Fix croaking on "my $_" when "use utf8" is in effect

perl-5.33.5-op.c-croak-on-my-_-when-use-utf8-is-in-effect.patch

@@ -0,0 +1,78 @@
+From 07319fdbb283f93cb655c3106b5237cbc7272038 Mon Sep 17 00:00:00 2001
+From: Tomasz Konojacki <me@xenu.pl>
+Date: Wed, 30 Dec 2020 14:03:02 +0100
+Subject: [PATCH] op.c: croak on "my $_" when "use utf8" is in effect
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Fixes #18449
+
+Signed-off-by: Petr Písař <ppisar@redhat.com>
+---
+ op.c         | 16 +++++++++-------
+ t/op/mydef.t | 11 +++++++++--
+ 2 files changed, 18 insertions(+), 9 deletions(-)
+
+diff --git a/op.c b/op.c
+index b2e12dd0c0..dce844d297 100644
+--- a/op.c
++++ b/op.c
+@@ -730,6 +730,7 @@ PADOFFSET
+ Perl_allocmy(pTHX_ const char *const name, const STRLEN len, const U32 flags)
+ {
+     PADOFFSET off;
++    bool is_idfirst, is_default;
+     const bool is_our = (PL_parser->in_my == KEY_our);
+ 
+     PERL_ARGS_ASSERT_ALLOCMY;
+@@ -738,14 +739,15 @@ Perl_allocmy(pTHX_ const char *const name, const STRLEN len, const U32 flags)
+ 	Perl_croak(aTHX_ "panic: allocmy illegal flag bits 0x%" UVxf,
+ 		   (UV)flags);
+ 
++    is_idfirst = flags & SVf_UTF8
++        ? isIDFIRST_utf8_safe((U8*)name + 1, name + len)
++        : isIDFIRST_A(name[1]);
++
++    /* $_, @_, etc. */
++    is_default = len == 2 && name[1] == '_';
++
+     /* complain about "my $<special_var>" etc etc */
+-    if (   len
+-        && !(  is_our
+-            || isALPHA(name[1])
+-            || (   (flags & SVf_UTF8)
+-                && isIDFIRST_utf8_safe((U8 *)name+1, name + len))
+-            || (name[1] == '_' && len > 2)))
+-    {
++    if (!is_our && (!is_idfirst || is_default)) {
+         const char * const type =
+               PL_parser->in_my == KEY_sigvar ? "subroutine signature" :
+               PL_parser->in_my == KEY_state  ? "\"state\""     : "\"my\"";
+diff --git a/t/op/mydef.t b/t/op/mydef.t
+index 42a81d9ab0..225ce98e51 100644
+--- a/t/op/mydef.t
++++ b/t/op/mydef.t
+@@ -6,10 +6,17 @@ BEGIN {
+     set_up_inc('../lib');
+ }
+ 
+-plan tests => 1;
+-
+ use strict;
+ 
+ eval 'my $_';
+ like $@, qr/^Can't use global \$_ in "my" at /;
+ 
++{
++    # using utf8 allows $_ to be declared with 'my'
++    # GH #18449
++    use utf8;
++    eval 'my $_;';
++    like $@, qr/^Can't use global \$_ in "my" at /;
++}
++
++done_testing;
+-- 
+2.26.2
+

perl.spec

@@ -251,6 +251,10 @@ Patch49:        perl-5.33.4-locale.c-Fix-typo-in-ifdef.patch
 # Fix fc() in Turkish locale, in upstream after 5.33.5
 Patch50:        perl-5.33.5-Fix-buggy-fc-in-Turkish-locale.patch
 
+# Fix croaking on "my $_" when "use utf8" is in effect, GH#18449,
+# in upstream after 5.33.5
+Patch51:        perl-5.33.5-op.c-croak-on-my-_-when-use-utf8-is-in-effect.patch
+
 # Link XS modules to libperl.so with EU::CBuilder on Linux, bug #960048
 Patch200:       perl-5.16.3-Link-XS-modules-to-libperl.so-with-EU-CBuilder-on-Li.patch
 
@@ -4302,6 +4306,7 @@ you're not running VMS, this module does nothing.
 %patch48 -p1
 %patch49 -p1
 %patch50 -p1
+%patch51 -p1
 %patch200 -p1
 %patch201 -p1
 
@@ -4351,6 +4356,7 @@ perl -x patchlevel.h \
     'Fedora Patch48: Make accessing environment by DynaLoader thread-safe' \
     'Fedora Patch49: Use duplocale() if available' \
     'Fedora Patch50: Fix fc() in Turkish locale' \
+    'Fedora Patch51: Fix croaking on "my $_" when "use utf8" is in effect (GH#18449)' \
     'Fedora Patch200: Link XS modules to libperl.so with EU::CBuilder on Linux' \
     'Fedora Patch201: Link XS modules to libperl.so with EU::MM on Linux' \
     %{nil}
@@ -7082,6 +7088,7 @@ popd
 - Make accessing environment by DynaLoader thread-safe
 - Use duplocale() if available
 - Fix fc() in Turkish locale
+- Fix croaking on "my $_" when "use utf8" is in effect (GH#18449)
 
 * Tue Jan 26 2021 Fedora Release Engineering <releng@fedoraproject.org> - 4:5.32.1-470
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_34_Mass_Rebuild