Re: [Qemu-devel] [PATCH (1.7?)] configure: Use -B switch only for Python versions which support it

[Peter Maydell]

On 14 November 2013 18:07, Stefan Weil <address@hidden> wrote:
> Commit 1d984a67a95d88f3e708b077dab8adeb47c38c93 added the -B switch
> unconditionally. This breaks Python versions before 2.6 which don't
> support that switch.
>
> Now configure adds -B only if it is accepted by the Python interpreter.
>
> This modification introduces a small incompatiblity because -B might now
> also be added when configure was called with --python=PYTHON_INTERPRETER.

That sounds like it's fixing a bug to me. If we think -B
is right then we should be using it whether we defaulted
to 'python' or the user passed us /usr/local/bin/python2
or whatever.

> Signed-off-by: Stefan Weil <address@hidden>
> ---
>  configure |    9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
>
> This is an optional patch. We need it for Python versions older than 5 years
> if we don't want to use the workaround --python=python.
>
> I don't think it is needed for 1.7, but maybe other people think different.

I think that as long as our requirements list says
python 2.4 is the minimum then bugs that mean we don't work
on that are fair game for fixing during hardfreeze; and
this is a pretty simple and safe fix. I think it's better
to put it into the release than deal with people after
release trying to run it on RHEL-whatever that doesn't
have a newer python.

> diff --git a/configure b/configure
> index 9a02610..3c25816 100755
> --- a/configure
> +++ b/configure
> @@ -593,7 +593,7 @@ fi
>
>  : ${make=${MAKE-make}}
>  : ${install=${INSTALL-install}}
> -: ${python=${PYTHON-python -B}}
> +: ${python=${PYTHON-python}}
>  : ${smbd=${SMBD-/usr/sbin/smbd}}
>
>  # Default objcc to clang if available, otherwise use CC
> @@ -1420,6 +1420,13 @@ if ! $python -c 'import sys; sys.exit(sys.version_info 
> < (2,4) or sys.version_in
>        "Use --python=/path/to/python to specify a supported Python."
>  fi
>
> +# The -B switch was added in Python 2.6.
> +# If it is supplied, compiled files are not written.
> +# Use it for Python versions which support it.
> +if $python -B -c 'import sys; sys.exit(0)' 2>/dev/null; then
> +  $python="$python -B"
> +fi
> +
>  if test -z "${target_list+xxx}" ; then
>      target_list="$default_target_list"
>  else

Reviewed-by: Peter Maydell <address@hidden>

thanks
-- PMM