This is a live mirror of the Perl 5 development currently hosted at https://github.com/perl/perl5
APItest/t/utf8.t: Fix test name
[perl5.git] / ext / XS-APItest / t / utf8.t
index 31d2d35..05693c0 100644 (file)
@@ -4,19 +4,27 @@ use strict;
 use Test::More;
 $|=1;
 
-use XS::APItest;
+no warnings 'deprecated'; # Some of the below are above IV_MAX on 32 bit
+                          # machines, and that is tested elsewhere
 
+use XS::APItest;
+use Data::Dumper;
 my $pound_sign = chr utf8::unicode_to_native(163);
 
 sub isASCII { ord "A" == 65 }
 
 sub display_bytes {
+    use bytes;
     my $string = shift;
     return   '"'
            . join("", map { sprintf("\\x%02x", ord $_) } split "", $string)
            . '"';
 }
 
+sub output_warnings(@) {
+    diag "The warnings were:\n" . join("", @_);
+}
+
 # This  test file can't use byte_utf8a_to_utf8n() from t/charset_tools.pl
 # because that uses the same functions we are testing here.  So UTF-EBCDIC
 # strings are hard-coded as I8 strings in this file instead, and we use array
@@ -42,30 +50,77 @@ my @i8_to_native = (    # Only code page 1047 so far.
 0xDC,0xDD,0xDE,0xDF,0xE1,0xEA,0xEB,0xEC,0xED,0xEE,0xEF,0xFA,0xFB,0xFC,0xFD,0xFE,
 );
 
+my @native_to_i8;
+for (my $i = 0; $i < 256; $i++) {
+    $native_to_i8[$i8_to_native[$i]] = $i;
+}
+
 *I8_to_native = (isASCII)
-                    ? sub { return shift }
-                    : sub { return join "", map { chr $i8_to_native[ord $_] }
+                ? sub { return shift }
+                : sub { return join "", map { chr $i8_to_native[ord $_] }
+                                            split "", shift };
+*native_to_I8 = (isASCII)
+                ? sub { return shift }
+                : sub { return join "", map { chr $native_to_i8[ord $_] }
                                             split "", shift };
+sub start_byte_to_cont($) {
+
+    # Extract the code point information from the input UTF-8 start byte, and
+    # return a continuation byte containing the same information.  This is
+    # used in constructing an overlong malformation from valid input.
+
+    my $byte = shift;
+    my $len = test_UTF8_SKIP($byte);
+    if ($len < 2) {
+        die "start_byte_to_cont() is expecting a UTF-8 variant";
+    }
+
+    $byte = ord native_to_I8($byte);
+
+    # Copied from utf8.h.  This gets rid of the leading 1 bits.
+    $byte &= ((($len) >= 7) ? 0x00 : (0x1F >> (($len)-2)));
+
+    $byte |= (isASCII) ? 0x80 : 0xA0;
+    return I8_to_native(chr $byte);
+}
 
 my $is64bit = length sprintf("%x", ~0) > 8;
 
 
-# Test utf8n_to_uvchr().  These provide essentially complete code coverage.
-# Copied from utf8.h
+# Test utf8n_to_uvchr_error().  These provide essentially complete code
+# coverage.  Copied from utf8.h
 my $UTF8_ALLOW_EMPTY            = 0x0001;
+my $UTF8_GOT_EMPTY              = $UTF8_ALLOW_EMPTY;
 my $UTF8_ALLOW_CONTINUATION     = 0x0002;
+my $UTF8_GOT_CONTINUATION       = $UTF8_ALLOW_CONTINUATION;
 my $UTF8_ALLOW_NON_CONTINUATION = 0x0004;
+my $UTF8_GOT_NON_CONTINUATION   = $UTF8_ALLOW_NON_CONTINUATION;
 my $UTF8_ALLOW_SHORT            = 0x0008;
+my $UTF8_GOT_SHORT              = $UTF8_ALLOW_SHORT;
 my $UTF8_ALLOW_LONG             = 0x0010;
-my $UTF8_DISALLOW_SURROGATE     = 0x0020;
-my $UTF8_WARN_SURROGATE         = 0x0040;
-my $UTF8_DISALLOW_NONCHAR       = 0x0080;
-my $UTF8_WARN_NONCHAR           = 0x0100;
-my $UTF8_DISALLOW_SUPER         = 0x0200;
-my $UTF8_WARN_SUPER             = 0x0400;
-my $UTF8_DISALLOW_FE_FF         = 0x0800;
-my $UTF8_WARN_FE_FF             = 0x1000;
-my $UTF8_CHECK_ONLY             = 0x2000;
+my $UTF8_GOT_LONG               = $UTF8_ALLOW_LONG;
+my $UTF8_GOT_OVERFLOW           = 0x0020;
+my $UTF8_DISALLOW_SURROGATE     = 0x0040;
+my $UTF8_GOT_SURROGATE          = $UTF8_DISALLOW_SURROGATE;
+my $UTF8_WARN_SURROGATE         = 0x0080;
+my $UTF8_DISALLOW_NONCHAR       = 0x0100;
+my $UTF8_GOT_NONCHAR            = $UTF8_DISALLOW_NONCHAR;
+my $UTF8_WARN_NONCHAR           = 0x0200;
+my $UTF8_DISALLOW_SUPER         = 0x0400;
+my $UTF8_GOT_SUPER              = $UTF8_DISALLOW_SUPER;
+my $UTF8_WARN_SUPER             = 0x0800;
+my $UTF8_DISALLOW_ABOVE_31_BIT  = 0x1000;
+my $UTF8_GOT_ABOVE_31_BIT       = $UTF8_DISALLOW_ABOVE_31_BIT;
+my $UTF8_WARN_ABOVE_31_BIT      = 0x2000;
+my $UTF8_CHECK_ONLY             = 0x4000;
+my $UTF8_DISALLOW_ILLEGAL_C9_INTERCHANGE
+                             = $UTF8_DISALLOW_SUPER|$UTF8_DISALLOW_SURROGATE;
+my $UTF8_DISALLOW_ILLEGAL_INTERCHANGE
+              = $UTF8_DISALLOW_ILLEGAL_C9_INTERCHANGE|$UTF8_DISALLOW_NONCHAR;
+my $UTF8_WARN_ILLEGAL_C9_INTERCHANGE
+                             = $UTF8_WARN_SUPER|$UTF8_WARN_SURROGATE;
+my $UTF8_WARN_ILLEGAL_INTERCHANGE
+              = $UTF8_WARN_ILLEGAL_C9_INTERCHANGE|$UTF8_WARN_NONCHAR;
 
 # Test uvchr_to_utf8().
 my $UNICODE_WARN_SURROGATE        = 0x0001;
@@ -84,8 +139,8 @@ my $look_for_everything_utf8n_to
                        | $UTF8_WARN_NONCHAR
                        | $UTF8_DISALLOW_SUPER
                        | $UTF8_WARN_SUPER
-                       | $UTF8_DISALLOW_FE_FF
-                       | $UTF8_WARN_FE_FF;
+                       | $UTF8_DISALLOW_ABOVE_31_BIT
+                       | $UTF8_WARN_ABOVE_31_BIT;
 my $look_for_everything_uvchr_to
                         = $UNICODE_DISALLOW_SURROGATE
                        | $UNICODE_WARN_SURROGATE
@@ -101,8 +156,10 @@ foreach ([0, '', '', 'empty'],
         [1, 'NN', 'N', '1 char substring'],
         [-2, 'Perl', 'Rules', 'different'],
         [0, $pound_sign, $pound_sign, 'pound sign'],
-        [1, $pound_sign . 10, $pound_sign . 1, '10 pounds is more than 1 pound'],
-        [1, $pound_sign . $pound_sign, $pound_sign, '2 pound signs are more than 1'],
+        [1, $pound_sign . 10, $pound_sign . 1,
+                                            '10 pounds is more than 1 pound'],
+        [1, $pound_sign . $pound_sign, $pound_sign,
+                                            '2 pound signs are more than 1'],
         [-2, ' $!', " \x{1F42B}!", 'Camels are worth more than 1 dollar'],
         [-1, '!', "!\x{1F42A}", 'Initial substrings match'],
        ) {
@@ -141,84 +198,345 @@ my %code_points = (
     # as of this writing, considers potentially problematic on ASCII
     0xD000     => (isASCII) ? "\xed\x80\x80" : I8_to_native("\xf1\xb4\xa0\xa0"),
 
