data symbols in Windows shared library

[loriab]

Building a dll on Windows with BUILD_SHARED_LIBS=ON works just fine. Both bin/int2.dll and lib/int2.lib are installed. But when one links to the library like in the hartree-fock++ test case, missing symbols errors appear. Using the relevant CMake property WINDOWS_EXPORT_ALL_SYMBOLS clears up symbols like libint2_cleanup_default and libint2_need_memory_1emultipole but still errors on the symbols below. Looking at the symbols in a Linux library with nm, the ones that are still problematic are the B (uninitialized data section) ones, not the T (text (code) section) ones. Since data symbols are what the CMake property won't handle (see link above), I suspect that the libint_build_* definitions need __declspec(dllexport)/__declspec(dllimport) in the generated L2 library source to make the Windows dll useable.

I'd be glad if someone gave the "decl-ing" a try — I don't want to attempt this over CI. I would like this to be working for the future Windows c-f conda package, but at the moment, this issue is an FYI (possibly misdiagnosed), not an impediment.

2022-02-09T14:57:28.8212847Z [2/2] Linking CXX executable hf++.exe
2022-02-09T14:57:28.8213849Z FAILED: hf++.exe 
2022-02-09T14:57:28.8221349Z cmd.exe /C "cd . && C:\Miniconda\envs\test\Library\bin\cmake.exe -E vs_link_exe --intdir=CMakeFiles\hf++.dir --rc=C:\PROGRA~2\WI3CF2~1\10\bin\100220~1.0\x64\rc.exe --mt=C:\PROGRA~2\WI3CF2~1\10\bin\100220~1.0\x64\mt.exe --manifests  -- C:\PROGRA~1\LLVM\bin\lld-link.exe /nologo CMakeFiles\hf++.dir\D_\a\libint\libint\libint\tests\hartree-fock\hartree-fock++.cc.obj  /out:hf++.exe /implib:hf++.lib /pdb:hf++.pdb /version:0.0 /machine:x64 /INCREMENTAL:NO /subsystem:console  D:\a\libint\libint\installed\lib\int2.lib  kernel32.lib user32.lib gdi32.lib winspool.lib shell32.lib ole32.lib oleaut32.lib uuid.lib comdlg32.lib advapi32.lib && cd ."
2022-02-09T14:57:28.8223980Z LINK: command "C:\PROGRA~1\LLVM\bin\lld-link.exe /nologo CMakeFiles\hf++.dir\D_\a\libint\libint\libint\tests\hartree-fock\hartree-fock++.cc.obj /out:hf++.exe /implib:hf++.lib /pdb:hf++.pdb /version:0.0 /machine:x64 /INCREMENTAL:NO /subsystem:console D:\a\libint\libint\installed\lib\int2.lib kernel32.lib user32.lib gdi32.lib winspool.lib shell32.lib ole32.lib oleaut32.lib uuid.lib comdlg32.lib advapi32.lib /MANIFEST /MANIFESTFILE:hf++.exe.manifest" failed (exit code 1) with the following output:
2022-02-09T14:57:28.8226292Z lld-link: error: undefined symbol: libint2_build_1emultipole
2022-02-09T14:57:28.8229203Z >>> referenced by CMakeFiles\hf++.dir\D_\a\libint\libint\libint\tests\hartree-fock\hartree-fock++.cc.obj:(private: void __cdecl libint2::Engine::_initialize(void))
2022-02-09T14:57:28.8230025Z ...
2022-02-09T14:57:28.8230444Z lld-link: error: undefined symbol: libint2_build_elecpot1
2022-02-09T14:57:28.8232267Z lld-link: error: undefined symbol: libint2_build_overlap1
2022-02-09T14:57:28.8237943Z lld-link: error: undefined symbol: libint2_build_kinetic1
2022-02-09T14:57:28.8277884Z lld-link: error: undefined symbol: libint2_build_1emultipole1
2022-02-09T14:57:28.8282387Z lld-link: error: undefined symbol: libint2_build_2emultipole1
2022-02-09T14:57:28.8283839Z lld-link: error: undefined symbol: libint2_build_2emultipole
2022-02-09T14:57:28.8305037Z lld-link: error: undefined symbol: libint2_build_3emultipole1
2022-02-09T14:57:28.8306567Z lld-link: error: undefined symbol: libint2_build_3emultipole
2022-02-09T14:57:28.8308082Z lld-link: error: undefined symbol: libint2_build_elecpot
2022-02-09T14:57:28.8309739Z lld-link: error: undefined symbol: libint2_build_overlap
2022-02-09T14:57:28.8311160Z lld-link: error: undefined symbol: libint2_build_kinetic
2022-02-09T14:57:28.8314037Z lld-link: error: undefined symbol: libint2_build_sphemultipole1
2022-02-09T14:57:28.8316019Z lld-link: error: undefined symbol: libint2_build_sphemultipole
2022-02-09T14:57:28.8318689Z lld-link: error: undefined symbol: libint2_build_3eri1
2022-02-09T14:57:28.8322221Z lld-link: error: undefined symbol: libint2_build_eri1
2022-02-09T14:57:28.8323604Z lld-link: error: undefined symbol: libint2_build_default
2022-02-09T14:57:28.8325154Z lld-link: error: undefined symbol: libint2_build_3eri
2022-02-09T14:57:28.8328701Z lld-link: error: undefined symbol: libint2_build_eri
2022-02-09T14:57:28.8329457Z >>> referenced by CMakeFiles\hf++.dir\D_\a\libint\libint\libint\tests\hartree-fock\hartree-fock++.cc.obj:(private: void __cdecl libint2::Engine::_initialize(void))
2022-02-09T14:57:28.8330171Z ninja: build stopped: subcommand failed.
2022-02-09T14:57:28.8343899Z ##[error]Process completed with exit code 1.
2022-02-09T14:57:28.8487126Z Cleaning up orphan processes

> nm install-25/lib64/libint2.so | grep libint2_ | grep overlap
00000000000a47c0 B libint2_build_overlap
00000000000a4520 B libint2_build_overlap1
0000000000019350 T libint2_cleanup_overlap
0000000000019430 T libint2_cleanup_overlap1
0000000000018ad0 T libint2_init_overlap
0000000000018f30 T libint2_init_overlap1
0000000000018820 T libint2_need_memory_overlap
0000000000018970 T libint2_need_memory_overlap1

Added: use REQUIRE_CXX_API_COMPILED=OFF to defer the error to linking int2.dll to L2 consumer, which is testable, rather than getting it at engine.cpp to int2.dll link time.