Re: Bash 5.2 SHLVL change and autoconf test failures

[Chet Ramey]

On 9/30/22 1:45 AM, Xi Ruoyao wrote:
> [Resend because the previous one was rejected due to my bad SPF setting]
>
> On Thu, 2022-09-29 at 11:19 -0400, Chet Ramey wrote:
> > On 9/28/22 11:25 PM, Xi Ruoyao wrote:
> > > (Sorry for cross posting, but the topic is related to both side)
> > >
> > > In Bash-5.2 there is a change:
> > >
> > > "ff. Some fixes to how subshells modify $SHLVL."
> >
> > The single change affects pipelines for which bash optimizes out a
> > second
> > fork, so it doesn't decrement $SHLVL twice. It comes from this 2020
> > report:
> >
> > https://lists.gnu.org/archive/html/help-bash/2020-10/msg00012.html
> >
> > (the ssh aspect of this report is a red herring).
>
> Hmm, it makes sense but I can't see how this affects autoconf test suite
> (I don't really understand M4).

It might also be the result of a different change that optimizes out some
unnecessary forks; there are a couple of those. I'm not sure why autoconf
is keeping track of SHLVL anyway, unless it's recording state.

--
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/