Split off the UTF-8 decoder tests, make them to check also

the error message.

p4raw-id: //depot/perl@7996

4 files changed, 190 insertions, 178 deletions

diff --git a/MANIFEST b/MANIFEST
index 4f30dd12ff..03be9636a8 100644
--- a/MANIFEST
+++ b/MANIFEST
@@ -1577,6 +1577,7 @@ t/op/tr.t		See if tr works
 t/op/undef.t		See if undef works
 t/op/universal.t	See if UNIVERSAL class works
 t/op/unshift.t		See if unshift works
+t/op/utf8decode.t	See if UTF-8 decoding works
 t/op/vec.t		See if vectors work
 t/op/ver.t		See if v-strings and the %v format flag work
 t/op/wantarray.t	See if wantarray works
diff --git a/t/op/utf8decode.t b/t/op/utf8decode.t
new file mode 100644
index 0000000000..c631c0a7a9
--- /dev/null
+++ b/t/op/utf8decode.t
@@ -0,0 +1,181 @@
+#!./perl
+
+BEGIN {
+    chdir 't' if -d 't';
+    @INC = '../lib';
+}
+
+print "1..78\n";
+
+my $test = 1;
+
+# This table is based on Markus Kuhn's UTF-8 Decode Stress Tester,
+# http://www.cl.cam.ac.uk/~mgk25/ucs/examples/UTF-8-test.txt,
+# version dated 2000-09-02. 
+
+# Note the \0 instead of a raw zero byte in 2.1.1: for example
+# GNU patch v2.1 has "issues" with raw zero bytes.
+
+my @MK = split(/\n/, <<__EOMK__);
+1	Correct UTF-8
+1.1.1 y "κόσμε"	-		11	ce:ba:e1:bd:b9:cf:83:ce:bc:ce:b5	5
+2	Boundary conditions 
+2.1	First possible sequence of certain length
+2.1.1 y "\0"			0		1	00	1
+2.1.2 y "€"			80		2	c2:80	1
+2.1.3 y "ࠀ"		800		3	e0:a0:80	1
+2.1.4 y "𐀀"		10000		4	f0:90:80:80	1
+2.1.5 y "�����"	200000		5	f8:88:80:80:80	1
+2.1.6 y "������"	4000000		6	fc:84:80:80:80:80	1
+2.2	Last possible sequence of certain length
+2.2.1 y ""			7f		1	7f	1
+2.2.2 y "߿"			7ff		2	df:bf	1
+# The ffff is illegal unless UTF8_ALLOW_FFFF
+2.2.3 n "￿"			ffff		3	ef:bf:bf	1	character 0xffff
+2.2.4 y "����"			1fffff		4	f7:bf:bf:bf	1
+2.2.5 y "�����"			3ffffff		5	fb:bf:bf:bf:bf	1
+2.2.6 y "������"		7fffffff	6	fd:bf:bf:bf:bf:bf	1
+2.3	Other boundary conditions
+2.3.1 y "퟿"		d7ff		3	ed:9f:bf	1
+2.3.2 y ""		e000		3	ee:80:80	1
+2.3.3 y "�"			fffd		3	ef:bf:bd	1
+2.3.4 y "􏿿"		10ffff		4	f4:8f:bf:bf	1
+2.3.5 y "����"		110000		4	f4:90:80:80	1
+3	Malformed sequences
+3.1	Unexpected continuation bytes
+3.1.1 n "�"			-		1	80	-	unexpected continuation byte 0x80
+3.1.2 n "�"			-		1	bf	-	unexpected continuation byte 0xbf
+3.1.3 n "��"			-		2	80:bf	-	unexpected continuation byte 0x80
+3.1.4 n "���"		-		3	80:bf:80	-	unexpected continuation byte 0x80
+3.1.5 n "����"		-		4	80:bf:80:bf	-	unexpected continuation byte 0x80
+3.1.6 n "�����"	-		5	80:bf:80:bf:80	-	unexpected continuation byte 0x80
