Re: fatal error: internal error with Gawk 5.2.1

[Vincent Forest]

Dear Arnold,

It seems to be the same issue that can be observed using noweb [1] with 
gawk 5.2.1, and the commit 2848045aed5ccfd7b582808288f7fcc18d319952 
seems to be one introducing the bug.

Anyway, it seems that the following code, taken from noweb's noidx 
script [2], is sufficient to reproduce the crash:

awk '
function tailmatch(string, tail, pos) {
  pos = length(string) - length(tail) + 1
  if (pos > 0 && substr(string, pos) == tail) {
    return 1
  } else {
    return 0
  }
}

BEGIN { defanchors[0] = 0 }
/^@defn / { 
  if(!tailmatch(defanchors["test"], "marker")) {
    defanchors["test"] = defanchors["test"] "marker"
  }
}' << EOF
@defn test
EOF

With best regards,

Vincent

[1] https://www.cs.tufts.edu/~nr/noweb/
[2] https://github.com/nrnrnr/noweb/blob/master/src/awk/noidx

> arnold <arnold@skeeve.com> wrote:
>
> Thanks for the report. I will try to find some time to
> investigate.
>
> Arnold
>
> Volodymyr Gubarkov <xonixx@gmail.com> wrote:
>
> > Hi!
> >
> > I beg pardon for a huge test case, but still better than nothing.
> >
> > I've prepared a repo with reproducible code:
> > https://github.com/xonixx/bugreport-1
> >
> > So it appears, Gawk 5.2.x crashes on it with:
> >
> > $ ./soft/gawk521 -f makesure.awk 27_parameterized_goals_10_errors.sh -l
> > gawk521: makesure.awk:674:
> > (FILENAME=tests/27_parameterized_goals_10_errors.sh FNR=23) fatal error:
> > internal error
> > Aborted (core dumped)
> >
> > Interestingly, if you rewrite line 674 into two lines:
> >
> >     gii = goalNameInstantiated SUBSEP i
> >     Dependencies[gii] = instantiate(dep,newArgs)
> >
> > the error changes:
> >
> > free(): double free detected in tcache 2
> > Aborted (core dumped)
> >
> > Code works as intended with Gawk 5.1.1 and bwk.
> >
> > Just in case:
> >
> > $ uname -a ; cat /etc/issue
> > Linux xonix 5.4.0-136-generic #153-Ubuntu SMP Thu Nov 24 15:56:58 UTC 2022
> > x86_64 x86_64 x86_64 GNU/Linux
> > Linux Mint 20.3 Una \n \l
> >
> > Though, I'm observing the same problem on macOS as well:
> > https://github.com/xonixx/makesure/actions/runs/3989059129/jobs/6841018914
> >
> > Best regards,
> > Volodymyr