doc/source/f2py/windows/index.rst
.. _f2py-windows:
.. warning::
F2PY support for Windows is not always at par with Linux support
.. note::
SciPy's documentation_ has some information on system-level dependencies
which are well tested for Fortran as well.
Broadly speaking, there are two issues working with F2PY on Windows:
The focus of this section is to establish a guideline for developing and extending Fortran modules for Python natively, via F2PY on Windows.
Currently supported toolchains are:
From a user perspective, the most UNIX compatible Windows development environment is through emulation, either via the Windows Subsystem on Linux, or facilitated by Docker. In a similar vein, traditional virtualization methods like VirtualBox are also reasonable methods to develop UNIX tools on Windows.
Native Windows support is typically stunted beyond the usage of commercial compilers.
However, as of 2022, most commercial compilers have free plans which are sufficient for
general use. Additionally, the Fortran language features supported by f2py
(partial coverage of Fortran 2003), means that newer toolchains are often not
required. Briefly, then, for an end user, in order of use:
Classic Intel Compilers (commercial)
These are maintained actively, though licensing restrictions may apply as
further detailed in :ref:f2py-win-intel.
Suitable for general use for those building native Windows programs by building off of MSVC.
MSYS2 (FOSS)
In conjunction with the mingw-w64 project, gfortran and gcc
toolchains can be used to natively build Windows programs.
Windows Subsystem for Linux
Assuming the usage of gfortran, this can be used for cross-compiling
Windows applications, but is significantly more complicated.
Conda
Windows support for compilers in conda is facilitated by pulling MSYS2
binaries, however these are outdated_, and therefore not recommended (as of 30-01-2022).
PGI Compilers (commercial)
Unmaintained but sufficient if an existing license is present. Works
natively, but has been superseded by the Nvidia HPC SDK, with no native Windows support_.
Cygwin (FOSS)
Can also be used for gfortran. However, the POSIX API compatibility layer provided by
Cygwin is meant to compile UNIX software on Windows, instead of building
native Windows programs. This means cross compilation is required.
Intel oneAPI
The newer Intel compilers (ifx, icx) are based on LLVM and can be
used for native compilation. Licensing requirements can be onerous.
Classic Flang (FOSS)
The backbone of the PGI compilers were cannibalized to form the "classic" or
legacy version of Flang. This may be compiled from source and used
natively. LLVM Flang does not support Windows yet (30-01-2022).
LFortran (FOSS) One of two LLVM based compilers. Not all of F2PY supported Fortran can be compiled yet (30-01-2022) but uses MSVC for native linking.
For this document we will assume the following basic tools:
Microsoft Visual Studio Code_Windows Terminal_Powershell 7.x_the Microsoft Store_ and this can be tested with
Get-Command python.exe resolving to
C:\Users\$USERNAME\AppData\Local\Microsoft\WindowsApps\python.exeWith this baseline configuration, we will further consider a configuration matrix as follows:
.. _table-f2py-winsup-mat:
.. table:: Support matrix, exe implies a Windows installer
+----------------------+--------------------+-------------------+ | Fortran Compiler | C/C++ Compiler | Source | +======================+====================+===================+ | Intel Fortran | MSVC / ICC | exe | +----------------------+--------------------+-------------------+ | GFortran | MSVC | MSYS2/exe | +----------------------+--------------------+-------------------+ | GFortran | GCC | WSL | +----------------------+--------------------+-------------------+ | Classic Flang | MSVC | Source / Conda | +----------------------+--------------------+-------------------+ | Anaconda GFortran | Anaconda GCC | exe | +----------------------+--------------------+-------------------+
For an understanding of the key issues motivating the need for such a matrix
Pauli Virtanen's in-depth post on wheels with Fortran for Windows_ is an
excellent resource. An entertaining explanation of an application binary
interface (ABI) can be found in this post by JeanHeyd Meneide_.
MSVC is installed either via the Visual Studio Bundle or the lighter (preferred)
Build Tools for Visual Studio_ with the Desktop development with C++
setting.
.. note::
This can take a significant amount of time as it includes a download of around 2GB and requires a restart.
