This is a bug report for perl from choroba@matfyz.cz, generated with the help of perlbug 1.41 running under perl 5.31.5. ----------------------------------------------------------------- [Please describe your issue here] Hi, Some edge case values (e.g. undef, empty string) aren't properly documented for the %SIG handler. Patch attached. Ch. [Please do not change anything below this line] ----------------------------------------------------------------- --- Flags: category=docs severity=low --- Site configuration information for perl 5.31.5: Configured by choroba at Tue Oct 8 13:12:35 CEST 2019. Summary of my perl5 (revision 5 version 31 subversion 5) configuration: Commit id: a578d0f3e37a8500429796cdeeba96dbba029778 Platform: osname=linux osvers=4.12.14-lp151.28.16-default archname=x86_64-linux-thread-multi uname='linux lenonovo 4.12.14-lp151.28.16-default #1 smp wed sep 18 05:32:19 utc 2019 (3e458e0) x86_64 x86_64 x86_64 gnulinux ' config_args='-rdes -Dusethreads -Dpthread -Dprefix=~/blead -Dusedevel' hint=recommended useposix=true d_sigaction=define useithreads=define usemultiplicity=define use64bitint=define use64bitall=define uselongdouble=undef usemymalloc=n default_inc_excludes_dot=define bincompat5005=undef Compiler: cc='cc' ccflags ='-D_REENTRANT -D_GNU_SOURCE -fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -D_FORTIFY_SOURCE=2' optimize='-O2' cppflags='-D_REENTRANT -D_GNU_SOURCE -fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include' ccversion='' gccversion='7.4.1 20190424 [gcc-7-branch revision 270538]' 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='cc' ldflags =' -fstack-protector-strong -L/usr/local/lib' libpth=/usr/local/lib /usr/lib64/gcc/x86_64-suse-linux/7/include-fixed /usr/lib64/gcc/x86_64-suse-linux/7/../../../../x86_64-suse-linux/lib /usr/lib /lib/../lib64 /usr/lib/../lib64 /lib /lib64 /usr/lib64 /usr/local/lib64 libs=-lpthread -lgdbm -ldb -ldl -lm -lcrypt -lutil -lc -lgdbm_compat perllibs=-lpthread -ldl -lm -lcrypt -lutil -lc libc=libc-2.26.so so=so useshrplib=false libperl=libperl.a gnulibc_version='2.26' Dynamic Linking: dlsrc=dl_dlopen.xs dlext=so d_dlsymun=undef ccdlflags='-Wl,-E' cccdlflags='-fPIC' lddlflags='-shared -O2 -L/usr/local/lib -fstack-protector-strong' --- @INC for perl 5.31.5: /home/choroba/blead/lib/perl5/site_perl/5.31.5/x86_64-linux-thread-multi /home/choroba/blead/lib/perl5/site_perl/5.31.5 /home/choroba/blead/lib/perl5/5.31.5/x86_64-linux-thread-multi /home/choroba/blead/lib/perl5/5.31.5 --- Environment for perl 5.31.5: HOME=/home/choroba LANG=en_US.utf8 LANGUAGE (unset) LC_CTYPE=en_US.UTF-8 LD_LIBRARY_PATH (unset) LOGDIR (unset) PATH=/home/choroba/bin:/usr/local/bin:/usr/bin:/bin:/usr/bin/X11:/home/choroba/perl5/bin:/home/choroba/opensource/worktime/bin:. PERL_BADLANG (unset) SHELL=/bin/bash

From 083e34454b5511db7aefa37e066deaeea8153c4e Mon Sep 17 00:00:00 2001 From: "E. Choroba" <choroba@cpan.org> Date: Fri, 11 Oct 2019 13:59:38 +0200 Subject: [PATCH] Document the SIG handler behaviour for weird hook values Values like undef or an empty string can be assigned to the SIG hash. Their behaviour is slightly different for signals and internal hooks and wasn't properly documented. --- pod/perlvar.pod | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/pod/perlvar.pod b/pod/perlvar.pod index 5f48dad7c0..930b823857 100644 --- a/pod/perlvar.pod +++ b/pod/perlvar.pod @@ -607,7 +607,8 @@ The hash C<%SIG> contains signal handlers for signals. For example: Using a value of C<'IGNORE'> usually has the effect of ignoring the signal, except for the C<CHLD> signal. See L<perlipc> for more about -this special case. +this special case. Using an empty string or C<undef> as the value has +the same effect as C<'DEFAULT'>. Here are some other examples: @@ -622,6 +623,11 @@ Here are some other examples: Be sure not to use a bareword as the name of a signal handler, lest you inadvertently call it. +Using a string that doesn't correspond to any existing function or a +glob that doesn't contain a code slot is equivalent to C<'IGNORE'>, +but a warning is emitted when the handler is being called (the warning +is not emitted for the internal hooks described below). + If your system has the C<sigaction()> function then signal handlers are installed using it. This means you get reliable signal handling. @@ -640,8 +646,9 @@ errors, like this: local $SIG{__WARN__} = sub { die $_[0] }; eval $proggie; -As the C<'IGNORE'> hook is not supported by C<__WARN__>, you can -disable warnings using the empty subroutine: +As the C<'IGNORE'> hook is not supported by C<__WARN__>, its effect is +the same as using C<'DEFAULT'>. You can disable warnings using the +empty subroutine: local $SIG{__WARN__} = sub {}; @@ -661,6 +668,9 @@ at a distance like rewriting a pending exception in C<$@>. Plans to rectify this have been scrapped, as users found that rewriting a pending exception is actually a useful feature, and not a bug. +The C<$SIG{__DIE__}> doesn't support C<'IGNORE'>, it has the same +effect as C<'DEFAULT'>. + C<__DIE__>/C<__WARN__> handlers are very special in one respect: they may be called to report (probable) errors found by the parser. In such a case the parser may be in inconsistent state, so any attempt to -- 2.16.4