Perl 5.20 regression: Hang when compiling while(1) in a list

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Migrated from rt.perl.org#122995 (status was 'resolved')

Searchable as RT122995$

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From @cpansprout

This hangs at compile time​:

$ perl5.20.1 -e 'sub foo { () = ($a, my $b, ($c, do { while(1) {} })) }'
^C

I found this by reading the source code. (C.f. commit 71a29c3
which fixed a similar bug long ago.)

I’ll have a fix ready soon.

--

Father Chrysostomos

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From @jkeenan

On Thu Oct 16 15​:53​:16 2014, sprout wrote​:

This hangs at compile time​:

$ perl5.20.1 -e 'sub foo { () = ($a, my $b, ($c, do { while(1) {} })) }'
^C

I found this by reading the source code. (C.f. commit 71a29c3
which fixed a similar bug long ago.)

I’ll have a fix ready soon.

Confirmed comparing 5.16.3 vs 5.20.1. Have you been able to bisect to determine the problematic commit?

Thank you very much.
Jim Keenan
--
James E Keenan (jkeenan@​cpan.org)

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The RT System itself - Status changed from 'new' to 'open'

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From @cpansprout

On Thu Oct 16 16​:33​:41 2014, jkeenan wrote​:

On Thu Oct 16 15​:53​:16 2014, sprout wrote​:

This hangs at compile time​:

$ perl5.20.1 -e 'sub foo { () = ($a, my $b, ($c, do { while(1) {}
})) }'
^C

I found this by reading the source code. (C.f. commit 71a29c3
which fixed a similar bug long ago.)

I’ll have a fix ready soon.

Confirmed comparing 5.16.3 vs 5.20.1. Have you been able to bisect to
determine the problematic commit?

It’s probably not necessary. The bad code was added by 7d3c8a6 according to git-blame.

I have just fixed it in 0d42e77, which should be backported to maint-5.20, IMO. (Please leave this ticket open till then.)

--

Father Chrysostomos

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@steve-m-hay - Status changed from 'open' to 'pending release'

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From @khwilliamson

Thanks for submitting this ticket

The issue should be resolved with the release today of Perl v5.22. If you find that the problem persists, feel free to reopen this ticket

--
Karl Williamson for the Perl 5 porters team

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@khwilliamson - Status changed from 'pending release' to 'resolved'