lexical sub decl clears stack

[p5pRT]

Migrated from rt.perl.org#132442 (status was 'resolved')

Searchable as RT132442$

[p5pRT]

From zefram@fysh.org

Created by zefram@fysh.org

$ perl -lwe 'print for qw(aa bb), do { my sub lleexx; 123 }, qw(cc dd)'
123
cc
dd

Observe that at the point of "my sub", at runtime, the main stack gets
cleared, losing the items that had been pushed by an outer scope and which
should have been retained through the execution of the do{} expression.
This gets even weirder if there are multiple levels of list in play​:

$ perl -MData​::Dumper -lwe 'print Dumper [ qw(aa bb), [qw(pp qq), do { my sub lleexx; 123 }, qw(rr ss)], qw(cc dd) ]'
$VAR1 = [
  123,
  'rr',
  [
  'ss'
  ],
  'cc',
  'dd'
  ];

Perl Info

Flags:
    category=core
    severity=medium

Site configuration information for perl 5.27.5:

Configured by zefram at Fri Oct 20 23:24:00 BST 2017.

Summary of my perl5 (revision 5 version 27 subversion 5) configuration:
   
  Platform:
    osname=linux
    osvers=3.16.0-4-amd64
    archname=x86_64-linux-thread-multi
    uname='linux barba.rous.org 3.16.0-4-amd64 #1 smp debian 3.16.43-2+deb8u2 (2017-06-26) x86_64 gnulinux '
    config_args='-des -Dprefix=/home/zefram/usr/perl/perl_install/perl-5.27.5-i64-f52 -Duselargefiles -Dusethreads -Uafs -Ud_csh -Uusesfio -Uusenm -Duseshrplib -Dusedevel -Uversiononly -Ui_db'
    hint=recommended
    useposix=true
    d_sigaction=define
    useithreads=define
    usemultiplicity=define
    use64bitint=define
    use64bitall=define
    uselongdouble=undef
    usemymalloc=n
    default_inc_excludes_dot=define
    bincompat5005=undef
  Compiler:
    cc='cc'
    ccflags ='-D_REENTRANT -D_GNU_SOURCE -fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -D_FORTIFY_SOURCE=2'
    optimize='-O2'
    cppflags='-D_REENTRANT -D_GNU_SOURCE -fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include'
    ccversion=''
    gccversion='4.9.2'
    gccosandvers=''
    intsize=4
    longsize=8
    ptrsize=8
    doublesize=8
    byteorder=12345678
    doublekind=3
    d_longlong=define
    longlongsize=8
    d_longdbl=define
    longdblsize=16
    longdblkind=3
    ivtype='long'
    ivsize=8
    nvtype='double'
    nvsize=8
    Off_t='off_t'
    lseeksize=8
    alignbytes=8
    prototype=define
  Linker and Libraries:
    ld='cc'
    ldflags =' -fstack-protector-strong -L/usr/local/lib'
    libpth=/usr/local/lib /usr/lib/gcc/x86_64-linux-gnu/4.9/include-fixed /usr/include/x86_64-linux-gnu /usr/lib /lib/x86_64-linux-gnu /lib/../lib /usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib
    libs=-lpthread -lnsl -ldb -ldl -lm -lcrypt -lutil -lc
    perllibs=-lpthread -lnsl -ldl -lm -lcrypt -lutil -lc
    libc=libc-2.19.so
    so=so
    useshrplib=true
    libperl=libperl.so
    gnulibc_version='2.19'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs
    dlext=so
    d_dlsymun=undef
    ccdlflags='-Wl,-E -Wl,-rpath,/home/zefram/usr/perl/perl_install/perl-5.27.5-i64-f52/lib/5.27.5/x86_64-linux-thread-multi/CORE'
    cccdlflags='-fPIC'
    lddlflags='-shared -O2 -L/usr/local/lib -fstack-protector-strong'



