Issues with automatic re-execution of configure with CONFIG_SHELL (was: Re: autoconf-2.68b released [beta])

[Stefano Lattarini]

Hi Tim, Paul, thanks for the report.

Tim Rice wrote:
> 
> On my UnixWare 7.1.4 box, the tests get stuck on
>  75: Configure re-execs self with CONFIG_SHELL
> 
> I'll try to do some more debugging in a couple of days.

Paul Eggert wrote:
> autoconf 2.68b loops on Solaris 10 sparc (test 75)
>
> The symptoms are:
>
> $ cd tests; make check TESTSUITEFLAGS=75
> make  check-local
> /bin/bash ./testsuite 75
> ## ------------------------------ ##
> ## GNU Autoconf 2.68b test suite. ##
> ## ------------------------------ ##
> 75: Configure re-execs self with CONFIG_SHELL
>
> and it hangs until I do a ^C.

I can reproduce the issues with dash-0.5.2:

  $ echo 'AC_INIT(x,0)' > configure.ac
  $ autoconf-2.68b
  $ CONFIG_SHELL=/opt/extra/bin/dash-0.5.2 ./configure # Loops
  ^C

It seems to me that the problem happens only with shells that do not
expand $LINENO, for which the rewrite-and-sourcing of configure.lineno
messes up our guard against infinite recursion.  The attached patch
should fix that.  OK for master?

Thanks,
  Stefano

0001-configure-don-t-infloop-when-re-executing-with-CONFI.patch
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