* Lookup is now performed according to the following order:
1. use `pkg-config` with `PKG_CONFIG_LIBDIR=LIBPC` from python
2. use plain `PKG_CONFIG_{LIBDIR,PATH}` from the environment
3. try to extract the information from SYSCONFIG
The second step is necessary for relocated python installations
and cross compilation scenarios, where the value of `LIBPC` might
be wrong.
Meson tries to find the interpreter path through the "py" launcher on Windows in all
cases which breaks if meson is run under MSYS2 and an official CPython is installed as well.
MSYS2 Python doesn't install a py launcher which results in meson finding the system one instead
even though python2/python3 is in PATH.
Always check if the interpreter name is in PATH before falling back to checking the py launcher.
All dependencies were using find_library, has_header, get_define, etc on
self.compiler assuming that it's a compiler that outputs and consumes
C-like libraries. This is not true for D (and in the future, for Rust)
since although they can consume C libraries, they do not use the
C ecosystem.
For such purposes, we now have self.clib_compiler. Nothing uses
self.compiler anymore as a result, and it has been removed.
pypy installations don't usuallyy ship with pkg-config files,
we thus need to replicate what their version of distutils does.
In addition, we also try our best to build against other
pythons that do not have pkg-config files.
What is actually defined here varies wildly on different python-versions
for different platforms.
On my python2.7 on Windows len(sysconfig.get_config_vars()) returns 17,
whereas in my Ubuntu that number is 517!
Hence it is useful to be able to check which keys are available, as
well as allowing specifying a default option.
Xavier Claessens