+########
+# multi-level uninitialised array/hash indexes
+use warnings 'uninitialized';
+
+our ($i0, $i2, $i4, $i6, $i8, $i10, $i12);
+my ($i1, $i3, $i5, $i7, $i9, $i11, $i13);
+
+my (@a,%h);
+my $v;
+
+
+# use enough depth that OP_MULTIDEREF needs more than one action word
+
+$v = $a[$i0]{$i1}[$i2]{$i3}[$i4]{$i5}[$i6]{$i7}[$i8]{$i9}[$i10]{$i11}[$i12]{$i13};
+$v = $h{$i0}[$i1]{$i2}[$i3]{$i4}[$i5]{$i6}[$i7]{$i8}[$i9]{$i10}[$i11]{$i12}[$i13];
+
+EXPECT
+Use of uninitialized value $i0 in array element at - line 13.
+Use of uninitialized value $i1 in hash element at - line 13.
+Use of uninitialized value $i2 in array element at - line 13.
+Use of uninitialized value $i3 in hash element at - line 13.
+Use of uninitialized value $i4 in array element at - line 13.
+Use of uninitialized value $i5 in hash element at - line 13.
+Use of uninitialized value $i6 in array element at - line 13.
+Use of uninitialized value $i7 in hash element at - line 13.
+Use of uninitialized value $i8 in array element at - line 13.
+Use of uninitialized value $i9 in hash element at - line 13.
+Use of uninitialized value $i10 in array element at - line 13.
+Use of uninitialized value $i11 in hash element at - line 13.
+Use of uninitialized value $i12 in array element at - line 13.
+Use of uninitialized value $i13 in hash element at - line 13.
+Use of uninitialized value $i0 in hash element at - line 14.
+Use of uninitialized value $i1 in array element at - line 14.
+Use of uninitialized value $i2 in hash element at - line 14.
+Use of uninitialized value $i3 in array element at - line 14.
+Use of uninitialized value $i4 in hash element at - line 14.
+Use of uninitialized value $i5 in array element at - line 14.
+Use of uninitialized value $i6 in hash element at - line 14.
+Use of uninitialized value $i7 in array element at - line 14.
+Use of uninitialized value $i8 in hash element at - line 14.
+Use of uninitialized value $i9 in array element at - line 14.
+Use of uninitialized value $i10 in hash element at - line 14.
+Use of uninitialized value $i11 in array element at - line 14.
+Use of uninitialized value $i12 in hash element at - line 14.
+Use of uninitialized value $i13 in array element at - line 14.
+########
+# misc multideref
+use warnings 'uninitialized';
+my ($i,$j,$k);
+my @a;
+my @ra = \@a;
+my $v;
+$v = exists $a[$i]{$k};
+$v = delete $a[$i]{$k};
+$v = local $a[$i]{$k};
+delete $a[$i]{$k};
+$v = $ra->[$i+$j]{$k};
+$v = ($ra//0)->[$i]{$k};
+$v = $a[length $i]{$k}
+EXPECT
+Use of uninitialized value $i in array element at - line 7.
+Use of uninitialized value $k in exists at - line 7.
+Use of uninitialized value $i in array element at - line 8.
+Use of uninitialized value $k in delete at - line 8.
+Use of uninitialized value $i in array element at - line 9.
+Use of uninitialized value $k in hash element at - line 9.
+Use of uninitialized value $k in hash element at - line 9.
+Use of uninitialized value $k in hash element at - line 9.
+Use of uninitialized value $i in array element at - line 10.
+Use of uninitialized value $k in delete at - line 10.
+Use of uninitialized value $j in addition (+) at - line 11.
+Use of uninitialized value $i in addition (+) at - line 11.
+Use of uninitialized value $k in hash element at - line 11.
+Use of uninitialized value $i in array element at - line 12.
+Use of uninitialized value $k in hash element at - line 12.
+Use of uninitialized value $i in array element at - line 13.
+Use of uninitialized value $k in hash element at - line 13.
+########
+# perl #127877
+use warnings 'uninitialized';
+my ($p, $q, $r, $s, $t, $u, $v, $w, $x, $y);
+$p = $p . "a";
+$q .= "a";
+$r = $r + 17;
+$s += 17;
+$t = $t - 17;
+$u -= 17;
+use integer;
+$v = $v + 17;
+$w += 17;
+$x = $x - 17;
+$y -= 17;
+EXPECT
+Use of uninitialized value $p in concatenation (.) or string at - line 4.
+Use of uninitialized value $r in addition (+) at - line 6.
+Use of uninitialized value $t in subtraction (-) at - line 8.
+Use of uninitialized value $v in integer addition (+) at - line 11.
+Use of uninitialized value $x in integer subtraction (-) at - line 13.
+########
+# NAME 64-bit array subscripts
+# SKIP ? length(pack "p", "") < 8
+use warnings 'uninitialized';
+
+# aelem + const
+use constant foo => \0;
+$SIG{__WARN__} = sub {
+ print STDERR
+ $_[0] =~ /\$a\[([^]]+)]/ && $1 == foo
+ ? "ok\n"
+ : ("$1 != ",0+foo,"\n")
+};
+() = "$a[foo]";
+undef $SIG{__WARN__};
+
+# Multideref
+() = "$a[140688675223280]";
+EXPECT
+ok
+Use of uninitialized value $a[140688675223280] in string at - line 15.
+########
+# RT #128940
+use warnings 'uninitialized';
+my $x = "" . open my $fh, "<", "no / such / file";
+EXPECT
+Use of uninitialized value in concatenation (.) or string at - line 3.
+########
+# RT #123910
+# undef's arg being undef doesn't trigger warnings - any warning will be
+# from tied/magic vars
+use warnings 'uninitialized';
+undef $0;
+EXPECT
+Use of uninitialized value in undef operator at - line 5.