Python dependency not found in project without `c` language on Windows

[dnicolodi]

py = import('python').find_installation()
dep = py.dependency()

is unable to find the Python dependency on Windows when the current project does not have the c compiler initialized. This is relevant for projects building extension modules in Rust, for example.

This does not work:

project('foo', 'rust')
py = import('python').find_installation()
dep = py.dependency()

but this does:

project('foo', 'c', 'rust')
py = import('python').find_installation()
dep = py.dependency()

The project is setup with meson setup foo _build --vsenv --native-file=native.txt where native.txt is something like

[binaries]
python = ${path to python.exe}

I haven't check yet what in the python Meson's module requires the C toolchain to detect the Python dependency.

[eli-schwartz]

This is nothing new. dependency() with custom dependency lookups that internally use cc.find_library() to find a C library have always needed C compilers available. It works without a C compiler if pkgconfig is available.

[bonzini]

I guess we could detect that situation and give a better error message at least.