configure m4 problem

[Niels Möller]

Ozkan Sezer <sezeroz at gmail.com> writes:

> This is what I got from our builders / configury maintainers:
>
> "The configure script is running flex using a nonexistent M4.
> That causes a sigpipe, which leaves a useless orphaned file.
> The configure script looks at that and says "ok, flex works".
> Under python, sigpipe gets filtered out.  So, flex cleans up
> after itself (as it should), thus deleting the file, and so
> the configure script thinks flex is broken (when in reality,
> the configure script is wrong and flex reported correctly.)
> M4 can't be defined before running AM_PROG_LEX, and it should
> not be defined al all in that fashion, either."

As far as I see, the configure script does not explicitly start any m4
when testing for flex. Also, it does not export the M4 variable.

My best guess is that

1. M4 is for some reason exported into the environment before configure
   is started.

2. The value is then changed by configure.

3. Flex then inherits the modified value (although neither the
   documentation nor strings indicates that flex examines $M4).

You could try adding an

  unexport M4

to the configure script to see if that makes any interesting difference.

Regards,
/Niels

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