+3.1.7 n "������"	-		6	80:bf:80:bf:80:bf	-	unexpected continuation byte 0x80
+3.1.8 n "�������"	-		7	80:bf:80:bf:80:bf:80	-	unexpected continuation byte 0x80
+3.1.9 n "����������������������������������������������������������������"				-	64	80:81:82:83:84:85:86:87:88:89:8a:8b:8c:8d:8e:8f:90:91:92:93:94:95:96:97:98:99:9a:9b:9c:9d:9e:9f:a0:a1:a2:a3:a4:a5:a6:a7:a8:a9:aa:ab:ac:ad:ae:af:b0:b1:b2:b3:b4:b5:b6:b7:b8:b9:ba:bb:bc:bd:be:bf	-	unexpected continuation byte 0x80
+3.2	Lonely start characters
+3.2.1 n "� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � "	-	64 	c0:20:c1:20:c2:20:c3:20:c4:20:c5:20:c6:20:c7:20:c8:20:c9:20:ca:20:cb:20:cc:20:cd:20:ce:20:cf:20:d0:20:d1:20:d2:20:d3:20:d4:20:d5:20:d6:20:d7:20:d8:20:d9:20:da:20:db:20:dc:20:dd:20:de:20:df:20	-	unexpected non-continuation byte 0x20 after byte 0xc0
+3.2.2 n "� � � � � � � � � � � � � � � � "	-	32	e0:20:e1:20:e2:20:e3:20:e4:20:e5:20:e6:20:e7:20:e8:20:e9:20:ea:20:eb:20:ec:20:ed:20:ee:20:ef:20	-	unexpected non-continuation byte 0x20 after byte 0xe0
+3.2.3 n "� � � � � � � � "	-	16	f0:20:f1:20:f2:20:f3:20:f4:20:f5:20:f6:20:f7:20	-	unexpected non-continuation byte 0x20 after byte 0xf0
+3.2.4 n "� � � � "		-	8	f8:20:f9:20:fa:20:fb:20	-	unexpected non-continuation byte 0x20 after byte 0xf8
+3.2.5 n "� � "			-	4	fc:20:fd:20	-	unexpected non-continuation byte 0x20 after byte 0xfc
+3.3	Sequences with last continuation byte missing
+3.3.1 n "�"			-	1	c0	-	1 byte, need 2
+3.3.2 n "��"			-	2	e0:80	-	2 bytes, need 3
+3.3.3 n "���"		-	3	f0:80:80	-	3 bytes, need 4
+3.3.4 n "����"		-	4	f8:80:80:80	-	4 bytes, need 5
+3.3.5 n "�����"	-	5	fc:80:80:80:80	-	5 bytes, need 6
+3.3.6 n "�"			-	1	df	-	1 byte, need 2
+3.3.7 n "�"			-	2	ef:bf	-	2 bytes, need 3
+3.3.8 n "���"			-	3	f7:bf:bf	-	3 bytes, need 4
+3.3.9 n "����"			-	4	fb:bf:bf:bf	-	4 bytes, need 5
+3.3.10 n "�����"		-	5	fd:bf:bf:bf:bf	-	5 bytes, need 6
+3.4	Concatenation of incomplete sequences
+3.4.1 n "�����������������������������"	-	30	c0:e0:80:f0:80:80:f8:80:80:80:fc:80:80:80:80:df:ef:bf:f7:bf:bf:fb:bf:bf:bf:fd:bf:bf:bf:bf	-	unexpected continuation byte 0xe0
+3.5	Impossible bytes
+3.5.1 n "�"			-	1	fe	-	byte 0xfe
+3.5.2 n "�"			-	1	ff	-	byte 0xff
+3.5.3 n "����"			-	4	fe:fe:ff:ff	-	byte 0xfe
+4	Overlong sequences
+4.1	Examples of an overlong ASCII character
+4.1.1 n "��"			-	2	c0:af	-	2 bytes, need 1
+4.1.2 n "���"		-	3	e0:80:af	-	3 bytes, need 1
+4.1.3 n "����"		-	4	f0:80:80:af	-	4 bytes, need 1
+4.1.4 n "�����"	-	5	f8:80:80:80:af	-	5 bytes, need 1
+4.1.5 n "������"	-	6	fc:80:80:80:80:af	-	6 bytes, need 1
+4.2	Maximum overlong sequences
