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[perl #107004] require parses barewords strangely

From:
Father Chrysostomos
Date:
December 25, 2011 14:21
Subject:
[perl #107004] require parses barewords strangely
Message ID:
rt-3.6.HEAD-14510-1324851649-1426.107004-75-0@perl.org
# New Ticket Created by  Father Chrysostomos 
# Please include the string:  [perl #107004]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org:443/rt3/Ticket/Display.html?id=107004 >


When require is followed by a bareword, if that bareword is followed by an operator that has higher precedence than require, it falls back to treating its argument as a normal expression, but not quite.

Here is the special behaviour:

$ perl5.15.5 -MO=Concise -e 'require a::b'
5  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 1 -e:1) v:{ ->3
4     <1> require sK/1 ->5
3        <$> const[PV "a/b.pm"] s/BARE ->4
-e syntax OK

Notice the "a/b.pm".

Now if we put ‘. 1’ after it (+1 doesn’t work, because of bug #105924):

$ perl5.15.5 -MO=Concise -we 'require a::b . 1'
7  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 1 -e:1) v:{ ->3
6     <1> require sK/1 ->7
5        <2> concat[t1] sK/2 ->6
3           <$> const[PV "a::b"] s/BARE ->4
4           <$> const[IV 1] s ->5
-e syntax OK

That I can understand, as a::b is a string in the absence of any other interpretation, ‘a::b . 1’ being the argument to require, which is more than a single bareword.

But if there is a subroutine named a::b, things get strange:

$ perl5.15.5 -MO=Concise -we 'sub a::b; require a::b . 1'
7  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 1 -e:1) v:{ ->3
6     <1> require sK/1 ->7
5        <2> concat[t1] sK/2 ->6
3           <$> const[PV "a::b"] s/BARE ->4
4           <$> const[IV 1] s ->5
-e syntax OK

The a::b should be a subroutine call.

This may be related to #36333.

---
Flags:
    category=core
    severity=low
---
Site configuration information for perl 5.15.5:

Configured by sprout at Sun Dec 18 11:26:14 PST 2011.

Summary of my perl5 (revision 5 version 15 subversion 5) configuration:
  Snapshot of: 5dca8ed9d28127c9f7a2e7ce5f8ba970da3608cd
  Platform:
    osname=darwin, osvers=10.5.0, archname=darwin-2level
    uname='darwin pint.local 10.5.0 darwin kernel version 10.5.0: fri nov 5 23:20:39 pdt 2010; root:xnu-1504.9.17~1release_i386 i386 '
    config_args='-de -Dusedevel -DDEBUGGING=-g'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=undef, usemultiplicity=undef
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
    use64bitint=undef, use64bitall=undef, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-fno-common -DPERL_DARWIN -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include',
    optimize='-O3 -g',
    cppflags='-fno-common -DPERL_DARWIN -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include'
    ccversion='', gccversion='4.2.1 (Apple Inc. build 5664)', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='env MACOSX_DEPLOYMENT_TARGET=10.3 cc', ldflags =' -fstack-protector -L/usr/local/lib'
    libpth=/usr/local/lib /usr/lib
    libs=-ldbm -ldl -lm -lutil -lc
    perllibs=-ldl -lm -lutil -lc
    libc=, so=dylib, useshrplib=false, libperl=libperl.a
    gnulibc_version=''
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=bundle, d_dlsymun=undef, ccdlflags=' '
    cccdlflags=' ', lddlflags=' -bundle -undefined dynamic_lookup -L/usr/local/lib -fstack-protector'

Locally applied patches:
    

---
@INC for perl 5.15.5:
    /usr/local/lib/perl5/site_perl/5.15.5/darwin-2level
    /usr/local/lib/perl5/site_perl/5.15.5
    /usr/local/lib/perl5/5.15.5/darwin-2level
    /usr/local/lib/perl5/5.15.5
    /usr/local/lib/perl5/site_perl
    .

---
Environment for perl 5.15.5:
    DYLD_LIBRARY_PATH (unset)
    HOME=/Users/sprout
    LANG=en_US.UTF-8
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin:/usr/local/bin
    PERL_BADLANG (unset)
    SHELL=/bin/bash




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