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Report information
Id: 132434
Status: rejected
Priority: 0/
Queue: perl5

Owner: Nobody
Requestors: jim.avera [at] gmail.com
Cc:
AdminCc:

Operating System: (no value)
PatchStatus: (no value)
Severity: low
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Perl Version: (no value)
Fixed In: (no value)



To: perlbug [...] perl.org
From: Jim Avera <jim.avera [...] gmail.com>
Date: Sat, 11 Nov 2017 16:08:57 -0800
Subject: print $outfh <$infh> gives Syntax Error
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This is a bug report for perl from jim.avera@gmail.com, generated with the help of perlbug 1.40 running under perl 5.24.1. ----------------------------------------------------------------- If print is called with $fh instead of an old-style FILEHANDLE (no comma in either case), then a Syntax Error occurs if the first data item is <$fh>.    print $outfh <$infh>    #Syntax Error No error occurs if $outfh or $infh is replaced by HANDLE, of if <$infh> is not the first data item. #!/usr/bin/perl use strict; use warnings; require File::Temp; open INFH,     "<", "/etc/timezone" or die; open my $infh, "<", "/etc/timezone" or die; open OUTFH,     ">&STDOUT" or die; open my $outfh, ">&STDOUT" or die; local $/;  #slurp print $outfh <$infh> or die;          # SYNTAX ERROR print $outfh "fooey", <$infh> or die; # ok print $outfh <INFH> or die;           # ok print OUTFH <$infh> or die;           # ok print OUTFH <INFH> or die;            # ok ----------------------------------------------------------------- --- Flags:     category=core     severity=low --- Site configuration information for perl 5.24.1: Configured by Debian Project at Sat Mar 18 17:00:39 UTC 2017. Summary of my perl5 (revision 5 version 24 subversion 1) configuration:   Platform:     osname=linux, osvers=3.16.0, archname=x86_64-linux-gnu-thread-multi     uname='linux localhost 3.16.0 #1 smp debian 3.16.0 x86_64 gnulinux '     config_args='-Dusethreads -Duselargefiles -Dcc=x86_64-linux-gnu-gcc -Dcpp=x86_64-linux-gnu-cpp -Dld=x86_64-linux-gnu-gcc -Dccflags=-DDEBIAN -Wdate-time -D_FORTIFY_SOURCE=2 -g -O2 -fdebug-prefix-map=/build/perl-gaNj0t/perl-5.24.1=. -fstack-protector-strong -Wformat -Werror=format-security -Dldflags= -Wl,-Bsymbolic-functions -Wl,-z,relro -Dlddlflags=-shared -Wl,-Bsymbolic-functions -Wl,-z,relro -Dcccdlflags=-fPIC -Darchname=x86_64-linux-gnu -Dprefix=/usr -Dprivlib=/usr/share/perl/5.24 -Darchlib=/usr/lib/x86_64-linux-gnu/perl/5.24 -Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5 -Dvendorarch=/usr/lib/x86_64-linux-gnu/perl5/5.24 -Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl/5.24.1 -Dsitearch=/usr/local/lib/x86_64-linux-gnu/perl/5.24.1 -Dman1dir=/usr/share/man/man1 -Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1 -Dsiteman3dir=/usr/local/man/man3 -Dusesitecustomize -Duse64bitint -Dman1ext=1 -Dman3ext=3perl -Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Ud_ualarm -Uusesfio -Uusenm -Ui_libutil -Uversiononly -DDEBUGGING=-g -Doptimize=-O2 -dEs -Duseshrplib -Dlibperl=libperl.so.5.24.1'     hint=recommended, useposix=true, d_sigaction=define     useithreads=define, usemultiplicity=define     use64bitint=define, use64bitall=define, uselongdouble=undef     usemymalloc=n, bincompat5005=undef   Compiler:     cc='x86_64-linux-gnu-gcc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fwrapv -fno-strict-aliasing -pipe -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',     optimize='-O2 -g',     cppflags='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fwrapv -fno-strict-aliasing -pipe -I/usr/local/include'     ccversion='', gccversion='6.3.0 20170316', gccosandvers=''     intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678, doublekind=3     d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16, longdblkind=3     ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8     alignbytes=8, prototype=define   Linker and Libraries:     ld='x86_64-linux-gnu-gcc', ldflags =' -fstack-protector-strong -L/usr/local/lib'     libpth=/usr/local/lib /usr/lib/gcc/x86_64-linux-gnu/6/include-fixed /usr/include/x86_64-linux-gnu /usr/lib /lib/x86_64-linux-gnu /lib/../lib /usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib     libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt     perllibs=-ldl -lm -lpthread -lc -lcrypt     libc=libc-2.24.so, so=so, useshrplib=true, libperl=libperl.so.5.24     gnulibc_version='2.24'   Dynamic Linking:     dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'     cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib -fstack-protector-strong' Locally applied patches:     DEBPKG:debian/cpan_definstalldirs - Provide a sensible INSTALLDIRS default for modules installed from CPAN.     DEBPKG:debian/db_file_ver - https://bugs.debian.org/340047 Remove overly restrictive DB_File version check.     DEBPKG:debian/doc_info - Replace generic man(1) instructions with Debian-specific information.     DEBPKG:debian/enc2xs_inc - https://bugs.debian.org/290336 Tweak enc2xs to follow symlinks and ignore missing @INC directories.     DEBPKG:debian/errno_ver - https://bugs.debian.org/343351 Remove Errno version check due to upgrade problems with long-running processes.     DEBPKG:debian/libperl_embed_doc - https://bugs.debian.org/186778 Note that libperl-dev package is required for embedded linking     DEBPKG:fixes/respect_umask - Respect umask during installation     DEBPKG:debian/writable_site_dirs - Set umask approproately for site install directories     DEBPKG:debian/extutils_set_libperl_path - EU:MM: set location of libperl.a under /usr/lib     DEBPKG:debian/no_packlist_perllocal - Don't install .packlist or perllocal.pod for perl or vendor     DEBPKG:debian/fakeroot - Postpone LD_LIBRARY_PATH evaluation to the binary targets.     DEBPKG:debian/instmodsh_doc - Debian policy doesn't install .packlist files for core or vendor.     DEBPKG:debian/ld_run_path - Remove standard libs from LD_RUN_PATH as per Debian policy.     DEBPKG:debian/libnet_config_path - Set location of libnet.cfg to /etc/perl/Net as /usr may not be writable.     DEBPKG:debian/mod_paths - Tweak @INC ordering for Debian     DEBPKG:debian/prune_libs - https://bugs.debian.org/128355 Prune the list of libraries wanted to what we actually need.     DEBPKG:fixes/net_smtp_docs - [rt.cpan.org #36038] https://bugs.debian.org/100195 Document the Net::SMTP 'Port' option     DEBPKG:debian/perlivp - https://bugs.debian.org/510895 Make perlivp skip include directories in /usr/local     DEBPKG:debian/deprecate-with-apt - https://bugs.debian.org/747628 Point users to Debian packages of deprecated core modules     DEBPKG:debian/squelch-locale-warnings - https://bugs.debian.org/508764 Squelch locale warnings in Debian package maintainer scripts     DEBPKG:debian/skip-upstream-git-tests - Skip tests specific to the upstream Git repository     DEBPKG:debian/patchlevel - https://bugs.debian.org/567489 List packaged patches for 5.24.1-2ubuntu1 in patchlevel.h     DEBPKG:debian/skip-kfreebsd-crash - https://bugs.debian.org/628493 [perl #96272] Skip a crashing test case in t/op/threads.t on GNU/kFreeBSD     DEBPKG:fixes/document_makemaker_ccflags - https://bugs.debian.org/628522 [rt.cpan.org #68613] Document that CCFLAGS should include $Config{ccflags}     DEBPKG:debian/find_html2text - https://bugs.debian.org/640479 Configure CPAN::Distribution with correct name