Add support for building with Mingw-gcc

[hmartinez82]

Tune CMakeLists to use the right compiler switches when using MINGW

$ ctest
Test project D:/Dev/Github/CalcMySky/build
      Start  1: Spectrum test 1
 1/12 Test  #1: Spectrum test 1 .....................................................   Passed    0.07 sec
      Start  2: Spectrum test 2
 2/12 Test  #2: Spectrum test 2 .....................................................   Passed    0.01 sec
      Start  3: Spectrum test 3
 3/12 Test  #3: Spectrum test 3 .....................................................   Passed    0.01 sec
      Start  4: Spectrum test 4
 4/12 Test  #4: Spectrum test 4 .....................................................   Passed    0.01 sec
      Start  5: Fourier interpolation,  odd-length input, identity transformation
 5/12 Test  #5: Fourier interpolation,  odd-length input, identity transformation ...   Passed    0.01 sec
      Start  6: Fourier interpolation, even-length input, identity transformation
 6/12 Test  #6: Fourier interpolation, even-length input, identity transformation ...   Passed    0.01 sec
      Start  7: Fourier interpolation,  odd-length input, integral upsampling
 7/12 Test  #7: Fourier interpolation,  odd-length input, integral upsampling .......   Passed    0.01 sec
      Start  8: Fourier interpolation, even-length input, integral upsampling
 8/12 Test  #8: Fourier interpolation, even-length input, integral upsampling .......   Passed    0.01 sec
      Start  9: Fourier interpolation,  odd-length input, fractional upsampling
 9/12 Test  #9: Fourier interpolation,  odd-length input, fractional upsampling .....   Passed    0.01 sec
      Start 10: Fourier interpolation, even-length input, fractional upsampling
10/12 Test #10: Fourier interpolation, even-length input, fractional upsampling .....   Passed    0.01 sec
      Start 11: Spline interpolation
11/12 Test #11: Spline interpolation ................................................   Passed    0.01 sec
      Start 12: Catching exceptions from libShowMySky
12/12 Test #12: Catching exceptions from libShowMySky ...............................   Passed    0.03 sec

100% tests passed, 0 tests failed out of 12

Total Test time (real) =   0.20 sec

[10110111]

What is the issue with external only TUs? I've never heard of it. Any link?

[hmartinez82]

It's a known issue and I'm still working on a solution. It's only a problem with clang. GCC does not have this issue :(
9 yr old - https://stackoverflow.com/questions/25050575/basic-use-of-c-archives-libraries-with-clang-linker
2 yr old and still happening https://stackoverflow.com/questions/67045075/why-is-clang-reporting-an-undefined-symbol-for-an-extern-variable-referenced-in

[hmartinez82]

So far I only got it locally building with clang if I remove the extern and convert it to a static and initialize its value in config.h instead of version.cpp

[10110111]

So far I only got it locally building with clang if I remove the extern and convert it to a static and initialize its value in config.h instead of version.cpp

Well this is not a good solution because it will force rebuilding of all sources from scratch on every commit (even CCache won't speed it up). Isolation of the change to a single file, version.cpp, was deliberate.

From your links I see that initializing the external definition helps the people with this problem. But here PROJECT_VERSION is already initialized, since it's a constant. Am I missing something?

[hmartinez82]

I forgot to add "and removing its initialization from version.cpp"

[10110111]

One relatively clean solution would be to turn this constant into a function: const char* PROJECT_VERSION();. Then version.cpp would contain the definition of this function, while config.h would declare it.

[hmartinez82]

Yes. I'm turning it into a function. After your comment about CCache, converting it into a function came to my mind

[hmartinez82]

I'm at a loss. Even after the conversion to a function above, now I'm getting:

[2/4] Linking CXX executable CalcMySky\calcmysky.exe
FAILED: CalcMySky/calcmysky.exe
cmd.exe /C "cd . && C:\msys64\clang64\bin\c++.exe -Werror=return-type -Wall -Wextra -fvisibility=hidden  CalcMySky/CMakeFiles/calcmysky.dir/calcmysky_autogen/mocs_compilation.cpp.obj CalcMySky/CMakeFiles/calcmysky.dir/main.cpp.obj CalcMySky/CMakeFiles/calcmysky.dir/util.cpp.obj CalcMySky/CMakeFiles/calcmysky.dir/glinit.cpp.obj CalcMySky/CMakeFiles/calcmysky.dir/cmdline.cpp.obj CalcMySky/CMakeFiles/calcmysky.dir/shaders.cpp.obj CalcMySky/CMakeFiles/calcmysky.dir/interpolation-guides.cpp.obj -o CalcMySky\calcmysky.exe -Wl,--out-implib,CalcMySky\libcalcmysky.dll.a -Wl,--major-image-version,0,--minor-image-version,0  libversion.a  libcommon.a  C:/msys64/clang64/lib/libQt6OpenGL.dll.a  C:/msys64/clang64/lib/libQt6Widgets.dll.a  C:/msys64/clang64/lib/libQt6Gui.dll.a  C:/msys64/clang64/lib/libQt6Core.dll.a  -pthread  -lmpr  -luserenv  -ld3d11  -ldxgi  -ldxguid  -lkernel32 -luser32 -lgdi32 -lwinspool -lshell32 -lole32 -loleaut32 -luuid -lcomdlg32 -ladvapi32 && cd ."
ld.lld: error: undefined symbol: GetProjectVersion()
>>> referenced by CalcMySky/CMakeFiles/calcmysky.dir/main.cpp.obj:(main)
c++: error: linker command failed with exit code 1 (use -v to see invocation)
[4/4] Linking CXX executable ShowMySky\showmysky.exe
FAILED: ShowMySky/showmysky.exe
cmd.exe /C "cd . && C:\msys64\clang64\bin\c++.exe -Werror=return-type -Wall -Wextra -fvisibility=hidden  ShowMySky/CMakeFiles/showmysky-cmd.dir/showmysky-cmd_autogen/mocs_compilation.cpp.obj ShowMySky/CMakeFiles/showmysky-cmd.dir/qrc_resources.cpp.obj ShowMySky/CMakeFiles/showmysky-cmd.dir/win32res.rc.obj ShowMySky/CMakeFiles/showmysky-cmd.dir/main.cpp.obj ShowMySky/CMakeFiles/showmysky-cmd.dir/util.cpp.obj ShowMySky/CMakeFiles/showmysky-cmd.dir/GLWidget.cpp.obj ShowMySky/CMakeFiles/showmysky-cmd.dir/MainWindow.cpp.obj ShowMySky/CMakeFiles/showmysky-cmd.dir/ToolsWidget.cpp.obj ShowMySky/CMakeFiles/showmysky-cmd.dir/Manipulator.cpp.obj ShowMySky/CMakeFiles/showmysky-cmd.dir/RadiancePlot.cpp.obj ShowMySky/CMakeFiles/showmysky-cmd.dir/DockScrollArea.cpp.obj ShowMySky/CMakeFiles/showmysky-cmd.dir/GLSLCosineQualityChecker.cpp.obj -o ShowMySky\showmysky.exe -Wl,--out-implib,ShowMySky\libshowmysky.dll.a -Wl,--major-image-version,0,--minor-image-version,0  libversion.a  libcommon.a  C:/msys64/clang64/lib/libQt6OpenGLWidgets.dll.a  C:/msys64/clang64/lib/libQt6Widgets.dll.a  C:/msys64/clang64/lib/libQt6OpenGL.dll.a  C:/msys64/clang64/lib/libQt6Gui.dll.a  C:/msys64/clang64/lib/libQt6Core.dll.a  -pthread  -lmpr  -luserenv  -ld3d11  -ldxgi  -ldxguid  -lkernel32 -luser32 -lgdi32 -lwinspool -lshell32 -lole32 -loleaut32 -luuid -lcomdlg32 -ladvapi32 && cd ."
ld.lld: error: undefined symbol: GetProjectVersion()

But only with clang! gcc and msvc ware linking correctly, grr

[10110111]

Even after the conversion to a function above, now I'm getting

What if you avoid -fvisibility=hidden?

[hmartinez82]

Same thing, removing -fvisibility=hidden was the very first thing I tried 😢

[10110111]

Interestingly, I experience no problem whatsoever when building with clang 10.0.0-4ubuntu1 on Ubuntu 20.04, even with the current master.

[hmartinez82]

I'm using 17.0.1 from MSYS2 I'm targeting x86_64-w64-windows-gnu

[10110111]

Well, what if you populate clang_dummy with the code to return the pointer, and call it instead of PROJECT_VERSION in the places of use? It seems strange that a simple renaming (and a change of return type) leads to a problem.

[hmartinez82]

I already did that, (well, not called clang_dymmy). you'll have to refresh this PR

[10110111]

I already did that, (well, not called clang_dymmy). you'll have to refresh this PR

No, I mean, your clang_dummy, IIUC, fixed the problem. But now the GetProjectVersion reintroduces it. So I suggest trying to go from the working state, checking what exact change reintroduces the problem.

[hmartinez82]

The original PR was also failing with the clang_dummy() call. It was a draft to have others chime in to help :)
That's why this is a Draft and not a full PR

[10110111]

The original PR was also failing with the clang_dummy() call.

Well, this you didn't mention :)
Anyway, since I can't reproduce this, I can't try to fix.

[hmartinez82]

Ok. I've changed the title. Let's chew one thing at a time. I'll start working on the MSYS2 recipe for this project. INDIlib is next.

[hmartinez82]

Here we go msys2/MINGW-packages#18697

[hmartinez82]

@10110111 where can I download .atmo files to test ShowMySky.exe ?

[10110111]

examples/sample.atmo

[10110111]

Ah, wait, it's for CalcMySky. For ShowMySky you can download the earth atmosphere model in the release assets list.