This is a live mirror of the Perl 5 development currently hosted at https://github.com/perl/perl5
(perl #129000) create a safer utf8_hop()
[perl5.git] / ext / XS-APItest / t / utf8.t
index 32f60e0..e366254 100644 (file)
@@ -8,7 +8,7 @@ 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 }
@@ -21,6 +21,10 @@ sub display_bytes {
            . '"';
 }
 
+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
@@ -59,26 +63,56 @@ for (my $i = 0; $i < 256; $i++) {
                     ? 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 "";
+    }
+
+    $byte = ord native_to_I8($byte);
+
+    # Copied from utf8.h.  This gets rid of the leading 1 bits.
+    $byte &= ((($len) >= 7) ? 0x00 : (0x1F >> (($len)-2)));
+
+    $byte |= (isASCII) ? 0x80 : ord I8_to_native("\xA0");
+    return 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_ABOVE_31_BIT  = 0x0800;
-my $UTF8_WARN_ABOVE_31_BIT      = 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
@@ -346,6 +380,9 @@ 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) {
@@ -395,7 +432,7 @@ 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 :
@@ -404,7 +441,7 @@ for my $u (sort { utf8::unicode_to_native($a) <=> utf8::unicode_to_native($b) }
                $u < 0x40000     ? 4 :
                $u < 0x400000    ? 5 :
                $u < 0x4000000   ? 6 :
-               $u < 0x40000000  ? 7 : 14 );
+               $u < 0x40000000  ? 7 : $max_bytes );
     }
 
     # If this test fails, subsequent ones are meaningless.
@@ -445,7 +482,7 @@ for my $u (sort { utf8::unicode_to_native($a) <=> utf8::unicode_to_native($b) }
         unless (is(scalar @warnings, 0,
                 "   Verify is_utf8_valid_partial_char_flags generated no warnings"))
         {
-            diag "The warnings were: " . join(", ", @warnings);
+            output_warnings(@warnings);
         }
 
         my $b = substr($n_chr, $j, 1);
@@ -535,19 +572,23 @@ for my $u (sort { utf8::unicode_to_native($a) <=> utf8::unicode_to_native($b) }
 
     my $display_flags = sprintf "0x%x", $this_utf8_flags;
     my $display_bytes = display_bytes($bytes);
-    my $ret_ref = test_utf8n_to_uvchr($bytes, $len, $this_utf8_flags);
+    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], $n,
-       "Verify utf8n_to_uvchr($display_bytes, $display_flags) returns $hex_n");
+                   "Verify utf8n_to_uvchr_error($display_bytes, $display_flags)"
+                 . "returns $hex_n");
     is($ret_ref->[1], $len,
-       "Verify utf8n_to_uvchr() for $hex_n returns expected length: $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;
 
@@ -557,7 +598,7 @@ for my $u (sort { utf8::unicode_to_native($a) <=> utf8::unicode_to_native($b) }
     unless (is(scalar @warnings, 0,
                "Verify isUTF8_CHAR() for $hex_n generated no warnings"))
     {
-        diag "The warnings were: " . join(", ", @warnings);
+        output_warnings(@warnings);
     }
 
     undef @warnings;
@@ -568,7 +609,7 @@ for my $u (sort { utf8::unicode_to_native($a) <=> utf8::unicode_to_native($b) }
     unless (is(scalar @warnings, 0,
                "Verify isUTF8_CHAR() generated no warnings"))
     {
-        diag "The warnings were: " . join(", ", @warnings);
+        output_warnings(@warnings);
     }
 
     undef @warnings;
@@ -579,7 +620,7 @@ for my $u (sort { utf8::unicode_to_native($a) <=> utf8::unicode_to_native($b) }
     unless (is(scalar @warnings, 0,
                "Verify isUTF8_CHAR_flags() for $hex_n generated no warnings"))
     {
-        diag "The warnings were: " . join(", ", @warnings);
+        output_warnings(@warnings);
     }
 
     undef @warnings;
@@ -590,7 +631,7 @@ for my $u (sort { utf8::unicode_to_native($a) <=> utf8::unicode_to_native($b) }
     unless (is(scalar @warnings, 0,
                "Verify isUTF8_CHAR_flags() generated no warnings"))
     {
-        diag "The warnings were: " . join(", ", @warnings);
+        output_warnings(@warnings);
     }
 