-    # Bracket the surrogates
-    0xD7FF     => (isASCII) ? "\xed\x9f\xbf" : I8_to_native("\xf1\xb5\xbf\xbf"),
-    0xE000     => (isASCII) ? "\xee\x80\x80" : I8_to_native("\xf1\xb8\xa0\xa0"),
-
-    # Bracket the 32 contiguous non characters
-    0xFDCF     => (isASCII) ? "\xef\xb7\x8f" : I8_to_native("\xf1\xbf\xae\xaf"),
-    0xFDF0      => (isASCII) ? "\xef\xb7\xb0" : I8_to_native("\xf1\xbf\xaf\xb0"),
-
-    # Mostly bracket non-characters, but some are transitions to longer
-    # strings
-    0xFFFD     => (isASCII) ? "\xef\xbf\xbd" : I8_to_native("\xf1\xbf\xbf\xbd"),
-    0x10000 - 1 => (isASCII) ? "\xef\xbf\xbf" : I8_to_native("\xf1\xbf\xbf\xbf"),
-    0x10000     => (isASCII) ? "\xf0\x90\x80\x80" : I8_to_native("\xf2\xa0\xa0\xa0"),
-    0x1FFFD     => (isASCII) ? "\xf0\x9f\xbf\xbd" : I8_to_native("\xf3\xbf\xbf\xbd"),
-    0x20000     => (isASCII) ? "\xf0\xa0\x80\x80" : I8_to_native("\xf4\xa0\xa0\xa0"),
-    0x2FFFD     => (isASCII) ? "\xf0\xaf\xbf\xbd" : I8_to_native("\xf5\xbf\xbf\xbd"),
-    0x30000     => (isASCII) ? "\xf0\xb0\x80\x80" : I8_to_native("\xf6\xa0\xa0\xa0"),
-    0x3FFFD     => (isASCII) ? "\xf0\xbf\xbf\xbd" : I8_to_native("\xf7\xbf\xbf\xbd"),
-    0x40000 - 1 => (isASCII) ? "\xf0\xbf\xbf\xbf" : I8_to_native("\xf7\xbf\xbf\xbf"),
-    0x40000     => (isASCII) ? "\xf1\x80\x80\x80" : I8_to_native("\xf8\xa8\xa0\xa0\xa0"),
-    0x4FFFD    => (isASCII) ? "\xf1\x8f\xbf\xbd" : I8_to_native("\xf8\xa9\xbf\xbf\xbd"),
-    0x50000     => (isASCII) ? "\xf1\x90\x80\x80" : I8_to_native("\xf8\xaa\xa0\xa0\xa0"),
-    0x5FFFD    => (isASCII) ? "\xf1\x9f\xbf\xbd" : I8_to_native("\xf8\xab\xbf\xbf\xbd"),
-    0x60000     => (isASCII) ? "\xf1\xa0\x80\x80" : I8_to_native("\xf8\xac\xa0\xa0\xa0"),
-    0x6FFFD    => (isASCII) ? "\xf1\xaf\xbf\xbd" : I8_to_native("\xf8\xad\xbf\xbf\xbd"),
-    0x70000     => (isASCII) ? "\xf1\xb0\x80\x80" : I8_to_native("\xf8\xae\xa0\xa0\xa0"),
-    0x7FFFD    => (isASCII) ? "\xf1\xbf\xbf\xbd" : I8_to_native("\xf8\xaf\xbf\xbf\xbd"),
-    0x80000     => (isASCII) ? "\xf2\x80\x80\x80" : I8_to_native("\xf8\xb0\xa0\xa0\xa0"),
-    0x8FFFD    => (isASCII) ? "\xf2\x8f\xbf\xbd" : I8_to_native("\xf8\xb1\xbf\xbf\xbd"),
-    0x90000     => (isASCII) ? "\xf2\x90\x80\x80" : I8_to_native("\xf8\xb2\xa0\xa0\xa0"),
-    0x9FFFD    => (isASCII) ? "\xf2\x9f\xbf\xbd" : I8_to_native("\xf8\xb3\xbf\xbf\xbd"),
-    0xA0000     => (isASCII) ? "\xf2\xa0\x80\x80" : I8_to_native("\xf8\xb4\xa0\xa0\xa0"),
-    0xAFFFD    => (isASCII) ? "\xf2\xaf\xbf\xbd" : I8_to_native("\xf8\xb5\xbf\xbf\xbd"),
-    0xB0000     => (isASCII) ? "\xf2\xb0\x80\x80" : I8_to_native("\xf8\xb6\xa0\xa0\xa0"),
-    0xBFFFD    => (isASCII) ? "\xf2\xbf\xbf\xbd" : I8_to_native("\xf8\xb7\xbf\xbf\xbd"),
-    0xC0000     => (isASCII) ? "\xf3\x80\x80\x80" : I8_to_native("\xf8\xb8\xa0\xa0\xa0"),
-    0xCFFFD    => (isASCII) ? "\xf3\x8f\xbf\xbd" : I8_to_native("\xf8\xb9\xbf\xbf\xbd"),
-    0xD0000     => (isASCII) ? "\xf3\x90\x80\x80" : I8_to_native("\xf8\xba\xa0\xa0\xa0"),
-    0xDFFFD    => (isASCII) ? "\xf3\x9f\xbf\xbd" : I8_to_native("\xf8\xbb\xbf\xbf\xbd"),
-    0xE0000     => (isASCII) ? "\xf3\xa0\x80\x80" : I8_to_native("\xf8\xbc\xa0\xa0\xa0"),
-    0xEFFFD    => (isASCII) ? "\xf3\xaf\xbf\xbd" : I8_to_native("\xf8\xbd\xbf\xbf\xbd"),
-    0xF0000     => (isASCII) ? "\xf3\xb0\x80\x80" : I8_to_native("\xf8\xbe\xa0\xa0\xa0"),
-    0xFFFFD    => (isASCII) ? "\xf3\xbf\xbf\xbd" : I8_to_native("\xf8\xbf\xbf\xbf\xbd"),
-    0x100000    => (isASCII) ? "\xf4\x80\x80\x80" : I8_to_native("\xf9\xa0\xa0\xa0\xa0"),
-    0x10FFFD   => (isASCII) ? "\xf4\x8f\xbf\xbd" : I8_to_native("\xf9\xa1\xbf\xbf\xbd"),
-    0x110000    => (isASCII) ? "\xf4\x90\x80\x80" : I8_to_native("\xf9\xa2\xa0\xa0\xa0"),
+    # Bracket the surrogates, and include several surrogates
+    0xD7FF     => (isASCII) ? "\xed\x9f\xbf" : I8_to_native("\xf1\xb5\xbf\xbf"),
+    0xD800     => (isASCII) ? "\xed\xa0\x80" : I8_to_native("\xf1\xb6\xa0\xa0"),
+    0xDC00     => (isASCII) ? "\xed\xb0\x80" : I8_to_native("\xf1\xb7\xa0\xa0"),
+    0xDFFF     => (isASCII) ? "\xee\x80\x80" : I8_to_native("\xf1\xb8\xa0\xa0"),
+    0xDFFF     => (isASCII) ? "\xed\xbf\xbf" : I8_to_native("\xf1\xb7\xbf\xbf"),
+    0xE000     => (isASCII) ? "\xee\x80\x80" : I8_to_native("\xf1\xb8\xa0\xa0"),
+
+    # Include the 32 contiguous non characters, and surrounding code points
+    0xFDCF     => (isASCII) ? "\xef\xb7\x8f" : I8_to_native("\xf1\xbf\xae\xaf"),
+    0xFDD0     => (isASCII) ? "\xef\xb7\x90" : I8_to_native("\xf1\xbf\xae\xb0"),
+    0xFDD1     => (isASCII) ? "\xef\xb7\x91" : I8_to_native("\xf1\xbf\xae\xb1"),
+    0xFDD2     => (isASCII) ? "\xef\xb7\x92" : I8_to_native("\xf1\xbf\xae\xb2"),
+    0xFDD3     => (isASCII) ? "\xef\xb7\x93" : I8_to_native("\xf1\xbf\xae\xb3"),
+    0xFDD4     => (isASCII) ? "\xef\xb7\x94" : I8_to_native("\xf1\xbf\xae\xb4"),
+    0xFDD5     => (isASCII) ? "\xef\xb7\x95" : I8_to_native("\xf1\xbf\xae\xb5"),
+    0xFDD6     => (isASCII) ? "\xef\xb7\x96" : I8_to_native("\xf1\xbf\xae\xb6"),
+    0xFDD7     => (isASCII) ? "\xef\xb7\x97" : I8_to_native("\xf1\xbf\xae\xb7"),
+    0xFDD8     => (isASCII) ? "\xef\xb7\x98" : I8_to_native("\xf1\xbf\xae\xb8"),
+    0xFDD9     => (isASCII) ? "\xef\xb7\x99" : I8_to_native("\xf1\xbf\xae\xb9"),
+    0xFDDA     => (isASCII) ? "\xef\xb7\x9a" : I8_to_native("\xf1\xbf\xae\xba"),
+    0xFDDB     => (isASCII) ? "\xef\xb7\x9b" : I8_to_native("\xf1\xbf\xae\xbb"),
+    0xFDDC     => (isASCII) ? "\xef\xb7\x9c" : I8_to_native("\xf1\xbf\xae\xbc"),
+    0xFDDD     => (isASCII) ? "\xef\xb7\x9d" : I8_to_native("\xf1\xbf\xae\xbd"),
+    0xFDDE     => (isASCII) ? "\xef\xb7\x9e" : I8_to_native("\xf1\xbf\xae\xbe"),
+    0xFDDF     => (isASCII) ? "\xef\xb7\x9f" : I8_to_native("\xf1\xbf\xae\xbf"),
+    0xFDE0     => (isASCII) ? "\xef\xb7\xa0" : I8_to_native("\xf1\xbf\xaf\xa0"),
+    0xFDE1     => (isASCII) ? "\xef\xb7\xa1" : I8_to_native("\xf1\xbf\xaf\xa1"),
+    0xFDE2     => (isASCII) ? "\xef\xb7\xa2" : I8_to_native("\xf1\xbf\xaf\xa2"),
+    0xFDE3     => (isASCII) ? "\xef\xb7\xa3" : I8_to_native("\xf1\xbf\xaf\xa3"),
+    0xFDE4     => (isASCII) ? "\xef\xb7\xa4" : I8_to_native("\xf1\xbf\xaf\xa4"),
+    0xFDE5     => (isASCII) ? "\xef\xb7\xa5" : I8_to_native("\xf1\xbf\xaf\xa5"),
+    0xFDE6     => (isASCII) ? "\xef\xb7\xa6" : I8_to_native("\xf1\xbf\xaf\xa6"),
+    0xFDE7     => (isASCII) ? "\xef\xb7\xa7" : I8_to_native("\xf1\xbf\xaf\xa7"),
+    0xFDE8     => (isASCII) ? "\xef\xb7\xa8" : I8_to_native("\xf1\xbf\xaf\xa8"),
+    0xFDEa     => (isASCII) ? "\xef\xb7\x99" : I8_to_native("\xf1\xbf\xaf\xa9"),
+    0xFDEA     => (isASCII) ? "\xef\xb7\xaa" : I8_to_native("\xf1\xbf\xaf\xaa"),
+    0xFDEB     => (isASCII) ? "\xef\xb7\xab" : I8_to_native("\xf1\xbf\xaf\xab"),
+    0xFDEC     => (isASCII) ? "\xef\xb7\xac" : I8_to_native("\xf1\xbf\xaf\xac"),
+    0xFDED     => (isASCII) ? "\xef\xb7\xad" : I8_to_native("\xf1\xbf\xaf\xad"),
+    0xFDEE     => (isASCII) ? "\xef\xb7\xae" : I8_to_native("\xf1\xbf\xaf\xae"),
+    0xFDEF     => (isASCII) ? "\xef\xb7\xaf" : I8_to_native("\xf1\xbf\xaf\xaf"),
+    0xFDF0     => (isASCII) ? "\xef\xb7\xb0" : I8_to_native("\xf1\xbf\xaf\xb0"),
+
+    # Mostly around non-characters, but some are transitions to longer strings
+    0xFFFD     => (isASCII) ? "\xef\xbf\xbd" : I8_to_native("\xf1\xbf\xbf\xbd"),
+    0x10000 - 1 => (isASCII)
+                   ?              "\xef\xbf\xbf"
+                   : I8_to_native("\xf1\xbf\xbf\xbf"),
+    0x10000     => (isASCII)
+                   ?              "\xf0\x90\x80\x80"
+                   : I8_to_native("\xf2\xa0\xa0\xa0"),
+    0x1FFFD     => (isASCII)
+                   ?              "\xf0\x9f\xbf\xbd"
+                   : I8_to_native("\xf3\xbf\xbf\xbd"),
+    0x1FFFE     => (isASCII)
+                   ?              "\xf0\x9f\xbf\xbe"
+                   : I8_to_native("\xf3\xbf\xbf\xbe"),
+    0x1FFFF     => (isASCII)
+                   ?              "\xf0\x9f\xbf\xbf"
+                   : I8_to_native("\xf3\xbf\xbf\xbf"),
+    0x20000     => (isASCII)
+                   ?              "\xf0\xa0\x80\x80"
+                   : I8_to_native("\xf4\xa0\xa0\xa0"),
+    0x2FFFD     => (isASCII)
+                   ?              "\xf0\xaf\xbf\xbd"
+                   : I8_to_native("\xf5\xbf\xbf\xbd"),
+    0x2FFFE     => (isASCII)
+                   ?              "\xf0\xaf\xbf\xbe"
+                   : I8_to_native("\xf5\xbf\xbf\xbe"),
+    0x2FFFF     => (isASCII)
+                   ?              "\xf0\xaf\xbf\xbf"
+                   : I8_to_native("\xf5\xbf\xbf\xbf"),
+    0x30000     => (isASCII)
+                   ?              "\xf0\xb0\x80\x80"
+                   : I8_to_native("\xf6\xa0\xa0\xa0"),
+    0x3FFFD     => (isASCII)
+                   ?              "\xf0\xbf\xbf\xbd"
+                   : I8_to_native("\xf7\xbf\xbf\xbd"),
+    0x3FFFE     => (isASCII)
+                   ?              "\xf0\xbf\xbf\xbe"
+                   : I8_to_native("\xf7\xbf\xbf\xbe"),
+    0x40000 - 1 => (isASCII)
+                   ?              "\xf0\xbf\xbf\xbf"
+                   : I8_to_native("\xf7\xbf\xbf\xbf"),
+    0x40000     => (isASCII)
+                   ?              "\xf1\x80\x80\x80"
+                   : I8_to_native("\xf8\xa8\xa0\xa0\xa0"),
+    0x4FFFD    => (isASCII)
+                   ?              "\xf1\x8f\xbf\xbd"
+                   : I8_to_native("\xf8\xa9\xbf\xbf\xbd"),
+    0x4FFFE    => (isASCII)
+                   ?              "\xf1\x8f\xbf\xbe"
+                   : I8_to_native("\xf8\xa9\xbf\xbf\xbe"),
+    0x4FFFF    => (isASCII)
+                   ?              "\xf1\x8f\xbf\xbf"
+                   : I8_to_native("\xf8\xa9\xbf\xbf\xbf"),
+    0x50000     => (isASCII)
+                   ?              "\xf1\x90\x80\x80"
+                   : I8_to_native("\xf8\xaa\xa0\xa0\xa0"),
+    0x5FFFD    => (isASCII)
+                   ?              "\xf1\x9f\xbf\xbd"
+                   : I8_to_native("\xf8\xab\xbf\xbf\xbd"),
+    0x5FFFE    => (isASCII)
+                   ?              "\xf1\x9f\xbf\xbe"
+                   : I8_to_native("\xf8\xab\xbf\xbf\xbe"),
+    0x5FFFF    => (isASCII)
+                   ?              "\xf1\x9f\xbf\xbf"
+                   : I8_to_native("\xf8\xab\xbf\xbf\xbf"),
+    0x60000     => (isASCII)
+                   ?              "\xf1\xa0\x80\x80"
+                   : I8_to_native("\xf8\xac\xa0\xa0\xa0"),
+    0x6FFFD    => (isASCII)
+                   ?              "\xf1\xaf\xbf\xbd"
+                   : I8_to_native("\xf8\xad\xbf\xbf\xbd"),
+    0x6FFFE    => (isASCII)
+                   ?              "\xf1\xaf\xbf\xbe"
+                   : I8_to_native("\xf8\xad\xbf\xbf\xbe"),
+    0x6FFFF    => (isASCII)
+                   ?              "\xf1\xaf\xbf\xbf"
+                   : I8_to_native("\xf8\xad\xbf\xbf\xbf"),
+    0x70000     => (isASCII)
+                   ?              "\xf1\xb0\x80\x80"
+                   : I8_to_native("\xf8\xae\xa0\xa0\xa0"),
+    0x7FFFD    => (isASCII)
+                   ?              "\xf1\xbf\xbf\xbd"
+                   : I8_to_native("\xf8\xaf\xbf\xbf\xbd"),
+    0x7FFFE    => (isASCII)
+                   ?              "\xf1\xbf\xbf\xbe"
+                   : I8_to_native("\xf8\xaf\xbf\xbf\xbe"),
+    0x7FFFF    => (isASCII)
+                   ?              "\xf1\xbf\xbf\xbf"
+                   : I8_to_native("\xf8\xaf\xbf\xbf\xbf"),
+    0x80000     => (isASCII)
+                   ?              "\xf2\x80\x80\x80"
+                   : I8_to_native("\xf8\xb0\xa0\xa0\xa0"),
+    0x8FFFD    => (isASCII)
+                   ?              "\xf2\x8f\xbf\xbd"
+                   : I8_to_native("\xf8\xb1\xbf\xbf\xbd"),
+    0x8FFFE    => (isASCII)
+                   ?              "\xf2\x8f\xbf\xbe"
+                   : I8_to_native("\xf8\xb1\xbf\xbf\xbe"),
+    0x8FFFF    => (isASCII)
+                   ?              "\xf2\x8f\xbf\xbf"
+                   : I8_to_native("\xf8\xb1\xbf\xbf\xbf"),
+    0x90000     => (isASCII)
+                   ?              "\xf2\x90\x80\x80"
+                   : I8_to_native("\xf8\xb2\xa0\xa0\xa0"),
+    0x9FFFD    => (isASCII)
+                   ?              "\xf2\x9f\xbf\xbd"
+                   : I8_to_native("\xf8\xb3\xbf\xbf\xbd"),
+    0x9FFFE    => (isASCII)
+                   ?              "\xf2\x9f\xbf\xbe"
+                   : I8_to_native("\xf8\xb3\xbf\xbf\xbe"),
+    0x9FFFF    => (isASCII)
+                   ?              "\xf2\x9f\xbf\xbf"
+                   : I8_to_native("\xf8\xb3\xbf\xbf\xbf"),
+    0xA0000     => (isASCII)
+                   ?              "\xf2\xa0\x80\x80"
+                   : I8_to_native("\xf8\xb4\xa0\xa0\xa0"),
+    0xAFFFD    => (isASCII)
+                   ?              "\xf2\xaf\xbf\xbd"
+                   : I8_to_native("\xf8\xb5\xbf\xbf\xbd"),
+    0xAFFFE    => (isASCII)
+                   ?              "\xf2\xaf\xbf\xbe"
+                   : I8_to_native("\xf8\xb5\xbf\xbf\xbe"),
+    0xAFFFF    => (isASCII)
+                   ?              "\xf2\xaf\xbf\xbf"
+                   : I8_to_native("\xf8\xb5\xbf\xbf\xbf"),
+    0xB0000     => (isASCII)
+                   ?              "\xf2\xb0\x80\x80"
+                   : I8_to_native("\xf8\xb6\xa0\xa0\xa0"),
+    0xBFFFD    => (isASCII)
+                   ?              "\xf2\xbf\xbf\xbd"
+                   : I8_to_native("\xf8\xb7\xbf\xbf\xbd"),
+    0xBFFFE    => (isASCII)
+                   ?              "\xf2\xbf\xbf\xbe"
+                   : I8_to_native("\xf8\xb7\xbf\xbf\xbe"),
+    0xBFFFF    => (isASCII)
+                   ?               "\xf2\xbf\xbf\xbf"
+                   : I8_to_native("\xf8\xb7\xbf\xbf\xbf"),
+    0xC0000     => (isASCII)
+                   ?               "\xf3\x80\x80\x80"
+                   : I8_to_native("\xf8\xb8\xa0\xa0\xa0"),
+    0xCFFFD    => (isASCII)
+                   ?               "\xf3\x8f\xbf\xbd"
+                   : I8_to_native("\xf8\xb9\xbf\xbf\xbd"),
+    0xCFFFE    => (isASCII)
+                   ?               "\xf3\x8f\xbf\xbe"
+                   : I8_to_native("\xf8\xb9\xbf\xbf\xbe"),
+    0xCFFFF    => (isASCII)
+                   ?               "\xf3\x8f\xbf\xbf"
+                   : I8_to_native("\xf8\xb9\xbf\xbf\xbf"),
+    0xD0000     => (isASCII)
+                   ?               "\xf3\x90\x80\x80"
+                   : I8_to_native("\xf8\xba\xa0\xa0\xa0"),
+    0xDFFFD    => (isASCII)
+                   ?               "\xf3\x9f\xbf\xbd"
+                   : I8_to_native("\xf8\xbb\xbf\xbf\xbd"),
+    0xDFFFE    => (isASCII)
+                   ?               "\xf3\x9f\xbf\xbe"
+                   : I8_to_native("\xf8\xbb\xbf\xbf\xbe"),
+    0xDFFFF    => (isASCII)
+                   ?               "\xf3\x9f\xbf\xbf"
+                   : I8_to_native("\xf8\xbb\xbf\xbf\xbf"),
+    0xE0000     => (isASCII)
+                   ?               "\xf3\xa0\x80\x80"
+                   : I8_to_native("\xf8\xbc\xa0\xa0\xa0"),
+    0xEFFFD    => (isASCII)
+                   ?               "\xf3\xaf\xbf\xbd"
+                   : I8_to_native("\xf8\xbd\xbf\xbf\xbd"),
+    0xEFFFE    => (isASCII)
+                   ?               "\xf3\xaf\xbf\xbe"
+                   : I8_to_native("\xf8\xbd\xbf\xbf\xbe"),
+    0xEFFFF    => (isASCII)
+                   ?               "\xf3\xaf\xbf\xbf"
+                   : I8_to_native("\xf8\xbd\xbf\xbf\xbf"),
+    0xF0000     => (isASCII)
+                   ?               "\xf3\xb0\x80\x80"
+                   : I8_to_native("\xf8\xbe\xa0\xa0\xa0"),
+    0xFFFFD    => (isASCII)
+                   ?               "\xf3\xbf\xbf\xbd"
+                   : I8_to_native("\xf8\xbf\xbf\xbf\xbd"),
+    0xFFFFE    => (isASCII)
+                   ?               "\xf3\xbf\xbf\xbe"
+                   : I8_to_native("\xf8\xbf\xbf\xbf\xbe"),
+    0xFFFFF    => (isASCII)
+                   ?               "\xf3\xbf\xbf\xbf"
+                   : I8_to_native("\xf8\xbf\xbf\xbf\xbf"),
+    0x100000    => (isASCII)
+                   ?               "\xf4\x80\x80\x80"
+                   : I8_to_native("\xf9\xa0\xa0\xa0\xa0"),
+    0x10FFFD   => (isASCII)
+                   ?               "\xf4\x8f\xbf\xbd"
+                   : I8_to_native("\xf9\xa1\xbf\xbf\xbd"),
+    0x10FFFE   => (isASCII)
+                   ?               "\xf4\x8f\xbf\xbe"
+                   : I8_to_native("\xf9\xa1\xbf\xbf\xbe"),
+    0x10FFFF   => (isASCII)
+                   ?               "\xf4\x8f\xbf\xbf"
+                   : I8_to_native("\xf9\xa1\xbf\xbf\xbf"),
+    0x110000    => (isASCII)
+                   ?               "\xf4\x90\x80\x80"
+                   : I8_to_native("\xf9\xa2\xa0\xa0\xa0"),
 