of html2text     DEBPKG:debian/perl5db-x-terminal-emulator.patch - https://bugs.debian.org/668490 Invoke x-terminal-emulator rather than xterm in perl5db.pl     DEBPKG:debian/cpan-missing-site-dirs - https://bugs.debian.org/688842 Fix CPAN::FirstTime defaults with nonexisting site dirs if a parent is writable     DEBPKG:fixes/memoize_storable_nstore - [rt.cpan.org #77790] https://bugs.debian.org/587650 Memoize::Storable: respect 'nstore' option not respected     DEBPKG:debian/regen-skip - Skip a regeneration check in unrelated git repositories     DEBPKG:debian/makemaker-pasthru - https://bugs.debian.org/758471 Pass LD settings through to subdirectories     DEBPKG:debian/makemaker-manext - https://bugs.debian.org/247370 Make EU::MakeMaker honour MANnEXT settings in generated manpage headers     DEBPKG:debian/devel-ppport-reproducibility - https://bugs.debian.org/801523 Sort the list of XS code files when generating RealPPPort.xs     DEBPKG:debian/encode-unicode-bom-doc - https://bugs.debian.org/798727 Document Debian backport of Encode::Unicode fix     DEBPKG:debian/kfreebsd-softupdates - https://bugs.debian.org/796798 Work around Debian Bug#796798     DEBPKG:fixes/autodie-scope - https://bugs.debian.org/798096 Fix a scoping issue with "no autodie" and the "system" sub     DEBPKG:fixes/crosscompile-no-targethost - [23695c0] [perl #127234] Fix the Configure escape with usecrosscompile but no targethost     DEBPKG:fixes/memoize-pod - [rt.cpan.org #89441] Fix POD errors in Memoize     DEBPKG:fixes/ok-pod - Added encoding for pod.     DEBPKG:debian/hurd-softupdates - https://bugs.debian.org/822735 Fix t/op/stat.t failures on hurd     DEBPKG:fixes/nntp_docs - https://bugs.debian.org/51962 Net::NNTP: Correct innd/nnrpd confusion in relation to Reader option     DEBPKG:fixes/math_complex_doc_great_circle - https://bugs.debian.org/697567 [rt.cpan.org #114104] Math::Trig: clarify definition of great_circle_midpoint     DEBPKG:fixes/math_complex_doc_see_also - https://bugs.debian.org/697568 [rt.cpan.org #114105] Math::Trig: add missing SEE ALSO     DEBPKG:fixes/math_complex_doc_angle_units - https://bugs.debian.org/731505 [rt.cpan.org #114106] Math::Trig: document angle units     DEBPKG:fixes/cpan_web_link - https://bugs.debian.org/367291 CPAN: Add link to main CPAN web site     DEBPKG:fixes/time_piece_doc - https://bugs.debian.org/817925 Time::Piece: Improve documentation for add_months and add_years     DEBPKG:fixes/perlbug-refactor - https://bugs.debian.org/822463 [perl #128020] perlbug: Refactor duplicated file reading code     DEBPKG:fixes/perlbug-linewrap - https://bugs.debian.org/822463 [perl #128020] perlbug: wrap overly long lines     DEBPKG:fixes/hurd_sigaction - https://bugs.debian.org/825016 [d54f4ed] ext/POSIX/t/sigaction.t: Skip uid and pid tests on GNU/Hurd     DEBPKG:fixes/hurd_hints - [4694301] https://bugs.debian.org/825020 [perl #128279] Modify hints for Hurd per Debian ticket 825020.     DEBPKG:fixes/extutils-parsexs-reproducibility - [perl #128517] https://bugs.debian.org/829296 Make the output of ExtUtils::ParseXS reproducible     DEBPKG:debian/CVE-2016-1238/sitecustomize-in-etc - Look for sitecustomize.pl in /etc/perl rather than sitelib on Debian systems     DEBPKG:debian/CVE-2016-1238/test-suite-without-dot - [perl #127810] Patch unit tests to explicitly insert "." into @INC when needed.     DEBPKG:debian/CVE-2016-1238/eumm-without-dot - [perl #127810] Add PERL_USE_UNSAFE_INC support to EU::MM for fortify_inc support.     