It is possible to use the resulting environment from a standard command prompt. However, it is more pleasant to use a developer powershell,
with a profile in Windows Terminal_. This can be achieved by adding the
following block to the profiles->list section of the JSON file used to
configure Windows Terminal (see Settings->Open JSON file):
.. code-block:: json
{ "name": "Developer PowerShell for VS 2019", "commandline": "powershell.exe -noe -c "$vsPath = (Join-Path ${env:ProgramFiles(x86)} -ChildPath 'Microsoft Visual Studio\2019\BuildTools'); Import-Module (Join-Path $vsPath 'Common7\Tools\Microsoft.VisualStudio.DevShell.dll'); Enter-VsDevShell -VsInstallPath $vsPath -SkipAutomaticLocation"", "icon": "ms-appx:///ProfileIcons/{61c54bbd-c2c6-5271-96e7-009a87ff44bf}.png" }
Now, testing the compiler toolchain could look like:
.. code-block:: powershell
$vsPath = (Join-Path ${env:ProgramFiles(x86)} -ChildPath 'Microsoft Visual Studio\2019\BuildTools'); Import-Module (Join-Path $vsPath 'Common7\Tools\Microsoft.VisualStudio.DevShell.dll'); Enter-VsDevShell -VsInstallPath $vsPath -SkipAutomaticLocation
** Visual Studio 2019 Developer PowerShell v16.11.9 ** Copyright (c) 2021 Microsoft Corporation
cd $HOME echo "#include<stdio.h>" > blah.cpp; echo 'int main(){printf("Hi");return 1;}' >> blah.cpp cl blah.cpp .\blah.exe
rm blah.cpp
It is also possible to check that the environment has been updated correctly
with $ENV:PATH.
The MS Windows version of Python discussed here installs to a non-deterministic
path using a hash. This needs to be added to the PATH variable.
.. code-block:: powershell
$Env:Path += ";$env:LOCALAPPDATA\packages\pythonsoftwarefoundation.python.3.10_qbz5n2kfra8p0\localcache\local-packages\python310\scripts"
.. toctree:: :maxdepth: 2
intel msys2 conda pgi
.. _the Microsoft Store: https://www.microsoft.com/en-us/p/python-310/9pjpw5ldxlz5 .. _Microsoft Visual Studio Code: https://code.visualstudio.com/Download .. _more complete POSIX environment: https://www.cygwin.com/ .. _This MSYS2 document: https://www.msys2.org/wiki/How-does-MSYS2-differ-from-Cygwin/ .. _Build Tools for Visual Studio: https://visualstudio.microsoft.com/downloads/#build-tools-for-visual-studio-2019 .. _Windows Terminal: https://www.microsoft.com/en-us/p/windows-terminal/9n0dx20hk701?activetab=pivot:overviewtab .. _Powershell 7.x: https://docs.microsoft.com/en-us/powershell/scripting/install/installing-powershell-on-windows?view=powershell-7.1 .. _standard command prompt: https://docs.microsoft.com/en-us/cpp/build/building-on-the-command-line?view=msvc-160#developer_command_file_locations .. _developer powershell: https://docs.microsoft.com/en-us/visualstudio/ide/reference/command-prompt-powershell?view=vs-2019 .. _profile in Windows Terminal: https://techcommunity.microsoft.com/t5/microsoft-365-pnp-blog/add-developer-powershell-and-developer-command-prompt-for-visual/ba-p/2243078 .. _Pauli Virtanen's in-depth post on wheels with Fortran for Windows: https://pav.iki.fi/blog/2017-10-08/pywingfortran.html#building-python-wheels-with-fortran-for-windows .. _Nvidia HPC SDK: https://www.pgroup.com/index.html .. _JeanHeyd Meneide: https://thephd.dev/binary-banshees-digital-demons-abi-c-c++-help-me-god-please .. _legacy version of Flang: https://github.com/flang-compiler/flang .. _native Windows support: https://developer.nvidia.com/nvidia-hpc-sdk-downloads#collapseFour .. _are outdated: https://github.com/conda-forge/conda-forge.github.io/issues/1044 .. _now deprecated: https://github.com/numpy/numpy/pull/20875 .. _LLVM Flang: https://releases.llvm.org/11.0.0/tools/flang/docs/ReleaseNotes.html .. _SciPy's documentation: https://scipy.github.io/devdocs/building/index.html#system-level-dependencies