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[perl #134452] ref should trigger warnings and doc needs work

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From:
rirans@comcast.net
Date:
September 27, 2019 22:08
Subject:
[perl #134452] ref should trigger warnings and doc needs work
Message ID:
rt-4.0.24-18330-1569547245-1372.134452-75-0@perl.org
# New Ticket Created by  rirans@comcast.net 
# Please include the string:  [perl #134452]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=134452 >



This is a bug report for perl from rirans@comcast.net,
generated with the help of perlbug 1.40 running under perl 5.24.1.


-----------------------------------------------------------------

Thanks again for a great product!

$ perldoc -f ref
...
    If the referenced object has been blessed into a package, then
    that package name is returned instead. But don't use that, as it's
    now considered "bad practice". For one reason, an object could be
    using a class called "Regexp" or "IO", or even "HASH". Also, "ref"
    doesn't take into account subclasses, like "isa" does.

    Instead, use "blessed" (in the Scalar::Util module) for boolean
    checks, "isa" for specific class checks and "reftype" (also from
    Scalar::Util) for type checks. (See perlobj for details and a
    "blessed"/"isa" example.)


Reading this I think ref should warn 'deprecated'.

Ref should warn 'imprecision' on any blessed object.

At best, it seems that ref should only be used when dealing with
an unblessed object.  That should be made clear.  The documentation
language is poor as the antecedent to "that" in "don't use that" is
distant.

But beyond clarifying this language, a clear "Using ref is now
considered bad practice." should be at the top of the page.

Note also that the reference to Scalar::Util::reftype is damaged by
the lack of rigor in its documentation.  Is a 'basic type' the
same as your 'builtin' type?  Very likely I'd guess, but I would
not want to guess that all 11 builtin types are handled by
Scalar::Util.


$ perldoc perlobj

The section

    "bless", "blessed", and "ref"

also lacks any mention of danger.

rir


[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
    category=core
    severity=medium
---
Site configuration information for perl 5.24.1:

Configured by Debian Project at Thu Nov 29 11:11:57 UTC 2018.

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-CWhbRh/perl-5.24.1=. -fstack-protector-strong -Wformat -Werror=format-security -Dldflags= -Wl,-z,relro -Dlddlflags=-shared -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 20170516', 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 5.24.1-3+deb9u5 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: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/file_path_chmod_race - https://bugs.debian.org/863870 [rt.cpan.org #121951] Prevent directory chmod race attack.
    DEBPKG:fixes/extutils_file_path_compat - Correct the order of tests of chmod(). (#294)
    DEBPKG:debian/customized - Update customized.dat for files patched in Debian
    DEBPKG:fixes/getopt-long-1 - https://bugs.debian.org/855532 [rt.cpan.org #114999] Fix bug RT#114999
    DEBPKG:fixes/getopt-long-2 - [rt.cpan.org #120300] Withdraw part of commit 5d9947fb445327c7299d8beb009d609bc70066c0, which tries to implement more GNU getopt_long campatibility. GNU
    DEBPKG:fixes/getopt-long-3 - provide a default value for optional arguments
    DEBPKG:fixes/getopt-long-4 - https://bugs.debian.org/864544 [rt.cpan.org #122068] Fix issue #122068.
    DEBPKG:fixes/fbm-instr-crash - [bb152a4] [perl #131575] https://bugs.debian.org/864782 don't call Perl_fbm_instr() with negative length
    DEBPKG:debian/CVE-2016-1238/base-pm-amends-pt2 - [1afa289] Limit dotless-INC effect on base.pm with guard:
    DEBPKG:fixes/CVE-2017-12837 - https://bugs.debian.org/875596 [perl #131582] [f7e5417] regcomp [perl #131582]
    DEBPKG:fixes/CVE-2017-12883 - https://bugs.debian.org/875597 [perl #131598] [40b3cda] PATCH: [perl #131598]
    DEBPKG:fixes/CVE-2018-6797 - [perl #132227] (perl #132227) restart a node if we change to uni rules within the node and encounter a sharp S
    DEBPKG:fixes/CVE-2018-6798/pt1 - [perl #132063] Heap buffer overflow
    DEBPKG:fixes/CVE-2018-6798/pt2 - [perl #132063] v5.24.3: fix TRIE_READ_CHAR and DECL_TRIE_TYPE to account for non-utf8 target
    DEBPKG:fixes/CVE-2018-6798/pt3 - [perl #132063] (perl #132063) we should no longer warn for this code
    DEBPKG:fixes/CVE-2018-6913 - [perl #131844] (perl #131844) fix various space calculation issues in pp_pack.c
    DEBPKG:fixes/CVE-2018-12015-Archive-Tar-directory-traversal - https://bugs.debian.org/900834 [rt.cpan.org #125523] Remove existing files before overwriting them
    DEBPKG:fixes/CVE-2018-18311 - Perl_my_setenv(); handle integer wrap
    DEBPKG:fixes/CVE-2018-18312 - for 5.26 maint
    DEBPKG:fixes/CVE-2018-18313 - regcomp.c: Convert some strchr to memchr
    DEBPKG:fixes/CVE-2018-18314 - fix #131649 - extended charclass can trigger assert

---
@INC for perl 5.24.1:
    /home/rir/Monet/Src/Monet/lib
    /home/rir/migate/lib
    //home/rir/Maker/Dist/Maker/lib
    /home/rir/lib
    /home/rir/LedgerSMB/lib
    /home/rir/LedgerSMB/old/lib
    /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/rir
    LANG=en_US.utf8
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/home/rir/bin:/home/rir/rakudo/install/bin:/home/rir/rakudo/install/share/perl6/site/bin:/home/rir/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games
    PERL5LIB=/home/rir/Monet/Src/Monet/lib:/home/rir/migate/lib://home/rir/Maker/Dist/Maker/lib:/home/rir/lib:/home/rir/LedgerSMB/lib:/home/rir/LedgerSMB/old/lib:
    PERL_BADLANG (unset)
    PERL_HASH_SEED=A1CD5A3
    PERL_PERTURB_KEYS=0
    SHELL=/bin/bash


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