Re: Building GNUstep for Windows using Clang

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 <[email protected]>:
>>
>> 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.li
 b
>>
>>
>>> 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
>>
>>
> 
>