Appveyor编译含Fortran扩展Python项目遇gnu95编译器未找到错误

问题背景 #

我的Python项目依赖Fortran扩展，此前用Appveyor的Visual Studio 2019镜像编译Windows二进制wheel，操作时先把C:/msys64/mingw64/bin加入PATH，再执行命令python.exe setup.py build_ext --inplace --compiler=mingw32 --fcompiler=gnu95，原本正常运行，现在报错：

numpy.distutils.fcompiler.CompilerNotFound: gnu95: f90 nor f77

根据Appveyor官网说明，C:/msys64应该还存在，怀疑是Fortran编译器路径变更或被移除，求可行解决办法。原.appveyor.yml配置如下：

skip_non_tags: true

image:
  - Visual Studio 2019

environment:
  matrix:
    - PYTHON: "C:/Python37-x64"
      NPVERS: "1.19.3"
    - PYTHON: "C:/Python38-x64"
      NPVERS: "1.19.3"
    - PYTHON: "C:/Python39-x64"
      NPVERS: "1.19.3"
    - PYTHON: "C:/Python310-x64"
      NPVERS: "1.23"
  MINGW_DIR: C:/msys64/mingw64/bin
  LDFLAGS: "-Wl,--default-image-base-low"
  TESTPYPI_USER: AmosEgel
  PYPI_USER: ... my user name
  TESTPYPI_PWD:
    secure: ... my password
  PYPI_PWD:    
    secure: ... my password

clone_depth: 5

init:
  - cmd: set PATH=%MINGW_DIR%;%PATH%

build: off

after_test:
  - "%PYTHON%\\python.exe -m pip install numpy==%NPVERS%"
  - "%PYTHON%\\python.exe -m pip install wheel"
  - "%PYTHON%\\python.exe setup.py prepare"
  - "%PYTHON%\\python.exe setup.py build_ext --inplace --compiler=mingw32 --fcompiler=gnu95 -f"
  - "%PYTHON%\\python.exe setup.py bdist_wheel"
 
artifacts:
  - path: dist\*
  
deploy_script:
  - "%PYTHON%\\python.exe -m pip install twine"
#  - "%PYTHON%\\python.exe -m twine upload -u %TESTPYPI_USER% -p %TESTPYPI_PWD% --repository testpypi --skip-existing dist/*.whl"
  - "%PYTHON%\\python.exe -m twine upload -u %PYPI_USER% -p %PYPI_PWD% --skip-existing dist/*.whl"

可行解决办法 #

1. 手动安装gfortran编译器 #

Appveyor的VS2019镜像中，默认可能不再预装gfortran，直接通过MSYS2的pacman命令安装：
修改init步骤，先安装编译器再配置PATH：

init:
  - cmd: C:\msys64\usr\bin\pacman -S --noconfirm mingw-w64-x86_64-gcc-fortran
  - cmd: set PATH=%MINGW_DIR%;%PATH%

2. 适配numpy版本与编译器别名 #

旧版numpy的distutils对gnu95的识别逻辑可能失效，换成新版本numpy支持的gnu别名，同时升级numpy版本适配新编译器：

• 修改编译命令中的--fcompiler参数：

%PYTHON%\\python.exe setup.py build_ext --inplace --compiler=mingw32 --fcompiler=gnu -f

• 对应Python3.10的numpy版本可升级到1.24+，比如把环境变量里的NPVERS改成1.24.3

3. 调整PATH优先级 #

确保MSYS2的路径在系统默认路径最前面，避免其他同名工具干扰：

init:
  - cmd: set PATH=C:\msys64\mingw64\bin;C:\msys64\usr\bin;%PATH%

4. 切换到MSYS2镜像编译 #

如果上述方法无效，直接改用Appveyor的MSYS2镜像，在原生MSYS2环境中安装所有依赖：
修改image配置：

image:
  - msys2

然后在init中安装所需工具：

init:
  - cmd: pacman -S --noconfirm python3 python3-pip python3-numpy mingw-w64-x86_64-gcc-fortran

修改后的完整.appveyor.yml示例 #

skip_non_tags: true

image:
  - Visual Studio 2019

environment:
  matrix:
    - PYTHON: "C:/Python37-x64"
      NPVERS: "1.19.3"
    - PYTHON: "C:/Python38-x64"
      NPVERS: "1.19.3"
    - PYTHON: "C:/Python39-x64"
      NPVERS: "1.19.3"
    - PYTHON: "C:/Python310-x64"
      NPVERS: "1.24.3"  # 升级numpy版本适配新编译器
  MINGW_DIR: C:/msys64/mingw64/bin
  LDFLAGS: "-Wl,--default-image-base-low"
  TESTPYPI_USER: AmosEgel
  PYPI_USER: ... my user name
  TESTPYPI_PWD:
    secure: ... my password
  PYPI_PWD:    
    secure: ... my password

clone_depth: 5

init:
  - cmd: C:\msys64\usr\bin\pacman -S --noconfirm mingw-w64-x86_64-gcc-fortran
  - cmd: set PATH=%MINGW_DIR%;%PATH%

build: off

after_test:
  - "%PYTHON%\\python.exe -m pip install numpy==%NPVERS%"
  - "%PYTHON%\\python.exe -m pip install wheel"
  - "%PYTHON%\\python.exe setup.py prepare"
  - "%PYTHON%\\python.exe setup.py build_ext --inplace --compiler=mingw32 --fcompiler=gnu -f"  # 修改编译器别名
  - "%PYTHON%\\python.exe setup.py bdist_wheel"
 
artifacts:
  - path: dist\*
  
deploy_script:
  - "%PYTHON%\\python.exe -m pip install twine"
#  - "%PYTHON%\\python.exe -m twine upload -u %TESTPYPI_USER% -p %TESTPYPI_PWD% --repository testpypi --skip-existing dist/*.whl"
  - "%PYTHON%\\python.exe -m twine upload -u %PYPI_USER% -p %PYPI_PWD% --skip-existing dist/*.whl"

内容的提问来源于stack exchange，提问作者Amos Egel