On 11.03.2018 09:59, Daniel James wrote:
On 11 March 2018 at 13:27, Stefan Seefeld via Boost
<boost@lists.boost.org> wrote:
I wonder whether anyone from the Boost.Build project would be able to
comment, and can explain the error message.
It's true I relatively recently added
but I don't see how this could cause the observed error (which doesn't
seem to be about a failed Python detection, but about an internal
Boost.Build error (to detect the `python.python_for_extensions` rule).

I can't reproduce the problem myself. From the generated output it seems
as if passing `--without-python` would suppress the failure, but that
hadn't been necessary before, or has it ?
If it wasn't clear, I found that commit by moving python to a
different directory so that boost build wouldn't find it, then running
the build with different versions of the boost python module. Before
the commit there would be a warning about python, but no error. After
that commit the build would fail with an error.

My guess is that 'python_for_extensions' is only defined when python
is installed, and the old 'rule lib_boost_python ( version )' would
only process its requirements as needed, if python wasn't installed,
the build would be cancelled and it wouldn't be run. But perhaps the
requirements for 'lib boost_python' are always processed, whether or
not python is installed.

Oh. In that case https://github.com/boostorg/python/commit/0021720a464742aec04b996e55c7f04560d6dad1 may be the solution ?


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