unexpected warning "old package separator '' deprecated"

[vividsnow]

Got unexpected deprecation warning: "Old package separator "'" deprecated" in following code:

use strict; use warnings;
$SIG{INT} = uc'default'; # warn
$SIG{INT} = uc 'default'; # no warn

---

Flags

• category=core
• severity=low

---

Perl configuration

Site configuration information for perl 5.38.2:

Configured by yk at Wed Apr 10 20:18:55 MSK 2024.

Summary of my perl5 (revision 5 version 38 subversion 2) configuration:
   
  Platform:
    osname=linux
    osvers=6.7.9-amd64
    archname=x86_64-linux
    uname='linux bu 6.7.9-amd64 #1 smp preempt_dynamic debian 6.7.9-2 (2024-03-13) x86_64 gnulinux '
    config_args='-Dprefix=/home/yk/.plenv/versions/5.38.2 -de -Dversiononly -Dman1dir=none -Dman3dir=none -A'eval:scriptdir=/home/yk/.plenv/versions/5.38.2/bin''
    hint=recommended
    useposix=true
    d_sigaction=define
    useithreads=undef
    usemultiplicity=undef
    use64bitint=define
    use64bitall=define
    uselongdouble=undef
    usemymalloc=n
    default_inc_excludes_dot=define
  Compiler:
    cc='cc'
    ccflags ='-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='-fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include'
    ccversion=''
    gccversion='13.2.0'
    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 =' -fstack-protector-strong -L/usr/local/lib'
    libpth=/usr/local/lib /usr/lib/x86_64-linux-gnu /usr/lib /usr/lib64
    libs=-lpthread -ldb -ldl -lm -lcrypt -lutil -lc
    perllibs=-lpthread -ldl -lm -lcrypt -lutil -lc
    libc=/lib/x86_64-linux-gnu/libc.so.6
    so=so
    useshrplib=false
    libperl=libperl.a
    gnulibc_version='2.37'
  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 5.38.2:
    /home/yk/.plenv/versions/5.38.2/lib/perl5/site_perl/5.38.2/x86_64-linux
    /home/yk/.plenv/versions/5.38.2/lib/perl5/site_perl/5.38.2
    /home/yk/.plenv/versions/5.38.2/lib/perl5/5.38.2/x86_64-linux
    /home/yk/.plenv/versions/5.38.2/lib/perl5/5.38.2

---
Environment for perl 5.38.2:
    HOME=/home/yk
    LANG=en_US.UTF-8
    LANGUAGE=en_US:en
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/home/yk/.plenv/versions/5.38.2/bin:/home/yk/.plenv/libexec:/home/yk/.plenv/plugins/perl-build/bin:/home/yk/.local/bin
    PERL_BADLANG (unset)
    SHELL=/bin/bash

[haarg]

This only happens for assignments to %SIG entries. There is a special warning for if you try to assign a bareword to a %SIG entry. It seems to be explicitly looking forward for barewords. This causes it to try to parse uc'DEFAULT as a bareword, when it otherwise wouldn't. This triggers the warning. If you try to actually use a ' package separator when assigning to a %SIG entry, you will get two Old package separator warnings (as well as a You need to quote "%s" warning).

perl5/toke.c

Lines 5444 to 5473 in 1edc2b4

	else if (*s == '{') {
	char *t;
	PL_tokenbuf[0] = '%';
	if ( strEQ(PL_tokenbuf+1, "SIG")
	&& ckWARN(WARN_SYNTAX)
	&& (t = (char *) memchr(s, '}', PL_bufend - s))
	&& (t = (char *) memchr(t, '=', PL_bufend - t)))
	{
	char tmpbuf[sizeof PL_tokenbuf];
	do {
	t++;
	} while (isSPACE(*t));
	if (isIDFIRST_lazy_if_safe(t, PL_bufend, UTF)) {
	STRLEN len;
	t = scan_word6(t, tmpbuf, sizeof tmpbuf, TRUE,
	&len, TRUE);
	while (isSPACE(*t))
	t++;
	if ( *t == ';'
	&& get_cvn_flags(tmpbuf, len, UTF
	? SVf_UTF8
	: 0))
	{
	Perl_warner(aTHX_ packWARN(WARN_SYNTAX),
	"You need to quote \"%" UTF8f "\"",
	UTF8fARG(UTF, len, tmpbuf));
	}
	}
	}
	}

Since this code is only looking ahead to check for a different warning, the fix may just be to change the warn_tick argument to the scan_word6 call from TRUE to FALSE.