     # Things that would be noncharacters if they were in Unicode, and might be
     # mistaken, if the C code is bad, to be nonchars
-    0x11FFFE    => (isASCII) ? "\xf4\x9f\xbf\xbe" : I8_to_native("\xf9\xa3\xbf\xbf\xbe"),
-    0x11FFFF    => (isASCII) ? "\xf4\x9f\xbf\xbf" : I8_to_native("\xf9\xa3\xbf\xbf\xbf"),
-    0x20FFFE    => (isASCII) ? "\xf8\x88\x8f\xbf\xbe" : I8_to_native("\xfa\xa1\xbf\xbf\xbe"),
-    0x20FFFF    => (isASCII) ? "\xf8\x88\x8f\xbf\xbf" : I8_to_native("\xfa\xa1\xbf\xbf\xbf"),
-
-    0x200000 - 1 => (isASCII) ? "\xf7\xbf\xbf\xbf" : I8_to_native("\xf9\xbf\xbf\xbf\xbf"),
-    0x200000     => (isASCII) ? "\xf8\x88\x80\x80\x80" : I8_to_native("\xfa\xa0\xa0\xa0\xa0"),
-    0x400000 - 1 => (isASCII) ? "\xf8\x8f\xbf\xbf\xbf" : I8_to_native("\xfb\xbf\xbf\xbf\xbf"),
-    0x400000     => (isASCII) ? "\xf8\x90\x80\x80\x80" : I8_to_native("\xfc\xa4\xa0\xa0\xa0\xa0"),
-    0x4000000 - 1 => (isASCII) ? "\xfb\xbf\xbf\xbf\xbf" : I8_to_native("\xfd\xbf\xbf\xbf\xbf\xbf"),
-    0x4000000     => (isASCII) ? "\xfc\x84\x80\x80\x80\x80" : I8_to_native("\xfe\xa2\xa0\xa0\xa0\xa0\xa0"),
-    0x4000000 - 1 => (isASCII) ? "\xfb\xbf\xbf\xbf\xbf" : I8_to_native("\xfd\xbf\xbf\xbf\xbf\xbf"),
-    0x4000000     => (isASCII) ? "\xfc\x84\x80\x80\x80\x80" : I8_to_native("\xfe\xa2\xa0\xa0\xa0\xa0\xa0"),
-    0x40000000 - 1 => (isASCII) ? "\xfc\xbf\xbf\xbf\xbf\xbf" : I8_to_native("\xfe\xbf\xbf\xbf\xbf\xbf\xbf"),
-    0x40000000     => (isASCII) ? "\xfd\x80\x80\x80\x80\x80" : I8_to_native("\xff\xa0\xa0\xa0\xa0\xa0\xa0\xa1\xa0\xa0\xa0\xa0\xa0\xa0"),
-    0x80000000 - 1 => (isASCII) ? "\xfd\xbf\xbf\xbf\xbf\xbf" : I8_to_native("\xff\xa0\xa0\xa0\xa0\xa0\xa0\xa1\xbf\xbf\xbf\xbf\xbf\xbf"),
+    0x11FFFE    => (isASCII)
+                   ?               "\xf4\x9f\xbf\xbe"
+                    : I8_to_native("\xf9\xa3\xbf\xbf\xbe"),
+    0x11FFFF    => (isASCII)
+                   ?               "\xf4\x9f\xbf\xbf"
+                    : I8_to_native("\xf9\xa3\xbf\xbf\xbf"),
+    0x20FFFE    => (isASCII)
+                   ?               "\xf8\x88\x8f\xbf\xbe"
+                    : I8_to_native("\xfa\xa1\xbf\xbf\xbe"),
+    0x20FFFF    => (isASCII)
+                   ?               "\xf8\x88\x8f\xbf\xbf"
+                    : I8_to_native("\xfa\xa1\xbf\xbf\xbf"),
+
+    0x200000 - 1 => (isASCII)
+                    ?              "\xf7\xbf\xbf\xbf"
+                    : I8_to_native("\xf9\xbf\xbf\xbf\xbf"),
+    0x200000     => (isASCII)
+                    ?              "\xf8\x88\x80\x80\x80"
+                    : I8_to_native("\xfa\xa0\xa0\xa0\xa0"),
+    0x400000 - 1 => (isASCII)
+                    ?              "\xf8\x8f\xbf\xbf\xbf"
+                    : I8_to_native("\xfb\xbf\xbf\xbf\xbf"),
+    0x400000     => (isASCII)
+                    ?              "\xf8\x90\x80\x80\x80"
+                    : I8_to_native("\xfc\xa4\xa0\xa0\xa0\xa0"),
+    0x4000000 - 1 => (isASCII)
+                     ?              "\xfb\xbf\xbf\xbf\xbf"
+                     : I8_to_native("\xfd\xbf\xbf\xbf\xbf\xbf"),
+    0x4000000     => (isASCII)
+                     ?              "\xfc\x84\x80\x80\x80\x80"
+                     : I8_to_native("\xfe\xa2\xa0\xa0\xa0\xa0\xa0"),
+    0x4000000 - 1 => (isASCII)
+                     ?              "\xfb\xbf\xbf\xbf\xbf"
+                     : I8_to_native("\xfd\xbf\xbf\xbf\xbf\xbf"),
+    0x4000000     => (isASCII)
+                     ?              "\xfc\x84\x80\x80\x80\x80"
+                     : I8_to_native("\xfe\xa2\xa0\xa0\xa0\xa0\xa0"),
+    0x40000000 - 1 => (isASCII)
+                      ?              "\xfc\xbf\xbf\xbf\xbf\xbf"
+                      : I8_to_native("\xfe\xbf\xbf\xbf\xbf\xbf\xbf"),
+    0x40000000     =>
+    (isASCII) ?    "\xfd\x80\x80\x80\x80\x80"
+    : I8_to_native("\xff\xa0\xa0\xa0\xa0\xa0\xa0\xa1\xa0\xa0\xa0\xa0\xa0\xa0"),
+    0x80000000 - 1 =>
+    (isASCII) ?    "\xfd\xbf\xbf\xbf\xbf\xbf"
+    : I8_to_native("\xff\xa0\xa0\xa0\xa0\xa0\xa0\xa1\xbf\xbf\xbf\xbf\xbf\xbf"),
+    0x80000000     =>
+    (isASCII) ?    "\xfe\x82\x80\x80\x80\x80\x80"
+    : I8_to_native("\xff\xa0\xa0\xa0\xa0\xa0\xa0\xa2\xa0\xa0\xa0\xa0\xa0\xa0"),
+    0xFFFFFFFF     =>
+    (isASCII) ?    "\xfe\x83\xbf\xbf\xbf\xbf\xbf"
+    : I8_to_native("\xff\xa0\xa0\xa0\xa0\xa0\xa0\xa3\xbf\xbf\xbf\xbf\xbf\xbf"),
 );
 
-if (isASCII) {
-    $code_points{0x80000000} = "\xfe\x82\x80\x80\x80\x80\x80";
-    $code_points{0xFFFFFFFF} = "\xfe\x83\xbf\xbf\xbf\xbf\xbf";
-}
-
 if ($is64bit) {
     no warnings qw(overflow portable);
-    $code_points{0x100000000}        = (isASCII) ? "\xfe\x84\x80\x80\x80\x80\x80" : I8_to_native("\xff\xa0\xa0\xa0\xa0\xa0\xa0\xa4\xa0\xa0\xa0\xa0\xa0\xa0");
-    $code_points{0x1000000000 - 1}   = (isASCII) ? "\xfe\xbf\xbf\xbf\xbf\xbf\xbf" : I8_to_native("\xff\xa0\xa0\xa0\xa0\xa0\xa1\xbf\xbf\xbf\xbf\xbf\xbf\xbf");
-    $code_points{0x1000000000}       = (isASCII) ? "\xff\x80\x80\x80\x80\x80\x81\x80\x80\x80\x80\x80\x80" : I8_to_native("\xff\xa0\xa0\xa0\xa0\xa0\xa2\xa0\xa0\xa0\xa0\xa0\xa0\xa0");
-    $code_points{0xFFFFFFFFFFFFFFFF} = (isASCII) ? "\xff\x80\x8f\xbf\xbf\xbf\xbf\xbf\xbf\xbf\xbf\xbf\xbf" : I8_to_native("\xff\xaf\xbf\xbf\xbf\xbf\xbf\xbf\xbf\xbf\xbf\xbf\xbf\xbf");
+    $code_points{0x100000000}
+     = (isASCII)
+     ?              "\xfe\x84\x80\x80\x80\x80\x80"
+     : I8_to_native("\xff\xa0\xa0\xa0\xa0\xa0\xa0\xa4\xa0\xa0\xa0\xa0\xa0\xa0");
+    $code_points{0x1000000000 - 1}
+     = (isASCII)
+     ?              "\xfe\xbf\xbf\xbf\xbf\xbf\xbf"
+     : I8_to_native("\xff\xa0\xa0\xa0\xa0\xa0\xa1\xbf\xbf\xbf\xbf\xbf\xbf\xbf");
+    $code_points{0x1000000000}
+     = (isASCII)
+     ?              "\xff\x80\x80\x80\x80\x80\x81\x80\x80\x80\x80\x80\x80"
+     : I8_to_native("\xff\xa0\xa0\xa0\xa0\xa0\xa2\xa0\xa0\xa0\xa0\xa0\xa0\xa0");
+    $code_points{0xFFFFFFFFFFFFFFFF}
+     = (isASCII)
+     ?              "\xff\x80\x8f\xbf\xbf\xbf\xbf\xbf\xbf\xbf\xbf\xbf\xbf"
+     : I8_to_native("\xff\xaf\xbf\xbf\xbf\xbf\xbf\xbf\xbf\xbf\xbf\xbf\xbf\xbf");
+    if (isASCII) {  # These could falsely show as overlongs in a naive
+                    # implementation
+        $code_points{0x40000000000}
+                      = "\xff\x80\x80\x80\x80\x81\x80\x80\x80\x80\x80\x80\x80";
+        $code_points{0x1000000000000}
+                      = "\xff\x80\x80\x80\x81\x80\x80\x80\x80\x80\x80\x80\x80";
+        $code_points{0x40000000000000}
+                      = "\xff\x80\x80\x81\x80\x80\x80\x80\x80\x80\x80\x80\x80";
+        $code_points{0x1000000000000000}
+                      = "\xff\x80\x81\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80";
+        # overflows
+        #$code_points{0xfoo}
+        #           = "\xff\x81\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80";
+    }
+}
+elsif (! isASCII) { # 32-bit EBCDIC.  64-bit is clearer to handle, so doesn't
+                    # need this test case
+    no warnings qw(overflow portable);
+    $code_points{0x40000000} = I8_to_native(
+                    "\xff\xa0\xa0\xa0\xa0\xa0\xa0\xa1\xa0\xa0\xa0\xa0\xa0\xa0");
 }
 
 # Now add in entries for each of code points 0-255, which require special
@@ -242,6 +560,9 @@ my $first_continuation = (isASCII) ? 0x80 : 0xA0;
 my $final_continuation = 0xBF;
 my $start = (isASCII) ? 0xC2 : 0xC5;
 
+my $max_bytes = (isASCII) ? 13 : 14; # Max number of bytes in a UTF-8 sequence
+                                     # representing a single code point
+
 my $continuation = $first_continuation - 1;
 
 while ($cp < 255) {
@@ -262,9 +583,16 @@ my @warnings;
 use warnings 'utf8';
 local $SIG{__WARN__} = sub { push @warnings, @_ };
 
-# This set of tests looks for basic sanity, and lastly tests the bottom level
-# decode routine for the given code point.  If the earlier tests for that code
-# point fail, that one probably will too.  Malformations are tested in later
+my %restriction_types;
+
+$restriction_types{""}{'valid_strings'} = "";
+$restriction_types{"c9strict"}{'valid_strings'} = "";
+$restriction_types{"strict"}{'valid_strings'} = "";
+$restriction_types{"fits_in_31_bits"}{'valid_strings'} = "";
+
+# This set of tests looks for basic sanity, and lastly tests various routines
+# for the given code point.  If the earlier tests for that code point fail,
+# the later ones probably will too.  Malformations are tested in later
 # segments of code.
 for my $u (sort { utf8::unicode_to_native($a) <=> utf8::unicode_to_native($b) }
           keys %code_points)
@@ -284,7 +612,7 @@ for my $u (sort { utf8::unicode_to_native($a) <=> utf8::unicode_to_native($b) }
                 $u < 0x200000       ? 4 :
                 $u < 0x4000000      ? 5 :
                 $u < 0x80000000     ? 6 : (($is64bit)
-                                        ? ($u < 0x1000000000 ? 7 : 13)
+                                        ? ($u < 0x1000000000 ? 7 : $max_bytes)
                                         : 7)
               )
             : ($u < 0xA0        ? 1 :
@@ -292,8 +620,8 @@ for my $u (sort { utf8::unicode_to_native($a) <=> utf8::unicode_to_native($b) }
                $u < 0x4000      ? 3 :
                $u < 0x40000     ? 4 :
                $u < 0x400000    ? 5 :
-               $u < 0x4000000   ? 6 : 7
-            );
+               $u < 0x4000000   ? 6 :
+               $u < 0x40000000  ? 7 : $max_bytes );
     }
 
     # If this test fails, subsequent ones are meaningless.
@@ -317,7 +645,30 @@ for my $u (sort { utf8::unicode_to_native($a) <=> utf8::unicode_to_native($b) }
         "Verify UTF8_SKIP(chr $hex_n) is $uvchr_skip_should_be");
 
     use bytes;
-    for (my $j = 0; $j < length $n_chr; $j++) {
+    my $byte_length = length $n_chr;
+    for (my $j = 0; $j < $byte_length; $j++) {
+        undef @warnings;
+
+        if ($j == $byte_length - 1) {
+            my $ret
+              = test_is_utf8_valid_partial_char_flags($n_chr, $byte_length, 0);
+            is($ret, 0, "   Verify is_utf8_valid_partial_char_flags("
+                      . display_bytes($n_chr)
+                      . ") returns 0 for full character");
+        }
+        else {
+            my $bytes_so_far = substr($n_chr, 0, $j + 1);
+            my $ret
+             = test_is_utf8_valid_partial_char_flags($bytes_so_far, $j + 1, 0);
+            is($ret, 1, "   Verify is_utf8_valid_partial_char_flags("
+                      . display_bytes($bytes_so_far)
+                      . ") returns 1");
+        }
+
+        is(scalar @warnings, 0, "   Verify is_utf8_valid_partial_char_flags"
+                              . " generated no warnings")
+          or output_warnings(@warnings);
+
         my $b = substr($n_chr, $j, 1);
         my $hex_b = sprintf("\"\\x%02x\"", ord $b);
 
@@ -377,29 +728,168 @@ for my $u (sort { utf8::unicode_to_native($a) <=> utf8::unicode_to_native($b) }
     # later section of the code tests for these kinds of things.
     my $this_utf8_flags = $look_for_everything_utf8n_to;
     my $len = length $bytes;
-    if ($n > 2 ** 31 - 1) {
-        $this_utf8_flags &= ~($UTF8_DISALLOW_FE_FF|$UTF8_WARN_FE_FF);
-    }
+
+    my $valid_under_strict = 1;
+    my $valid_under_c9strict = 1;
+    my $valid_for_fits_in_31_bits = 1;
     if ($n > 0x10FFFF) {
         $this_utf8_flags &= ~($UTF8_DISALLOW_SUPER|$UTF8_WARN_SUPER);
+        $valid_under_strict = 0;
+        $valid_under_c9strict = 0;
+        if ($n > 2 ** 31 - 1) {
+            $this_utf8_flags &=
+                        ~($UTF8_DISALLOW_ABOVE_31_BIT|$UTF8_WARN_ABOVE_31_BIT);
+            $valid_for_fits_in_31_bits = 0;
+        }
     }
-    elsif (($n & 0xFFFE) == 0xFFFE) {
+    elsif (($n >= 0xFDD0 && $n <= 0xFDEF) || ($n & 0xFFFE) == 0xFFFE) {
         $this_utf8_flags &= ~($UTF8_DISALLOW_NONCHAR|$UTF8_WARN_NONCHAR);
+        $valid_under_strict = 0;
+    }
+    elsif ($n >= 0xD800 && $n <= 0xDFFF) {
+        $this_utf8_flags &= ~($UTF8_DISALLOW_SURROGATE|$UTF8_WARN_SURROGATE);
+        $valid_under_c9strict = 0;
+        $valid_under_strict = 0;
     }
 
     undef @warnings;
 
     my $display_flags = sprintf "0x%x", $this_utf8_flags;
-    my $ret_ref = test_utf8n_to_uvchr($bytes, $len, $this_utf8_flags);
     my $display_bytes = display_bytes($bytes);
-    is($ret_ref->[0], $n, "Verify utf8n_to_uvchr($display_bytes, $display_flags) returns $hex_n");
-    is($ret_ref->[1], $len, "Verify utf8n_to_uvchr() for $hex_n returns expected length");
+    my $ret_ref = test_utf8n_to_uvchr_error($bytes, $len, $this_utf8_flags);
+
+    # Rest of tests likely meaningless if it gets the wrong code point.
+    next unless is($ret_ref->[0], $n,
+                   "Verify utf8n_to_uvchr_error($display_bytes, $display_flags)"
+                 . "returns $hex_n");
+    is($ret_ref->[1], $len,
+       "Verify utf8n_to_uvchr_error() for $hex_n returns expected length:"
+     . " $len");
 