     undef @warnings;
@@ -602,7 +643,7 @@ for my $u (sort { utf8::unicode_to_native($a) <=> utf8::unicode_to_native($b) }
     unless (is(scalar @warnings, 0,
                "Verify isSTRICT_UTF8_CHAR() for $hex_n generated no warnings"))
     {
-        diag "The warnings were: " . join(", ", @warnings);
+        output_warnings(@warnings);
     }
 
     undef @warnings;
@@ -613,7 +654,7 @@ for my $u (sort { utf8::unicode_to_native($a) <=> utf8::unicode_to_native($b) }
     unless (is(scalar @warnings, 0,
                "Verify isSTRICT_UTF8_CHAR() generated no warnings"))
     {
-        diag "The warnings were: " . join(", ", @warnings);
+        output_warnings(@warnings);
     }
 
     undef @warnings;
@@ -624,7 +665,7 @@ for my $u (sort { utf8::unicode_to_native($a) <=> utf8::unicode_to_native($b) }
     unless (is(scalar @warnings, 0,
                "Verify isUTF8_CHAR() for $hex_n generated no warnings"))
     {
-        diag "The warnings were: " . join(", ", @warnings);
+        output_warnings(@warnings);
     }
 
     undef @warnings;
@@ -636,7 +677,7 @@ for my $u (sort { utf8::unicode_to_native($a) <=> utf8::unicode_to_native($b) }
     unless (is(scalar @warnings, 0,
                "Verify isC9_STRICT_UTF8_CHAR() for $hex_n generated no warnings"))
     {
-        diag "The warnings were: " . join(", ", @warnings);
+        output_warnings(@warnings);
     }
 
     undef @warnings;
@@ -647,7 +688,7 @@ for my $u (sort { utf8::unicode_to_native($a) <=> utf8::unicode_to_native($b) }
     unless (is(scalar @warnings, 0,
                "Verify isC9_STRICT_UTF8_CHAR() generated no warnings"))
     {
-        diag "The warnings were: " . join(", ", @warnings);
+        output_warnings(@warnings);
     }
 
     undef @warnings;
@@ -658,7 +699,7 @@ for my $u (sort { utf8::unicode_to_native($a) <=> utf8::unicode_to_native($b) }
     unless (is(scalar @warnings, 0,
                "Verify isUTF8_CHAR() for $hex_n generated no warnings"))
     {
-        diag "The warnings were: " . join(", ", @warnings);
+        output_warnings(@warnings);
     }
 
     undef @warnings;
@@ -670,7 +711,7 @@ for my $u (sort { utf8::unicode_to_native($a) <=> utf8::unicode_to_native($b) }
     unless (is(scalar @warnings, 0,
                "Verify valid_utf8_to_uvchr() for $hex_n generated no warnings"))
     {
-        diag "The warnings were: " . join(", ", @warnings);
+        output_warnings(@warnings);
     }
 
     # Similarly for uvchr_to_utf8
@@ -699,7 +740,7 @@ for my $u (sort { utf8::unicode_to_native($a) <=> utf8::unicode_to_native($b) }
     unless (is(scalar @warnings, 0,
         "Verify uvchr_to_utf8_flags($hex_n, $display_flags) for $hex_n generated no warnings"))
     {
-        diag "The warnings were: " . join(", ", @warnings);
+        output_warnings(@warnings);
     }
 