+4.2.1 n "��"			-	2	c1:bf	-	2 bytes, need 1
+4.2.2 n "���"		-	3	e0:9f:bf	-	3 bytes, need 2
+4.2.3 n "����"		-	4	f0:8f:bf:bf	-	4 bytes, need 3
+4.2.4 n "�����"		-	5	f8:87:bf:bf:bf	-	5 bytes, need 4
+4.2.5 n "������"		-	6	fc:83:bf:bf:bf:bf	-	6 bytes, need 5
+4.3	Overlong representation of the NUL character
+4.3.1 n "��"			-	2	c0:80	-	2 bytes, need 1
+4.3.2 n "���"		-	3	e0:80:80	-	3 bytes, need 1
+4.3.3 n "����"		-	4	f0:80:80:80	-	4 bytes, need 1
+4.3.4 n "�����"	-	5	f8:80:80:80:80	-	5 bytes, need 1
+4.3.5 n "������"	-	6	fc:80:80:80:80:80	-	6 bytes, need 1
+5	Illegal code positions
+5.1	Single UTF-16 surrogates
+5.1.1 n "���"		-	3	ed:a0:80	-	UTF-16 surrogate 0xd800
+5.1.2 n "���"			-	3	ed:ad:bf	-	UTF-16 surrogate 0xdb7f
+5.1.3 n "���"		-	3	ed:ae:80	-	UTF-16 surrogate 0xdb80
+5.1.4 n "���"			-	3	ed:af:bf	-	UTF-16 surrogate 0xdbff
+5.1.5 n "���"		-	3	ed:b0:80	-	UTF-16 surrogate 0xdc00
+5.1.6 n "���"		-	3	ed:be:80	-	UTF-16 surrogate 0xdf80
+5.1.7 n "���"			-	3	ed:bf:bf	-	UTF-16 surrogate 0xdfff
+5.2	Paired UTF-16 surrogates
+5.2.1 n "������"		-	6	ed:a0:80:ed:b0:80	-	UTF-16 surrogate 0xd800
+5.2.2 n "������"		-	6	ed:a0:80:ed:bf:bf	-	UTF-16 surrogate 0xd800
+5.2.3 n "������"		-	6	ed:ad:bf:ed:b0:80	-	UTF-16 surrogate 0xdb7f
+5.2.4 n "������"		-	6	ed:ad:bf:ed:bf:bf	-	UTF-16 surrogate 0xdb7f
+5.2.5 n "������"		-	6	ed:ae:80:ed:b0:80	-	UTF-16 surrogate 0xdb80
+5.2.6 n "������"		-	6	ed:ae:80:ed:bf:bf	-	UTF-16 surrogate 0xdb80
+5.2.7 n "������"		-	6	ed:af:bf:ed:b0:80	-	UTF-16 surrogate 0xdbff
+5.2.8 n "������"		-	6	ed:af:bf:ed:bf:bf	-	UTF-16 surrogate 0xdbff
+5.3	Other illegal code positions
+5.3.1 n "￾"			-	3	ef:bf:be	-	byte order mark 0xfffe
+# The ffff is illegal unless UTF8_ALLOW_FFFF
+5.3.2 n "￿"			-	3	ef:bf:bf	-	character 0xffff
+__EOMK__
+
+# 104..181
+{
+    my $WARNCNT;
+    my $id;
+
+    local $SIG{__WARN__} =
+	sub {
+	    # print "# $id: @_";
+	    $WARNCNT++;
+	    $WARNMSG = "@_";
+	};
+
+    sub moan {
+	print "$id: @_";
+    }
+    
+    sub test_unpack_U {
+	$WARNCNT = 0;
+	$WARNMSG = "";
+	unpack('U*', $_[0]);
+    }
+
+    for (@MK) {
+	if (/^(?:\d+(?:\.\d+)?)\s/ || /^#/) {
+	    # print "# $_\n";
+	} elsif (/^(\d+\.\d+\.\d+[bu]?)\s+([yn])\s+"(.+)"\s+([0-9a-f]{1,8}|-)\s+(\d+)\s+([0-9a-f]{2}(?::[0-9a-f]{2})*)(?:\s+((?:\d+|-)(?:\s+(.+))?))?$/) {
+	    $id = $1;
+	    my ($okay, $bytes, $Unicode, $byteslen, $hex, $charslen, $error) =
+		($2, $3, $4, $5, $6, $7, $8);
+	    my @hex = split(/:/, $hex);
+	    unless (@hex == $byteslen) {
+		my $nhex = @hex;
+		moan "amount of hex ($nhex) not equal to byteslen ($byteslen)\n";
+	    }
+	    {