DEBPKG:debian/CVE-2016-1238/cpan-without-dot - [perl #127810] Set PERL_USE_UNSAFE_INC for cpan usage     DEBPKG:debian/document_inc_removal - Document in perlvar that we remove '.' from @INC by default     DEBPKG:fixes/extutils_makemaker_reproducible - https://bugs.debian.org/835815 https://bugs.debian.org/834190 Make perllocal.pod files reproducible     DEBPKG:debian/CVE-2016-1238/remove-inc-test - Remove test for '.' in @INC as it might not be     DEBPKG:debian/customized - Update customized.dat for files patched in Debian     DEBPKG:fixes/file_path_hurd_errno - File-Path: Fix test failure in Hurd due to hard-coded ENOENT     DEBPKG:debian/hppa_op_optimize_workaround - https://bugs.debian.org/838613 Temporarily lower the optimization of op.c on hppa due to gcc-6 problems     DEBPKG:fixes/test-builder-warning - https://bugs.debian.org/840968 Silence a 'used only once' warning in Test::Builder     DEBPKG:fixes/longdblinf-randomness - [dd68853] [perl #130133] https://bugs.debian.org/844752 Configure: fix garbage filtering with 80-bit long doubles     DEBPKG:debian/installman-utf8 - https://bugs.debian.org/840211 Generate man pages with UTF-8 characters     DEBPKG:fixes/list_assign_leak - [1050723] [perl #130766] https://bugs.debian.org/855064 avoid a leak in list assign from/to magic values     DEBPKG:fixes/perlfunc_inc_doc - [a03e9f8] https://bugs.debian.org/839536 [perl #130832] Documentation fixes for '.' possibly no longer being in @INC DEBPKG:fixes/Compress-Raw-Zlib-2.071-Adapt-tests-to-zlib-1.2.11.patch - [PATCH] Adapt tests to zlib 1.2.11     DEBPKG:fixes/0001-Adapt-tests-to-zlib-1.2.11.patch - [PATCH] Adapt tests to zlib 1.2.11 --- @INC for perl 5.24.1: /home/jima/perl5/lib/perl5/5.24.1/x86_64-linux-gnu-thread-multi     /home/jima/perl5/lib/perl5/5.24.1 /home/jima/perl5/lib/perl5/x86_64-linux-gnu-thread-multi     /home/jima/perl5/lib/perl5     /home/jima/lib/perl     /etc/perl     /usr/local/lib/x86_64-linux-gnu/perl/5.24.1     /usr/local/share/perl/5.24.1     /usr/lib/x86_64-linux-gnu/perl5/5.24     /usr/share/perl5     /usr/lib/x86_64-linux-gnu/perl/5.24     /usr/share/perl/5.24     /usr/local/lib/site_perl     /usr/lib/x86_64-linux-gnu/perl-base --- Environment for perl 5.24.1:     HOME=/home/jima     LANG=en_US.UTF-8     LANGUAGE=en_US     LC_COLLATE=C     LD_LIBRARY_PATH (unset)     LOGDIR (unset) PATH=/home/jima/perl5/bin:/home/jima/bin:/home/jima/jima_tools/x86_64/bin:/home/jima/jima_tools/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/bin/X11:/usr/local/bin:/usr/local/sbin:/usr/games:/usr/local/games:/usr/lib/jvm/java-8-oracle/bin:/usr/lib/jvm/java-8-oracle/db/bin:/usr/lib/jvm/java-8-oracle/jre/bin:.     PERL5LIB=/home/jima/perl5/lib/perl5:/home/jima/lib/perl     PERL_BADLANG (unset)     PERL_LOCAL_LIB_ROOT=/home/jima/perl5     PERL_MB_OPT=--install_base "/home/jima/perl5"     PERL_MM_OPT=INSTALL_BASE=/home/jima/perl5     SHELL=/bin/bash
To: perl5-porters [...] perl.org
From: Zefram <zefram [...] fysh.org>
Date: Sun, 12 Nov 2017 00:16:23 +0000
Subject: Re: [perl #132434] print $outfh <$infh> gives Syntax Error
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> print $outfh <$infh> #Syntax Error
"$outfh <$infh" parses as a comparison expression. A syntax error of this kind is to be expected from such ambiguity; it is not a bug. You can avoid this by wrapping $outfh in braces. -zefram
From: Jim Avera <jim.avera [...] gmail.com>
To: perlbug-followup [...] perl.org
Subject: Re: [perl #132434] print $outfh <$infh> gives Syntax Error
Date: Sun, 12 Nov 2017 00:20:12 -0800
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Ah, thanks.    I had no idea that braces were allowed to be used like that. Can you briefly explain why this is legal syntax?   Is it a special case just for indirect object syntax    methodname {expr yielding object ref} args... or is this an example of a more general concept?   Normally I would expect {...} where a value is expected to be a hash constructor (obviously not the case here).   So I'm surprised. Just point me to the docs and I'll read. Thanks again, -Jim On 11/11/2017 04:16 PM, Zefram via RT wrote: Show quoted text