     # Now append this code point to a string that we will test various
@@ -975,139 +1016,139 @@ my $REPLACEMENT = 0xFFFD;
 # Now test the malformations.  All these raise category utf8 warnings.
 my @malformations = (
     [ "zero length string malformation", "", 0,
-        $UTF8_ALLOW_EMPTY, 0, 0,
+        $UTF8_ALLOW_EMPTY, $UTF8_GOT_EMPTY, 0, 0,
         qr/empty string/
     ],
     [ "orphan continuation byte malformation", I8_to_native("${I8c}a"),
         2,
-        $UTF8_ALLOW_CONTINUATION, $REPLACEMENT, 1,
+        $UTF8_ALLOW_CONTINUATION, $UTF8_GOT_CONTINUATION, $REPLACEMENT, 1,
         qr/unexpected continuation byte/
     ],
     [ "premature next character malformation (immediate)",
         (isASCII) ? "\xc2\xc2\x80" : I8_to_native("\xc5\xc5\xa0"),
         3,
-        $UTF8_ALLOW_NON_CONTINUATION, $REPLACEMENT, 1,
+        $UTF8_ALLOW_NON_CONTINUATION, $UTF8_GOT_NON_CONTINUATION, $REPLACEMENT, 1,
         qr/unexpected non-continuation byte.*immediately after start byte/
     ],
     [ "premature next character malformation (non-immediate)",
-        I8_to_native("\xf0${I8c}a"),
+        I8_to_native("\xf1${I8c}a"),
         3,
-        $UTF8_ALLOW_NON_CONTINUATION, $REPLACEMENT, 2,
+        $UTF8_ALLOW_NON_CONTINUATION, $UTF8_GOT_NON_CONTINUATION, $REPLACEMENT, 2,
         qr/unexpected non-continuation byte .* 2 bytes after start byte/
     ],
-    [ "too short malformation", I8_to_native("\xf0${I8c}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,
+        $UTF8_ALLOW_SHORT, $UTF8_GOT_SHORT, $REPLACEMENT, 2,
         qr/2 bytes, need 4/
     ],
     [ "overlong malformation, lowest 2-byte",
         (isASCII) ? "\xc0\x80" : I8_to_native("\xc0\xa0"),
         2,
-        $UTF8_ALLOW_LONG,
+        $UTF8_ALLOW_LONG, $UTF8_GOT_LONG,
         0,   # NUL
         2,
-        qr/2 bytes, need 1/
+        qr/overlong/
     ],
     [ "overlong malformation, highest 2-byte",
         (isASCII) ? "\xc1\xbf" : I8_to_native("\xc4\xbf"),
         2,
-        $UTF8_ALLOW_LONG,
-        (isASCII) ? 0x7F : utf8::unicode_to_native(0xBF),
+        $UTF8_ALLOW_LONG, $UTF8_GOT_LONG,
+        (isASCII) ? 0x7F : utf8::unicode_to_native(0x9F),
         2,
-        qr/2 bytes, need 1/
+        qr/overlong/
     ],
     [ "overlong malformation, lowest 3-byte",
         (isASCII) ? "\xe0\x80\x80" : I8_to_native("\xe0\xa0\xa0"),
         3,
-        $UTF8_ALLOW_LONG,
+        $UTF8_ALLOW_LONG, $UTF8_GOT_LONG,
         0,   # NUL
         3,
-        qr/3 bytes, need 1/
+        qr/overlong/
     ],
     [ "overlong malformation, highest 3-byte",
         (isASCII) ? "\xe0\x9f\xbf" : I8_to_native("\xe0\xbf\xbf"),
         3,
-        $UTF8_ALLOW_LONG,
+        $UTF8_ALLOW_LONG, $UTF8_GOT_LONG,
         (isASCII) ? 0x7FF : 0x3FF,
         3,
-        qr/3 bytes, need 2/
+        qr/overlong/
     ],
     [ "overlong malformation, lowest 4-byte",
         (isASCII) ? "\xf0\x80\x80\x80" : I8_to_native("\xf0\xa0\xa0\xa0"),
         4,
-        $UTF8_ALLOW_LONG,
+        $UTF8_ALLOW_LONG, $UTF8_GOT_LONG,
         0,   # NUL
         4,
-        qr/4 bytes, need 1/
+        qr/overlong/
     ],
     [ "overlong malformation, highest 4-byte",
         (isASCII) ? "\xf0\x8F\xbf\xbf" : I8_to_native("\xf0\xaf\xbf\xbf"),
         4,
-        $UTF8_ALLOW_LONG,
+        $UTF8_ALLOW_LONG, $UTF8_GOT_LONG,
         (isASCII) ? 0xFFFF : 0x3FFF,
         4,
-        qr/4 bytes, need 3/
+        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_ALLOW_LONG, $UTF8_GOT_LONG,
         0,   # NUL
         5,
-        qr/5 bytes, need 1/
+        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_ALLOW_LONG, $UTF8_GOT_LONG,
         (isASCII) ? 0x1FFFFF : 0x3FFFF,
         5,
-        qr/5 bytes, need 4/
+        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_ALLOW_LONG, $UTF8_GOT_LONG,
         0,   # NUL
         6,
-        qr/6 bytes, need 1/
+        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_ALLOW_LONG, $UTF8_GOT_LONG,
         (isASCII) ? 0x3FFFFFF : 0x3FFFFF,
         6,
-        qr/6 bytes, need 5/
+        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_ALLOW_LONG, $UTF8_GOT_LONG,
         0,   # NUL
         7,
-        qr/7 bytes, need 1/
+        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_ALLOW_LONG, $UTF8_GOT_LONG,
         (isASCII) ? 0x7FFFFFFF : 0x3FFFFFF,
         7,
-        qr/7 bytes, need 6/
+        qr/overlong/
     ],
 );
 
