[perl #130010] v5.25.5-184-ga5540cf breaks texinfo

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[perl #130010] v5.25.5-184-ga5540cf breaks texinfo

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From:

James E Keenan via RT

Date:

November 8, 2016 01:12

Subject:

[perl #130010] v5.25.5-184-ga5540cf breaks texinfo

Message ID:

rt-4.0.24-6212-1478567545-200.130010-15-0@perl.org

On Mon, 07 Nov 2016 16:59:37 GMT, jkeenan wrote:
> On Mon, 07 Nov 2016 16:29:40 GMT, jkeenan wrote:
> > On Mon, 07 Nov 2016 13:47:55 GMT, jkeenan wrote:
> > >
> > > The question is:  What is it about this the pattern:
> > >
> > > #####
> > > /([^\S\x{202f}\x{00a0}]+)|(\p{InFullwidth})|((?:[^\s\p{InFullwidth}]|[\x{202f}\x{00a0}])+)/
> > > #####
> > >
> > > ... that (a) as of commit C<a5540cf> but not previously; and (b) in
> > > the context of this test suite but not in isolation, perceives
> > > something to be a read-only value not subject to modification?
> >
> > My next brainstorm:  Add "use re 'debug';" to sub add_text() in
> > tp/Texinfo/Convert/ParagraphNonXS.pm.
> >
> > When I did so and ran the debugging program found in one of my
> > previous attachments, I got this output:
> >
> > #####
> > Texinfo::Convert::ParagraphNonXS::add_text(../../tp/Texinfo/Convert/ParagraphNonXS.pm:329):
> > 329:      my @segments = split
> > 330:
> > /([^\S\x{202f}\x{00a0}]+)|(\p{InFullwidth})|((?:[^\s\p{InFullwidth}]|[\x{202f}\x{00a0}])+)/,
> > 331:        $text;
> >   DB<6> n
> > Matching REx
> > "([^\S\x{202f}\x{00a0}]+)|(\p{InFullwidth})|((?:[^\s\p{InFull"...
> > against "This is "
> >    0 <> <This is >           |   0| 1:BRANCH(18)
> >    0 <> <This is >           |   1|  2:OPEN1(4)
> >    0 <> <This is >           |   1|  4:PLUS(16)
> >                              |   1|  ANYOF[\t\n\x0B\f\r \x85][1680
> > 2000-200A 2028-2029 205F 3000] can match 0 times out of 2147483647...
> >                              |   1|  failed...
> >    0 <> <This is >           |   0| 18:BRANCH(34)
> >    0 <> <This is >           |   1|  19:OPEN2(21)
> >    0 <> <This is >           |   1|
> > 21:ANYOF[+utf8::Texinfo::Convert::ParagraphNonXS::InFullwidth](32)
> >                              |   1|  failed...
> >    0 <> <This is >           |   0| 34:BRANCH(68)
> >    0 <> <This is >           |   1|  35:OPEN3(37)
> >    0 <> <This is >           |   1|  37:CURLYM[0]{1,INFTY}(66)
> >    0 <> <This is >           |   2|   39:BRANCH(51)
> >    0 <> <This is >           |   3|    40:ANYOF[^\t\n\x0B\f\r
> > \x85\xA0{+utf8::Texinfo::Convert::ParagraphNonXS::InFullwidth}1680
> > 2000-200A 2028-2029 202F 205F 3000](64)
> > Modification of a read-only value attempted at
> > ../../tp/Texinfo/Convert/ParagraphNonXS.pm line 329.
> >  at ../../tp/Texinfo/Convert/ParagraphNonXS.pm line 329.
> >         Texinfo::Convert::ParagraphNonXS::add_text(Texinfo::Convert::ParagraphNonXS=HASH(0x35ba938),
> > "This is ") called at ../../tp/Texinfo/Convert/Info.pm line 308
> >         Texinfo::Convert::Info::_info_header(Texinfo::Convert::Info=HASH(0x35b3038))
> > called at ../../tp/Texinfo/Convert/Info.pm line 81
> >         Texinfo::Convert::Info::output(Texinfo::Convert::Info=HASH(0x35b3038),
> > HASH(0x35ab7c0)) called at ../texi2any.pl line 1348
> > panic: POPSTACK
> > Debugged program terminated.
> > #####
> >
> > Since I have never previously used the regex debugger, I have no idea
> > if there are any clues to a solution in that output.
> >
> 
> Compiling perl at what has been identified as the last good commit,
> and then running the test program through the debugger, I got much
> better output.  It's quite long, so I'm posting it here:
> 
> https://gist.github.com/jkeenan/184d2aaf914e4aa0410fe2ea1f36da91
> 
> Thank you very much.

Yet another gist (actually, excerpts):

https://gist.github.com/jkeenan/faad48a7d3dfe0c40eab07684388edfb

At the first "bad" commit, I build perl with -DDEBUGGING.  I reduced the invocation of the Perl script from within the texinfo test suite that I had been using to the minimum number of command-line switches that would still generate the panic.  I got the output in the gist.

I got similar output when I used the Perl debugger and stepped through to the failure point and then, unlike previously I called 's' *into* the 'my @segments' line.  But, whatever debugging procedure I use, I always seem to end up with output like this:

#####
Matching REx "([^\S\x{202f}\x{00a0}]+)|(\p{InFullwidth})|((?:[^\s\p{InFullwidth}]|[\x{202f}\x{00a0}])+)" against "This is "
   0 <> <This is >           |   0| 1:BRANCH(18)
   0 <> <This is >           |   1|  2:OPEN1(4)
   0 <> <This is >           |   1|  4:PLUS(16)
                             |   1|  ANYOF[\t\n\x0B\f\r \x85][1680 2000-200A 2028-2029 205F 3000] can match 0 times out of 2147483647...
                             |   1|  failed...
   0 <> <This is >           |   0| 18:BRANCH(34)
   0 <> <This is >           |   1|  19:OPEN2(21)
   0 <> <This is >           |   1|  21:ANYOF[+utf8::Texinfo::Convert::ParagraphNonXS::InFullwidth](32)
                             |   1|  failed...
   0 <> <This is >           |   0| 34:BRANCH(68)
   0 <> <This is >           |   1|  35:OPEN3(37)
   0 <> <This is >           |   1|  37:CURLYM[0]{1,INFTY}(66)
   0 <> <This is >           |   2|   39:BRANCH(51)
   0 <> <This is >           |   3|    40:ANYOF[^\t\n\x0B\f\r \x85\xA0{+utf8::Texinfo::Convert::ParagraphNonXS::InFullwidth}1680 2000-200A 2028-2029 202F 205F 3000](64)
Modification of a read-only value attempted at tp/../tp/Texinfo/Convert/ParagraphNonXS.pm line 328.
panic: POPSTACK
#####

... with no insight into what the read-only value is and where the 'modification' is being attempted.

Thank you very much.

-- 
James E Keenan (jkeenan@cpan.org)

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