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semicolons on *_DIAG_{IGNORE,RESTORE} #15863

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p5pRT opened this issue Feb 6, 2017 · 9 comments
Closed

semicolons on *_DIAG_{IGNORE,RESTORE} #15863

p5pRT opened this issue Feb 6, 2017 · 9 comments

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@p5pRT
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@p5pRT p5pRT commented Feb 6, 2017

Migrated from rt.perl.org#130726 (status was 'resolved')

Searchable as RT130726$

@p5pRT
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@p5pRT p5pRT commented Feb 6, 2017

From @hvds

Created by @hvds

From perl.h​:
[...]
* which makes compilers mildly cranky. Therefore at file level one
* should use the GCC_DIAG_IGNORE and GCC_DIAG_RESTORE_FILE *without*
* the semicolons.

% # probably correct
% grep -Pr '(GCC|CLANG)_DIAG_(IGNORE\(.*?\)|RESTORE)(?!\s*;)' | wc -l
17
% # probably incorrect
% grep -Pr '(GCC|CLANG)_DIAG_(IGNORE\(.*?\)|RESTORE)(?=\s*;)' | wc -l
70
%

Is it worth fixing these wholesale?

(Prompted by surprise at d7f10d9 from James Keenan earlier today.)

Perl Info

Flags:
    category=core
    severity=low

Site configuration information for perl 5.18.2:

Configured by Debian Project at Tue Mar  1 17:12:59 UTC 2016.

Summary of my perl5 (revision 5 version 18 subversion 2) configuration:
   
  Platform:
    osname=linux, osvers=3.13.0-79-generic, archname=x86_64-linux-gnu-thread-multi
    uname='linux lgw01-37 3.13.0-79-generic #123-ubuntu smp fri feb 19 14:27:58 utc 2016 x86_64 x86_64 x86_64 gnulinux '
    config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN -D_FORTIFY_SOURCE=2 -g -O2 -fstack-protector --param=ssp-buffer-size=4 -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/5.18 -Darchlib=/usr/lib/perl/5.18 -Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5 -Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl/5.18.2 -Dsitearch=/usr/local/lib/perl/5.18.2 -Dman1dir=/usr/share/man/man1 -Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1 -Dsiteman3dir=/usr/local/man/man3 -Duse64bitint -Dman1ext=1 -Dman3ext=3perl -Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Ud_ualarm -Uusesfio -Uusenm -Ui_libutil -Uversiononly -DDEBUGGING=-g -Doptimize=-O2 -Duseshrplib -Dlibperl=libperl.so.5.18.2 -des'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=define, usemultiplicity=define
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
    use64bitint=define, use64bitall=define, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fstack-protector -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 -fstack-protector -fno-strict-aliasing -pipe -I/usr/local/include'
    ccversion='', gccversion='4.8.2', gccosandvers=''
    intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
    ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='cc', ldflags =' -fstack-protector -L/usr/local/lib'
    libpth=/usr/local/lib /lib/x86_64-linux-gnu /lib/../lib /usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib /usr/lib
    libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
    perllibs=-ldl -lm -lpthread -lc -lcrypt
    libc=, so=so, useshrplib=true, libperl=libperl.so.5.18.2
    gnulibc_version='2.19'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib -fstack-protector'

