From krolnik@lsil.com

This is a bug report for perl from krolnik@​lsil.com,
generated with the help of perlbug 1.26 running under perl 5.00503.

# Here are three forms of regular expressions
# that should only be differing by whitespace.

$a =~ s/c|d|e//x;

$a1 =~ s/c #
  |d # here \
  |e //x;

# The above two do fine - parse correctly.

$a2 =~ s/c # /
  |d # here \
  |e //x;

This similar example (differing in 1 character) causes parsing
problems. perl (5.00503 and 5.6 ) -wc produces (among others)

Unquoted string "x" may clash with future reserved word at /tmp/spl line 16.

The slash at the end of the first line of the regular expression
terminates the regular expression - incorrectly.

Site configuration information for perl 5.00503​:

Configured by greg at Thu Oct 7 17​:35​:08 CDT 1999.

Summary of my perl5 (5.0 patchlevel 5 subversion 3) configuration​:
  Platform​:
  osname=solaris, osvers=2.6, archname=sun4-solaris
  uname='sunos dts49 5.6 generic_105181-15 sun4u sparc sunw,ultra-enterprise '
  hint=previous, useposix=true, d_sigaction=define
  usethreads=undef useperlio=undef d_sfio=undef
  Compiler​:
  cc='gcc', optimize='-O', gccversion=2.8.1
  cppflags='-I/usr/local/include'
  ccflags ='-I/usr/local/include'
  stdchar='unsigned char', d_stdstdio=define, usevfork=false
  intsize=4, longsize=4, ptrsize=4, doublesize=8
  d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
  alignbytes=8, usemymalloc=y, prototype=define
  Linker and Libraries​:
  ld='gcc', ldflags =' -L/usr/local/lib'
  libpth=/usr/local/lib /lib /usr/lib /usr/ccs/lib
  libs=-lsocket -lnsl -ldl -lm -lc -lcrypt
  libc=/lib/libc.so, so=so, useshrplib=false, libperl=libperl.a
  Dynamic Linking​:
  dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags=' '
  cccdlflags='-fPIC', lddlflags='-G -L/usr/local/lib'

Locally applied patches​:
 

@​INC for perl 5.00503​:
  /design/db/lib/perl
  /usr/local/apps/perl/5.005_03/lib/5.00503/sun4-solaris
  /usr/local/apps/perl/5.005_03/lib/5.00503
  /usr/local/apps/perl/5.005_03/lib/site_perl/5.005/sun4-solaris
  /usr/local/apps/perl/5.005_03/lib/site_perl/5.005
  .

Environment for perl 5.00503​:
  HOME=/user/krolnik
  LANG=C
  LANGUAGE (unset)
  LD_LIBRARY_PATH=/usr/local/lib​:/usr/openwin/lib​:/tools/lsi_fs/2.0/arch/SunOS-5.7​:/tools/cadence/4.42/tools/lib​:/tools/cadence/4.42/tools/leapfrog/lib​:/tools/cadence/4.42/tools/verilog/lib​:/tools/summit/hdlscore/2.0.5/SunOS5/lib​:/user/krolnik/lib​:/usr/local/lib/X11
  LOGDIR (unset)
  PATH=/usr/dt/bin​:.​:/usr/openwin/bin​:/bin​:/usr/bin​:/usr/ucb​:/usr/sbin​:/usr/dt/bin​:/tools/flex/bin​:/usr/local/bin​:/user/krolnik/bin​:.​:/usr/ccs/bin​:/usr/ccs/lib​:/tools/frame/5.5.3/bin​:/tools/uslsiapp/3.0/shared​:/tools/uslsiapp/3.0/bin/sunv​:/tools/askk/5.0/common/bin​:/tools/lsi_fs/2.0/bin/SunOS-5.7​:/tools/cadence/4.42/tools/bin​:/tools/lsf/3.2/bin​:/tools/modeltech/5.3a/bin​:/design/db/com​:/design/db/blaze/com​:/design/db/blaze/bin​:/tools/Razor/Razor/bin​:/tools/Razor/Razor/scripts​:/design/db/blaze/.RAZORDB/403DB/RAZOR_UNIVERSE/Scripts​:/design/db/blaze/source/zsp_tools/sdspI/bin​:/design/db/blaze/work/z16402/bin​:/tools/debussy//4.4/bin​:/tools/summit/hdlscore/2.0.5/bin​:/design/db/blaze/com​:/design/db/blaze/bin​:/usr/openwin/bin​:/user/krolnik/bin
  PERL5LIB=/design/db/lib/perl
  PERL_BADLANG (unset)
  SHELL (unset)

From [Unknown Contact. See original ticket]

This is a bug report for perl from krolnik@​lsil.com,
generated with the help of perlbug 1.26 running under perl 5.00503.

# Here are three forms of regular expressions
# that should only be differing by whitespace.

$a =~ s/c|d|e//x;

$a1 =~ s/c #
  |d # here \
  |e //x;

# The above two do fine - parse correctly.

$a2 =~ s/c # /
  |d # here \
  |e //x;

This similar example (differing in 1 character) causes parsing
problems. perl (5.00503 and 5.6 ) -wc produces (among others)

Unquoted string "x" may clash with future reserved word at /tmp/spl line 16.

The slash at the end of the first line of the regular expression
terminates the regular expression - incorrectly.

Site configuration information for perl 5.00503​:

Configured by greg at Thu Oct 7 17​:35​:08 CDT 1999.

