bug#25740: [PATCH] Swallow m4traces that have no file/line number

[Zack Weinberg]

I would like to get this bug fixed for autoconf 2.70, but the trouble
is I have no idea how to reproduce the problem on my computer.  The
various old reports you originally linked to, all seem to involve
filesystem-level bugs on MacOS, which I don't have convenient access
to, or with archaic versions of the Linux CIFS driver.

You wrote:

> The root cause is m4 traces without a file/line number shown.
> So instead of something like:
>
>   m4trace:configure.ac:48: -1- ...
>
> you have something like:
>
>  m4trace: -1- ...
>
> In the scenarios I ran into, this is due to some error that throws m4 out.

Are you aware of a way to reproduce this effect on an ordinary local
file system?  If so, can you send me a minimal configure.ac, plus any
other necessary files, and instructions for using them to make m4 do
this?

zw