bug#51225: Possible bug in python.m4, automake 1.16.4+

[bluemoon]

Am 17.10.21 um 04:30 schrieb Joshua Root:
> On 2021-10-17 12:32 , Karl Berry wrote:
> >      
> > https://git.savannah.gnu.org/cgit/automake.git/commit/m4/python.m4?id=ed8daa069a6c8ed34f7856c42402ec46f305e670 
> >
> >
> >      However, this change leads to pkg-config .pc files containing the
> >      variable name $PYTHON_PREFIX, not its content
> >
> > I admit I didn't test much explicitly, but my understanding was that the
> > use of ${PYTHON_PREFIX} in various places instead of its value was
> > intentional, to allow for overriding at make time.
> >
> > Thus, whatever the process is for creating .pc files, I guess it
> > may need to change. A previous setting in the Makefile.am should yield
> > the value of PYTHON_PREFIX to be substituted.
>
> The documentation mentions in several places that the variables set by 
> Automake are only really designed to be used in the Makefiles that it 
> generates. Using AC_SUBST to directly substitute them into other kinds 
> of files comes with the risk of exactly this kind of thing happening.
>
> You could equally complain that some variables you want to use in the 
> .pc file are defined in terms of $prefix; except it just happens that 
> most .pc files already contain a prefix variable, so it works.
>
> As Karl alluded to, if you want the fully expanded path, the .pc file 
> needs to be generated by make, not configure. If you don't do it that 
> way, the way these Makefile variables are defined will change and break 
> your non-Makefiles sometimes.
>
> - Josh

@Josh sorry, but only just now did I see you already sent a patch to 
xcb-proto. This does solve the issue for me.

Anyway, thanks again to both of you! :)