[perl #80764] "open FH, '<:raw', $filehandle" makes filehandle unbuffered

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This is a bug report for perl from leon@leon-laptop.(none),
generated with the help of perlbug 1.39 running under perl 5.12.1.


-----------------------------------------------------------------

Opening a file with :raw doesn't work as documented. It opens the file with only the :unix layer, without a perlio layer, hence it will be unbuffered. Opening a file without a specific mode and using binmode later does give the correct result. I've could replicate this bug on 5.8.9, 5.10.1, 5.12.1 and blead.

Example code:

use Data::Dumper;
use PerlIO;

#works incorrectly
open my $fh, '<:raw', $0;
print Dumper([ PerlIO::get_layers($fh) ]);
#got: [ 'unix' ]
#expected: [ 'unix', 'perlio' ]

#works correctly
open my $fh2, '<', $0;
binmode $fh2, ':raw';
print Dumper([ PerlIO::get_layers($fh2) ]);
#got: [ 'unix', 'perlio' ]
#expected: [ 'unix', 'perlio' ]

-----------------------------------------------------------------
---
Flags:
    category=core
    severity=medium
---
Site configuration information for perl 5.12.1:

Configured by leon at Fri Aug 20 20:56:31 EEST 2010.

Summary of my perl5 (revision 5 version 12 subversion 1) configuration:
   
  Platform:
    osname=linux, osvers=2.6.32-24-generic, archname=x86_64-linux
    uname='linux leon-laptop 2.6.32-24-generic #41-ubuntu smp thu aug 19 01:38:40 utc 2010 x86_64 gnulinux '
    config_args='-de -Dprefix=/home/leon/perl5/perlbrew/perls/perl-5.12.1'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=undef, usemultiplicity=undef
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
    use64bitint=define, use64bitall=define, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O2',
    cppflags='-fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include'
    ccversion='', gccversion='4.4.3', gccosandvers=''
    intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
    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 -L/usr/local/lib'
    libpth=/usr/local/lib /lib /usr/lib /lib64 /usr/lib64
    libs=-lnsl -ldl -lm -lcrypt -lutil -lc
    perllibs=-lnsl -ldl -lm -lcrypt -lutil -lc
    libc=/lib/libc-2.11.1.so, so=so, useshrplib=false, libperl=libperl.a
    gnulibc_version='2.11.1'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -O2 -L/usr/local/lib -fstack-protector'

Locally applied patches:
    

---
@INC for perl 5.12.1:
    /home/leon/perl5/perlbrew/perls/perl-5.12.1/lib/site_perl/5.12.1/x86_64-linux
    /home/leon/perl5/perlbrew/perls/perl-5.12.1/lib/site_perl/5.12.1
    /home/leon/perl5/perlbrew/perls/perl-5.12.1/lib/5.12.1/x86_64-linux
    /home/leon/perl5/perlbrew/perls/perl-5.12.1/lib/5.12.1
    .

---
Environment for perl 5.12.1:
    HOME=/home/leon
    LANG=en_US.utf8
    LANGUAGE=en_US:en_GB:en
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/home/leon/perl5/perlbrew/bin:/home/leon/perl5/perlbrew/perls/current/bin:/home/leon/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games
    PERL_BADLANG (unset)
    SHELL=/bin/bash

• [perl #80764] "open FH, '<:raw', $filehandle" makes filehandle unbuffered by perlbug-followup