From @ikegami

Created by @ikegami

This is a bug report for perl from ikegami@​adaelis.com,
generated with the help of perlbug 1.39 running under perl 5.14.0.
-----------------------------------------------------------------

Hi,

Does the "p" modifier apply to the operator (like "o") or the pattern (like
"s")? It seems to me it applies to the operator.

That said, (?​:) supports p, although it has no effect (sometimes with
warning, sometimes without).

perl -wE"'x' =~ /x/p or die; say ${^MATCH} // '-';"
x

perl -wE"'x' =~ /(?p​:x)/ or die; say ${^MATCH} // '-';"
-

perl -wE"'x' =~ /(?-p​:x)/p or die; say ${^MATCH} // '-';"
Useless use of (?-p) in regex; marked by <-- HERE in m/(?-p <-- HERE :x)/ at
-e line 1.
x

Except sometimes it does have an effect.

perl -wE"$re=qr/x/p; 'x' =~ /${re}/ or die; say ${^MATCH} // '-';"
x

perl -wE"$re=qr/x/p; 'xy' =~ /${re}y/ or die; say ${^MATCH} // '-';"
-

And then there's the case where (?-p​:) warns even though it appears to work.

perl -wE"$re=qr/x/p; 'x' =~ /$re/ or die; say ${^MATCH} // '-';"
x

perl -wE"$re=qr/x/p; 'x' =~ /(?-p​:$re)/ or die; say ${^MATCH} // '-';"
Useless use of (?-p) in regex; marked by <-- HERE in m/(?-p <-- HERE
:(?^up​:x))/ at -e line 1.
-

From a user's perspective, none of this makes no sense. It was probably done
this way so C<< $re = qr/.../p; $_ =~ $re >> works, but that doesn't really
make sense either. "p" should be a m// modifier, it shouldn't be qr//
modifier, and it should be allowed in (?​:).

- Eric

Flags:
    category=core
    severity=low

Site configuration information for perl 5.14.0:

Configured by gecko at Thu May 12 09:33:39 2011.

Summary of my perl5 (revision 5 version 14 subversion 0) configuration:

  Platform:
    osname=MSWin32, osvers=5.2, archname=MSWin32-x86-multi-thread
    uname=''
    config_args='undef'
    hint=recommended, useposix=true, d_sigaction=undef
    useithreads=define, usemultiplicity=define
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
    use64bitint=undef, use64bitall=undef, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='C:/Progs/PERL51~4/site/bin/gcc.exe', ccflags ='-DNDEBUG -DWIN32
-D_CONSOLE -DNO_STRICT -DPERL_TEXTMODE_SCRIPTS -DUSE_SITECUSTOMIZE
-DPERL_IMPLICIT_CONTEXT -DPERL_IMPLICIT_SYS -DUSE_PERLIO -D_USE_32BIT_TIME_T
-DHASATTRIBUTE -fno-strict-aliasing -mms-bitfields',
    optimize='-O2',
    cppflags='-DWIN32'
    ccversion='', gccversion='3.4.5 (mingw-vista special r3)',
gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
    d_longlong=undef, longlongsize=8, d_longdbl=define, longdblsize=8
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='__int64',
lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='C:\Progs\PERL51~4\site\bin\g++.exe', ldflags
='-L"C:\Progs\perl5140-ap1400\lib\CORE"'
    libpth=\lib
    libs=-lkernel32 -luser32 -lgdi32 -lwinspool -lcomdlg32 -ladvapi32
-lshell32 -lole32 -loleaut32 -lnetapi32 -luuid -lws2_32 -lmpr -lwinmm
-lversion -lodbc32 -lodbccp32 -lcomctl32 -lmsvcrt
    perllibs=-lkernel32 -luser32 -lgdi32 -lwinspool -lcomdlg32 -ladvapi32
-lshell32 -lole32 -loleaut32 -lnetapi32 -luuid -lws2_32 -lmpr -lwinmm
-lversion -lodbc32 -lodbccp32 -lcomctl32 -lmsvcrt
    libc=msvcrt.lib, so=dll, useshrplib=true, libperl=perl514.lib
    gnulibc_version=''
  Dynamic Linking:
    dlsrc=dl_win32.xs, dlext=dll, d_dlsymun=undef, ccdlflags=' '
    cccdlflags=' ', lddlflags='-mdll -L"C:\Progs\perl5140-ap1400\lib\CORE"'

Locally applied patches:
    ACTIVEPERL_LOCAL_PATCHES_ENTRY


@INC for perl 5.14.0:
    C:/Progs/perl5140-ap1400/site/lib
    C:/Progs/perl5140-ap1400/lib
    .


Environment for perl 5.14.0:
    HOME (unset)
    LANG (unset)
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)

PATH=c:\bin;C:\Progs\perl5140-ap1400\site\bin;C:\Progs\perl5140-ap1400\bin;...
    PERL_BADLANG (unset)
    SHELL (unset)

From @ikegami

On Fri Oct 21 21​:08​:11 2011, ikegami@​adaelis.com wrote​:

"p" should be a m// modifier, it shouldn't be qr//
modifier, and it should be allowed in (?​:).

doh! I meant

"p" should be a m// modifier, it shouldn't be qr// modifier, and it
*shouldn't* be allowed in (?​:).