Locally applied patches:
    DEBPKG:debian/cpan_definstalldirs - Provide a sensible INSTALLDIRS default for modules installed from CPAN.
    DEBPKG:debian/db_file_ver - http://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 - http://bugs.debian.org/290336 Tweak enc2xs to follow symlinks and ignore missing @INC directories.
    DEBPKG:debian/errno_ver - http://bugs.debian.org/343351 Remove Errno version check due to upgrade problems with long-running processes.
    DEBPKG:debian/libperl_embed_doc - http://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 to /usr/lib
    DEBPKG:debian/no_packlist_perllocal - Don't install .packlist or perllocal.pod for perl or vendor
    DEBPKG:debian/prefix_changes - Fiddle with *PREFIX and variables written to the makefile
    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/module_build_man_extensions - http://bugs.debian.org/479460 Adjust Module::Build manual page extensions for the Debian Perl policy
    DEBPKG:debian/prune_libs - http://bugs.debian.org/128355 Prune the list of libraries wanted to what we actually need.
    DEBPKG:fixes/net_smtp_docs - [rt.cpan.org #36038] http://bugs.debian.org/100195 Document the Net::SMTP 'Port' option
    DEBPKG:debian/perlivp - http://bugs.debian.org/510895 Make perlivp skip include directories in /usr/local
    DEBPKG:debian/cpanplus_definstalldirs - http://bugs.debian.org/533707 Configure CPANPLUS to use the site directories by default.
    DEBPKG:debian/cpanplus_config_path - Save local versions of CPANPLUS::Config::System into /etc/perl.
    DEBPKG:debian/deprecate-with-apt - http://bugs.debian.org/702096 Point users to Debian packages of deprecated core modules
    DEBPKG:debian/squelch-locale-warnings - http://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 - http://bugs.debian.org/567489 List packaged patches for 5.18.2-2ubuntu1.1 in patchlevel.h
    DEBPKG:debian/skip-kfreebsd-crash - http://bugs.debian.org/628493 [perl #96272] Skip a crashing test case in t/op/threads.t on GNU/kFreeBSD
    DEBPKG:fixes/document_makemaker_ccflags - http://bugs.debian.org/628522 [rt.cpan.org #68613] Document that CCFLAGS should include $Config{ccflags}
    DEBPKG:debian/find_html2text - http://bugs.debian.org/640479 Configure CPAN::Distribution with correct name of html2text
    DEBPKG:debian/hurd_test_skip_stack - http://bugs.debian.org/650175 Disable failing GNU/Hurd tests dist/threads/t/stack.t
    DEBPKG:fixes/manpage_name_Test-Harness - http://bugs.debian.org/650451 [rt.cpan.org #73399] cpan/Test-Harness: add NAME headings in modules with POD
    DEBPKG:debian/makemaker-pasthru - http://bugs.debian.org/660195 [rt.cpan.org #28632] Make EU::MM pass LD through to recursive Makefile.PL invocations
    DEBPKG:debian/perl5db-x-terminal-emulator.patch - http://bugs.debian.org/668490 Invoke x-terminal-emulator rather than xterm in perl5db.pl
    DEBPKG:debian/cpan-missing-site-dirs - http://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] http://bugs.debian.org/587650 Memoize::Storable: respect 'nstore' option not respected
    DEBPKG:fixes/net_ftp_failed_command - [rt.cpan.org #37700] http://bugs.debian.org/491062 Net::FTP: cope gracefully with a failed command
    DEBPKG:fixes/perlbug-patchlist - [3541c11] http://bugs.debian.org/710842 [perl #118433] Make perlbug look up the list of local patches at run time
    DEBPKG:fixes/module_metadata_security_doc - [68cdd4b] CVE-2013-1437 documentation fix
    DEBPKG:fixes/module_metadata_taint_fix - [bff978f] http://bugs.debian.org/722210 [rt.cpan.org #88576] untaint version, if needed, in Module::Metadata
    DEBPKG:fixes/IPC-SysV-spelling - http://bugs.debian.org/730558 [rt.cpan.org #86736] Fix spelling of IPC_CREAT in IPC-SysV documentation
    DEBPKG:fixes/fix-undef-source -
    DEBPKG:fixes/CVE-2013-7422.patch - [PATCH] [perl #119505] Segfault from bad backreference
    DEBPKG:fixes/CVE-2014-4330.patch - [PATCH] don't recurse infinitely in Data::Dumper
    DEBPKG:fixes/CVE-2016-2381.patch - [PATCH 1/2] remove duplicate environment variables from environ


@INC for perl 5.18.2:
    /etc/perl
    /usr/local/lib/perl/5.18.2
    /usr/local/share/perl/5.18.2
    /usr/lib/perl5
    /usr/share/perl5
    /usr/lib/perl/5.18
    /usr/share/perl/5.18
    /usr/local/lib/site_perl
    .


Environment for perl 5.18.2:
    HOME=/home/hv
    LANG=C
    LANGUAGE=en_GB:en
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=<elided>
    PERL_BADLANG (unset)
    SHELL=/bin/bash

@p5pRT
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@p5pRT p5pRT commented Feb 7, 2017

From @jkeenan

On Mon, 06 Feb 2017 14​:17​:33 GMT, hv wrote​:

This is a bug report for perl from hv@​crypt.org,
generated with the help of perlbug 1.39 running under perl 5.18.2.

-----------------------------------------------------------------
[Please describe your issue here]

From perl.h​:
[...]
* which makes compilers mildly cranky. Therefore at file level one
* should use the GCC_DIAG_IGNORE and GCC_DIAG_RESTORE_FILE *without*
* the semicolons.

% # probably correct
% grep -Pr '(GCC|CLANG)_DIAG_(IGNORE\(.*?\)|RESTORE)(?!\s*;)' | wc -l
17
% # probably incorrect
% grep -Pr '(GCC|CLANG)_DIAG_(IGNORE\(.*?\)|RESTORE)(?=\s*;)' | wc -l
70
%

Is it worth fixing these wholesale?