@INC for perl 5.27.5:
    /home/zefram/usr/perl/perl_install/perl-5.27.5-i64-f52/lib/site_perl/5.27.5/x86_64-linux-thread-multi
    /home/zefram/usr/perl/perl_install/perl-5.27.5-i64-f52/lib/site_perl/5.27.5
    /home/zefram/usr/perl/perl_install/perl-5.27.5-i64-f52/lib/5.27.5/x86_64-linux-thread-multi
    /home/zefram/usr/perl/perl_install/perl-5.27.5-i64-f52/lib/5.27.5


Environment for perl 5.27.5:
    HOME=/home/zefram
    LANG (unset)
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/home/zefram/usr/perl/perl_install/perl-5.27.5-i64-f52/bin:/home/zefram/usr/perl/util:/home/zefram/pub/x86_64-unknown-linux-gnu/bin:/home/zefram/pub/common/bin:/usr/bin:/bin:/usr/local/bin:/usr/games
    PERLDOC=-oman
    PERL_BADLANG (unset)
    SHELL=/usr/bin/zsh

[p5pRT]

From @cpansprout

On Mon, 13 Nov 2017 22​:25​:29 -0800, zefram@​fysh.org wrote​:

This is a bug report for perl from zefram@​fysh.org,
generated with the help of perlbug 1.40 running under perl 5.27.5.

-----------------------------------------------------------------
[Please describe your issue here]

$ perl -lwe 'print for qw(aa bb), do { my sub lleexx; 123 }, qw(cc
dd)'
123
cc
dd

Observe that at the point of "my sub", at runtime, the main stack gets
cleared, losing the items that had been pushed by an outer scope and
which
should have been retained through the execution of the do{}
expression.
This gets even weirder if there are multiple levels of list in play​:

$ perl -MData​::Dumper -lwe 'print Dumper [ qw(aa bb), [qw(pp qq), do {
my sub lleexx; 123 }, qw(rr ss)], qw(cc dd) ]'
$VAR1 = [
123,
'rr',
[
'ss'
],
'cc',
'dd'
];

Even better​:

$ ./perl -lwe 'print join "-", qw(aa bb), do { my sub l; 123 }, qw(cc dd ee ff gg)'
cc123dd123ee123ff123gg

I have a fix. I’m just waiting for tests to finish.

--

Father Chrysostomos

[p5pRT]

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

[p5pRT]

From @cpansprout

On Tue, 14 Nov 2017 16​:23​:02 -0800, sprout wrote​:

On Mon, 13 Nov 2017 22​:25​:29 -0800, zefram@​fysh.org wrote​:

This is a bug report for perl from zefram@​fysh.org,
generated with the help of perlbug 1.40 running under perl 5.27.5.

-----------------------------------------------------------------
[Please describe your issue here]

$ perl -lwe 'print for qw(aa bb), do { my sub lleexx; 123 }, qw(cc
dd)'
123
cc
dd

Observe that at the point of "my sub", at runtime, the main stack
gets
cleared, losing the items that had been pushed by an outer scope and
which
should have been retained through the execution of the do{}
expression.
This gets even weirder if there are multiple levels of list in play​:

$ perl -MData​::Dumper -lwe 'print Dumper [ qw(aa bb), [qw(pp qq), do
{
my sub lleexx; 123 }, qw(rr ss)], qw(cc dd) ]'
$VAR1 = [
123,
'rr',
[
'ss'
],
'cc',
'dd'
];

Even better​:

$ ./perl -lwe 'print join "-", qw(aa bb), do { my sub l; 123 }, qw(cc
dd ee ff gg)'
cc123dd123ee123ff123gg

I have a fix. I’m just waiting for tests to finish.

Fixed in 695d658.

--

Father Chrysostomos

[p5pRT]

@cpansprout - Status changed from 'open' to 'pending release'

[p5pRT]

From @khwilliamson

Thank you for filing this report. You have helped make Perl better.

With the release yesterday of Perl 5.28.0, this and 185 other issues have been
resolved.

Perl 5.28.0 may be downloaded via​:
https://metacpan.org/release/XSAWYERX/perl-5.28.0

If you find that the problem persists, feel free to reopen this ticket.

[p5pRT]

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