@@ -1118,17 +1159,19 @@ if (isASCII && ! $is64bit) {    # 32-bit ASCII platform
             "\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,
-            qr/overflow/
+            qr/overflows/
         ],
         [ "overflow malformation, can tell on first byte",
             "\xff\x80\x80\x80\x80\x80\x81\x80\x80\x80\x80\x80\x80",
-            13,
+            $max_bytes,
             0,  # There is no way to allow this malformation
+            $UTF8_GOT_OVERFLOW,
             $REPLACEMENT,
-            13,
-            qr/overflow/
+            $max_bytes,
+            qr/overflows/
         ];
 }
 else {
@@ -1142,32 +1185,33 @@ else {
             (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"),
-            (isASCII) ? 13 : 14,
-            $UTF8_ALLOW_LONG,
+            $max_bytes,
+            $UTF8_ALLOW_LONG, $UTF8_GOT_LONG,
             0,   # NUL
-            (isASCII) ? 13 : 14,
-            qr/1[34] bytes, need 1/,    # 1[34] to work on either ASCII or EBCDIC
+            $max_bytes,
+            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"),
-            (isASCII) ? 13 : 14,
-            $UTF8_ALLOW_LONG,
+            $max_bytes,
+            $UTF8_ALLOW_LONG, $UTF8_GOT_LONG,
             (isASCII) ? 0xFFFFFFFFF : 0x3FFFFFFF,
-            (isASCII) ? 13 : 14,
-            qr/1[34] bytes, need 7/,
+            $max_bytes,
+            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"),
-            14,
+            $max_bytes,
             0,  # There is no way to allow this malformation
+            $UTF8_GOT_OVERFLOW,
             $REPLACEMENT,
-            14,
-            qr/overflow/
+            $max_bytes,
+            qr/overflows/
         ];
     }
     else {  # 64-bit
@@ -1176,19 +1220,27 @@ else {
                (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"),
-                (isASCII) ? 13 : 14,
+                $max_bytes,
                 0,  # There is no way to allow this malformation
+                $UTF8_GOT_OVERFLOW,
                 $REPLACEMENT,
-                (isASCII) ? 13 : 14,
-                qr/overflow/
+                $max_bytes,
+                qr/overflows/
             ];
     }
 }
 
 foreach my $test (@malformations) {
-    my ($testname, $bytes, $length, $allow_flags, $allowed_uv, $expected_len, $message ) = @$test;
-
-    next if ! ok(length($bytes) >= $length, "$testname: Make sure won't read beyond buffer: " . length($bytes) . " >= $length");
+    my ($testname, $bytes, $length, $allow_flags, $expected_error_flags,
+        $allowed_uv, $expected_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;
 
@@ -1197,7 +1249,7 @@ foreach my $test (@malformations) {
     unless (is(scalar @warnings, 0,
                "$testname: isUTF8_CHAR() generated no warnings"))
     {
-        diag "The warnings were: " . join(", ", @warnings);
+        output_warnings(@warnings);
     }
 
     undef @warnings;
@@ -1207,7 +1259,7 @@ foreach my $test (@malformations) {
     unless (is(scalar @warnings, 0,
                "$testname: isUTF8_CHAR() generated no warnings"))
     {
-        diag "The warnings were: " . join(", ", @warnings);
+        output_warnings(@warnings);
     }
 
     $ret = test_isSTRICT_UTF8_CHAR($bytes, $length);
@@ -1215,7 +1267,7 @@ foreach my $test (@malformations) {
     unless (is(scalar @warnings, 0,
                "$testname: isSTRICT_UTF8_CHAR() generated no warnings"))
     {
-        diag "The warnings were: " . join(", ", @warnings);
+        output_warnings(@warnings);
     }
 