     unless (is(scalar @warnings, 0,
-               "Verify utf8n_to_uvchr() for $hex_n generated no warnings"))
+             "Verify utf8n_to_uvchr_error() for $hex_n generated no warnings"))
     {
-        diag "The warnings were: " . join(", ", @warnings);
+        output_warnings(@warnings);
     }
+    is($ret_ref->[2], 0,
+       "Verify utf8n_to_uvchr_error() returned no error bits");
+
+    undef @warnings;
+
+    my $ret = test_isUTF8_CHAR($bytes, $len);
+    is($ret, $len,
+            "Verify isUTF8_CHAR($display_bytes) returns expected length: $len");
+
+    unless (is(scalar @warnings, 0,
+               "Verify isUTF8_CHAR() for $hex_n generated no warnings"))
+    {
+        output_warnings(@warnings);
+    }
+
+    undef @warnings;
+
+    $ret = test_isUTF8_CHAR($bytes, $len - 1);
+    is($ret, 0,
+            "Verify isUTF8_CHAR() with too short length parameter returns 0");
+
+    is(scalar @warnings, 0, "Verify isUTF8_CHAR() generated no warnings")
+      or output_warnings(@warnings);
+
+    undef @warnings;
+
+    $ret = test_isUTF8_CHAR_flags($bytes, $len, 0);
+    is($ret, $len, "Verify isUTF8_CHAR_flags($display_bytes, 0)"
+                 . " returns expected length: $len");
+
+    is(scalar @warnings, 0,
+               "Verify isUTF8_CHAR_flags() for $hex_n generated no warnings")
+      or output_warnings(@warnings);
+
+    undef @warnings;
+
+    $ret = test_isUTF8_CHAR_flags($bytes, $len - 1, 0);
+    is($ret, 0,
+        "Verify isUTF8_CHAR_flags() with too short length parameter returns 0");
+
+    is(scalar @warnings, 0, "Verify isUTF8_CHAR_flags() generated no warnings")
+      or output_warnings(@warnings);
+
+    undef @warnings;
+
+    $ret = test_isSTRICT_UTF8_CHAR($bytes, $len);
+    my $expected_len = ($valid_under_strict) ? $len : 0;
+    is($ret, $expected_len, "Verify isSTRICT_UTF8_CHAR($display_bytes)"
+                          . " returns expected length: $expected_len");
+
+    is(scalar @warnings, 0,
+               "Verify isSTRICT_UTF8_CHAR() for $hex_n generated no warnings")
+      or output_warnings(@warnings);
+
+    undef @warnings;
+
+    $ret = test_isSTRICT_UTF8_CHAR($bytes, $len - 1);
+    is($ret, 0,
+       "Verify isSTRICT_UTF8_CHAR() with too short length parameter returns 0");
+
+    is(scalar @warnings, 0, "Verify isSTRICT_UTF8_CHAR() generated no warnings")
+      or output_warnings(@warnings);
+
+    undef @warnings;
+
+    $ret = test_isUTF8_CHAR_flags($bytes, $len,
+                                            $UTF8_DISALLOW_ILLEGAL_INTERCHANGE);
+    is($ret, $expected_len,
+                    "Verify isUTF8_CHAR_flags('DISALLOW_ILLEGAL_INTERCHANGE')"
+                  . " acts like isSTRICT_UTF8_CHAR");
+
+    is(scalar @warnings, 0,
+               "Verify isUTF8_CHAR() for $hex_n generated no warnings")
+      or output_warnings(@warnings);
+
+    undef @warnings;
+
+    $ret = test_isC9_STRICT_UTF8_CHAR($bytes, $len);
+    $expected_len = ($valid_under_c9strict) ? $len : 0;
+    is($ret, $expected_len, "Verify isC9_STRICT_UTF8_CHAR($display_bytes)"
+                          . " returns expected length: $len");
+
+    is(scalar @warnings, 0,
+            "Verify isC9_STRICT_UTF8_CHAR() for $hex_n generated no warnings")
+      or output_warnings(@warnings);
+
+    undef @warnings;
+
+    $ret = test_isC9_STRICT_UTF8_CHAR($bytes, $len - 1);
+    is($ret, 0,
+    "Verify isC9_STRICT_UTF8_CHAR() with too short length parameter returns 0");
+
+    is(scalar @warnings, 0,
+               "Verify isC9_STRICT_UTF8_CHAR() generated no warnings")
+      or output_warnings(@warnings);
+
+    undef @warnings;
+
+    $ret = test_isUTF8_CHAR_flags($bytes, $len,
+                                        $UTF8_DISALLOW_ILLEGAL_C9_INTERCHANGE);
+    is($ret, $expected_len,
+                   "Verify isUTF8_CHAR_flags('DISALLOW_ILLEGAL_C9_INTERCHANGE')"
+                  ." acts like isC9_STRICT_UTF8_CHAR");
+
+    is(scalar @warnings, 0,
+               "Verify isUTF8_CHAR() for $hex_n generated no warnings")
+      or output_warnings(@warnings);
+
+    undef @warnings;
+
+    $ret_ref = test_valid_utf8_to_uvchr($bytes);
+    is($ret_ref->[0], $n,
+                   "Verify valid_utf8_to_uvchr($display_bytes) returns $hex_n");
+    is($ret_ref->[1], $len,
+       "Verify valid_utf8_to_uvchr() for $hex_n returns expected length: $len");
+
+    is(scalar @warnings, 0,
+               "Verify valid_utf8_to_uvchr() for $hex_n generated no warnings")
+      or output_warnings(@warnings);
 
     # Similarly for uvchr_to_utf8
     my $this_uvchr_flags = $look_for_everything_uvchr_to;
@@ -410,629 +900,1565 @@ for my $u (sort { utf8::unicode_to_native($a) <=> utf8::unicode_to_native($b) }
     if ($n > 0x10FFFF) {
         $this_uvchr_flags &= ~($UNICODE_DISALLOW_SUPER|$UNICODE_WARN_SUPER);
     }
-    elsif (($n & 0xFFFE) == 0xFFFE) {
+    elsif (($n >= 0xFDD0 && $n <= 0xFDEF) || ($n & 0xFFFE) == 0xFFFE) {
         $this_uvchr_flags &= ~($UNICODE_DISALLOW_NONCHAR|$UNICODE_WARN_NONCHAR);
     }
+    elsif ($n >= 0xD800 && $n <= 0xDFFF) {
+        $this_uvchr_flags
+                     &= ~($UNICODE_DISALLOW_SURROGATE|$UNICODE_WARN_SURROGATE);
+    }
     $display_flags = sprintf "0x%x", $this_uvchr_flags;
 
     undef @warnings;
 
-    my $ret = test_uvchr_to_utf8_flags($n, $this_uvchr_flags);
-    ok(defined $ret, "Verify uvchr_to_utf8_flags($hex_n, $display_flags) returned success");
-    is($ret, $bytes, "Verify uvchr_to_utf8_flags($hex_n, $display_flags) returns correct bytes");
+    $ret = test_uvchr_to_utf8_flags($n, $this_uvchr_flags);
+    ok(defined $ret,
+        "Verify uvchr_to_utf8_flags($hex_n, $display_flags) returned success");
+    is($ret, $bytes,
+    "Verify uvchr_to_utf8_flags($hex_n, $display_flags) returns correct bytes");
+
+    is(scalar @warnings, 0,
+                "Verify uvchr_to_utf8_flags($hex_n, $display_flags) for $hex_n"
+              . " generated no warnings")
+      or output_warnings(@warnings);
+
+    # Now append this code point to a string that we will test various
+    # versions of is_foo_utf8_string_bar on, and keep a count of how many code
+    # points are in it.  All the code points in this loop are valid in Perl's
+    # extended UTF-8, but some are not valid under various restrictions.  A
+    # string and count is kept separately that is entirely valid for each
+    # restriction.  And, for each restriction, we note the first occurrence in
+    # the unrestricted string where we find something not in the restricted
+    # string.
+    $restriction_types{""}{'valid_strings'} .= $bytes;
+    $restriction_types{""}{'valid_counts'}++;
+
+    if ($valid_under_c9strict) {
+        $restriction_types{"c9strict"}{'valid_strings'} .= $bytes;
+        $restriction_types{"c9strict"}{'valid_counts'}++;
+    }
+    elsif (! exists $restriction_types{"c9strict"}{'first_invalid_offset'}) {
+        $restriction_types{"c9strict"}{'first_invalid_offset'}
+                    = length $restriction_types{"c9strict"}{'valid_strings'};
+        $restriction_types{"c9strict"}{'first_invalid_count'}
+                            = $restriction_types{"c9strict"}{'valid_counts'};
+    }
 
-    unless (is(scalar @warnings, 0,
-        "Verify uvchr_to_utf8_flags($hex_n, $display_flags) for $hex_n generated no warnings"))
+    if ($valid_under_strict) {
+        $restriction_types{"strict"}{'valid_strings'} .= $bytes;
+        $restriction_types{"strict"}{'valid_counts'}++;
+    }
+    elsif (! exists $restriction_types{"strict"}{'first_invalid_offset'}) {
+        $restriction_types{"strict"}{'first_invalid_offset'}
+                        = length $restriction_types{"strict"}{'valid_strings'};
+        $restriction_types{"strict"}{'first_invalid_count'}
+                                = $restriction_types{"strict"}{'valid_counts'};
+    }
+
+    if ($valid_for_fits_in_31_bits) {
+        $restriction_types{"fits_in_31_bits"}{'valid_strings'} .= $bytes;
+        $restriction_types{"fits_in_31_bits"}{'valid_counts'}++;
+    }
+    elsif (! exists
+                $restriction_types{"fits_in_31_bits"}{'first_invalid_offset'})
     {
-        diag "The warnings were: " . join(", ", @warnings);
+        $restriction_types{"fits_in_31_bits"}{'first_invalid_offset'}
+                = length $restriction_types{"fits_in_31_bits"}{'valid_strings'};
+        $restriction_types{"fits_in_31_bits"}{'first_invalid_count'}
+                        = $restriction_types{"fits_in_31_bits"}{'valid_counts'};
+    }
+}
+
+my $I8c = (isASCII) ? "\x80" : "\xa0";    # A continuation byte
+my $cont_byte = I8_to_native($I8c);
+my $p = (isASCII) ? "\xe1\x80" : I8_to_native("\xE4\xA0");  # partial
+
+# The loop above tested the single or partial character functions/macros,
+# while building up strings to test the string functions, which we do now.
+
+for my $restriction (sort keys %restriction_types) {
+    use bytes;
+
+    for my $use_flags ("", "_flags") {
+
+        # For each restriction, we test it in both the is_foo_flags functions
+        # and the specially named foo function.  But not if there isn't such a
+        # specially named function.  Currently, this is the only tested
+        # restriction that doesn't have a specially named function
+        next if $use_flags eq "" && $restriction eq "fits_in_31_bits";
+
+        # Start building up the name of the function we will test.
+        my $base_name = "is_";
+
+        if (! $use_flags  && $restriction ne "") {
+            $base_name .= $restriction . "_";
+        }
+
+        # We test both "is_utf8_string_foo" and "is_fixed_width_buf" functions
+        foreach my $operand ('string', 'fixed_width_buf') {
+
+            # Currently, the only fixed_width_buf functions have the '_flags'
+            # suffix.
+            next if $operand eq 'fixed_width_buf' && $use_flags eq "";
+
+            my $name = "${base_name}utf8_$operand";
+
+            # We test each version of the function
+            for my $function ("_loclen", "_loc", "") {
+
+                # We test each function against
+                #   a) valid input
+                #   b) invalid input created by appending an out-of-place
+                #      continuation character to the valid string
+                #   c) input created by appending a partial character.  This
+                #      is valid in the 'fixed_width' functions, but invalid in
+                #   the 'string' ones
+                #   d) invalid input created by calling a function that is
+                #      expecting a restricted form of the input using the string
+                #      that's valid when unrestricted
+                for my $error_type (0, $cont_byte, $p, $restriction) {
+                    #diag "restriction=$restriction, use_flags=$use_flags, function=$function, error_type=" . display_bytes($error_type);
+
+                    # If there is no restriction, the error type will be "",
+                    # which is redundant with 0.
+                    next if $error_type eq "";
+
+                    my $this_name = "$name$function$use_flags";
+                    my $bytes
+                            = $restriction_types{$restriction}{'valid_strings'};
+                    my $expected_offset = length $bytes;
+                    my $expected_count
+                            = $restriction_types{$restriction}{'valid_counts'};
+                    my $test_name_suffix = "";
+
+                    my $this_error_type = $error_type;
+                    if ($this_error_type) {
+
+                        # Appending a bare continuation byte or a partial
+                        # character doesn't change the character count or
+                        # offset.  But in the other cases, we have saved where
+                        # the failures should occur, so use those.  Appending
+                        # a continuation byte makes it invalid; appending a
+                        # partial character makes the 'string' form invalid,
+                        # but not the 'fixed_width_buf' form.
+                        if (   $this_error_type eq $cont_byte
+                            || $this_error_type eq $p)
+                        {
+                            $bytes .= $this_error_type;
+                            if ($this_error_type eq $cont_byte) {
+                                $test_name_suffix
+                                            = " for an unexpected continuation";
+                            }
+                            else {
+                                $test_name_suffix
+                                        = " if ends with a partial character";
+                                $this_error_type
+                                        = 0 if $operand eq "fixed_width_buf";
+                            }
+                        }
+                        else {
+                            $test_name_suffix
+                                        = " if contains forbidden code points";
+                            if ($this_error_type eq "c9strict") {
+                                $bytes = $restriction_types{""}{'valid_strings'};
+                                $expected_offset
+                                 = $restriction_types{"c9strict"}
+                                                     {'first_invalid_offset'};
+                                $expected_count
+                                  = $restriction_types{"c9strict"}
+                                                      {'first_invalid_count'};
+                            }
+                            elsif ($this_error_type eq "strict") {
+                                $bytes = $restriction_types{""}{'valid_strings'};
+                                $expected_offset
+                                  = $restriction_types{"strict"}
+                                                      {'first_invalid_offset'};
+                                $expected_count
+                                  = $restriction_types{"strict"}
+                                                      {'first_invalid_count'};
+
+                            }
+                            elsif ($this_error_type eq "fits_in_31_bits") {
+                                $bytes = $restriction_types{""}{'valid_strings'};
+                                $expected_offset
+                                  = $restriction_types{"fits_in_31_bits"}
+                                                      {'first_invalid_offset'};
+                                $expected_count
+                                    = $restriction_types{"fits_in_31_bits"}
+                                                        {'first_invalid_count'};
+                            }
+                            else {
+                                fail("Internal test error: Unknown error type "
+                                . "'$this_error_type'");
+                                next;
+                            }
+                        }
+                    }
+
+                    my $length = length $bytes;
+                    my $ret_ref;
+
+                    my $test = "\$ret_ref = test_$this_name(\$bytes, $length";
+
+                    # If using the _flags functions, we have to figure out what
+                    # flags to pass.  This is done to match the restriction.
+                    if ($use_flags eq "_flags") {
+                        if (! $restriction) {
+                            $test .= ", 0";     # The flag
+
+                            # Indicate the kind of flag in the test name.
+                            $this_name .= "(0)";
+                        }
+                        else {
+                            $this_name .= "($restriction)";
+                            if ($restriction eq "c9strict") {
+                                $test
+                                  .= ", $UTF8_DISALLOW_ILLEGAL_C9_INTERCHANGE";
+                            }
+                            elsif ($restriction eq "strict") {
+                                $test .= ", $UTF8_DISALLOW_ILLEGAL_INTERCHANGE";
+                            }
+                            elsif ($restriction eq "fits_in_31_bits") {
+                                $test .= ", $UTF8_DISALLOW_ABOVE_31_BIT";
+                            }
+                            else {
+                                fail("Internal test error: Unknown restriction "
+                                . "'$restriction'");
+                                next;
+                            }
+                        }
+                    }
+                    $test .= ")";
+
+                    # Actually run the test
+                    eval $test;
+                    if ($@) {
+                        fail($test);
+                        diag $@;
+                        next;
+                    }
+
+                    my $ret;
+                    my $error_offset;
+                    my $cp_count;
+
+                    if ($function eq "") {
+                        $ret = $ret_ref;    # For plain function, there's only a
+                                            # single return value
+                    }
+                    else {  # Otherwise, the multiple values come in an array.
+                        $ret = shift @$ret_ref ;
+                        $error_offset = shift @$ret_ref;
+                        $cp_count = shift@$ret_ref if $function eq "_loclen";
+                    }
+
+                    if ($this_error_type) {
+                        is($ret, 0,
+                           "Verify $this_name is FALSE$test_name_suffix");
+                    }
+                    else {
+                        unless(is($ret, 1,
+                                  "Verify $this_name is TRUE for valid input"
+                                . "$test_name_suffix"))
+                        {
+                            diag("    The bytes starting at offset"
+                               . " $error_offset are"
+                               . display_bytes(substr(
+                                          $restriction_types{$restriction}
+                                                            {'valid_strings'},
+                                          $error_offset)));
+                            next;
+                        }
+                    }
+
+                    if ($function ne "") {
+                        unless (is($error_offset, $expected_offset,
+                                   "\tAnd returns the correct offset"))
+                        {
+                            my $min = ($error_offset < $expected_offset)
+                                    ? $error_offset
+                                    : $expected_offset;
+                            diag("    The bytes starting at offset" . $min
+                              . " are " . display_bytes(substr($bytes, $min)));
+                        }
+
+                        if ($function eq '_loclen') {
+                            is($cp_count, $expected_count,
+                               "\tAnd returns the correct character count");
+                        }
+                    }
+                }
+            }
+        }
     }
 }
 
 my $REPLACEMENT = 0xFFFD;
 
