Re: [PATCH 8/8] configure: automatically parse command line for meson -D options

[Paolo Bonzini]

On 13/01/21 11:31, Daniel P. Berrangé wrote:
> > - because we need to run the script to generate the full help, we
> >    cannot rely on the user supplying the path to a Python interpreter
> >    with --python.  For this reason, the script is written in Perl.
> >    Perl 5 is universally available as "/usr/bin/env perl", while
> >    (even ignoring the Python 2/3 difference) some systems do not
> >    have a "python" or "python3" binary on the path.
>
> Can't we just use  "/usr/bin/env python3", and if that doesn't
> exist in $PATH, simply show truncated --help output, with a
> message requesting that they pass --python to see full help.

We can and it's what the RFC did, but I found it to be ugly for the 
user.  For example the rest of the build defaults not to "/usr/bin/env 
python3" but to whatever Python interpreter /usr/bin/meson uses.

Not that Perl is pretty, :) but developer ugliness ranks a notch lower 
than user-visible ugliness.  I cannot think of anything else that is 
already required to build QEMU and can parse JSON.

I don't expect this script to see any change ever, except for 
occasionally updating SKIP_OPTIONS.  Meson introspection data is 
backwards-compatible.

Paolo