(Prompted by surprise at d7f10d9 from James Keenan earlier today.)

Errrrm ... probably not (yet).

I was playing around with the approach being explored by Andy Lester -- compile with clang under '-Weverything'. I came up with exactly one instance of '-Wextra-semi' in the entire core distribution -- the one in threads.xs. A one-character correction, reviewed by threads maintainer Jerry Hedden. Extremely low hanging fruit.

But I can tell that many of the other warnings generated under '-Weverything' need more careful thought before we touch them. I don't have much experience in this area.

Thank you very much.

--
James E Keenan (jkeenan@​cpan.org)

@p5pRT
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@p5pRT p5pRT commented Feb 7, 2017

The RT System itself - Status changed from 'new' to 'open'

@p5pRT
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@p5pRT p5pRT commented Feb 7, 2017

From @hvds

On Tue, 07 Feb 2017 09​:55​:26 -0800, jkeenan wrote​:

On Mon, 06 Feb 2017 14​:17​:33 GMT, hv wrote​:

This is a bug report for perl from hv@​crypt.org,
generated with the help of perlbug 1.39 running under perl 5.18.2.

-----------------------------------------------------------------
[Please describe your issue here]

From perl.h​:
[...]
* which makes compilers mildly cranky. Therefore at file level one
* should use the GCC_DIAG_IGNORE and GCC_DIAG_RESTORE_FILE *without*
* the semicolons.

% # probably correct
% grep -Pr '(GCC|CLANG)_DIAG_(IGNORE\(.*?\)|RESTORE)(?!\s*;)' | wc -l
17
% # probably incorrect
% grep -Pr '(GCC|CLANG)_DIAG_(IGNORE\(.*?\)|RESTORE)(?=\s*;)' | wc -l
70
%

Is it worth fixing these wholesale?

(Prompted by surprise at d7f10d9 from James Keenan earlier today.)

Errrrm ... probably not (yet).

I was playing around with the approach being explored by Andy Lester
-- compile with clang under '-Weverything'. I came up with exactly
one instance of '-Wextra-semi' in the entire core distribution -- the
one in threads.xs. A one-character correction, reviewed by threads
maintainer Jerry Hedden. Extremely low hanging fruit.

But I can tell that many of the other warnings generated under '-
Weverything' need more careful thought before we touch them. I don't
have much experience in this area.

I'm not talking about wholesale fixes for -Weverything, just about wholesale fixes to the correct usage of these particular 4 macros - correct usage that we've already gone to the bother of documenting in perl.h but apparently mostly ignored for actual use.

If avoiding the semicolon is the correct thing to do, then it should be "extremely low-hanging fruit" everywhere - I think due diligence would consist at most in checking that they're preceded and followed by something well-formed. It also feels more sane to fix at least the *.[ch] examples in one commit than in 70-odd separate ones.

An alternative approach would be to decide that we don't care - perhaps that we gain more from visual consistency with other statement-type macros in the source than we do from -Weverything-cleanliness - in which case we'd probably be better off changing the perl.h recommendation and consistently having the semicolon everywhere. The mess of a halfway house is what loses us the most.

Hugo

@p5pRT
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@p5pRT p5pRT commented Dec 16, 2017

From zefram@fysh.org

We can't in practice prevent people using semicolons, so
semicolon-friendly macro definitions are to be preferred. This
necessitates using distinct macros for statement and declaration contexts.
Implemented in commit 7347ee5.

-zefram

@p5pRT
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@p5pRT p5pRT commented Dec 17, 2017

From @hvds

On Fri, 15 Dec 2017 23​:16​:09 -0800, zefram@​fysh.org wrote​:

We can't in practice prevent people using semicolons, so
semicolon-friendly macro definitions are to be preferred. This
necessitates using distinct macros for statement and declaration contexts.
Implemented in commit 7347ee5.

Looks good to me; the only matches now updated versions of my original greps are on the macro declarations themselves.

Setting as pending release.

Hugo

@p5pRT
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@p5pRT p5pRT commented Dec 17, 2017

@hvds - Status changed from 'open' to 'pending release'

@p5pRT
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@p5pRT p5pRT commented Jun 23, 2018

From @khwilliamson

Thank you for filing this report. You have helped make Perl better.

With the release yesterday of Perl 5.28.0, this and 185 other issues have been
resolved.

Perl 5.28.0 may be downloaded via​:
https://metacpan.org/release/XSAWYERX/perl-5.28.0

If you find that the problem persists, feel free to reopen this ticket.

@p5pRT
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@p5pRT p5pRT commented Jun 23, 2018

@khwilliamson - Status changed from 'pending release' to 'resolved'

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