[feature] C and Python bindings when building on native Windows with Intel OneAPI

[dfnca]

Problem / use case
The C and Python bindings don't build "out of the box" in native Windows with the Intel OneAPI compiler set. This can be a problem in environments where WSL or Msys alternatives are not available.

Proposed solution
Update build configuration and documentation to successfully build in native Windows using Intel OneAPI while not affecting any other platform / compiler combinations.

Additional context
I have a working configuration that I pushed to my fork for review / comment:

https://github.com/dfnca/cea/tree/feat/icxPythonBinding

1. Updated several CMakeLists.txt to use the proper flags for static linking (the gfortran flags were hardwired originally). Also imposed static linking on Intel linux so that a developer environment isn't needed to run cea.
2. Added a compiler definition on windows to ensure that the Intel compiler workarounds in the numpy headers are triggered when using icx.
3. Removed a system path update in the pytest conftest.py that was causing some tests to skip instead of execute on Windows
4. Added a cmake preset to capture some settings for a release build on Windows using ifc/ifx

Open questions:

1. how should the difference in Windows / linux compiler options be handled (e.g., -std08 vs -stand:f08
2. should documentation be updated with a walkthrough for building on this platform / compiler?
3. testing with previous compiler releases. This update has only been tested with Intel 2025.3.2 and gfortran.

[markleader]

@dfnca Thanks for putting this together - this looks good. Can you submit a PR so we can check if CI passes? That will give a good indication of general support on other build systems.

Addressing your questions:

1. You can add something like this to CMakeLists.txt:

set(CMAKE_Fortran_STANDARD 2008)
set(CMAKE_Fortran_STANDARD_REQUIRED ON)

include(cmake/CompilerFlags.cmake)
project_enable_fortran_std(project_warnings)

where CompilerFlags.cmake is a new helper function that looks like:

# cmake/CompilerFlags.cmake
function(project_enable_fortran_std target)
  # GNU Fortran
  target_compile_options(${target} INTERFACE
    $<$<COMPILE_LANG_AND_ID:Fortran,GNU>:-std=f2008>
  )

  # Intel classic ifort (Windows uses /, Linux often accepts - or -stand)
  target_compile_options(${target} INTERFACE
    $<$<COMPILE_LANG_AND_ID:Fortran,Intel>:
      $<$<BOOL:WIN32>:/stand:f08>
      $<$<NOT:$<BOOL:WIN32>>:-stand f08>
    >
  )

  # IntelLLVM ifx
  target_compile_options(${target} INTERFACE
    $<$<COMPILE_LANG_AND_ID:Fortran,IntelLLVM>:
      $<$<BOOL:WIN32>:/stand:f08>
      $<$<NOT:$<BOOL:WIN32>>:-stand f08>
    >
  )
endfunction()

and the std flags can be removed from CMakePresets.json.

2. Updating the documentation to cover the full build including Python on Windows with OneAPI would be extremely helpful.

3. I will confirm that it still works on my computer (Mac OS + gcc), but we will rely on CI to test other build configurations.

[dfnca]

I submitted a PR and it looks like all of the basic builds passed.

I still need to update the docs with instructions for windows

[dfnca]

I added a new doc page with a step-by-step walkthrough for building on native Windows with C and Python bindings. I think this is com plete.

[markleader]

closed by #23