From hmbrand@cpan.org

Created by hmbrand@cpan.org

$ perl -wle'"a\x1"=~s/a(?=\x1)//'
Illegal hexadecimal digit ')' ignored at -e line 1.
Illegal hexadecimal digit ')' ignored at -e line 1.
Can't modify constant item in substitution (s///) at -e line 1, at EOF
Execution of -e aborted due to compilation errors.

The documented syntax for hex escapes is \xHH

* Why do I get a double warning
* Why does the assignment not warn

$ perl -wle'$_="a\x1)"'
Illegal hexadecimal digit ')' ignored at -e line 1.

Here it *does* warn

Same behaviour in 5.8.8

Flags:
    category=core
    severity=low

Site configuration information for perl 5.10.0:

Configured by merijn at Tue Dec 18 13:34:32 CET 2007.

Summary of my perl5 (revision 5 version 10 subversion 0) configuration:
  Platform:
    osname=linux, osvers=2.6.22.13-0.3-default, archname=i686-linux-64int
    uname='linux nb09 2.6.22.13-0.3-default #1 smp 20071119 15:02:58 utc i686 i686 i386 gnulinux '
    config_args='-Duse64bitint -des'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=undef, usemultiplicity=undef
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
    use64bitint=define, use64bitall=undef, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-fno-strict-aliasing -pipe -I/pro/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O2 -g',
    cppflags='-fno-strict-aliasing -pipe -I/pro/local/include'
    ccversion='', gccversion='4.2.1 (SUSE Linux)', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=12345678
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
    ivtype='long long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=4, prototype=define
  Linker and Libraries:
    ld='cc', ldflags ='-L/pro/local/lib'
    libpth=/pro/local/lib /lib /usr/lib /usr/local/lib
    libs=-lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lc
    perllibs=-lnsl -ldl -lm -lcrypt -lutil -lc
    libc=/lib/libc-2.6.1.so, so=so, useshrplib=false, libperl=libperl.a
    gnulibc_version='2.6.1'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -O2 -L/pro/local/lib'

Locally applied patches:
    


@INC for perl 5.10.0:
    /pro/lib/perl5/5.10.0/i686-linux-64int
    /pro/lib/perl5/5.10.0
    /pro/lib/perl5/site_perl/5.10.0/i686-linux-64int
    /pro/lib/perl5/site_perl/5.10.0
    .


Environment for perl 5.10.0:
    HOME=/home/merijn
    LANG=en_US.UTF-8
    LANGUAGE (unset)
    LD_LIBRARY_PATH=/usr/lib/mpi/gcc/openmpi/lib
    LOGDIR (unset)
    PATH=.:/home/merijn/bin/private:/home/merijn/bin:/pro/local/bin:/pro/bin:/usr/local/bin:/usr/lib/mpi/gcc/openmpi/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/X11/bin:/usr/bin/X11:/usr/X11R6/bin:/usr/games:/opt/kde3/bin:/opt/cross/bin:/usr/lib/mit/bin:/usr/lib/mit/sbin:/opt/gnome/bin:/usr/lib/qt3/bin:/pro/to/bin:/pro/local/sbin:/pro/lib/PTLinux/Helpers:/usr/libexec/git-core:/pro/3gl/CPAN/bin
    PERL_BADLANG (unset)
    SHELL=/bin/tcsh

From p5p@spam.wizbit.be

$ perl -wle'"a\x1"=~s/a(?=\x1)//'
Illegal hexadecimal digit ')' ignored at -e line 1.
Illegal hexadecimal digit ')' ignored at -e line 1.
Can't modify constant item in substitution (s///) at -e line 1, at EOF
Execution of -e aborted due to compilation errors.

The documented syntax for hex escapes is \xHH

* Why do I get a double warning
* Why does the assignment not warn

$ perl -wle'$_="a\x1)"'
Illegal hexadecimal digit ')' ignored at -e line 1.

Here it *does* warn

Same behaviour in 5.8.8

(also said on #p5p)

$_="a\x1"; does not warn since there are no characters after the 1.
m/a\x1/; also does not warn

If we look at octal​:

$ perl -wle 'print "\01A";'
A

$ perl -wle 'print "\018";'
Illegal octal digit '8' ignored at -e line 1.
8

Doing a similar thing for hex should be possible (only warn if the
symbol is in the [G-Zg-z] range) but I personally see very little value
in this warning.

