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Aug 7, 2012, 6:47 AM
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[perl #114414] indirect object heuristic misparses foo bar->baz
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# New Ticket Created by l.mai [at] web
# Please include the string: [perl #114414]
# in the subject line of all future correspondence about this issue.
# <URL: https://rt.perl.org:443/rt3/Ticket/Display.html?id=114414 >
This is a bug report for perl from l.mai [at] web,
generated with the help of perlbug 1.39 running under perl 5.16.0.
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[Please describe your issue here]
Let's create a dog and wash it:
% perl -MO=Deparse -e '{package Dog} sub wash {}' -e 'wash Dog->new;'
{;};
sub wash {
}
'Dog'->wash->new;
-e syntax OK
Wait, that's not what I meant! Maybe like this?
% perl -MO=Deparse -e '{package Dog} sub wash {}' -e 'wash Dog::->new;'
{;};
sub wash {
}
'Dog'->wash->new;
-e syntax OK
No, same problem. Hmm ...
% perl -MO=Deparse -e '{package Dog} sub wash {}' -e 'wash ::Dog->new;'
{;};
sub wash {
}
wash '::Dog'->new;
-e syntax OK
OK, that at least parses the sub call correctly. But:
% perl -e '{package Dog} sub wash {}' -e 'wash ::Dog->new;'
Can't call method "new" without a package or object reference at -e line 2.
Looks like '::Dog' doesn't work as 'Dog'. Finally:
% perl -MO=Deparse -e '{package Dog} sub wash {}' -e 'wash +Dog->new;'
{;};
sub wash {
}
wash 'Dog'->new;
-e syntax OK
This is what I wanted all along.
I think the indirect object heuristic is too trigger-happy and should be dialed
back a bit. 'foo bar->baz' should not be parsed as an indirect invocation of
'bar->foo', especially not if the parser knows 'foo' to be a sub in the current
scope.
In fact, I'd be glad to see indirect object syntax simply go away completely
(except for builtin special cases like print/system/exec/etc). Otherwise, a
pragma to disable it would be nice[1]. Otherwise, the parser should prefer the
non-indirect-object interpretation of code where possible.
[1]
'no indirect' is a nice pragma but it doesn't disable indirect object syntax;
it just recognizes it and makes it into an error after the fact. That is, the
default interpretation of my first example is silently wrong, 'no indirect'
makes it loudly wrong, and I want it to be silently right.
[Please do not change anything below this line]
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---
Flags:
category=core
severity=medium
---
This perlbug was built using Perl 5.12.1 - Thu Jun 3 20:09:15 CEST 2010
It is being executed now by Perl 5.16.0 - Mon May 21 12:24:16 CEST 2012.
Site configuration information for perl 5.16.0:
Configured by mauke at Mon May 21 12:24:16 CEST 2012.
Summary of my perl5 (revision 5 version 16 subversion 0) configuration:
Platform:
osname=linux, osvers=2.6.38-gentoo-r6, archname=i686-linux
uname='linux nora 2.6.38-gentoo-r6 #1 preempt sat aug 6 03:05:34 cest 2011 i686 amd athlon(tm) 64 processor 3200+ authenticamd gnulinux '
config_args='-Dcc=cgcc -Dprefix=/home/mauke/usr/local -Dman1dir=none -Dman3dir=none -Dinc_version_list=none -Doptimize=-O2 -flto'
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='cgcc', ccflags ='-fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
optimize='-O2 -flto',
cppflags='-fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include'
ccversion='', gccversion='4.6.3', gccosandvers=''
intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
alignbytes=4, prototype=define
Linker and Libraries:
ld='cgcc', ldflags ='-fstack-protector -L/usr/local/lib -O2 -flto'
libpth=/usr/local/lib /lib/../lib /usr/lib/../lib /lib /usr/lib
libs=-lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lc -lgdbm_compat
perllibs=-lnsl -ldl -lm -lcrypt -lutil -lc
libc=/lib/libc-2.14.1.so, so=so, useshrplib=false, libperl=libperl.a
gnulibc_version='2.14.1'
Dynamic Linking:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
cccdlflags='-fPIC', lddlflags='-shared -O2 -flto -L/usr/local/lib -fstack-protector'
Locally applied patches:
SAVEARGV0 - disable magic open in <ARGV>
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@INC for perl 5.16.0:
/home/mauke/usr/local/lib/perl5/site_perl/5.16.0/i686-linux
/home/mauke/usr/local/lib/perl5/site_perl/5.16.0
/home/mauke/usr/local/lib/perl5/5.16.0/i686-linux
/home/mauke/usr/local/lib/perl5/5.16.0
.
---
Environment for perl 5.16.0:
HOME=/home/mauke
LANG=en_US.UTF-8
LANGUAGE (unset)
LC_COLLATE=POSIX
LD_LIBRARY_PATH=/home/mauke/usr/local/lib
LOGDIR (unset)
PATH=/home/mauke/usr/perlbrew/bin:/home/mauke/usr/local/bin:/usr/local/bin:/usr/bin:/bin:/opt/bin:/usr/i686-pc-linux-gnu/gcc-bin/4.4.5:/opt/sun-jdk-1.4.2.13/bin:/opt/sun-jdk-1.4.2.13/jre/bin:/opt/sun-jdk-1.4.2.13/jre/javaws:/opt/dmd/bin:/usr/games/bin
PERLBREW_BASHRC_VERSION=0.43
PERLBREW_HOME=/home/mauke/.perlbrew
PERLBREW_PATH=/home/mauke/usr/perlbrew/bin
PERLBREW_ROOT=/home/mauke/usr/perlbrew
PERLBREW_VERSION=0.27
PERL_BADLANG (unset)
PERL_UNICODE=SAL
SHELL=/bin/bash
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