     $ret = test_isC9_STRICT_UTF8_CHAR($bytes, $length);
@@ -1223,7 +1275,7 @@ foreach my $test (@malformations) {
     unless (is(scalar @warnings, 0,
                "$testname: isC9_STRICT_UTF8_CHAR() generated no warnings"))
     {
-        diag "The warnings were: " . join(", ", @warnings);
+        output_warnings(@warnings);
     }
 
     for my $j (1 .. $length - 1) {
@@ -1234,9 +1286,15 @@ foreach my $test (@malformations) {
         $ret = test_is_utf8_valid_partial_char_flags($bytes, $j, 0);
         my $ret_should_be = 0;
         my $comment = "";
-        if ($testname =~ /premature|short/ && $j < 2) {
-            $ret_should_be = 1;
-            $comment = ", but need 2 bytes to discern:";
+        if ($testname =~ /premature|short/ && $j < 3) {
+
+            # The tests are hard-coded so these relationships hold
+            my $cut_off = 2;
+            $cut_off = 3 if $testname =~ /non-immediate/;
+            if ($j < $cut_off) {
+                $ret_should_be = 1;
+                $comment = ", but need $cut_off bytes to discern:";
+            }
         }
         elsif ($testname =~ /overlong/ && ! isASCII && $length == 3) {
             # 3-byte overlongs on EBCDIC are determinable on the first byte
@@ -1271,56 +1329,103 @@ foreach my $test (@malformations) {
         unless (is(scalar @warnings, 0,
                 "$testname: is_utf8_valid_partial_char_flags() generated no warnings"))
         {
-            diag "The warnings were: " . join(", ", @warnings);
+            output_warnings(@warnings);
         }
     }
 
 
     # 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: utf8n_to_uvchr(), 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");
+    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, "$testname: utf8n_to_uvchr(), disallowed: no warnings 'utf8': Returns 0");
-        is($ret_ref->[1], $expected_len, "$testname: utf8n_to_uvchr(), disallowed: no warnings 'utf8': Returns expected length: $expected_len");
-        if (!is(scalar @warnings, 0, "$testname: utf8n_to_uvchr(), 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, "$testname: CHECK_ONLY: returns -1 for length");
     if (! is(scalar @warnings, 0, "$testname: CHECK_ONLY: 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");
 
     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: utf8n_to_uvchr(), allowed: Returns expected uv: " . sprintf("0x%04X", $allowed_uv));
-    is($ret_ref->[1], $expected_len, "$testname: utf8n_to_uvchr(), allowed: Returns expected length: $expected_len");
-    if (!is(scalar @warnings, 0, "$testname: utf8n_to_uvchr(), 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");
+}
+
+sub nonportable_regex ($) {
+
+    # 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
@@ -1328,289 +1433,289 @@ foreach my $test (@malformations) {
 my @tests = (
     [ "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,
         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,
         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,
         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/
+        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_WARN_SUPER, $UTF8_DISALLOW_SUPER, $UTF8_GOT_SUPER,
         'non_unicode',
         (isASCII) ? 0x140000 : 0x200000,
         (isASCII) ? 4 : 5,
-        qr/not Unicode.* may not be portable/
+        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,
         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,
         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,
         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,
         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,
         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,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0x1FFFE, 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,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0x1FFFF, 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,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0x2FFFE, 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,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0x2FFFF, 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,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0x3FFFE, 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,
+        $UTF8_WARN_NONCHAR, $UTF8_DISALLOW_NONCHAR, $UTF8_GOT_NONCHAR,
         'nonchar', 0x3FFFF, 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,
         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,
         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,
         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,
         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,
         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,
         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,
         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,
         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,
         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,
         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,
         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,
         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,
         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,
         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,
         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,
         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,
         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,
         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,
         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,
         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,
         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,
         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,
         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,
         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,
         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,
         qr/Unicode non-character.*is not recommended for open interchange/
@@ -1622,16 +1727,26 @@ my @tests = (
         # This code point is chosen so that it is representable in a UV on
         # 32-bit machines
         $UTF8_WARN_ABOVE_31_BIT, $UTF8_DISALLOW_ABOVE_31_BIT,
-        'utf8', 0x80000000, (isASCII) ? 7 :14,
-        qr/Code point 0x80000000 is not Unicode, and not portable/
+        $UTF8_GOT_ABOVE_31_BIT,
+        'utf8', 0x80000000, (isASCII) ? 7 : $max_bytes,
+        nonportable_regex(0x80000000)
+    ],
+    [ "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,
+        nonportable_regex(0xffffffff)
     ],
     [ "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', 0x80000000, (isASCII) ? 7 :14,
-        qr/Code point 0x80000000 is not Unicode, and not portable/
+        $UTF8_WARN_SUPER, $UTF8_DISALLOW_SUPER, $UTF8_GOT_SUPER,
+        'utf8', 0x80000000, (isASCII) ? 7 : $max_bytes,
+        nonportable_regex(0x80000000)
     ],
     [ "overflow with warnings/disallow for more than 31 bits",
         # This tests the interaction of WARN_ABOVE_31_BIT/DISALLOW_ABOVE_31_BIT
@@ -1649,18 +1764,29 @@ my @tests = (
         : ((isASCII)
            ?              "\xfe\x86\x80\x80\x80\x80\x80"
            : I8_to_native("\xff\xa0\xa0\xa0\xa0\xa0\xa0\xa4\xa0\xa0\xa0\xa0\xa0\xa0"))),
-
-        # We include both warning categories to make sure the ABOVE_31_BIT one
-        # has precedence
-        "$UTF8_WARN_ABOVE_31_BIT|$UTF8_WARN_SUPER",
-        "$UTF8_DISALLOW_ABOVE_31_BIT",
+        $UTF8_WARN_ABOVE_31_BIT,
+        $UTF8_DISALLOW_ABOVE_31_BIT,
+        $UTF8_GOT_ABOVE_31_BIT,
         'utf8', 0,
-        (! isASCII) ? 14 : ($is64bit) ? 13 : 7,
-        qr/overflow at byte .*, after start byte 0xf/
+        (! isASCII) ? $max_bytes : ($is64bit) ? $max_bytes : 7,   # XXX
+        qr/overflows/
     ],
 );
 