 # Now test the malformations.  All these raise category utf8 warnings.
-my $c = (isASCII) ? "\x80" : "\xa0";    # A continuation byte
 my @malformations = (
+    # ($testname, $bytes, $length, $allow_flags, $expected_error_flags,
+    #  $allowed_uv, $expected_len, $needed_to_discern_len, $message )
     [ "zero length string malformation", "", 0,
-        $UTF8_ALLOW_EMPTY, 0, 0,
+        $UTF8_ALLOW_EMPTY, $UTF8_GOT_EMPTY, 0, 0, 0,
         qr/empty string/
     ],
-    [ "orphan continuation byte malformation", I8_to_native("${c}a"),
-        2,
-        $UTF8_ALLOW_CONTINUATION, $REPLACEMENT, 1,
+    [ "orphan continuation byte malformation", I8_to_native("${I8c}a"), 2,
+        $UTF8_ALLOW_CONTINUATION, $UTF8_GOT_CONTINUATION, $REPLACEMENT,
+        1, 1,
         qr/unexpected continuation byte/
     ],
     [ "premature next character malformation (immediate)",
-        (isASCII) ? "\xc2a" : I8_to_native("\xc5") ."a",
-        2,
-        $UTF8_ALLOW_NON_CONTINUATION, $REPLACEMENT, 1,
+        (isASCII) ? "\xc2\xc2\x80" : I8_to_native("\xc5\xc5\xa0"),
+        3,
+        $UTF8_ALLOW_NON_CONTINUATION, $UTF8_GOT_NON_CONTINUATION, $REPLACEMENT,
+        1, 2,
         qr/unexpected non-continuation byte.*immediately after start byte/
     ],
     [ "premature next character malformation (non-immediate)",
-        I8_to_native("\xf0${c}a"),
-        3,
-        $UTF8_ALLOW_NON_CONTINUATION, $REPLACEMENT, 2,
+        I8_to_native("\xef${I8c}a"), 3,
+        $UTF8_ALLOW_NON_CONTINUATION, $UTF8_GOT_NON_CONTINUATION, $REPLACEMENT,
+        2, 3,
         qr/unexpected non-continuation byte .* 2 bytes after start byte/
     ],
-    [ "too short malformation", I8_to_native("\xf0${c}a"), 2,
+    [ "too short malformation", I8_to_native("\xf1${I8c}a"), 2,
         # Having the 'a' after this, but saying there are only 2 bytes also
         # tests that we pay attention to the passed in length
-        $UTF8_ALLOW_SHORT, $REPLACEMENT, 2,
-        qr/2 bytes, need 4/
+        $UTF8_ALLOW_SHORT, $UTF8_GOT_SHORT, $REPLACEMENT,
+        2, 2,
+        qr/2 bytes available, need 4/
     ],
-    [ "overlong malformation", I8_to_native("\xc0$c"), 2,
-        $UTF8_ALLOW_LONG,
+    [ "overlong malformation, lowest 2-byte",
+        (isASCII) ? "\xc0\x80" : I8_to_native("\xc0\xa0"),
+        2,
+        $UTF8_ALLOW_LONG, $UTF8_GOT_LONG,
         0,   # NUL
+        2, 1,
+        qr/overlong/
+    ],
+    [ "overlong malformation, highest 2-byte",
+        (isASCII) ? "\xc1\xbf" : I8_to_native("\xc4\xbf"),
         2,
-        qr/2 bytes, need 1/
-    ]
+        $UTF8_ALLOW_LONG, $UTF8_GOT_LONG,
+        (isASCII) ? 0x7F : utf8::unicode_to_native(0x9F),
+        2, 1,
+        qr/overlong/
+    ],
+    [ "overlong malformation, lowest 3-byte",
+        (isASCII) ? "\xe0\x80\x80" : I8_to_native("\xe0\xa0\xa0"),
+        3,
+        $UTF8_ALLOW_LONG, $UTF8_GOT_LONG,
+        0,   # NUL
+        3, (isASCII) ? 2 : 1,
+        qr/overlong/
+    ],
+    [ "overlong malformation, highest 3-byte",
+        (isASCII) ? "\xe0\x9f\xbf" : I8_to_native("\xe0\xbf\xbf"),
+        3,
+        $UTF8_ALLOW_LONG, $UTF8_GOT_LONG,
+        (isASCII) ? 0x7FF : 0x3FF,
+        3, (isASCII) ? 2 : 1,
+        qr/overlong/
+    ],
+    [ "overlong malformation, lowest 4-byte",
+        (isASCII) ? "\xf0\x80\x80\x80" : I8_to_native("\xf0\xa0\xa0\xa0"),
+        4,
+        $UTF8_ALLOW_LONG, $UTF8_GOT_LONG,
+        0,   # NUL
+        4, 2,
+        qr/overlong/
+    ],
+    [ "overlong malformation, highest 4-byte",
+        (isASCII) ? "\xf0\x8F\xbf\xbf" : I8_to_native("\xf0\xaf\xbf\xbf"),
+        4,
+        $UTF8_ALLOW_LONG, $UTF8_GOT_LONG,
+        (isASCII) ? 0xFFFF : 0x3FFF,
+        4, 2,
+        qr/overlong/
+    ],
+    [ "overlong malformation, lowest 5-byte",
+        (isASCII)
+         ?              "\xf8\x80\x80\x80\x80"
+         : I8_to_native("\xf8\xa0\xa0\xa0\xa0"),
+        5,
+        $UTF8_ALLOW_LONG, $UTF8_GOT_LONG,
+        0,   # NUL
+        5, 2,
+        qr/overlong/
+    ],
+    [ "overlong malformation, highest 5-byte",
+        (isASCII)
+         ?              "\xf8\x87\xbf\xbf\xbf"
+         : I8_to_native("\xf8\xa7\xbf\xbf\xbf"),
+        5,
+        $UTF8_ALLOW_LONG, $UTF8_GOT_LONG,
+        (isASCII) ? 0x1FFFFF : 0x3FFFF,
+        5, 2,
+        qr/overlong/
+    ],
+    [ "overlong malformation, lowest 6-byte",
+        (isASCII)
+         ?              "\xfc\x80\x80\x80\x80\x80"
+         : I8_to_native("\xfc\xa0\xa0\xa0\xa0\xa0"),
+        6,
+        $UTF8_ALLOW_LONG, $UTF8_GOT_LONG,
+        0,   # NUL
+        6, 2,
+        qr/overlong/
+    ],
+    [ "overlong malformation, highest 6-byte",
+        (isASCII)
+         ?              "\xfc\x83\xbf\xbf\xbf\xbf"
+         : I8_to_native("\xfc\xa3\xbf\xbf\xbf\xbf"),
+        6,
+        $UTF8_ALLOW_LONG, $UTF8_GOT_LONG,
+        (isASCII) ? 0x3FFFFFF : 0x3FFFFF,
+        6, 2,
+        qr/overlong/
+    ],
+    [ "overlong malformation, lowest 7-byte",
+        (isASCII)
+         ?              "\xfe\x80\x80\x80\x80\x80\x80"
+         : I8_to_native("\xfe\xa0\xa0\xa0\xa0\xa0\xa0"),
+        7,
+        $UTF8_ALLOW_LONG, $UTF8_GOT_LONG,
+        0,   # NUL
+        7, 2,
+        qr/overlong/
+    ],
+    [ "overlong malformation, highest 7-byte",
+        (isASCII)
+         ?              "\xfe\x81\xbf\xbf\xbf\xbf\xbf"
+         : I8_to_native("\xfe\xa1\xbf\xbf\xbf\xbf\xbf"),
+        7,
+        $UTF8_ALLOW_LONG, $UTF8_GOT_LONG,
+        (isASCII) ? 0x7FFFFFFF : 0x3FFFFFF,
+        7, 2,
+        qr/overlong/
+    ],
 );
 
-if (isASCII) {
+if (isASCII && ! $is64bit) {    # 32-bit ASCII platform
+    no warnings 'portable';
+    push @malformations,
+        [ "overflow malformation",
+            "\xfe\x84\x80\x80\x80\x80\x80",  # Represents 2**32
+            7,
+            0,  # There is no way to allow this malformation
+            $UTF8_GOT_OVERFLOW,
+            $REPLACEMENT,
+            7, 2,
+            qr/overflows/
+        ],
+        [ "overflow malformation",
+            "\xff\x80\x80\x80\x80\x80\x81\x80\x80\x80\x80\x80\x80",
+            $max_bytes,
+            0,  # There is no way to allow this malformation
+            $UTF8_GOT_OVERFLOW,
+            $REPLACEMENT,
+            $max_bytes, 1,
+            qr/overflows/
+        ];
+}
+else { # 64-bit ASCII, or EBCDIC of any size.
+    # On EBCDIC platforms, another overlong test is needed even on 32-bit
+    # systems, whereas it doesn't happen on ASCII except on 64-bit ones.
+
+    no warnings 'portable';
+    no warnings 'overflow'; # Doesn't run on 32-bit systems, but compiles
     push @malformations,
-    [ "overflow malformation",
-                    # These are the smallest overflowing on 64 byte machines:
-                    # 2**64
-        "\xff\x80\x90\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0",
-        13,
-        0,  # There is no way to allow this malformation
-        $REPLACEMENT,
-        13,
-        qr/overflow/
-    ];
+        [ "overlong malformation, lowest max-byte",
+            (isASCII)
+             ?      "\xff\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80"
+             : I8_to_native(
+                    "\xff\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0"),
+            $max_bytes,
+            $UTF8_ALLOW_LONG, $UTF8_GOT_LONG,
+            0,   # NUL
+            $max_bytes, (isASCII) ? 7 : 8,
+            qr/overlong/,
+        ],
+        [ "overlong malformation, highest max-byte",
+            (isASCII)    # 2**36-1 on ASCII; 2**30-1 on EBCDIC
+             ?      "\xff\x80\x80\x80\x80\x80\x80\xbf\xbf\xbf\xbf\xbf\xbf"
+             : I8_to_native(
+                    "\xff\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xbf\xbf\xbf\xbf\xbf\xbf"),
+            $max_bytes,
+            $UTF8_ALLOW_LONG, $UTF8_GOT_LONG,
+            (isASCII) ? 0xFFFFFFFFF : 0x3FFFFFFF,
+            $max_bytes, (isASCII) ? 7 : 8,
+            qr/overlong/,
+        ];
+
+    if (! $is64bit) {   # 32-bit EBCDIC
+        push @malformations,
+        [ "overflow malformation",
+            I8_to_native(
+                    "\xff\xa0\xa0\xa0\xa0\xa0\xa0\xa4\xa0\xa0\xa0\xa0\xa0\xa0"),
+            $max_bytes,
+            0,  # There is no way to allow this malformation
+            $UTF8_GOT_OVERFLOW,
+            $REPLACEMENT,
+            $max_bytes, 8,
+            qr/overflows/
+        ];
+    }
+    else {  # 64-bit, either ASCII or EBCDIC
+        push @malformations,
+            [ "overflow malformation",
+               (isASCII)
+                ?   "\xff\x80\x90\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0"
+                : I8_to_native(
+                    "\xff\xb0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0"),
+                $max_bytes,
+                0,  # There is no way to allow this malformation
+                $UTF8_GOT_OVERFLOW,
+                $REPLACEMENT,
+                $max_bytes, (isASCII) ? 3 : 2,
+                qr/overflows/
+            ];
+    }
 }
 
 foreach my $test (@malformations) {
-    my ($testname, $bytes, $length, $allow_flags, $allowed_uv, $expected_len, $message ) = @$test;
+    my ($testname, $bytes, $length, $allow_flags, $expected_error_flags,
+        $allowed_uv, $expected_len, $needed_to_discern_len, $message ) = @$test;
+
+    if (length($bytes) < $length) {
+        fail("Internal test error: actual buffer length (" . length($bytes)
+           . ") must be at least as high as how far we are allowed to read"
+           . " into it ($length)");
+        diag($testname);
+        next;
+    }
+
+    undef @warnings;
+
+    my $ret = test_isUTF8_CHAR($bytes, $length);
+    is($ret, 0, "$testname: isUTF8_CHAR returns 0");
+    is(scalar @warnings, 0, "$testname: isUTF8_CHAR() generated no warnings")
+      or output_warnings(@warnings);
+
+    undef @warnings;
+
+    $ret = test_isUTF8_CHAR_flags($bytes, $length, 0);
+    is($ret, 0, "$testname: isUTF8_CHAR_flags returns 0");
+    is(scalar @warnings, 0, "$testname: isUTF8_CHAR_flags() generated no"
+                          . " warnings")
+      or output_warnings(@warnings);
+
+    $ret = test_isSTRICT_UTF8_CHAR($bytes, $length);
+    is($ret, 0, "$testname: isSTRICT_UTF8_CHAR returns 0");
+    is(scalar @warnings, 0,
+                    "$testname: isSTRICT_UTF8_CHAR() generated no warnings")
+      or output_warnings(@warnings);
+
+    $ret = test_isC9_STRICT_UTF8_CHAR($bytes, $length);
+    is($ret, 0, "$testname: isC9_STRICT_UTF8_CHAR returns 0");
+    is(scalar @warnings, 0,
+               "$testname: isC9_STRICT_UTF8_CHAR() generated no warnings")
+      or output_warnings(@warnings);
+
+    for my $j (1 .. $length - 1) {
+        my $partial = substr($bytes, 0, $j);
+
+        undef @warnings;
+
+        $ret = test_is_utf8_valid_partial_char_flags($bytes, $j, 0);
+
+        my $ret_should_be = 0;
+        my $comment = "";
+        if ($j < $needed_to_discern_len) {
+            $ret_should_be = 1;
+            $comment = ", but need $needed_to_discern_len bytes to discern:";
+        }
+
+        is($ret, $ret_should_be, "$testname: is_utf8_valid_partial_char_flags("
+                                . display_bytes($partial)
+                                . ")$comment returns $ret_should_be");
+        is(scalar @warnings, 0,
+                "$testname: is_utf8_valid_partial_char_flags() generated"
+              . " no warnings")
+          or output_warnings(@warnings);
+    }
 
-    next if ! ok(length($bytes) >= $length, "$testname: Make sure won't read beyond buffer: " . length($bytes) . " >= $length");
 
     # Test what happens when this malformation is not allowed
     undef @warnings;
-    my $ret_ref = test_utf8n_to_uvchr($bytes, $length, 0);
+    my $ret_ref = test_utf8n_to_uvchr_error($bytes, $length, 0);
     is($ret_ref->[0], 0, "$testname: disallowed: Returns 0");
-    is($ret_ref->[1], $expected_len, "$testname: disallowed: Returns expected length");
-    if (is(scalar @warnings, 1, "$testname: disallowed: Got a single warning ")) {
-        like($warnings[0], $message, "$testname: disallowed: Got expected warning");
+    is($ret_ref->[1], $expected_len,
+       "$testname: utf8n_to_uvchr_error(), disallowed: Returns expected"
+     . " length: $expected_len");
+    if (is(scalar @warnings, 1,
+           "$testname: disallowed: Got a single warning "))
+    {
+        like($warnings[0], $message,
+             "$testname: disallowed: Got expected warning");
     }
     else {
         if (scalar @warnings) {
-            diag "The warnings were: " . join(", ", @warnings);
+            output_warnings(@warnings);
         }
     }
+    is($ret_ref->[2], $expected_error_flags,
+       "$testname: utf8n_to_uvchr_error(), disallowed:"
+     . " Returns expected error");
 
     {   # Next test when disallowed, and warnings are off.
         undef @warnings;
         no warnings 'utf8';
-        my $ret_ref = test_utf8n_to_uvchr($bytes, $length, 0);
-        is($ret_ref->[0], 0, "$testname: disallowed: no warnings 'utf8': Returns 0");
-        is($ret_ref->[1], $expected_len, "$testname: disallowed: no warnings 'utf8': Returns expected length");
-        if (!is(scalar @warnings, 0, "$testname: disallowed: no warnings 'utf8': no warnings generated")) {
-            diag "The warnings were: " . join(", ", @warnings);
+        my $ret_ref = test_utf8n_to_uvchr_error($bytes, $length, 0);
+        is($ret_ref->[0], 0,
+           "$testname: utf8n_to_uvchr_error(), disallowed: no warnings 'utf8':"
+         . " Returns 0");
+        is($ret_ref->[1], $expected_len,
+           "$testname: utf8n_to_uvchr_error(), disallowed: no warnings 'utf8':"
+         . " Returns expected length: $expected_len");
+        if (!is(scalar @warnings, 0,
+            "$testname: utf8n_to_uvchr_error(), disallowed: no warnings 'utf8':"
+          . " no warnings generated"))
+        {
+            output_warnings(@warnings);
         }
+        is($ret_ref->[2], $expected_error_flags,
+           "$testname: utf8n_to_uvchr_error(), disallowed: Returns"
+         . " expected error");
     }
 
     # Test with CHECK_ONLY
     undef @warnings;
-    $ret_ref = test_utf8n_to_uvchr($bytes, $length, $UTF8_CHECK_ONLY);
+    $ret_ref = test_utf8n_to_uvchr_error($bytes, $length, $UTF8_CHECK_ONLY);
     is($ret_ref->[0], 0, "$testname: CHECK_ONLY: Returns 0");
-    is($ret_ref->[1], -1, "$testname: CHECK_ONLY: returns expected length");
-    if (! is(scalar @warnings, 0, "$testname: CHECK_ONLY: no warnings generated")) {
-        diag "The warnings were: " . join(", ", @warnings);
+    is($ret_ref->[1], -1, "$testname: CHECK_ONLY: returns -1 for length");
+    if (! is(scalar @warnings, 0,
+                               "$testname: CHECK_ONLY: no warnings generated"))
+    {
+        output_warnings(@warnings);
     }
+    is($ret_ref->[2], $expected_error_flags,
+       "$testname: utf8n_to_uvchr_error(), disallowed: Returns expected"
+     . " error");
 
     next if $allow_flags == 0;    # Skip if can't allow this malformation
 
     # Test when the malformation is allowed
     undef @warnings;
-    $ret_ref = test_utf8n_to_uvchr($bytes, $length, $allow_flags);
-    is($ret_ref->[0], $allowed_uv, "$testname: allowed: Returns expected uv");
-    is($ret_ref->[1], $expected_len, "$testname: allowed: Returns expected length");
-    if (!is(scalar @warnings, 0, "$testname: allowed: no warnings generated"))
+    $ret_ref = test_utf8n_to_uvchr_error($bytes, $length, $allow_flags);
+    is($ret_ref->[0], $allowed_uv,
+       "$testname: utf8n_to_uvchr_error(), allowed: Returns expected uv: "
+     . sprintf("0x%04X", $allowed_uv));
+    is($ret_ref->[1], $expected_len,
+       "$testname: utf8n_to_uvchr_error(), allowed: Returns expected length:"
+     . " $expected_len");
+    if (!is(scalar @warnings, 0,
+            "$testname: utf8n_to_uvchr_error(), allowed: no warnings"
+          . " generated"))
     {
-        diag "The warnings were: " . join(", ", @warnings);
+        output_warnings(@warnings);
     }
+    is($ret_ref->[2], $expected_error_flags,
+       "$testname: utf8n_to_uvchr_error(), disallowed: Returns"
+     . " expected error");
 }
 