+		use bytes;
+		my $bytesbyteslen = length($bytes);
+		unless ($bytesbyteslen == $byteslen) {
+		    moan "bytes length() ($bytesbyteslen) not equal to $byteslen\n";
+		}
+	    }
+	    if ($okay eq 'y') {
+		test_unpack_U($bytes);
+		if ($WARNCNT) {
+		    moan "unpack('U*') false negative\n";
+		    print "not ";
+		}
+	    } elsif ($okay eq 'n') {
+		test_unpack_U($bytes);
+		if ($WARNCNT == 0 || ($error ne '' && $WARNMSG !~ /$error/)) {
+		    moan "unpack('U*') false positive\n";
+		    print "not ";
+		}
+	    }
+	    print "ok $test\n";
+	    $test++;
+ 	} else {
+	    moan "unknown format\n";
+	}
+    }
+}
diff --git a/t/pragma/utf8.t b/t/pragma/utf8.t
index 3d8693efc0..827be5a2ab 100755
--- a/t/pragma/utf8.t
+++ b/t/pragma/utf8.t
@@ -10,7 +10,7 @@ BEGIN {
     }
 }
 
-print "1..181\n";
+print "1..103\n";
 
 my $test = 1;
 
@@ -564,173 +564,3 @@ sub nok_bytes {
     print "ok $test\n";
     $test++;
 }
-
-# This table is based on Markus Kuhn's UTF-8 Decode Stress Tester,
-# http://www.cl.cam.ac.uk/~mgk25/ucs/examples/UTF-8-test.txt,
-# version dated 2000-09-02. 
-
-# Note the \0 instead of a raw zero byte in 2.1.1: for example
-# GNU patch v2.1 has "issues" with raw zero bytes.
-
-my @MK = split(/\n/, <<__EOMK__);
-1	Correct UTF-8
-1.1.1 y "κόσμε"	-		11	ce:ba:e1:bd:b9:cf:83:ce:bc:ce:b5	5
-2	Boundary conditions 
-2.1	First possible sequence of certain length
-2.1.1 y "\0"			0		1	00	1
-2.1.2 y "€"			80		2	c2:80	1
-2.1.3 y "ࠀ"		800		3	e0:a0:80	1
-2.1.4 y "𐀀"		10000		4	f0:90:80:80	1
-2.1.5 y "�����"	200000		5	f8:88:80:80:80	1
-2.1.6 y "������"	4000000		6	fc:84:80:80:80:80	1
-2.2	Last possible sequence of certain length
-2.2.1 y ""			7f		1	7f	1
-2.2.2 y "߿"			7ff		2	df:bf	1
-# The ffff is illegal unless UTF8_ALLOW_FFFF
-2.2.3 n "￿"			ffff		3	ef:bf:bf	1
-2.2.4 y "����"			1fffff		4	f7:bf:bf:bf	1
-2.2.5 y "�����"			3ffffff		5	fb:bf:bf:bf:bf	1
-2.2.6 y "������"		7fffffff	6	fd:bf:bf:bf:bf:bf	1
-2.3	Other boundary conditions
-2.3.1 y "퟿"		d7ff		3	ed:9f:bf	1
-2.3.2 y ""		e000		3	ee:80:80	1
-2.3.3 y "�"			fffd		3	ef:bf:bd	1
-2.3.4 y "􏿿"		10ffff		4	f4:8f:bf:bf	1
-2.3.5 y "����"		110000		4	f4:90:80:80	1
-3	Malformed sequences
-3.1	Unexpected continuation bytes
-3.1.1 n "�"			-		1	80
-3.1.2 n "�"			-		1	bf
-3.1.3 n "��"			-		2	80:bf
-3.1.4 n "���"		-		3	80:bf:80
-3.1.5 n "����"		-		4	80:bf:80:bf
-3.1.6 n "�����"	-		5	80:bf:80:bf:80
-3.1.7 n "������"	-		6	80:bf:80:bf:80:bf
-3.1.8 n "�������"	-		7	80:bf:80:bf:80:bf:80
