So it seems that we need to generate a module definition (.def) file in order to have all the ObjC class symbols exported in the DLL. This is also what WinObjC is doing, I’ll try to come up with a script to generate this file from the object file symbols. https://github.com/microsoft/WinObjC/blob/develop/build/Foundation/dll/Foundation.def <https://github.com/microsoft/WinObjC/blob/develop/build/Foundation/dll/Foundation.def>
However after manually creating a .def file with a few relevant symbols I still get the following linker error, which happens for any referenced Foundation class (NSArray is just an example): > lld-link: error: undefined symbol: $_OBJC_REF_CLASS_NSArray > >>> referenced by test.m:16 > >>> C:\msys64\tmp\test-b84674.o:(WinMain) I confirmed with dumpbin /exports that the .lib and DLL both contain these $_OBJC_REF_CLASS_ symbols, so I really don’t understand why it’s not found. I’ve reproduced the issue from scratch using only libobjc2 and have written down the steps to reproduce here: https://github.com/gnustep/libobjc2/issues/191 <https://github.com/gnustep/libobjc2/issues/191> Hopefully I’m just missing some flag somewhere when creating the DLL. I’d appreciate any thoughts. Thanks! Frederik > Am 19.01.2021 um 20:50 schrieb Frederik Seiffert <frede...@algoriddim.com>: > > Hi David, > >> Am 19.01.2021 um 18:40 schrieb David Chisnall <gnus...@theravensnest.org >> <mailto:gnus...@theravensnest.org>>: >> >> 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. > > I’m using "ar cr ..." instead of "ld -r" as the subproject merge command, as > that’s what the MinGW targets were using with Clang. I can also see all the > NS*.m.o object files of the various classes that I’m getting errors for being > passed directly to the linker, so I’m guessing that’s not it. > > I can see with nm that the object files contain the relevant symbols, but the > generated gnustep-base.lib does not (not sure about the DLL). I’m wondering > if these symbols need to be specially marked to be exported or I’m missing > some linker flag? With MinGW we’re passing the object files between > --whole-archive / --no-whole-archive, but that flag isn’t recognized by > lld-link. > > This is the (abbreviated) linker invocation I have right now: > > clang -Wl,-dll -Wl,-export-all-symbols -fuse-ld=lld -Wl,/subsystem:console -o > ./obj/gnustep-base-1_27.dll obj/libgnustep-base.obj/GSArray.m.o > <all-other-object-files> Additions/obj/subproject.o win32/obj/subproject.o > -lffi -lWs2_32 -lpthread -ladvapi32 -luser32 -lshell32 -lnetapi32 -lobjc > > Thanks! > > Frederik >