-my $FF_ret;
+sub nonportable_regex ($) {
 
-if ($is64bit) {
-    no warnings qw{portable overflow};
-    $FF_ret = 0x1000000000;
-}
-else {  # The above overflows unless a quad platform
-    $FF_ret = 0;
+    # Returns a pattern that matches the non-portable message raised either
+    # for the specific input code point, or the one generated when there
+    # is some malformation that precludes the message containing the specific
+    # code point
+
+    my $code_point = shift;
+
+    my $string = sprintf '(Code point 0x%X is not Unicode, and'
+                       . '|Any UTF-8 sequence that starts with'
+                       . ' "(\\\x[[:xdigit:]]{2})+" is for a'
+                       . ' non-Unicode code point, and is) not portable',
+                    $code_point;
+    return qr/$string/;
 }
 
 # Now test the cases where a legal code point is generated, but may or may not
 # be allowed/warned on.
 my @tests = (
+     # ($testname, $bytes, $warn_flags, $disallow_flags, $expected_error_flags,
+     #  $category, $allowed_uv, $expected_len, $needed_to_discern_len, $message )
     [ "lowest surrogate",
         (isASCII) ? "\xed\xa0\x80" : I8_to_native("\xf1\xb6\xa0\xa0"),
-        $UTF8_WARN_SURROGATE, $UTF8_DISALLOW_SURROGATE,
+        $UTF8_WARN_SURROGATE, $UTF8_DISALLOW_SURROGATE, $UTF8_GOT_SURROGATE,
         'surrogate', 0xD800,
         (isASCII) ? 3 : 4,
+        2,
         qr/surrogate/
     ],
     [ "a middle surrogate",
         (isASCII) ? "\xed\xa4\x8d" : I8_to_native("\xf1\xb6\xa8\xad"),
-        $UTF8_WARN_SURROGATE, $UTF8_DISALLOW_SURROGATE,
+        $UTF8_WARN_SURROGATE, $UTF8_DISALLOW_SURROGATE, $UTF8_GOT_SURROGATE,
         'surrogate', 0xD90D,
         (isASCII) ? 3 : 4,
+        2,
         qr/surrogate/
     ],
     [ "highest surrogate",
         (isASCII) ? "\xed\xbf\xbf" : I8_to_native("\xf1\xb7\xbf\xbf"),
-        $UTF8_WARN_SURROGATE, $UTF8_DISALLOW_SURROGATE,
+        $UTF8_WARN_SURROGATE, $UTF8_DISALLOW_SURROGATE, $UTF8_GOT_SURROGATE,
         'surrogate', 0xDFFF,
         (isASCII) ? 3 : 4,
+        2,
         qr/surrogate/
     ],
     [ "first non_unicode",
         (isASCII) ? "\xf4\x90\x80\x80" : I8_to_native("\xf9\xa2\xa0\xa0\xa0"),
-        $UTF8_WARN_SUPER, $UTF8_DISALLOW_SUPER,
+        $UTF8_WARN_SUPER, $UTF8_DISALLOW_SUPER, $UTF8_GOT_SUPER,
         'non_unicode', 0x110000,
         (isASCII) ? 4 : 5,
-        qr/not Unicode.* may not be portable/
+        2,
+        qr/(not Unicode|for a non-Unicode code point).* may not be portable/
+    ],
+    [ "non_unicode whose first byte tells that",
+        (isASCII) ? "\xf5\x80\x80\x80" : I8_to_native("\xfa\xa0\xa0\xa0\xa0"),
+        $UTF8_WARN_SUPER, $UTF8_DISALLOW_SUPER, $UTF8_GOT_SUPER,
+        'non_unicode',
+        (isASCII) ? 0x140000 : 0x200000,
+        (isASCII) ? 4 : 5,
+        1,
+        qr/(not Unicode|for a non-Unicode code point).* may not be portable/
     ],
     [ "first of 32 consecutive non-character code points",
         (isASCII) ? "\xef\xb7\x90" : I8_to_native("\xf1\xbf\xae\xb0"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0xFDD0,
         (isASCII) ? 3 : 4,
+        (isASCII) ? 3 : 4,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "a mid non-character code point of the 32 consecutive ones",
         (isASCII) ? "\xef\xb7\xa0" : I8_to_native("\xf1\xbf\xaf\xa0"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0xFDE0,
         (isASCII) ? 3 : 4,
+        (isASCII) ? 3 : 4,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "final of 32 consecutive non-character code points",
         (isASCII) ? "\xef\xb7\xaf" : I8_to_native("\xf1\xbf\xaf\xaf"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0xFDEF,
         (isASCII) ? 3 : 4,
+        (isASCII) ? 3 : 4,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+FFFE",
         (isASCII) ? "\xef\xbf\xbe" : I8_to_native("\xf1\xbf\xbf\xbe"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0xFFFE,
         (isASCII) ? 3 : 4,
+        (isASCII) ? 3 : 4,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+FFFF",
         (isASCII) ? "\xef\xbf\xbf" : I8_to_native("\xf1\xbf\xbf\xbf"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0xFFFF,
         (isASCII) ? 3 : 4,
+        (isASCII) ? 3 : 4,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+1FFFE",
         (isASCII) ? "\xf0\x9f\xbf\xbe" : I8_to_native("\xf3\xbf\xbf\xbe"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
-        'nonchar', 0x1FFFE, 4,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
+        'nonchar', 0x1FFFE,
+        4, 4,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+1FFFF",
         (isASCII) ? "\xf0\x9f\xbf\xbf" : I8_to_native("\xf3\xbf\xbf\xbf"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
-        'nonchar', 0x1FFFF, 4,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
+        'nonchar', 0x1FFFF,
+        4, 4,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+2FFFE",
         (isASCII) ? "\xf0\xaf\xbf\xbe" : I8_to_native("\xf5\xbf\xbf\xbe"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
-        'nonchar', 0x2FFFE, 4,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
+        'nonchar', 0x2FFFE,
+        4, 4,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+2FFFF",
         (isASCII) ? "\xf0\xaf\xbf\xbf" : I8_to_native("\xf5\xbf\xbf\xbf"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
-        'nonchar', 0x2FFFF, 4,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
+        'nonchar', 0x2FFFF,
+        4, 4,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+3FFFE",
         (isASCII) ? "\xf0\xbf\xbf\xbe" : I8_to_native("\xf7\xbf\xbf\xbe"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
-        'nonchar', 0x3FFFE, 4,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
+        'nonchar', 0x3FFFE,
+        4, 4,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+3FFFF",
         (isASCII) ? "\xf0\xbf\xbf\xbf" : I8_to_native("\xf7\xbf\xbf\xbf"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
-        'nonchar', 0x3FFFF, 4,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
+        'nonchar', 0x3FFFF,
+        4, 4,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+4FFFE",
         (isASCII) ? "\xf1\x8f\xbf\xbe" : I8_to_native("\xf8\xa9\xbf\xbf\xbe"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0x4FFFE,
         (isASCII) ? 4 : 5,
+        (isASCII) ? 4 : 5,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+4FFFF",
         (isASCII) ? "\xf1\x8f\xbf\xbf" : I8_to_native("\xf8\xa9\xbf\xbf\xbf"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0x4FFFF,
         (isASCII) ? 4 : 5,
+        (isASCII) ? 4 : 5,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+5FFFE",
         (isASCII) ? "\xf1\x9f\xbf\xbe" : I8_to_native("\xf8\xab\xbf\xbf\xbe"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0x5FFFE,
         (isASCII) ? 4 : 5,
+        (isASCII) ? 4 : 5,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+5FFFF",
         (isASCII) ? "\xf1\x9f\xbf\xbf" : I8_to_native("\xf8\xab\xbf\xbf\xbf"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0x5FFFF,
         (isASCII) ? 4 : 5,
+        (isASCII) ? 4 : 5,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+6FFFE",
         (isASCII) ? "\xf1\xaf\xbf\xbe" : I8_to_native("\xf8\xad\xbf\xbf\xbe"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0x6FFFE,
         (isASCII) ? 4 : 5,
+        (isASCII) ? 4 : 5,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+6FFFF",
         (isASCII) ? "\xf1\xaf\xbf\xbf" : I8_to_native("\xf8\xad\xbf\xbf\xbf"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0x6FFFF,
         (isASCII) ? 4 : 5,
+        (isASCII) ? 4 : 5,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+7FFFE",
         (isASCII) ? "\xf1\xbf\xbf\xbe" : I8_to_native("\xf8\xaf\xbf\xbf\xbe"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0x7FFFE,
         (isASCII) ? 4 : 5,
+        (isASCII) ? 4 : 5,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+7FFFF",
         (isASCII) ? "\xf1\xbf\xbf\xbf" : I8_to_native("\xf8\xaf\xbf\xbf\xbf"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0x7FFFF,
         (isASCII) ? 4 : 5,
+        (isASCII) ? 4 : 5,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+8FFFE",
         (isASCII) ? "\xf2\x8f\xbf\xbe" : I8_to_native("\xf8\xb1\xbf\xbf\xbe"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0x8FFFE,
         (isASCII) ? 4 : 5,
+        (isASCII) ? 4 : 5,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+8FFFF",
         (isASCII) ? "\xf2\x8f\xbf\xbf" : I8_to_native("\xf8\xb1\xbf\xbf\xbf"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0x8FFFF,
         (isASCII) ? 4 : 5,
+        (isASCII) ? 4 : 5,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+9FFFE",
         (isASCII) ? "\xf2\x9f\xbf\xbe" : I8_to_native("\xf8\xb3\xbf\xbf\xbe"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0x9FFFE,
         (isASCII) ? 4 : 5,
+        (isASCII) ? 4 : 5,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+9FFFF",
         (isASCII) ? "\xf2\x9f\xbf\xbf" : I8_to_native("\xf8\xb3\xbf\xbf\xbf"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0x9FFFF,
         (isASCII) ? 4 : 5,
+        (isASCII) ? 4 : 5,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+AFFFE",
         (isASCII) ? "\xf2\xaf\xbf\xbe" : I8_to_native("\xf8\xb5\xbf\xbf\xbe"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0xAFFFE,
         (isASCII) ? 4 : 5,
+        (isASCII) ? 4 : 5,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+AFFFF",
         (isASCII) ? "\xf2\xaf\xbf\xbf" : I8_to_native("\xf8\xb5\xbf\xbf\xbf"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0xAFFFF,
         (isASCII) ? 4 : 5,
+        (isASCII) ? 4 : 5,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+BFFFE",
         (isASCII) ? "\xf2\xbf\xbf\xbe" : I8_to_native("\xf8\xb7\xbf\xbf\xbe"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0xBFFFE,
         (isASCII) ? 4 : 5,
+        (isASCII) ? 4 : 5,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+BFFFF",
         (isASCII) ? "\xf2\xbf\xbf\xbf" : I8_to_native("\xf8\xb7\xbf\xbf\xbf"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0xBFFFF,
         (isASCII) ? 4 : 5,
+        (isASCII) ? 4 : 5,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+CFFFE",
         (isASCII) ? "\xf3\x8f\xbf\xbe" : I8_to_native("\xf8\xb9\xbf\xbf\xbe"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0xCFFFE,
         (isASCII) ? 4 : 5,
+        (isASCII) ? 4 : 5,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+CFFFF",
         (isASCII) ? "\xf3\x8f\xbf\xbf" : I8_to_native("\xf8\xb9\xbf\xbf\xbf"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0xCFFFF,
         (isASCII) ? 4 : 5,
+        (isASCII) ? 4 : 5,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+DFFFE",
         (isASCII) ? "\xf3\x9f\xbf\xbe" : I8_to_native("\xf8\xbb\xbf\xbf\xbe"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0xDFFFE,
         (isASCII) ? 4 : 5,
+        (isASCII) ? 4 : 5,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+DFFFF",
         (isASCII) ? "\xf3\x9f\xbf\xbf" : I8_to_native("\xf8\xbb\xbf\xbf\xbf"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0xDFFFF,
         (isASCII) ? 4 : 5,
+        (isASCII) ? 4 : 5,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+EFFFE",
         (isASCII) ? "\xf3\xaf\xbf\xbe" : I8_to_native("\xf8\xbd\xbf\xbf\xbe"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0xEFFFE,
         (isASCII) ? 4 : 5,
+        (isASCII) ? 4 : 5,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+EFFFF",
         (isASCII) ? "\xf3\xaf\xbf\xbf" : I8_to_native("\xf8\xbd\xbf\xbf\xbf"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0xEFFFF,
         (isASCII) ? 4 : 5,
+        (isASCII) ? 4 : 5,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+FFFFE",
         (isASCII) ? "\xf3\xbf\xbf\xbe" : I8_to_native("\xf8\xbf\xbf\xbf\xbe"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0xFFFFE,
         (isASCII) ? 4 : 5,
+        (isASCII) ? 4 : 5,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+FFFFF",
         (isASCII) ? "\xf3\xbf\xbf\xbf" : I8_to_native("\xf8\xbf\xbf\xbf\xbf"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0xFFFFF,
         (isASCII) ? 4 : 5,
+        (isASCII) ? 4 : 5,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+10FFFE",
         (isASCII) ? "\xf4\x8f\xbf\xbe" : I8_to_native("\xf9\xa1\xbf\xbf\xbe"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0x10FFFE,
         (isASCII) ? 4 : 5,
+        (isASCII) ? 4 : 5,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
     [ "non-character code point U+10FFFF",
         (isASCII) ? "\xf4\x8f\xbf\xbf" : I8_to_native("\xf9\xa1\xbf\xbf\xbf"),
-        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0x10FFFF,
         (isASCII) ? 4 : 5,
+        (isASCII) ? 4 : 5,
         qr/Unicode non-character.*is not recommended for open interchange/
     ],
-);
-
-
-if (isASCII) {
-    push @tests,
-    [ "is at least 2*31",
-         "\xfe\x82\x80\x80\x80\x80\x80",
-
+    [ "requires at least 32 bits",
+        (isASCII)
+         ?  "\xfe\x82\x80\x80\x80\x80\x80"
+         : I8_to_native(
+            "\xff\xa0\xa0\xa0\xa0\xa0\xa0\xa2\xa0\xa0\xa0\xa0\xa0\xa0"),
         # This code point is chosen so that it is representable in a UV on
         # 32-bit machines
-        $UTF8_WARN_FE_FF, $UTF8_DISALLOW_FE_FF,
-        'utf8', 0x80000000, 7,
-        qr/Code point 0x80000000 is not Unicode, and not portable/
+        $UTF8_WARN_ABOVE_31_BIT, $UTF8_DISALLOW_ABOVE_31_BIT,
+        $UTF8_GOT_ABOVE_31_BIT,
+        'utf8', 0x80000000,
+        (isASCII) ? 7 : $max_bytes,
+        (isASCII) ? 1 : 8,
+        nonportable_regex(0x80000000)
     ],
-    [ "is at least 2*31, and use SUPER-type flags, instead of FE_FF",
-         "\xfe\x82\x80\x80\x80\x80\x80",
-        $UTF8_WARN_SUPER, $UTF8_DISALLOW_SUPER,
-        'utf8', 0x80000000, 7,
-        qr/Code point 0x80000000 is not Unicode, and not portable/
+    [ "highest 32 bit code point",
+        (isASCII)
+         ?  "\xfe\x83\xbf\xbf\xbf\xbf\xbf"
+         : I8_to_native(
+            "\xff\xa0\xa0\xa0\xa0\xa0\xa0\xa3\xbf\xbf\xbf\xbf\xbf\xbf"),
+        $UTF8_WARN_ABOVE_31_BIT, $UTF8_DISALLOW_ABOVE_31_BIT,
+        $UTF8_GOT_ABOVE_31_BIT,
+        'utf8', 0xFFFFFFFF,
+        (isASCII) ? 7 : $max_bytes,
+        (isASCII) ? 1 : 8,
+        nonportable_regex(0xffffffff)
     ],
-    [ "overflow with FE/FF",
-        # This tests the interaction of WARN_FE_FF/DISALLOW_FE_FF with
-        # overflow.  The overflow malformation is never allowed, so preventing
-        # it takes precedence if the FE_FF options would otherwise allow in an
-        # overflowing value.  These two code points (1 for 32-bits; 1 for 64)
-        # were chosen because the old overflow detection algorithm did not
-        # catch them; this means this test also checks for that fix.
-        ($is64bit)
-            ? "\xff\x80\x90\x90\x90\xbf\xbf\xbf\xbf\xbf\xbf\xbf\xbf"
-            : "\xfe\x86\x80\x80\x80\x80\x80",
-
-        # We include both warning categories to make sure the FE_FF one has
-        # precedence
-        "$UTF8_WARN_FE_FF|$UTF8_WARN_SUPER", "$UTF8_DISALLOW_FE_FF",
+    [ "requires at least 32 bits, and use SUPER-type flags, instead of"
+    . " ABOVE_31_BIT",
+        (isASCII)
+         ? "\xfe\x82\x80\x80\x80\x80\x80"
+         : I8_to_native(
+           "\xff\xa0\xa0\xa0\xa0\xa0\xa0\xa2\xa0\xa0\xa0\xa0\xa0\xa0"),
+        $UTF8_WARN_SUPER, $UTF8_DISALLOW_SUPER, $UTF8_GOT_SUPER,
+        'utf8', 0x80000000,
+        (isASCII) ? 7 : $max_bytes,
+        1,
+        nonportable_regex(0x80000000)
+    ],
+    [ "overflow with warnings/disallow for more than 31 bits",
+        # This tests the interaction of WARN_ABOVE_31_BIT/DISALLOW_ABOVE_31_BIT
+        # with overflow.  The overflow malformation is never allowed, so
+        # preventing it takes precedence if the ABOVE_31_BIT options would
+        # otherwise allow in an overflowing value.  The ASCII code points (1
+        # for 32-bits; 1 for 64) were chosen because the old overflow
+        # detection algorithm did not catch them; this means this test also
+        # checks for that fix.  The EBCDIC are arbitrary overflowing ones
+        # since we have no reports of failures with it.
+       (($is64bit)
+        ? ((isASCII)
+           ?    "\xff\x80\x90\x90\x90\xbf\xbf\xbf\xbf\xbf\xbf\xbf\xbf"
+           : I8_to_native(
+                "\xff\xB0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0"))
+        : ((isASCII)
+           ?    "\xfe\x86\x80\x80\x80\x80\x80"
+           : I8_to_native(
+                "\xff\xa0\xa0\xa0\xa0\xa0\xa0\xa4\xa0\xa0\xa0\xa0\xa0\xa0"))),
+        $UTF8_WARN_ABOVE_31_BIT,
+        $UTF8_DISALLOW_ABOVE_31_BIT,
+        $UTF8_GOT_ABOVE_31_BIT,
         'utf8', 0,
-        ($is64bit) ? 13 : 7,
-        qr/overflow at byte .*, after start byte 0xf/
+        (! isASCII || $is64bit) ? $max_bytes : 7,
+        (isASCII || $is64bit) ? 2 : 8,
+        qr/overflows/
     ],
-    ;
-}
+);
 
