Description
In a narrow situation, use strict allows some undeclared names to be used as string literals, when it previously didn't in pre-5.28 releases. This was initially reported by Lintian maintainer Felix Lechner on IRC earlier today. Ether did some digging and found that it was introduced in 5.27.6 and has given a guess that it's related to OP_MULTICONCAT but no bisection has happened yet to confirm this.
Steps to Reproduce
Reproduces: perl -wle'use strict; use warnings; sub foo { "foo" }; print foo() . SLASH . "bar"'
Doesn't Reproduce: perl -wle'use strict; use warnings; print "foo" . SLASH . "bar"'
Expected behavior
There should be an error from use strict about the use of SLASH in this manner
Perl configuration
Summary of my perl5 (revision 5 version 28 subversion 2) configuration:
Platform:
osname=linux
osvers=5.1.11-x86_64-linode127
archname=x86_64-linux
uname='linux simcop2387.info 5.1.11-x86_64-linode127 #1 smp preempt mon jun 17 21:18:26 utc 2019 x86_64 gnulinux '
config_args='-Dprefix=/home/perlbot/perl5/custom/5.28.2 -de -Dusedevel -Duseshrplib -Dusemymalloc=y -Accflags=-fpie -fPIC -mtune=native -fstack-protector-all -pie -D_FORTIFY_SOURCE=2 -ggdb -DPERL_EMERGENCY_SBRK -Aldflags=-Wl,-z,now -Wl,-zrelro -Wl,-z,noexecstack -A'eval:scriptdir=/home/perlbot/perl5/custom/5.28.2/bin''
hint=recommended
useposix=true
d_sigaction=define
useithreads=undef
usemultiplicity=undef
use64bitint=define
use64bitall=define
uselongdouble=undef
usemymalloc=y
default_inc_excludes_dot=define
bincompat5005=undef
Compiler:
cc='cc'
ccflags ='-fpie -fPIC -mtune=native -fstack-protector-all -pie -D_FORTIFY_SOURCE=2 -ggdb -DPERL_EMERGENCY_SBRK -fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64'
optimize='-O2'
cppflags='-fpie -fPIC -mtune=native -fstack-protector-all -pie -D_FORTIFY_SOURCE=2 -ggdb -DPERL_EMERGENCY_SBRK -fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include'
ccversion=''
gccversion='8.3.0'
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 =' -Wl,-z,now -Wl,-zrelro -Wl,-z,noexecstack -fstack-protector-strong -L/usr/local/lib'
libpth=/usr/local/lib /usr/lib/gcc/x86_64-linux-gnu/8/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=-lpthread -lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lc
perllibs=-lpthread -lnsl -ldl -lm -lcrypt -lutil -lc
libc=libc-2.28.so
so=so
useshrplib=true
libperl=libperl.so
gnulibc_version='2.28'
Dynamic Linking:
dlsrc=dl_dlopen.xs
dlext=so
d_dlsymun=undef
ccdlflags='-Wl,-E -Wl,-rpath,/home/perlbot/perl5/custom/5.28.2/lib/5.28.2/x86_64-linux/CORE'
cccdlflags='-fPIC'
lddlflags='-shared -O2 -L/usr/local/lib -fstack-protector-strong'
Characteristics of this binary (from libperl):
Compile-time options:
HAS_TIMES
MYMALLOC
PERLIO_LAYERS
PERL_COPY_ON_WRITE
PERL_DONT_CREATE_GVSV
PERL_MALLOC_WRAP
PERL_OP_PARENT
PERL_PRESERVE_IVUV
PERL_USE_DEVEL
USE_64_BIT_ALL
USE_64_BIT_INT
USE_LARGE_FILES
USE_LOCALE
USE_LOCALE_COLLATE
USE_LOCALE_CTYPE
USE_LOCALE_NUMERIC
USE_LOCALE_TIME
USE_PERLIO
USE_PERL_ATOF
Locally applied patches:
Devel::PatchPerl 1.64
Built under linux
Compiled at Aug 23 2019 17:24:22
%ENV:
PERLBREW_HOME="/home/ryan/.perlbrew"
PERLBREW_MANPATH="/home/ryan/perl5/perlbrew/perls/perlbot-mainbot/man"
PERLBREW_PATH="/home/ryan/perl5/perlbrew/bin:/home/ryan/perl5/perlbrew/perls/perlbot-mainbot/bin"
PERLBREW_PERL="perlbot-mainbot"
PERLBREW_ROOT="/home/ryan/perl5/perlbrew"
PERLBREW_SHELLRC_VERSION="0.84"
PERLBREW_VERSION="0.84"
@INC:
/home/perlbot/perl5/custom/5.28.2/lib/site_perl/5.28.2/x86_64-linux
/home/perlbot/perl5/custom/5.28.2/lib/site_perl/5.28.2
/home/perlbot/perl5/custom/5.28.2/lib/5.28.2/x86_64-linux
/home/perlbot/perl5/custom/5.28.2/lib/5.28.2
On IRC ether did a bit of diagnosis and work to try to identify what happened:
13:41:12 < ether> looks like it happened between 5.27.5 and 5.27.6. to get down to the exact commit requires a bisection in blead
13:41:24 < simcop2387> ether++
13:41:37 < ether> 5.27.6 was my release hangs head
...
13:42:49 < ether> demonstrates the issue: perl -wle'use strict; use warnings; sub foo { "foo" }; print foo() . SLASH . "bar"'
13:42:56 < ether> does not : perl -wle'use strict; use warnings; print "foo" . SLASH . "bar"'
13:43:16 < ether> so it's something peculiar in how the sub is parsed
...
13:48:04 < ether> 5.27.6 contained the first set of changes for OP_MULTICONCAT -- I bet it happened in there
13:48:28 < simcop2387> ether: that makes sense, that changed how a lot of the parsing went to optimize it right?
13:48:38 < ether> yup
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