[Mesa-dev] [RFC] configure.ac: Don't check for python mako module if python is not installed

[Matt Turner]

On Sat, Feb 28, 2015 at 3:10 AM, Emil Velikov <emil.l.velikov at gmail.com> wrote:
> On 27/02/15 17:42, Matt Turner wrote:
>> For flex and bison, we check if a generated source file exists, which
>> is probably a good idea. That way configure will fail in a git
>> checkout if you don't have python.
>>
> Checking for the presence of one auto-generated file does not sound like
> a great idea imho. What happens if any of the other files is not present
> - should we keep the whole list in configure.ac ? Keeping the list in
> sync seems quite error prone.

I copied the check-for-a-file pattern from libxkbcommon at the
recommendation of Gaetan Nadon more than three years ago, and as far
as I'm aware it's worked just fine. That's not to say that it's
perfect, but claiming something that's been working fine for three
years is "not a great idea" without offering a suggestion is a bit off
putting.


Maybe I've misunderstood how this patch works. From the sound of
"without Python it is going to fail anyway because Python is not
present when trying to autogenerate the files" it seems that we're
okay with not checking for mako if Python isn't present because
running make is going to fail anyway?

That doesn't sound like what we want -- it's configure's job to
determine if we have the necessary dependencies for make to succeed.

I'll think about this some more.

> A hacky alternative is to set the variable (BISON/LEX/PYTHON2) to
> something like `echo "Missing XXX dependency" && return 1` when empty.
> Yet that looks quite nasty, plus it shows rather late in the build
> process :\
>
>> I have in my todo list to add some remaining source files generated by
>> python to the autotools distribution. After we commit some version of
>> this patch, Emil or I should make sure that all the python-generated
>> code is included in the tarball.
>>
> I was under the impression that we already do, but I will double-check.
>
>
> On a mildly related note:
> For anyone that missed it Ken voiced concerns over shipping the
> lex/bison generated files. Main idea is that as(if) security bugs are
> found and fixed in those products, mesa has been released with such
> vulnerable files.
> I can see his point, and I tend to agree with him. How do others feel on
> the topic ?

Someone concerned should talk to the automake/bison/flex upstreams and
see what they think. It is of course automake that adds the generated
code to the distribution.

We're certainly not the only project shipping code generated by flex and bison.