-3.1.9 n "����������������������������������������������������������������"				-	64	80:81:82:83:84:85:86:87:88:89:8a:8b:8c:8d:8e:8f:90:91:92:93:94:95:96:97:98:99:9a:9b:9c:9d:9e:9f:a0:a1:a2:a3:a4:a5:a6:a7:a8:a9:aa:ab:ac:ad:ae:af:b0:b1:b2:b3:b4:b5:b6:b7:b8:b9:ba:bb:bc:bd:be:bf
-3.2	Lonely start characters
-3.2.1 n "� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � "	-	64 	c0:20:c1:20:c2:20:c3:20:c4:20:c5:20:c6:20:c7:20:c8:20:c9:20:ca:20:cb:20:cc:20:cd:20:ce:20:cf:20:d0:20:d1:20:d2:20:d3:20:d4:20:d5:20:d6:20:d7:20:d8:20:d9:20:da:20:db:20:dc:20:dd:20:de:20:df:20
-3.2.2 n "� � � � � � � � � � � � � � � � "	-	32	e0:20:e1:20:e2:20:e3:20:e4:20:e5:20:e6:20:e7:20:e8:20:e9:20:ea:20:eb:20:ec:20:ed:20:ee:20:ef:20
-3.2.3 n "� � � � � � � � "	-	16	f0:20:f1:20:f2:20:f3:20:f4:20:f5:20:f6:20:f7:20
-3.2.4 n "� � � � "		-	8	f8:20:f9:20:fa:20:fb:20
-3.2.5 n "� � "			-	4	fc:20:fd:20
-3.3	Sequences with last continuation byte missing
-3.3.1 n "�"			-	1	c0
-3.3.2 n "��"			-	2	e0:80
-3.3.3 n "���"		-	3	f0:80:80
-3.3.4 n "����"		-	4	f8:80:80:80
-3.3.5 n "�����"	-	5	fc:80:80:80:80
-3.3.6 n "�"			-	1	df
-3.3.7 n "�"			-	2	ef:bf
-3.3.8 n "���"			-	3	f7:bf:bf
-3.3.9 n "����"			-	4	fb:bf:bf:bf
-3.3.10 n "�����"		-	5	fd:bf:bf:bf:bf
-3.4	Concatenation of incomplete sequences
-3.4.1 n "�����������������������������"	-	30	c0:e0:80:f0:80:80:f8:80:80:80:fc:80:80:80:80:df:ef:bf:f7:bf:bf:fb:bf:bf:bf:fd:bf:bf:bf:bf
-3.5	Impossible bytes
-3.5.1 n "�"			-	1	fe
-3.5.2 n "�"			-	1	ff
-3.5.3 n "����"			-	4	fe:fe:ff:ff
-4	Overlong sequences
-4.1	Examples of an overlong ASCII character
-4.1.1 n "��"			-	2	c0:af
-4.1.2 n "���"		-	3	e0:80:af
-4.1.3 n "����"		-	4	f0:80:80:af
-4.1.4 n "�����"	-	5	f8:80:80:80:af
-4.1.5 n "������"	-	6	fc:80:80:80:80:af
-4.2	Maximum overlong sequences
-4.2.1 n "��"			-	2	c1:bf
-4.2.2 n "���"		-	3	e0:9f:bf
-4.2.3 n "����"		-	4	f0:8f:bf:bf
-4.2.4 n "�����"		-	5	f8:87:bf:bf:bf
-4.2.5 n "������"		-	6	fc:83:bf:bf:bf:bf
-4.3	Overlong representation of the NUL character
-4.3.1 n "��"			-	2	c0:80
-4.3.2 n "���"		-	3	e0:80:80
-4.3.3 n "����"		-	4	f0:80:80:80
-4.3.4 n "�����"	-	5	f8:80:80:80:80
-4.3.5 n "������"	-	6	fc:80:80:80:80:80
-5	Illegal code positions
-5.1	Single UTF-16 surrogates
-5.1.1 n "���"		-	3	ed:a0:80
-5.1.2 n "���"			-	3	ed:ad:bf
-5.1.3 n "���"		-	3	ed:ae:80
-5.1.4 n "���"			-	3	ed:af:bf
-5.1.5 n "���"		-	3	ed:b0:80
-5.1.6 n "���"		-	3	ed:be:80
-5.1.7 n "���"			-	3	ed:bf:bf
-5.2	Paired UTF-16 surrogates
-5.2.1 n "������"		-	6	ed:a0:80:ed:b0:80
-5.2.2 n "������"		-	6	ed:a0:80:ed:bf:bf
-5.2.3 n "������"		-	6	ed:ad:bf:ed:b0:80
-5.2.4 n "������"		-	6	ed:ad:bf:ed:bf:bf
-5.2.5 n "������"		-	6	ed:ae:80:ed:b0:80
-5.2.6 n "������"		-	6	ed:ae:80:ed:bf:bf
