mg.c	AOK

  No such signal: SIG%s
    $SIG{FRED} = sub {}

  SIG%s handler \"%s\" not defined.
    $SIG{"INT"} = "ok3"; kill "INT",$$;

__END__
# mg.c
use warnings 'signal' ;
$SIG{FRED} = sub {};
EXPECT
No such signal: SIGFRED at - line 3.
########
# mg.c
no warnings 'signal' ;
$SIG{FRED} = sub {};
EXPECT

########
# mg.c
use warnings 'signal' ;
if ($^O eq 'MSWin32' || $^O eq 'VMS') {
    print "SKIPPED\n# $^O, can't kill() to raise()\n"; exit;
}
$|=1;
$SIG{"INT"} = "fred"; kill "INT",$$;
EXPECT
SIGINT handler "fred" not defined.
########
# mg.c
no warnings 'signal' ;
if ($^O eq 'MSWin32' || $^O eq 'VMS') {
    print "SKIPPED\n# $^O, can't kill() to raise()\n"; exit;
}
$|=1;
$SIG{"INT"} = "fred"; kill "INT",$$;
EXPECT

########
# mg.c
use warnings 'signal' ;
if ($^O eq 'MSWin32' || $^O eq 'VMS') {
    print "SKIPPED\n# $^O, can't kill() to raise()\n"; exit;
}
$|=1;
$SIG{__WARN__} = sub { warn shift =~ s/\0/\\0/rugs };
$SIG{"INT"} = "fr\0d"; kill "INT",$$;
EXPECT
SIGINT handler "fr\0d" not defined.
########
# mg.c
use warnings 'signal' ;
use open ":std", ":utf8";
use utf8;
if ($^O eq 'MSWin32' || $^O eq 'VMS') {
    print "SKIPPED\n# $^O, can't kill() to raise()\n"; exit;
}
$|=1;
$SIG{"INT"} = "프레드"; kill "INT",$$;
EXPECT
SIGINT handler "프레드" not defined.
########
# mg.c
use warnings 'uninitialized';
'foo' =~ /(foo)/;
oct $3;
EXPECT
Use of uninitialized value $3 in oct at - line 4.
########
# mg.c
use warnings 'uninitialized';
oct $3;
EXPECT
Use of uninitialized value $3 in oct at - line 3.
########
# mg.c
use warnings 'uninitialized';
$ENV{FOO} = undef; # should not warn
EXPECT
########
# NAME Use of uninitialized value $_[0] in defined operator
# github 22423
use warnings 'uninitialized';
sub f { defined $_[0] }
my $s;
my %h;
f($h{$s});
EXPECT
Use of uninitialized value $s in hash element at - line 6.
########
# NAME Use of uninitialized value $_[0] in defined operator (tied)
# github 22423
# should we allow tied hashes to distinguish between undef and ""
# without warning?  For now test the current behaviour, this
# didn't produce the warning described in github #22423 since
# if the hash is tied for the call the PVLV uses packelem (tie)
# magic rather than defelem magic
use v5.36;
++$|;
sub f { defined $_[0] }
my $s;
tie my %h, "Foo";
f($h{$s});
$h{+undef} = 1;
$h{""} = 2;
say $h{+undef};
f($h{$s});

package Foo;

sub TIEHASH {
  bless {}, shift;
}
sub STORE {
  my ($self, $index, $val) = @_;
  $self->{defined $index ? $index : "+undef"} = $val;
}
sub FETCH {
  my ($self, $index) = @_;
  $self->{defined $index ? $index : "+undef"};
}
sub EXISTS {
  my ($self, $index) = @_;
  exists $self->{defined $index ? $index : "+undef"};
}

EXPECT
Use of uninitialized value $s in hash element at - line 12.
Use of uninitialized value in hash element at - line 13.
Use of uninitialized value in hash element at - line 15.
1
Use of uninitialized value $s in hash element at - line 16.
########
# NAME Use of uninitialized value $_[0] in defined operator (tied2)
# github 22423
# In this case we have a tied hash, but it's only tied after the
# PVLV is created for the element. This *does* produce the warning
# complained about in #22423
use v5.36;
++$|;
my %h;
sub f {
  tie %h, "Foo";
  defined $_[0];
}
my $s;
say f($h{$s}) ? "defined" : "undefined";

package Foo;

sub TIEHASH {
  bless { "+undef" => "tied-undef" }, shift;
}
sub STORE($self, $index, $val) {
  $self->{defined $index ? $index : "+undef"} = $val;
}
sub FETCH($self, $index) {
  $self->{defined $index ? $index : "+undef"};
}
sub EXISTS($self, $index) {
  exists $self->{defined $index ? $index : "+undef"};
}
sub DELETE($self, $index) {
  delete $self->{defined $index ? $index : "+undef"};
}
EXPECT
Use of uninitialized value $s in hash element at - line 13.
Use of uninitialized value $_[0] in defined operator at - line 10.
defined