Native Windows build

[tobiasdiez]

The goal of this PR is to provide a native Windows build of Sage using MSVC (using the new Meson build system).

Instructions on how to test are under the Windows tab at https://doc-pr-38872--sagemath.netlify.app/html/en/installation/meson.
Afterwards, you should be able to import some sage modules in a normal python install (but most modules actually don't properly import due to various errors that will be fixed peu a peu in follow-up PRs)

State of Windows support of dependencies

• m4rie: upstream (https://github.com/malb/m4rie) doesn't provide win build
• ec: not sure if upstream (https://github.com/JohnCremona/eclib) provide win build
• ecm: upstream (https://gitlab.inria.fr/zimmerma/ecm) doesn't provide native win build (only Cygwin)
• ntl: upstream provides win build (kind of), but it's not yet available on conda (Build for windows with CMake conda-forge/ntl-feedstock#16)
• maxima/ecl: upstream provides win build, but it's not yet available on conda (Windows build conda-forge/maxima-feedstock#38)
• GAP: only cygiwn build exists Thoughts for a native (well, mingw) Window version of GAP gap-system/gap#4157
• pari: upstream supports building on Windows using mingw, but it's not yet available on conda (Windows version conda-forge/pari-feedstock#45)
• cypari2: no windows support yet merge cypari and cypari2 cypari2#19
• lrcalc
• pplpy
• primecountpy
• fpylll
• rw
• cliquer
• lcalc
• ecl
• braiding
• gc
• homfly
• iml
• brial_groebner

Conda Issues:

• Meson cannot find libraries without pkg-config files.
  • Workaround: Check that set LIB includes the conda env (e.g. ...\.conda\envs\sage-dev\Library\lib). If not, run conda deactivate followed by conda activate sage-dev and then check again.
  • Alternatively, set LIB=%CONDA_PREFIX%\Library\lib;%LIB%
  • Possible upstream improvement: the compilers conda package should set LIB
• If you don't have the debug version of Python installed, you may get "LINK : fatal error LNK1104: cannot open file 'python311_d.lib'"
  • Workaround: meson setup builddir -Dbuildtype=release
  • Alternatively, in <path to conda>\sage-dev\include\pyconfig.h uncomment: //# define Py_DEBUG and change python311_d.lib to python311.lib
  • Possible upstream improvement: conda should either ship a debug version of python or a correct pyconfig.h
• pkgconfig is wrong conda-forge/gsl-feedstock#63
  • Workaround: Fallback to find_library in meson and/or change the gsl.pc to match:

    prefix=C:/Users/Tobia/.conda/envs/sage-dev/Library
    exec_prefix=C:/Users/Tobia/.conda/envs/sage-dev/Library
    libdir=C:/Users/Tobia/.conda/envs/sage-dev/Library/lib
    sharedlibdir=C:/Users/Tobia/.conda/envs/sage-dev/Library/lib
    includedir=C:/Users/Tobia/.conda/envs/sage-dev/Library/include
    GSL_CBLAS_LIB=-lgslcblas
    
    Name: GSL
    Description: GNU Scientific Library
    Version: 2.7
    Libs: -L${libdir} -lgsl ${GSL_CBLAS_LIB}  
    Cflags: -I${includedir}
    

• When installingc-compiler on Windows, VS 2022 Build Tools init file is not installed conda-forge/compilers-feedstock#66
  • Workaround: Run everything in "VS x64 Native Tools Command Prompt" (for 64bit) or "Developer Command Prompt for VS2022 (or 2019)" (for 32bit)
• Doesn't include a pkg-config file (on Windows) conda-forge/libgd-feedstock#55
  • Workaround: Fallback to find_library in meson
• Linker issue LNK2019: unresolved external symbol on Windows conda-forge/m4ri-feedstock#15
  • Workaround: Don't try to use m4ri on windows
• winpthreads-related issue when compiling against flint conda-forge/libflint-feedstock#38
  • Workaround: Don't try to use flint on windows

Upstream issues

Singular

• Improve symbol exports on Windows Singular/Singular#1245
• Use dynamic arrays when the have non-constant length Singular/Singular#1246
• Add NOMINMAX for Windows compatibility Singular/Singular#1247

Flint:

• Fix name conflicts with small macro from rpcndr flintlib/flint#2100
• Using winpthreads with python leads to confliciting pid_t mingw-w64/mingw-w64#65 (indirectly since pthread is flint dependency). Would be fixed by winpthreads-related issue when compiling against flint conda-forge/libflint-feedstock#38.
  -> Workaround: Change typedef __int64 pid_t; to typedef int pid_t; in .conda\envs\sage-dev\Library\include\pthread_compat.h
• Replace inline assembly with function prototypes in sanity check flintlib/flint#2101:
  -> Workaround: disable compilation of fraction_field_FpT for now

Cysignals:

• Fix compilation on Windows cysignals#207
• Update build system to use Meson cysignals#206

📝 Checklist

• The title is concise and informative.
• The description explains in detail what this PR is about.
• I have linked a relevant issue or discussion.
• I have created tests covering the changes.
• I have updated the documentation and checked the documentation preview.

⌛ Dependencies

[github-actions]

Documentation preview for this PR (built with commit 0bb2c5b; changes) is ready! 🎉
This preview will update shortly after each push to this PR.

[tobiasdiez]

@soehms Thanks you very much for giving this a run, and sorry for not providing enough installation instructions. I've added most of your steps now to the documentation.

Having it "compile" is currently the best I can provide. As you saw, importing sage.all is not working since it requires that all of sage's modules can actually be imported - which is not the case on Windows as not all dependencies are available to actually compile all cython modules. Locally, I have a solution for this issue (will be a new PR) but even then many other things need further work. It's just the first step, of many.
I've added a few warnings to the docs to make it clearer that you cannot expect much at the moment.

[isuruf]

gsl, libgd issues are fixed now and bdw-gc and pari should be available now.

[isuruf]

m4ri and libflint issues are fixed too

[dimpase]

gsl, libgd issues are fixed now and bdw-gc and pari should be available now.

@isuruf - is Windows pari Cygwin-based? That is, linking to libpari needs Cygwin?

[isuruf]

@isuruf - is Windows pari Cygwin-based? That is, linking to libpari needs Cygwin?

No, it's compiled using UCRT based MinGW. Since it's only C, no problem mixing with MSVC builds. We have the UCRT based MinGW toolchain and runtime libraries packaged in conda-forge.

[dimpase]

@isuruf - is Windows pari Cygwin-based? That is, linking to libpari needs Cygwin?

No, it's compiled using UCRT based MinGW. Since it's only C, no problem mixing with MSVC builds. We have the UCRT based MinGW toolchain and runtime libraries packaged in conda-forge.

OK, so then the next thing would be to port cypari2 ?

[isuruf]

OK, so then the next thing would be to port cypari2 ?

Yes