Summary of my perl5 (5.0 patchlevel 5 subversion 3) configuration​:
  Platform​:
  osname=solaris, osvers=2.6, archname=sun4-solaris
  uname='sunos dts49 5.6 generic_105181-15 sun4u sparc sunw,ultra-enterprise
'
  hint=previous, useposix=true, d_sigaction=define
  usethreads=undef useperlio=undef d_sfio=undef
  Compiler​:
  cc='gcc', optimize='-O', gccversion=2.8.1
  cppflags='-I/usr/local/include'
  ccflags ='-I/usr/local/include'
  stdchar='unsigned char', d_stdstdio=define, usevfork=false
  intsize=4, longsize=4, ptrsize=4, doublesize=8
  d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
  alignbytes=8, usemymalloc=y, prototype=define
  Linker and Libraries​:
  ld='gcc', ldflags =' -L/usr/local/lib'
  libpth=/usr/local/lib /lib /usr/lib /usr/ccs/lib
  libs=-lsocket -lnsl -ldl -lm -lc -lcrypt
  libc=/lib/libc.so, so=so, useshrplib=false, libperl=libperl.a
  Dynamic Linking​:
  dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags=' '
  cccdlflags='-fPIC', lddlflags='-G -L/usr/local/lib'

Locally applied patches​:
 

@​INC for perl 5.00503​:
  /design/db/lib/perl
  /usr/local/apps/perl/5.005_03/lib/5.00503/sun4-solaris
  /usr/local/apps/perl/5.005_03/lib/5.00503
  /usr/local/apps/perl/5.005_03/lib/site_perl/5.005/sun4-solaris
  /usr/local/apps/perl/5.005_03/lib/site_perl/5.005
  .

Environment for perl 5.00503​:
  HOME=/user/krolnik
  LANG=C
  LANGUAGE (unset)
 
LD_LIBRARY_PATH=/usr/local/lib​:/usr/openwin/lib​:/tools/lsi_fs/2.0/arch/SunOS-5.7​:/tools/cadence/4.42/tools/lib​:/tools/cadence/4.42/tools/leapfrog/lib​:/tools/cadence/4.42/tools/verilog/lib​:/tools/summit/hdlscore/2.0.5/SunOS5/lib​:/user/krolnik/lib​:/usr/local/lib/X11
  LOGDIR (unset)
 
PATH=/usr/dt/bin​:.​:/usr/openwin/bin​:/bin​:/usr/bin​:/usr/ucb​:/usr/sbin​:/usr/dt/bin​:/tools/flex/bin​:/usr/local/bin​:/user/krolnik/bin​:.​:/usr/ccs/bin​:/usr/ccs/lib​:/tools/frame/5.5.3/bin​:/tools/uslsiapp/3.0/shared​:/tools/uslsiapp/3.0/bin/sunv​:/tools/askk/5.0/common/bin​:/tools/lsi_fs/2.0/bin/SunOS-5.7​:/tools/cadence/4.42/tools/bin​:/tools/lsf/3.2/bin​:/tools/modeltech/5.3a/bin​:/design/db/com​:/design/db/blaze/com​:/design/db/blaze/bin​:/tools/Razor/Razor/bin​:/tools/Razor/Razor/scripts​:/design/db/blaze/.RAZORDB/403DB/RAZOR_UNIVERSE/Scripts​:/design/db/blaze/source/zsp_tools/sdspI/bin​:/design/db/blaze/work/z16402/bin​:/tools/debussy//4.4/bin​:/tools/summit/hdlscore/2.0.5/bin​:/design/db/blaze/com​:/design/db/blaze/bin​:/usr/openwin/bin​:/user/krolnik/bin
  PERL5LIB=/design/db/lib/perl
  PERL_BADLANG (unset)
  SHELL (unset)

From [Unknown Contact. See original ticket]

This is a bug report for perl from krolnik@​lsil.com,
generated with the help of perlbug 1.26 running under perl 5.00503.

$a =~ s/c|d|e//x;

$a1 =~ s/c #
|d # here \
|e //x;

# The above two do fine - parse correctly.

$a2 =~ s/c # /
|d # here \
|e //x;

Unquoted string "x" may clash with future reserved word at
/tmp/spl line 16.

All is correct - you try to divide s/// by x.
s/// / x; is probably not what you want.

Vadim.

From [Unknown Contact. See original ticket]

Annoying, but as documented​: see the perlre man page. Basically,
perl's main parser, which knows nothing about the effects of the /x
flag, uses the chosen regex delimiter to decide what to hand off to
the specialized regex parser. The regex parser subsequently uses the
/x flag, if present, to modify the way in which it parses what it's
been handed. Fixing the small niggle you've stumbled across would
require modifying the main parser to find and interpret the /x flag.
It was decided a long time ago that the gain was not worth the pain.

From [Unknown Contact. See original ticket]

Dominic Dunlop <domo@​computer.org> wrote

Fixing the small niggle you've stumbled across would
require modifying the main parser to find and interpret the /x flag.
It was decided a long time ago that the gain was not worth the pain.

It's worse than that. Examples of this sort are actually ambiguous,
and regexes existed long before the /x switch. So backwards
compatibility precludes "fixing" anything.

Mike Guy

From [Unknown Contact. See original ticket]

"Fixing" this is not just not a case where the gain is not worth the pain,
it is a case where the *pain* is not worth the pain!

Consider the following code​:

if ($foo =~ /#/) {
  # Do something
}
# Time passes
print "eg. In DOS you would use /x instead of -x\n";

How should that be parsed?

Cheers,
Ben

From @iabyn

not-a-bug

@iabyn - Status changed from 'open' to 'resolved'