-if ($is64bit) {    # All FF's will overflow on 32 bit
+if (! $is64bit) {
+    if (isASCII) {
+        no warnings qw{portable overflow};
+        push @tests,
+            [ "Lowest 33 bit code point: overflow",
+                "\xFE\x84\x80\x80\x80\x80\x80",
+                $UTF8_WARN_ABOVE_31_BIT, $UTF8_DISALLOW_ABOVE_31_BIT,
+                $UTF8_GOT_ABOVE_31_BIT,
+                'utf8', 0x100000000,
+                7, 1,
+                qr/and( is)? not portable/
+            ];
+    }
+}
+else {
+    no warnings qw{portable overflow};
     push @tests,
-        [ "begins with FF", "\xff\x80\x80\x80\x80\x80\x81\x80\x80\x80\x80\x80\x80",
-            $UTF8_WARN_FE_FF, $UTF8_DISALLOW_FE_FF,
-            'utf8', $FF_ret, 13,
-            qr/Code point 0x.* is not Unicode, and not portable/
+        [ "More than 32 bits",
+            (isASCII)
+            ?       "\xff\x80\x80\x80\x80\x80\x81\x80\x80\x80\x80\x80\x80"
+            : I8_to_native(
+                    "\xff\xa0\xa0\xa0\xa0\xa0\xa2\xa0\xa0\xa0\xa0\xa0\xa0\xa0"),
+            $UTF8_WARN_ABOVE_31_BIT, $UTF8_DISALLOW_ABOVE_31_BIT,
+            $UTF8_GOT_ABOVE_31_BIT,
+            'utf8', 0x1000000000,
+            $max_bytes, (isASCII) ? 1 : 7,
+            qr/and( is)? not portable/
         ];
+    if (! isASCII) {
+        push @tests,   # These could falsely show wrongly in a naive
+                       # implementation
+            [ "requires at least 32 bits",
+                I8_to_native(
+                    "\xff\xa0\xa0\xa0\xa0\xa0\xa1\xa0\xa0\xa0\xa0\xa0\xa0\xa0"),
+                $UTF8_WARN_ABOVE_31_BIT,$UTF8_DISALLOW_ABOVE_31_BIT,
+                $UTF8_GOT_ABOVE_31_BIT,
+                'utf8', 0x800000000,
+                $max_bytes, 7,
+                nonportable_regex(0x80000000)
+            ],
+            [ "requires at least 32 bits",
+                I8_to_native(
+                    "\xff\xa0\xa0\xa0\xa0\xa1\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0"),
+                $UTF8_WARN_ABOVE_31_BIT,$UTF8_DISALLOW_ABOVE_31_BIT,
+                $UTF8_GOT_ABOVE_31_BIT,
+                'utf8', 0x10000000000,
+                $max_bytes, 6,
+                nonportable_regex(0x10000000000)
+            ],
+            [ "requires at least 32 bits",
+                I8_to_native(
+                    "\xff\xa0\xa0\xa0\xa1\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0"),
+                $UTF8_WARN_ABOVE_31_BIT,$UTF8_DISALLOW_ABOVE_31_BIT,
+                $UTF8_GOT_ABOVE_31_BIT,
+                'utf8', 0x200000000000,
+                $max_bytes, 5,
+                nonportable_regex(0x20000000000)
+            ],
+            [ "requires at least 32 bits",
+                I8_to_native(
+                    "\xff\xa0\xa0\xa1\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0"),
+                $UTF8_WARN_ABOVE_31_BIT,$UTF8_DISALLOW_ABOVE_31_BIT,
+                $UTF8_GOT_ABOVE_31_BIT,
+                'utf8', 0x4000000000000,
+                $max_bytes, 4,
+                nonportable_regex(0x4000000000000)
+            ],
+            [ "requires at least 32 bits",
+                I8_to_native(
+                    "\xff\xa0\xa1\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0"),
+                $UTF8_WARN_ABOVE_31_BIT,$UTF8_DISALLOW_ABOVE_31_BIT,
+                $UTF8_GOT_ABOVE_31_BIT,
+                'utf8', 0x80000000000000,
+                $max_bytes, 3,
+                nonportable_regex(0x80000000000000)
+            ],
+            [ "requires at least 32 bits",
+                I8_to_native(
+                    "\xff\xa1\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0"),
+                $UTF8_WARN_ABOVE_31_BIT,$UTF8_DISALLOW_ABOVE_31_BIT,
+                $UTF8_GOT_ABOVE_31_BIT,
+                'utf8', 0x1000000000000000,
+                $max_bytes, 2,
+                nonportable_regex(0x1000000000000000)
+            ];
+    }
 }
 
 foreach my $test (@tests) {
-    my ($testname, $bytes, $warn_flags, $disallow_flags, $category, $allowed_uv, $expected_len, $message ) = @$test;
+    my ($testname, $bytes, $warn_flags, $disallow_flags, $expected_error_flags,
+        $category, $allowed_uv, $expected_len, $needed_to_discern_len, $message
+       ) = @$test;
 
     my $length = length $bytes;
-    my $will_overflow = $testname =~ /overflow/;
+    my $will_overflow = $testname =~ /overflow/ ? 'overflow' : "";
+
+    {
+        use warnings;
+        undef @warnings;
+        my $ret = test_isUTF8_CHAR($bytes, $length);
+        my $ret_flags = test_isUTF8_CHAR_flags($bytes, $length, 0);
+        if ($will_overflow) {
+            is($ret, 0, "isUTF8_CHAR() $testname: returns 0");
+            is($ret_flags, 0, "isUTF8_CHAR_flags() $testname: returns 0");
+        }
+        else {
+            is($ret, $length,
+               "isUTF8_CHAR() $testname: returns expected length: $length");
+            is($ret_flags, $length, "isUTF8_CHAR_flags(...,0) $testname:"
+                                  . " returns expected length: $length");
+        }
+        is(scalar @warnings, 0,
+                "isUTF8_CHAR() and isUTF8_CHAR()_flags $testname: generated"
+              . " no warnings")
+          or output_warnings(@warnings);
+
+        undef @warnings;
+        $ret = test_isSTRICT_UTF8_CHAR($bytes, $length);
+        if ($will_overflow) {
+            is($ret, 0, "isSTRICT_UTF8_CHAR() $testname: returns 0");
+        }
+        else {
+            my $expected_ret = (   $testname =~ /surrogate|non-character/
+                                || $allowed_uv > 0x10FFFF)
+                               ? 0
+                               : $length;
+            is($ret, $expected_ret, "isSTRICT_UTF8_CHAR() $testname: returns"
+                                  . " expected length: $expected_ret");
+            $ret = test_isUTF8_CHAR_flags($bytes, $length,
+                                          $UTF8_DISALLOW_ILLEGAL_INTERCHANGE);
+            is($ret, $expected_ret,
+                            "isUTF8_CHAR_flags('DISALLOW_ILLEGAL_INTERCHANGE')"
+                          . " acts like isSTRICT_UTF8_CHAR");
+        }
+        is(scalar @warnings, 0,
+                "isSTRICT_UTF8_CHAR() and isUTF8_CHAR_flags $testname:"
+              . " generated no warnings")
+          or output_warnings(@warnings);
+
+        undef @warnings;
+        $ret = test_isC9_STRICT_UTF8_CHAR($bytes, $length);
+        if ($will_overflow) {
+            is($ret, 0, "isC9_STRICT_UTF8_CHAR() $testname: returns 0");
+        }
+        else {
+            my $expected_ret = (   $testname =~ /surrogate/
+                                || $allowed_uv > 0x10FFFF)
+                               ? 0
+                               : $length;
+            is($ret, $expected_ret, "isC9_STRICT_UTF8_CHAR() $testname:"
+                                   ." returns expected length: $expected_ret");
+            $ret = test_isUTF8_CHAR_flags($bytes, $length,
+                                          $UTF8_DISALLOW_ILLEGAL_C9_INTERCHANGE);
+            is($ret, $expected_ret,
+                          "isUTF8_CHAR_flags('DISALLOW_ILLEGAL_C9_INTERCHANGE')"
+                        . " acts like isC9_STRICT_UTF8_CHAR");
+        }
+        is(scalar @warnings, 0,
+                "isC9_STRICT_UTF8_CHAR() and isUTF8_CHAR_flags $testname:"
+              . " generated no warnings")
+          or output_warnings(@warnings);
+
+        # Test partial character handling, for each byte not a full character
+        for my $j (1.. $length - 1) {
+
+            # Skip the test for the interaction between overflow and above-31
+            # bit.  It is really testing other things than the partial
+            # character tests, for which other tests in this file are
+            # sufficient
+            last if $testname =~ /overflow/;
+
+            foreach my $disallow_flag (0, $disallow_flags) {
+                my $partial = substr($bytes, 0, $j);
+                my $ret_should_be;
+                my $comment;
+                if ($disallow_flag) {
+                    $ret_should_be = 0;
+                    $comment = "disallowed";
+                    if ($j < $needed_to_discern_len) {
+                        $ret_should_be = 1;
+                        $comment .= ", but need $needed_to_discern_len bytes"
+                                 .  " to discern:";
+                    }
+                }
+                else {
+                    $ret_should_be = 1;
+                    $comment = "allowed";
+                }
+
+                undef @warnings;
+
+                $ret = test_is_utf8_valid_partial_char_flags($partial, $j,
+                                                             $disallow_flag);
+                is($ret, $ret_should_be,
+                                "$testname: is_utf8_valid_partial_char_flags("
+                                        . display_bytes($partial)
+                                        . "), $comment: returns $ret_should_be");
+                is(scalar @warnings, 0,
+                        "$testname: is_utf8_valid_partial_char_flags()"
+                      . " generated no warnings")
+                  or output_warnings(@warnings);
+            }
+        }
+    }
 
     # This is more complicated than the malformations tested earlier, as there
     # are several orthogonal variables involved.  We test all the subclasses
     # of utf8 warnings to verify they work with and without the utf8 class,
     # and don't have effects on other sublass warnings
     foreach my $warning ('utf8', 'surrogate', 'nonchar', 'non_unicode') {
-        foreach my $warn_flag (0, $warn_flags) {
-            foreach my $disallow_flag (0, $disallow_flags) {
-                foreach my $do_warning (0, 1) {
+      foreach my $warn_flag (0, $warn_flags) {
+        foreach my $disallow_flag (0, $disallow_flags) {
+          foreach my $do_warning (0, 1) {
+
+            # We try each of the above with various combinations of
+            # malformations that can occur on the same input sequence.
+            foreach my $short ("", "short") {
+              foreach my $unexpected_noncont ("",
+                                              "unexpected non-continuation")
+              {
+                foreach my $overlong ("", "overlong") {
+
+                    # If we're already at the longest possible, we
+                    # can't create an overlong (which would be longer)
+                    # can't handle anything larger.
+                    next if $overlong && $expected_len >= $max_bytes;
+
+                    my @malformations;
+                    my @expected_errors;
+                    push @malformations, $short if $short;
+                    push @malformations, $unexpected_noncont
+                                                      if $unexpected_noncont;
+                    push @malformations, $overlong if $overlong;
+
+                    # The overflow malformation test in the input
+                    # array is coerced into being treated like one of
+                    # the others.
+                    if ($will_overflow) {
+                        push @malformations, 'overflow';
+                        push @expected_errors, $UTF8_GOT_OVERFLOW;
+                    }
+
+                    my $malformations_name = join "/", @malformations;
+                    $malformations_name .= " malformation"
+                                                if $malformations_name;
+                    $malformations_name .= "s" if @malformations > 1;
+                    my $this_bytes = $bytes;
+                    my $this_length = $length;
+                    my $expected_uv = $allowed_uv;
+                    my $this_expected_len = $expected_len;
+                    my $this_needed_to_discern_len = $needed_to_discern_len;
+                    if ($malformations_name) {
+                        $expected_uv = 0;
+
+                        # Coerce the input into the desired
+                        # malformation
+                        if ($malformations_name =~ /overlong/) {
+
+                            # For an overlong, we convert the original
+                            # start byte into a continuation byte with
+                            # the same data bits as originally. ...
+                            substr($this_bytes, 0, 1)
+                                = start_byte_to_cont(substr($this_bytes,
+                                                            0, 1));
+
+                            # ... Then we prepend it with a known
+                            # overlong sequence.  This should evaluate
+                            # to the exact same code point as the
+                            # original.
+                            $this_bytes
+                            = I8_to_native("\xff")
+                            . (I8_to_native(chr $first_continuation)
+                            x ( $max_bytes - 1 - length($this_bytes)))
+                            . $this_bytes;
+                            $this_length = length($this_bytes);
+                            $this_needed_to_discern_len
+                                 = $max_bytes - ($this_expected_len
+                                               - $this_needed_to_discern_len);
+                            $this_expected_len = $max_bytes;
+                            push @expected_errors, $UTF8_GOT_LONG;
+                        }
+                        if ($malformations_name =~ /short/) {
+
+                            # Just tell the test to not look far
+                            # enough into the input.
+                            $this_length--;
+                            $this_expected_len--;
+                            push @expected_errors, $UTF8_GOT_SHORT;
+                        }
+                        if ($malformations_name
+                                                =~ /non-continuation/)
+                        {
+                            # Change the final continuation byte into
+                            # a non one.
+                            my $pos = ($short) ? -2 : -1;
+                            substr($this_bytes, $pos, 1) = '?';
+                            $this_expected_len--;
+                            push @expected_errors,
+                                            $UTF8_GOT_NON_CONTINUATION;
+                        }
+                    }
 
                     my $eval_warn = $do_warning
-                                  ? "use warnings '$warning'"
-                                  : $warning eq "utf8"
+                                ? "use warnings '$warning'"
+                                : $warning eq "utf8"
                                     ? "no warnings 'utf8'"
-                                    : "use warnings 'utf8'; no warnings '$warning'";
-
-                    # is effectively disallowed if will overflow, even if the
-                    # flag indicates it is allowed, fix up test name to
-                    # indicate this as well
-                    my $disallowed = $disallow_flag || $will_overflow;
-
-                    my $this_name = "utf8n_to_uvchr() $testname: " . (($disallow_flag)
-                                                    ? 'disallowed'
-                                                    : ($disallowed)
-                                                        ? 'FE_FF allowed'
-                                                        : 'allowed');
+                                    : ( "use warnings 'utf8';"
+                                    . " no warnings '$warning'");
+
+                    # Is effectively disallowed if we've set up a
+                    # malformation, even if the flag indicates it is
+                    # allowed.  Fix up test name to indicate this as
+                    # well
+                    my $disallowed = $disallow_flag
+                                || $malformations_name;
+                    my $this_name = "utf8n_to_uvchr_error() $testname: "
+                                                . (($disallow_flag)
+                                                ? 'disallowed'
+                                                : $disallowed
+                                                    ? $disallowed
+                                                    : 'allowed');
                     $this_name .= ", $eval_warn";
                     $this_name .= ", " . (($warn_flag)
-                                          ? 'with warning flag'
-                                          : 'no warning flag');
+                                        ? 'with warning flag'
+                                        : 'no warning flag');
 
                     undef @warnings;
                     my $ret_ref;
-                    my $display_bytes = display_bytes($bytes);
-                    my $call = "Call was: $eval_warn; \$ret_ref = test_utf8n_to_uvchr('$display_bytes', $length, $warn_flag|$disallow_flag)";
-                    my $eval_text =      "$eval_warn; \$ret_ref = test_utf8n_to_uvchr('$bytes', $length, $warn_flag|$disallow_flag)";
+                    my $display_bytes = display_bytes($this_bytes);
+                    my $call = "    Call was: $eval_warn; \$ret_ref"
+                            . " = test_utf8n_to_uvchr_error("
+                            . "'$display_bytes', $this_length,"
+                            . "$warn_flag"
+                            . "|$disallow_flag)";
+                    my $eval_text =      "$eval_warn; \$ret_ref"
+                            . " = test_utf8n_to_uvchr_error("
+                            . "'$this_bytes',"
+                            . " $this_length, $warn_flag"
+                            . "|$disallow_flag)";
                     eval "$eval_text";
-                    if (! ok ("$@ eq ''", "$this_name: eval succeeded")) {
+                    if (! ok ("$@ eq ''",
+                        "$this_name: eval succeeded"))
+                    {
                         diag "\$!='$!'; eval'd=\"$call\"";
                         next;
                     }
                     if ($disallowed) {
-                        unless (is($ret_ref->[0], 0, "$this_name: Returns 0"))
-                        {
-                            diag $call;
-                        }
+                        is($ret_ref->[0], 0, "$this_name: Returns 0")
+                          or diag $call;
                     }
                     else {
-                        unless (is($ret_ref->[0], $allowed_uv,
-                                            "$this_name: Returns expected uv"))
+                        is($ret_ref->[0], $expected_uv,
+                                "$this_name: Returns expected uv: "
+                                . sprintf("0x%04X", $expected_uv))
+                          or diag $call;
+                    }
+                    is($ret_ref->[1], $this_expected_len,
+                                        "$this_name: Returns expected length:"
+                                      . " $this_expected_len")
+                      or diag $call;
+
+                    my $errors = $ret_ref->[2];
+
+                    for (my $i = @expected_errors - 1; $i >= 0; $i--) {
+                        if (ok($expected_errors[$i] & $errors,
+                            "Expected and got error bit return"
+                            . " for $malformations[$i] malformation"))
                         {
-                            diag $call;
+                            $errors &= ~$expected_errors[$i];
                         }
+                        splice @expected_errors, $i, 1;
                     }
-                    unless (is($ret_ref->[1], $expected_len,
-                                    "$this_name: Returns expected length"))
+                    is(scalar @expected_errors, 0,
+                            "Got all the expected malformation errors")
+                      or diag Dumper \@expected_errors;
+
+                    if (   $this_expected_len >= $this_needed_to_discern_len
+                        && ($warn_flag || $disallow_flag))
                     {
-                        diag $call;
+                        is($errors, $expected_error_flags,
+                                "Got the correct error flag")
+                          or diag $call;
+                    }
+                    else {
+                        is($errors, 0, "Got no other error flag");
                     }
 