@ikegami - Status changed from 'new' to 'open'

From @cpansprout

On Fri Oct 21 21​:08​:11 2011, ikegami@​adaelis.com wrote​:

This is a bug report for perl from ikegami@​adaelis.com,
generated with the help of perlbug 1.39 running under perl 5.14.0.
-----------------------------------------------------------------

Hi,

Does the "p" modifier apply to the operator (like "o") or the pattern
(like
"s")? It seems to me it applies to the operator.

That said, (?​:) supports p, although it has no effect (sometimes with
warning, sometimes without).

perl -wE"'x' =~ /x/p or die; say ${^MATCH} // '-';"
x

perl -wE"'x' =~ /(?p​:x)/ or die; say ${^MATCH} // '-';"
-

perl -wE"'x' =~ /(?-p​:x)/p or die; say ${^MATCH} // '-';"
Useless use of (?-p) in regex; marked by <-- HERE in m/(?-p <-- HERE
:x)/ at
-e line 1.
x

Except sometimes it does have an effect.

perl -wE"$re=qr/x/p; 'x' =~ /${re}/ or die; say ${^MATCH} // '-';"
x

perl -wE"$re=qr/x/p; 'xy' =~ /${re}y/ or die; say ${^MATCH} // '-';"
-

And then there's the case where (?-p​:) warns even though it appears to
work.

perl -wE"$re=qr/x/p; 'x' =~ /$re/ or die; say ${^MATCH} // '-';"
x

perl -wE"$re=qr/x/p; 'x' =~ /(?-p​:$re)/ or die; say ${^MATCH} // '-
';"
Useless use of (?-p) in regex; marked by <-- HERE in m/(?-p <-- HERE
:(?^up​:x))/ at -e line 1.
-

From a user's perspective, none of this makes no sense.

I would say *all* of this makes no sense. :-)

It makes as much sense as $x = qr/foo/g; s/$x/bar/; (which, come to
think of it, is just like JavaScript).

Notice I didn’t add /p support to ‘use re '/flags'’.

From @ikegami

On Sat, Oct 22, 2011 at 1​:22 AM, Father Chrysostomos via RT <
perlbug-followup@​perl.org> wrote​:

From a user's perspective, none of this makes no sense.

I would say *all* of this makes no sense. :-)

sigh, I'm wearing my contacts for the first time in many months, and
apparently, that's causing me to negate everything I say! X_X

Yes, that's what I meant, thanks.

From @Abigail

On Fri, Oct 21, 2011 at 09​:08​:11PM -0700, Eric Brine wrote​:

# New Ticket Created by "Eric Brine"
# Please include the string​: [perl #101938]
# in the subject line of all future correspondence about this issue.
# <URL​: https://rt-archive.perl.org/perl5/Ticket/Display.html?id=101938 >

This is a bug report for perl from ikegami@​adaelis.com,
generated with the help of perlbug 1.39 running under perl 5.14.0.
-----------------------------------------------------------------

Hi,

Does the "p" modifier apply to the operator (like "o") or the pattern (like
"s")? It seems to me it applies to the operator.

That said, (?​:) supports p, although it has no effect (sometimes with
warning, sometimes without).

perl -wE"'x' =~ /x/p or die; say ${^MATCH} // '-';"
x

perl -wE"'x' =~ /(?p​:x)/ or die; say ${^MATCH} // '-';"
-

perl -wE"'x' =~ /(?-p​:x)/p or die; say ${^MATCH} // '-';"
Useless use of (?-p) in regex; marked by <-- HERE in m/(?-p <-- HERE :x)/ at
-e line 1.
x

Except sometimes it does have an effect.

perl -wE"$re=qr/x/p; 'x' =~ /${re}/ or die; say ${^MATCH} // '-';"
x

perl -wE"$re=qr/x/p; 'xy' =~ /${re}y/ or die; say ${^MATCH} // '-';"
-

That can be explained by the fact that /${re}/ doesn't do a
stringification-regexp compile roundtrip, where /${re}y/ does.
It's a side-effect of the optimization.

And then there's the case where (?-p​:) warns even though it appears to work.

perl -wE"$re=qr/x/p; 'x' =~ /$re/ or die; say ${^MATCH} // '-';"
x

perl -wE"$re=qr/x/p; 'x' =~ /(?-p​:$re)/ or die; say ${^MATCH} // '-';"
Useless use of (?-p) in regex; marked by <-- HERE in m/(?-p <-- HERE
:(?^up​:x))/ at -e line 1.
-

Again, that's due to the stringification-regexp compile roundtrip.
Replacing (?-p by (?-i makes it print '-' as well.

From a user's perspective, none of this makes no sense. It was probably done
this way so C<< $re = qr/.../p; $_ =~ $re >> works, but that doesn't really
make sense either. "p" should be a m// modifier, it shouldn't be qr//
modifier, and it should be allowed in (?​:).

Abigail

From @ikegami

On Sat, Oct 22, 2011 at 10​:45 AM, Abigail <abigail@​abigail.be> wrote​:

That can be explained by the fact that /${re}/ doesn't do a
stringification-regexp compile roundtrip, where /${re}y/ does.
It's a side-effect of the optimization.

Explain to whom? To me? I know that. To the users? I could be wrong, but I
don't think they care.