bug#10227: Python installation fails for Python 3

[Roumen Petrov]

Stefano Lattarini wrote:
> tags 10227 - moreinfo
> thanks
>
> On 11/21/2012 06:58 PM, Reuben Thomas wrote:
> > On 21 November 2012 13:41, Stefano Lattarini <address@hidden>wrote:
> >
> > > tags 10227 + moreinfo
> > > thanks
> > >
> > > Hi Roumen, Reuben.
> > >
> > > I'm going through old open bugs, and I've noticed this one.  Is the
> > > problem still present, after the recent updates to the python support?
[SNIP]
> > > on my Ubuntu 12.10 system). I'm sorry, I can't tell whether, as Roumen
> > > suggests, this is an Ubuntu packaging bug, or an automake bug.
It seems to me this is a feature as I found this one:

http://patch-tracker.debian.org/patch/series/view/python2.6/2.6.6-8/distutils-install-layout.diff

> OK, thanks for explaining it once again.  I can now reproduce the same
> issue on Debian.  I think this is something we should try to work around,
> since we cannot have our installation rules broken by default on both
> Debian and Ubuntu ...
Lets say platforms that use the "/posix_local/" installation scheme 
instead wrong or broken.

> > It seems to me that this is the sort of thing the pyconfigure people
> > ought to know about.
> By peeking at their repository, I came up with the minimal patch below,
> which should do the trick.  Can you verify it works for you as well?
>
> Regards,
>    Stefano
>
> ---- 8< ---- 8< ---- 8< ---- 8< ---- 8< ---- 8< ---- 8< ---- 8< ---- 8< ----
>
>  From 30463e31e481537462713cb680279aded6a9d449 Mon Sep 17 00:00:00 2001
> Message-Id: <address@hidden>
> From: Stefano Lattarini <address@hidden>
> Date: Thu, 22 Nov 2012 12:03:07 +0100
> Subject: [PATCH] python: make installed modules find by default on Debian and 
> Ubuntu
>
> This change fixes automake bug#10227.
>
> The code used to get the python package directory was wrong for Python 3,
> at least on Debian and Ubuntu distributions.  In the case the installation
> was using the default prefix "/usr/local", python modules were incorrectly
> installed in the directory
>
>      /usr/local/lib/python3/dist-packages
>
> (which is *not* searched by default), rather than in a directory like
>
>      /usr/local/lib/python3.x/dist-packages
>
> which is searched by default.
>
> * m4/python.m4 (AM_PATH_PYTHON): Try to use the 'sysconfig' module if
> possible, for better interactions with python 3.x.



> Signed-off-by: Stefano Lattarini <address@hidden>
> ---
>   [SNIP]
>
> @@ -122,7 +141,14 @@ AC_DEFUN([AM_PATH_PYTHON],
>        else
>          am_py_prefix=$prefix
>        fi
> -     am_cv_python_pythondir=`$PYTHON -c "import sys; from distutils import sysconfig; 
> sys.stdout.write(sysconfig.get_python_lib(0,0,prefix='$am_py_prefix'))" 2>/dev/null`
> +     am_cv_python_pythondir=`$PYTHON -c "
> +$am_python_setup_sysconfig
> +if can_use_sysconfig:
> +    sitedir = sysconfig.get_path('purelib', vars={'base':'$am_py_prefix'})
> +else:
> +    from distutils import sysconfig
> +    sitedir = sysconfig.get_python_lib(0, 0, prefix='$am_py_prefix')
> +sys.stdout.write(sitedir)"`

Tested with python build from master branch on  2012-11-13 - both paths 
(sysconfig and distutils.sysconfig based) return same results.

>        case $am_cv_python_pythondir in
>        $am_py_prefix*)
>          am__strip_prefix=`echo "$am_py_prefix" | sed 's|.|.|g'`
> @@ -157,7 +183,14 @@ AC_DEFUN([AM_PATH_PYTHON],
>        else
>          am_py_exec_prefix=$exec_prefix
>        fi
> -     am_cv_python_pyexecdir=`$PYTHON -c "import sys; from distutils import sysconfig; 
> sys.stdout.write(sysconfig.get_python_lib(1,0,prefix='$am_py_exec_prefix'))" 
> 2>/dev/null`
> +     am_cv_python_pyexecdir=`$PYTHON -c "
> +$am_python_setup_sysconfig
> +if can_use_sysconfig:
> +    sitedir = sysconfig.get_path('platlib', vars={'base':'$am_py_prefix'})

Stefano, please use platbase as variable - see Lib/sysconfig.py :
....
INSTALL_SCHEMES = {
    'posix_prefix': {
...
        'purelib': '{base}/lib/python{py_version_short}/site-packages',
        'platlib': '{platbase}/lib/python{py_version_short}/site-packages',
...

> +else:
> +    from distutils import sysconfig
> +    sitedir = sysconfig.get_python_lib(1, 0, prefix='$am_py_prefix')
> +sys.stdout.write(sitedir)"`
>        case $am_cv_python_pyexecdir in
>        $am_py_exec_prefix*)
>          am__strip_prefix=`echo "$am_py_exec_prefix" | sed 's|.|.|g'`

Also I think that python experts should confirm if patch is correct.

Roumen