-                    if (! $do_warning
-                        && ($warning eq 'utf8' || $warning eq $category))
-                    {
-                        if (!is(scalar @warnings, 0,
-                                            "$this_name: No warnings generated"))
-                        {
-                            diag $call;
-                            diag "The warnings were: " . join(", ", @warnings);
+                    if (@malformations) {
+                        if (! $do_warning && $warning eq 'utf8') {
+                            goto no_warnings_expected;
+                        }
+
+                        # Check that each malformation generates a
+                        # warning, removing that warning if found
+                    MALFORMATION:
+                        foreach my $malformation (@malformations) {
+                            foreach (my $i = 0; $i < @warnings; $i++) {
+                                if ($warnings[$i] =~ /$malformation/) {
+                                    pass("Expected and got"
+                                    . "'$malformation' warning");
+                                    splice @warnings, $i, 1;
+                                    next MALFORMATION;
+                                }
+                            }
+                            fail("Expected '$malformation' warning"
+                            . " but didn't get it");
+
                         }
                     }
-                    elsif ($will_overflow
-                           && ! $disallow_flag
-                           && $warning eq 'utf8')
-                    {
 
-                        # Will get the overflow message instead of the expected
-                        # message under these circumstances, as they would
-                        # otherwise accept an overflowed value, which the code
-                        # should not allow, so falls back to overflow.
+                    # Any overflow will override any super or above-31
+                    # warnings.
+                    goto no_warnings_expected
+                                if $will_overflow || $this_expected_len
+                                        < $this_needed_to_discern_len;
+
+                    if (    ! $do_warning
+                        && (   $warning eq 'utf8'
+                            || $warning eq $category))
+                    {
+                        goto no_warnings_expected;
+                    }
+                    elsif ($warn_flag) {
                         if (is(scalar @warnings, 1,
-                               "$this_name: Got a single warning "))
+                            "$this_name: Got a single warning "))
                         {
-                            unless (like($warnings[0], qr/overflow/,
-                                        "$this_name: Got overflow warning"))
-                            {
-                                diag $call;
-                            }
+                            like($warnings[0], $message,
+                                    "$this_name: Got expected warning")
+                                or diag $call;
                         }
                         else {
                             diag $call;
                             if (scalar @warnings) {
-                                diag "The warnings were: "
-                                                        . join(", ", @warnings);
+                                output_warnings(@warnings);
                             }
                         }
                     }
-                    elsif ($warn_flag
-                           && ($warning eq 'utf8' || $warning eq $category))
-                    {
-                        if (is(scalar @warnings, 1,
-                               "$this_name: Got a single warning "))
+                    else {
+                    no_warnings_expected:
+                        unless (is(scalar @warnings, 0,
+                                "$this_name: Got no warnings"))
                         {
-                        TODO: {
-                            local $TODO = "Doesn't give dire warning for code points 2**31" if $allowed_uv >= 2**31 && $warnings[0] =~ /may not be portable/;
-                            unless (like($warnings[0], $message,
-                                        "$this_name: Got expected warning"))
-                            {
-                                diag $call;
-                            }
-                            }
-                        }
-                        else {
                             diag $call;
-                            if (scalar @warnings) {
-                                diag "The warnings were: "
-                                                        . join(", ", @warnings);
-                            }
+                            output_warnings(@warnings);
                         }
                     }
 
-                    # Check CHECK_ONLY results when the input is disallowed.  Do
-                    # this when actually disallowed, not just when the
-                    # $disallow_flag is set
+                    # Check CHECK_ONLY results when the input is
+                    # disallowed.  Do this when actually disallowed,
+                    # not just when the $disallow_flag is set
                     if ($disallowed) {
                         undef @warnings;
-                        $ret_ref = test_utf8n_to_uvchr($bytes, $length,
-                                                $disallow_flag|$UTF8_CHECK_ONLY);
-                        unless (is($ret_ref->[0], 0, "$this_name, CHECK_ONLY: Returns 0")) {
-                            diag $call;
-                        }
-                        unless (is($ret_ref->[1], -1,
-                            "$this_name: CHECK_ONLY: returns expected length"))
-                        {
-                            diag $call;
-                        }
+                        $ret_ref = test_utf8n_to_uvchr_error(
+                                    $this_bytes, $this_length,
+                                    $disallow_flag|$UTF8_CHECK_ONLY);
+                        is($ret_ref->[0], 0,
+                                        "$this_name, CHECK_ONLY: Returns 0")
+                          or diag $call;
+                        is($ret_ref->[1], -1,
+                            "$this_name: CHECK_ONLY: returns -1 for length")
+                          or diag $call;
                         if (! is(scalar @warnings, 0,
-                            "$this_name, CHECK_ONLY: no warnings generated"))
+                            "$this_name, CHECK_ONLY: no warnings"
+                        . " generated"))
                         {
                             diag $call;
-                            diag "The warnings were: " . join(", ", @warnings);
+                            output_warnings(@warnings);
                         }
                     }
 
                     # Now repeat some of the above, but for
                     # uvchr_to_utf8_flags().  Since this comes from an
-                    # existing code point, it hasn't overflowed.
-                    next if $will_overflow;
+                    # existing code point, it hasn't overflowed, and
+                    # isn't malformed.
+                    next if @malformations;
 
                     # The warning and disallow flags passed in are for
-                    # utf8n_to_uvchr().  Convert them for
+                    # utf8n_to_uvchr_error().  Convert them for
                     # uvchr_to_utf8_flags().
                     my $uvchr_warn_flag = 0;
                     my $uvchr_disallow_flag = 0;
@@ -1046,32 +2472,40 @@ foreach my $test (@tests) {
                         elsif ($warn_flag == $UTF8_WARN_SUPER) {
                             $uvchr_warn_flag = $UNICODE_WARN_SUPER
                         }
-                        elsif ($warn_flag == $UTF8_WARN_FE_FF) {
-                            $uvchr_warn_flag = $UNICODE_WARN_ABOVE_31_BIT;
+                        elsif ($warn_flag == $UTF8_WARN_ABOVE_31_BIT) {
+                            $uvchr_warn_flag
+                                        = $UNICODE_WARN_ABOVE_31_BIT;
                         }
                         else {
                             fail(sprintf "Unexpected warn flag: %x",
-                                 $warn_flag);
+                                $warn_flag);
                             next;
                         }
                     }
                     if ($disallow_flag) {
-                        if ($disallow_flag == $UTF8_DISALLOW_SURROGATE) {
-                            $uvchr_disallow_flag = $UNICODE_DISALLOW_SURROGATE
+                        if ($disallow_flag == $UTF8_DISALLOW_SURROGATE)
+                        {
+                            $uvchr_disallow_flag
+                                        = $UNICODE_DISALLOW_SURROGATE;
                         }
-                        elsif ($disallow_flag == $UTF8_DISALLOW_NONCHAR) {
-                            $uvchr_disallow_flag = $UNICODE_DISALLOW_NONCHAR
+                        elsif ($disallow_flag == $UTF8_DISALLOW_NONCHAR)
+                        {
+                            $uvchr_disallow_flag
+                                        = $UNICODE_DISALLOW_NONCHAR;
                         }
                         elsif ($disallow_flag == $UTF8_DISALLOW_SUPER) {
-                            $uvchr_disallow_flag = $UNICODE_DISALLOW_SUPER
+                            $uvchr_disallow_flag
+                                        = $UNICODE_DISALLOW_SUPER;
                         }
-                        elsif ($disallow_flag == $UTF8_DISALLOW_FE_FF) {
+                        elsif ($disallow_flag
+                                        == $UTF8_DISALLOW_ABOVE_31_BIT)
+                        {
                             $uvchr_disallow_flag =
-                            $UNICODE_DISALLOW_ABOVE_31_BIT;
+                                        $UNICODE_DISALLOW_ABOVE_31_BIT;
                         }
                         else {
                             fail(sprintf "Unexpected disallow flag: %x",
-                                 $disallow_flag);
+                                $disallow_flag);
                             next;
                         }
                     }
@@ -1079,73 +2513,122 @@ foreach my $test (@tests) {
                     $disallowed = $uvchr_disallow_flag;
 
                     $this_name = "uvchr_to_utf8_flags() $testname: "
-                                                  . (($uvchr_disallow_flag)
-                                                    ? 'disallowed'
-                                                    : ($disallowed)
-                                                      ? 'ABOVE_31_BIT allowed'
-                                                      : 'allowed');
+                                            . (($uvchr_disallow_flag)
+                                                ? 'disallowed'
+                                                : ($disallowed)
+                                                ? 'ABOVE_31_BIT allowed'
+                                                : 'allowed');
                     $this_name .= ", $eval_warn";
                     $this_name .= ", " . (($uvchr_warn_flag)
-                                          ? 'with warning flag'
-                                          : 'no warning flag');
+                                        ? 'with warning flag'
+                                        : 'no warning flag');
 
                     undef @warnings;
                     my $ret;
                     my $warn_flag = sprintf "0x%x", $uvchr_warn_flag;
-                    my $disallow_flag = sprintf "0x%x", $uvchr_disallow_flag;
-                    $call = sprintf "call was: $eval_warn; \$ret = test_uvchr_to_utf8_flags(0x%x, $warn_flag|$disallow_flag)", $allowed_uv;
-                    $eval_text = "$eval_warn; \$ret = test_uvchr_to_utf8_flags($allowed_uv, $warn_flag|$disallow_flag)";
+                    my $disallow_flag = sprintf "0x%x",
+                                                $uvchr_disallow_flag;
+                    $call = sprintf("    Call was: $eval_warn; \$ret"
+                                . " = test_uvchr_to_utf8_flags("
+                                . " 0x%x, $warn_flag|$disallow_flag)",
+                                $allowed_uv);
+                    $eval_text = "$eval_warn; \$ret ="
+                            . " test_uvchr_to_utf8_flags("
+                            . "$allowed_uv, $warn_flag|"
+                            . "$disallow_flag)";
                     eval "$eval_text";
-                    if (! ok ("$@ eq ''", "$this_name: eval succeeded")) {
+                    if (! ok ("$@ eq ''", "$this_name: eval succeeded"))
+                    {
                         diag "\$!='$!'; eval'd=\"$eval_text\"";
                         next;
                     }
                     if ($disallowed) {
-                        unless (is($ret, undef, "$this_name: Returns undef")) {
-                            diag $call;
-                        }
+                        is($ret, undef, "$this_name: Returns undef")
+                          or diag $call;
                     }
                     else {
-                        unless (is($ret, $bytes, "$this_name: Returns expected string")) {
-                            diag $call;
-                        }
+                        is($ret, $bytes, "$this_name: Returns expected string")
+                          or diag $call;
                     }
                     if (! $do_warning
                         && ($warning eq 'utf8' || $warning eq $category))
                     {
                         if (!is(scalar @warnings, 0,
-                                            "$this_name: No warnings generated"))
+                                "$this_name: No warnings generated"))
                         {
                             diag $call;
-                            diag "The warnings were: " . join(", ", @warnings);
+                            output_warnings(@warnings);
                         }
                     }
-                    elsif ($uvchr_warn_flag
-                           && ($warning eq 'utf8' || $warning eq $category))
+                    elsif (       $uvchr_warn_flag
+                        && (   $warning eq 'utf8'
+                            || $warning eq $category))
                     {
                         if (is(scalar @warnings, 1,
-                               "$this_name: Got a single warning "))
+                            "$this_name: Got a single warning "))
                         {
-                            TODO: {
-                                local $TODO = "Doesn't give dire warning for code points 2**31" if $allowed_uv >= 2**31 && $warnings[0] =~ /may not be portable/;
-                            unless (like($warnings[0], $message,
-                                            "$this_name: Got expected warning"))
-                            {
-                                diag $call;
-                            }
-                            }
+                            like($warnings[0], $message,
+                                    "$this_name: Got expected warning")
+                                or diag $call;
                         }
                         else {
                             diag $call;
-                            if (scalar @warnings) {
-                                diag "The warnings were: "
-                                                        . join(", ", @warnings);
-                            }
+                            output_warnings(@warnings)
+                                                if scalar @warnings;
                         }
                     }
                 }
+              }
             }
+          }
         }
+      }
+    }
+}
+
+SKIP:
+{
+    isASCII
+      or skip "These tests probably break on non-ASCII", 1;
+    my $simple = join "", "A" .. "J";
+    my $utf_ch = "\x{7fffffff}";
+    utf8::encode($utf_ch);
+    my $utf_ch_len = length $utf_ch;
+    note "utf_ch_len $utf_ch_len";
+    my $utf = $utf_ch x 10;
+    my $bad_start = substr($utf, 1);
+    # $bad_end ends with a start byte and a single continuation
+    my $bad_end = substr($utf, 0, length($utf)-$utf_ch_len+2);
+
+    # WARNING: all offsets are *byte* offsets
+    my @hop_tests =
+      (
+       # string      s                off        expected         name
+       [ $simple,    0,               5,         5,               "simple in range, forward" ],
+       [ $simple,    10,              -5,        5,               "simple in range, backward" ],
+       [ $simple,    5,               10,        10,              "simple out of range, forward" ],
+       [ $simple,    5,               -10,       0,               "simple out of range, backward" ],
+       [ $utf,       $utf_ch_len * 5, 5,         length($utf),    "utf in range, forward" ],
+       [ $utf,       $utf_ch_len * 5, -5,        0,               "utf in range, backward" ],
+       [ $utf,       $utf_ch_len * 5, 4,         $utf_ch_len * 9, "utf in range b, forward" ],
+       [ $utf,       $utf_ch_len * 5, -4,        $utf_ch_len,     "utf in range b, backward" ],
+       [ $utf,       $utf_ch_len * 5, 6,         length($utf),    "utf out of range, forward" ],
+       [ $utf,       $utf_ch_len * 5, -6,        0,               "utf out of range, backward"  ],
+       [ $bad_start, 0,               1,         1,               "bad start, forward 1 from 0" ],
+       [ $bad_start, 0,               $utf_ch_len-1, $utf_ch_len-1, "bad start, forward ch_len-1 from 0" ],
+       [ $bad_start, 0,               $utf_ch_len, $utf_ch_len*2-1, "bad start, forward ch_len from 0" ],
+       [ $bad_start, $utf_ch_len-1,   -1,        0,                "bad start, back 1 from first start byte" ],
+       [ $bad_start, $utf_ch_len-2,   -1,        0,                "bad start, back 1 from before first start byte" ],
+       [ $bad_start, 0,               -1,        0,                "bad start, back 1 from 0" ],
+       [ $bad_start, length $bad_start, -10,     0,                "bad start, back 10 from end" ],
+       [ $bad_end,   0,               10,        length $bad_end, "bad end, forward 10 from 0" ],
+       [ $bad_end,   length($bad_end)-1, 10,     length $bad_end, "bad end, forward 1 from end-1" ],
+       );
+
+    for my $test (@hop_tests) {
+        my ($str, $s_off, $off, $want, $name) = @$test;
+        my $result = test_utf8_hop_safe($str, $s_off, $off);
+        is($result, $want, "utf8_hop_safe: $name");
     }
 }