enter/leave messages (was: Re: Output sync completed (?))

[Paul Smith]

On Mon, 2013-05-06 at 10:26 +0200, Stefano Lattarini wrote:
> >       * Extraneous enter/leave lines are not printed any longer.
> >
> I still see them actually, if I try to build the latest coreutils

I guess it depends on your definition of "extraneous" :-).

I was considering "extraneous" to mean "multiple identical enter/leave
lines in a row", which we used to get and are clearly useless.  I don't
see those anymore, even with the coreutils build.

If you consider "extraneous" to mean "more than there used to be", then
they're still there: there's one surrounding each synchronized sequence
of output with -O enabled.

After thinking about it, the output-sync changes introduced two separate
features bundled together: not only the sync changes but also changes to
the enter/leave behavior.  One doesn't require the other, really.

I understand the impetus for the change: tools that read make output and
try to track the build can be confused during parallel builds, since
targets are built across different recursive make invocations at the
same time.  However this is no worse than it was before output-sync.

I think you want to be able to select the granularity of enter/leave
separately from whether or not you're using -O.

But that brings us to the next issue: there's no portable way to control
this.  It has to be added to MAKEFLAGS but automake, for example, which
wants to generate a portable makefile, is out of luck: it can't add this
non-portable flag to MAKEFLAGS in a portable makefile.  You pretty much
have to leave it up to the person invoking make to remember to do it.

Given all this I think the best thing would be to not force the new
enter/leave behavior by default, and come up with a different way to
enable/disable it.