see if that makes the 
problem go away?  I don't think that PE/COFF linkage really has any 
concept that maps to how we do the subproject thing in -make.

David

On 19/01/2021 14:53, Frederik Seiffert wrote:
> Hi all,
>
> Another update on the Clang MSVC ABI support front (which I’m trying to get to 
> work in addition to MinGW + Clang)...
>
> I’ve been making some good progress and was able to build Base as a DLL with 
> this setup. The necessary build system changes are on the following branches 
> (work in progress), which I will clean up and submit as PRs when this is 
> working:
> https://github.com/gnustep/tools-make/tree/clang-msvc-support
> https://github.com/gnustep/libs-base/tree/clang-msvc-support
>
>
> However it seems that the generated gnustep-base.lib does not contain symbols 
> for the ObjC classes. I’m getting linker errors for each ObjC class I am 
> referencing in a test program:
>
> > lld-link: error: undefined symbol: $_OBJC_REF_CLASS_NSArray
> > > > > referenced by C:\Dev\tools-android\test.m:16
> > > > >                C:\msys64\tmp\test-aef6cd.o:(WinMain)
> >
> > lld-link: error: undefined symbol: __declspec(dllimport) 
> > $_OBJC_CLASS_NSConstantString
> > > > > referenced by C:\msys64\tmp\test-aef6cd.o:(.objc_early_init)
>
> Is there some flag I need to pass to lld-link to ensure these are exported? I 
> currently have -dll and -export-all-symbols. I also tried adding 
> __declspec(dllexport) to the @interface declaration of these classes to no 
> avail.
>
>
> Regarding the previous issue:
>
> > However, it fails checking for objc_sync_enter with the following linker errors 
> > – any ideas what these could be about?
>
> I am guessing these somehow happen because referencing ObjC built-ins in a C 
> file doesn’t work on Windows. I’m planning to skip these config checks when 
> using this setup.
>
>
> Thanks,
> Frederik
>
>
> > Am 12.01.2021 um 21:47 schrieb Frederik Seiffert <frederik@algoriddim.com>:
> >
> > Hi all,
> >
> > As a second option I’ve been working on trying to build using the MSVC ABI 
> > (i.e. without MinGW).
> >
> > Using the latest Clang 11 from the LLVM website and Pthreads-win32, plus 
> > removing -lm from target.make, I was able to get quite a bit further running 
> > Base configure.
> >
> > However, it fails checking for objc_sync_enter with the following linker errors 
> > – any ideas what these could be about?
> >
> > > configure:8038: checking for objc_sync_enter
> > > configure:8038: /C/LLVM/bin/clang -o conftest.exe -g  -I/c/GNUstep/MSVC/x64/include 
> > > -I/c/GNUstep/MSVC/x64/include -I/c/GNUstep/MSVC/x64/include 
> > > -I/c/GNUstep/MSVC/x64/include  -x objective-c -fuse-ld=lld -L/c/GNUstep/MSVC/x64/lib 
> > > -L/c/GNUstep/MSVC/x64/lib -L/c/GNUstep/MSVC/x64/lib -L/c/GNUstep/MSVC/x64/lib 
> > > conftest.c  -lpthread -fuse-ld=lld -pthread -fexceptions -fobjc-runtime=gnustep-2.0 
> > > -fblocks -L/home/Frederik -LSeiffert/GNUstep/Library/Libraries 
> > > -L/c/GNUstep/MSVC/x64/lib -lobjc     >&5
> > > conftest.c:119:6: warning: incompatible redeclaration of library function 
> > > 'objc_sync_enter' [-Wincompatible-library-redeclaration]
> > > char objc_sync_enter ();
> > >      ^
> > > conftest.c:119:6: note: 'objc_sync_enter' is a builtin with type 'int (id)'
> > > 1 warning generated.