-5.2.7 n "������"		-	6	ed:af:bf:ed:b0:80
-5.2.8 n "������"		-	6	ed:af:bf:ed:bf:bf
-5.3	Other illegal code positions
-5.3.1 n "￾"			-	3	ef:bf:be
-# The ffff is illegal unless UTF8_ALLOW_FFFF
-5.3.2 n "￿"			-	3	ef:bf:bf
-__EOMK__
-
-# 104..181
-{
-    my $WARN;
-    my $id;
-
-    local $SIG{__WARN__} =
-	sub {
-	    # print "# $id: @_";
-	    $WARN++;
-	};
-
-    sub moan {
-	print "$id: @_";
-    }
-    
-    sub test_unpack_U {
-	$WARN = 0;
-	unpack('U*', $_[0]);
-    }
-
-    for (@MK) {
-	if (/^(?:\d+(?:\.\d+)?)\s/ || /^#/) {
-	    # print "# $_\n";
-	} elsif (/^(\d+\.\d+\.\d+[bu]?)\s+([yn])\s+"(.+)"\s+([0-9a-f]{1,8}|-)\s+(\d+)\s+([0-9a-f]{2}(?::[0-9a-f]{2})*)(?:\s+(\d+))?$/) {
-	    $id = $1;
-	    my ($okay, $bytes, $Unicode, $byteslen, $hex, $charslen) =
-		($2, $3, $4, $5, $6, $7);
-	    my @hex = split(/:/, $hex);
-	    unless (@hex == $byteslen) {
-		my $nhex = @hex;
-		moan "amount of hex ($nhex) not equal to byteslen ($byteslen)\n";
-	    }
-	    {
-		use bytes;
-		my $bytesbyteslen = length($bytes);
-		unless ($bytesbyteslen == $byteslen) {
-		    moan "bytes length() ($bytesbyteslen) not equal to $byteslen\n";
-		}
-	    }
-	    if ($okay eq 'y') {
-		test_unpack_U($bytes);
-		unless ($WARN == 0) {
-		    moan "unpack('U*') false negative\n";
-		    print "not ";
-		}
-	    } elsif ($okay eq 'n') {
-		test_unpack_U($bytes);
-		unless ($WARN) {
-		    moan "unpack('U*') false positive\n";
-		    print "not ";
-		}
-	    }
-	    print "ok $test\n";
-	    $test++;
- 	} else {
-	    moan "unknown format\n";
-	}
-    }
-}
-
diff --git a/utf8.c b/utf8.c
index 5e018260fa..bc0a52178d 100644
--- a/utf8.c
+++ b/utf8.c
@@ -309,13 +309,6 @@ Perl_utf8_to_uv(pTHX_ U8* s, STRLEN curlen, STRLEN* retlen, U32 flags)
 			"Malformed UTF-8 character (byte order mark 0x%04"UVxf")",
 			uv);
 	goto malformed;
-    } else if ((uv == 0xffff) &&
-	       !(flags & UTF8_ALLOW_FFFF)) {
-	if (dowarn)
-	    Perl_warner(aTHX_ WARN_UTF8,
-			"Malformed UTF-8 character (character 0x%04"UVxf")",
-			uv);
-	goto malformed;
     } else if ((expectlen > UNISKIP(uv)) &&
 	       !(flags & UTF8_ALLOW_LONG)) {
 	if (dowarn)
@@ -323,6 +316,13 @@ Perl_utf8_to_uv(pTHX_ U8* s, STRLEN curlen, STRLEN* retlen, U32 flags)
 			"Malformed UTF-8 character (%d byte%s, need %d)",
 			expectlen, expectlen == 1 ? "": "s", UNISKIP(uv));
 	goto malformed;
+    } else if ((uv == 0xffff) &&
+	       !(flags & UTF8_ALLOW_FFFF)) {
+	if (dowarn)
+	    Perl_warner(aTHX_ WARN_UTF8,
+			"Malformed UTF-8 character (character 0x%04"UVxf")",
+			uv);
+	goto malformed;
     }
 
     return uv;