>> print $outfh <$infh> #Syntax Error
> "$outfh <$infh" parses as a comparison expression. A syntax error > of this kind is to be expected from such ambiguity; it is not a bug. > You can avoid this by wrapping $outfh in braces. > > -zefram >
To: perl5-porters [...] perl.org
From: Zefram <zefram [...] fysh.org>
Date: Sun, 12 Nov 2017 08:52:11 +0000
Subject: Re: [perl #132434] print $outfh <$infh> gives Syntax Error
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Jim Avera wrote: Show quoted text
>Can you briefly explain why this is legal syntax?
It's legal by fiat. A braced block is one of the permitted forms of indirect object. The main purpose of it is to permit an arbitrarily complicated subexpression to be used as an indirect object. It's not well documented, but the entry for "print" in perlfunc(1) describes it, with examples. Show quoted text
> Normally I would expect >{...} where a value is expected to be a hash constructor (obviously not the >case here).
There's an ambiguity between hash constructors and code blocks in many situations, including here. perl guesses which is meant, and occasionally gets it wrong. You can force the correct interpretation by opening the construct with "+{" for a hash constructor or "{;" for a code block. -zefram
Subject: Re: [perl #132434] print $outfh <$infh> gives Syntax Error
Date: Sun, 12 Nov 2017 10:06:28 +0100
From: Sawyer X <xsawyerx [...] gmail.com>
To: jim.avera [...] gmail.com, perlbug-followup [...] perl.org
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On 11/12/2017 09:20 AM, Jim Avera wrote: Show quoted text
> Ah, thanks.    I had no idea that braces were allowed to be used like > that. > Can you briefly explain why this is legal syntax?   Is it a special > case just for indirect object syntax > >    methodname {expr yielding object ref} args... > > or is this an example of a more general concept?   Normally I would > expect {...} where a value is expected to be a hash constructor > (obviously not the case here).   So I'm surprised. > > Just point me to the docs and I'll read.
Hi, Jim. :) The docs for print (perldoc -f print) include the following paragraph:         If you're storing handles in an array or hash, or in general whenever         you're using any expression more complex than a bareword handle or a         plain, unsubscripted scalar variable to retrieve it, you will have to         use a block returning the filehandle value instead, in which case the         LIST may not be omitted:             print { $files[$i] } "stuff\n";             print { $OK ? *STDOUT : *STDERR } "stuff\n"; This is what includes the ability to do (as also mentioned by Perl Best Practices) the following: print {$fh} "foo";
From: Jim Avera <jim.avera [...] gmail.com>
To: perlbug-followup [...] perl.org
Subject: Re: [perl #132434] print $outfh <$infh> gives Syntax Error
Date: Sun, 12 Nov 2017 23:07:01 -0800
Thank you Zefram & Sawyer for the explanation.  I appreciate it. Sorry for the bogus bugrep -Jim
Date: Mon, 13 Nov 2017 10:28:54 +0100
Subject: Re: [perl #132434] print $outfh <$infh> gives Syntax Error
To: jim.avera [...] gmail.com, perlbug-followup [...] perl.org
From: Sawyer X <xsawyerx [...] gmail.com>
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On 11/13/2017 08:07 AM, Jim Avera wrote: Show quoted text
> Thank you Zefram & Sawyer for the explanation.  I appreciate it. > > Sorry for the bogus bugrep
Don't worry about it. :)


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