> > > lld-link: error: relocation against symbol in discarded section: 
> > > __start_.objcrt$SEL
> > > > > > referenced by C:\tmp\conftest-78a937.o:(.objc_init)
> > >
> > > lld-link: error: relocation against symbol in discarded section: 
> > > __stop.objcrt$SEL
> > > > > > referenced by C:\tmp\conftest-78a937.o:(.objc_init)
> > >
> > > lld-link: error: relocation against symbol in discarded section: 
> > > __start_.objcrt$CLS
> > > > > > referenced by C:\tmp\conftest-78a937.o:(.objc_init)
> > >
> > > lld-link: error: relocation against symbol in discarded section: 
> > > __stop.objcrt$CLS
> > > > > > referenced by C:\tmp\conftest-78a937.o:(.objc_init)
> > >
> > > lld-link: error: relocation against symbol in discarded section: 
> > > __start_.objcrt$CLR
> > > > > > referenced by C:\tmp\conftest-78a937.o:(.objc_init)
> > >
> > > lld-link: error: relocation against symbol in discarded section: 
> > > __stop.objcrt$CLR
> > > > > > referenced by C:\tmp\conftest-78a937.o:(.objc_init)
> > >
> > > lld-link: error: relocation against symbol in discarded section: 
> > > __start_.objcrt$CAT
> > > > > > referenced by C:\tmp\conftest-78a937.o:(.objc_init)
> > >
> > > lld-link: error: relocation against symbol in discarded section: 
> > > __stop.objcrt$CAT
> > > > > > referenced by C:\tmp\conftest-78a937.o:(.objc_init)
> > >
> > > lld-link: error: relocation against symbol in discarded section: 
> > > __start_.objcrt$PCL
> > > > > > referenced by C:\tmp\conftest-78a937.o:(.objc_init)
> > >
> > > lld-link: error: relocation against symbol in discarded section: 
> > > __stop.objcrt$PCL
> > > > > > referenced by C:\tmp\conftest-78a937.o:(.objc_init)
> > >
> > > lld-link: error: relocation against symbol in discarded section: 
> > > __start_.objcrt$PCR
> > > > > > referenced by C:\tmp\conftest-78a937.o:(.objc_init)
> > >
> > > lld-link: error: relocation against symbol in discarded section: 
> > > __stop.objcrt$PCR
> > > > > > referenced by C:\tmp\conftest-78a937.o:(.objc_init)
> > >
> > > lld-link: error: relocation against symbol in discarded section: 
> > > __start_.objcrt$CAL
> > > > > > referenced by C:\tmp\conftest-78a937.o:(.objc_init)
> > >
> > > lld-link: error: relocation against symbol in discarded section: 
> > > __stop.objcrt$CAL
> > > > > > referenced by C:\tmp\conftest-78a937.o:(.objc_init)
> > >
> > > lld-link: error: relocation against symbol in discarded section: 
> > > __start_.objcrt$STR
> > > > > > referenced by C:\tmp\conftest-78a937.o:(.objc_init)
> > >
> > > lld-link: error: relocation against symbol in discarded section: 
> > > __stop.objcrt$STR
> > > > > > referenced by C:\tmp\conftest-78a937.o:(.objc_init)
> > > PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash 
> > > backtrace.
> > > 0.      Program arguments: C:\LLVM\bin\lld-link -out:conftest.exe 
> > > -defaultlib:libcmt -libpath:C:\Program Files (x86)\Microsoft Visual 
> > > Studio\2019\Professional\VC\Tools\MSVC\14.28.29333\lib\x64 -libpath:C:\Program 
> > > Files (x86)\Microsoft Visual 
> > > Studio\2019\Professional\VC\Tools\MSVC\14.28.29333\atlmfc\lib\x64 
> > > -libpath:C:\Program Files (x86)\Windows Kits\10\Lib\10.0.18362.0\ucrt\x64 
> > > -libpath:C:\Program Files (x86)\Windows Kits\10\Lib\10.0.18362.0\um\x64 
> > > -libpath:C:\LLVM\lib\clang\11.0.0\lib\windows -libpath:C:/GNUstep/MSVC/x64/lib 
> > > -libpath:C:/GNUstep/MSVC/x64/lib -libpath:C:/GNUstep/MSVC/x64/lib 
> > > -libpath:C:/GNUstep/MSVC/x64/lib -libpath:C:/msys64/home/Frederik 
> > > -libpath:Seiffert/GNUstep/Library/Libraries -libpath:C:/GNUstep/MSVC/x64/lib 
> > > -nologo -debug C:\tmp\conftest-76158a.o pthread.lib objc.lib
> >
> >
> > > configure:8038: result: no
> > > configure:8052: error: The objc runtime library does not appear to have 
> > > synchronisation support.  Try re-configuring gnustep-make with a CPPFLAGS 
> > > variable containing a -L point to specify the directory containing the correct 
> > > libobjc, or using the --with-objc-lib-flag=... option.
> >
> >
> > Thanks,
> > Frederik