A warning about \018 is useful since the user might be confusing
decimal with octal... But with what can you possible confuse \x1Z ?

Kind regards,

Bram

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

From p5p@spam.wizbit.be

$ perl -wle'"a\x1"=~s/a(?=\x1)//'
Illegal hexadecimal digit ')' ignored at -e line 1.
Illegal hexadecimal digit ')' ignored at -e line 1.
Can't modify constant item in substitution (s///) at -e line 1, at EOF
Execution of -e aborted due to compilation errors.
The documented syntax for hex escapes is \xHH

• Why do I get a double warning
• Why does the assignment not warn
  $ perl -wle'$_="a\x1)"'
  Illegal hexadecimal digit ')' ignored at -e line 1.
  Here it does warn
  Same behaviour in 5.8.8

(also said on #p5p)

$_="a\x1"; does not warn since there are no characters after the 1.
m/a\x1/; also does not warn

If we look at octal​:

$ perl -wle 'print "\01A";'
A

$ perl -wle 'print "\018";'
Illegal octal digit '8' ignored at -e line 1.
8

Doing a similar thing for hex should be possible (only warn if the
symbol is in the [G-Zg-z] range) but I personally see very little value
in this warning.

A warning about \018 is useful since the user might be confusing
decimal with octal... But with what can you possible confuse \x1Z ?

Kind regards,

Bram

The double warning was eliminated in perl-5.22.

$ perlbrew use perl-5.20.0
$ perl -wle'"a\x1"=~s/a(?=\x1)//'
Illegal hexadecimal digit ')' ignored at -e line 1.
Illegal hexadecimal digit ')' ignored at -e line 1.
Can't modify constant item in substitution (s///) at -e line 1, at EOF
Execution of -e aborted due to compilation errors.

$ perlbrew use perl-5.22.0
[p5p] 564 $ perl -wle'"a\x1"=~s/a(?=\x1)//'
Illegal hexadecimal digit ')' ignored at -e line 1.
Can't modify constant item in substitution (s///) at -e line 1, at EOF
Execution of -e aborted due to compilation errors.

Taking this ticket for the purpose of closing it within 7 days unless someone objects.

@Tux

From p5p@spam.wizbit.be

$ perl -wle'"a\x1"=~s/a(?=\x1)//'
Illegal hexadecimal digit ')' ignored at -e line 1.
Illegal hexadecimal digit ')' ignored at -e line 1.
Can't modify constant item in substitution (s///) at -e line 1, at EOF
Execution of -e aborted due to compilation errors.
The documented syntax for hex escapes is \xHH

• Why do I get a double warning
• Why does the assignment not warn
  $ perl -wle'$_="a\x1)"'
  Illegal hexadecimal digit ')' ignored at -e line 1.
  Here it does warn
  Same behaviour in 5.8.8

(also said on #p5p)
$_="a\x1"; does not warn since there are no characters after the 1.
m/a\x1/; also does not warn
If we look at octal​:
$ perl -wle 'print "\01A";'
A
$ perl -wle 'print "\018";'
Illegal octal digit '8' ignored at -e line 1.
8
Doing a similar thing for hex should be possible (only warn if the
symbol is in the [G-Zg-z] range) but I personally see very little value
in this warning.
A warning about \018 is useful since the user might be confusing
decimal with octal... But with what can you possible confuse \x1Z ?
Kind regards,
Bram

The double warning was eliminated in perl-5.22.

$ perlbrew use perl-5.20.0
$ perl -wle'"a\x1"=~s/a(?=\x1)//'
Illegal hexadecimal digit ')' ignored at -e line 1.
Illegal hexadecimal digit ')' ignored at -e line 1.
Can't modify constant item in substitution (s///) at -e line 1, at EOF
Execution of -e aborted due to compilation errors.

$ perlbrew use perl-5.22.0
[p5p] 564 $ perl -wle'"a\x1"=~s/a(?=\x1)//'
Illegal hexadecimal digit ')' ignored at -e line 1.
Can't modify constant item in substitution (s///) at -e line 1, at EOF
Execution of -e aborted due to compilation errors.

Taking this ticket for the purpose of closing it within 7 days unless someone objects.

@Tux

Closing as per schedule.