-if ($is64bit) {
+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,
+                $UTF8_GOT_ABOVE_31_BIT,
+                'utf8', 0x100000000, 7,
+                qr/and( is)? not portable/
+            ];
+    }
+}
+else {
     no warnings qw{portable overflow};
     push @tests,
         [ "More than 32 bits",
@@ -1668,55 +1794,64 @@ if ($is64bit) {
             ?              "\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', 0x1000000000, (isASCII) ? 13 : 14,
-            qr/Code point 0x.* is not Unicode, and not portable/
+            $UTF8_GOT_ABOVE_31_BIT,
+            'utf8', 0x1000000000, $max_bytes,
+            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', 0x800000000, 14,
-                qr/Code point 0x800000000 is not Unicode, and not portable/
+                $UTF8_GOT_ABOVE_31_BIT,
+                'utf8', 0x800000000, $max_bytes,
+                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', 0x10000000000, 14,
-                qr/Code point 0x10000000000 is not Unicode, and not portable/
+                $UTF8_GOT_ABOVE_31_BIT,
+                'utf8', 0x10000000000, $max_bytes,
+                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', 0x200000000000, 14,
-                qr/Code point 0x200000000000 is not Unicode, and not portable/
+                $UTF8_GOT_ABOVE_31_BIT,
+                'utf8', 0x200000000000, $max_bytes,
+                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', 0x4000000000000, 14,
-                qr/Code point 0x4000000000000 is not Unicode, and not portable/
+                $UTF8_GOT_ABOVE_31_BIT,
+                'utf8', 0x4000000000000, $max_bytes,
+                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', 0x80000000000000, 14,
-                qr/Code point 0x80000000000000 is not Unicode, and not portable/
+                $UTF8_GOT_ABOVE_31_BIT,
+                'utf8', 0x80000000000000, $max_bytes,
+                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"),
+                   #IBM-1047  \xFE\x41\x41\x41\x41\x41\x41\x43\x41\x41\x41\x41\x41\x41
                 $UTF8_WARN_ABOVE_31_BIT,$UTF8_DISALLOW_ABOVE_31_BIT,
-                'utf8', 0x1000000000000000, 14,
-                qr/Code point 0x1000000000000000 is not Unicode, and not portable/
+                $UTF8_GOT_ABOVE_31_BIT,
+                'utf8', 0x1000000000000000, $max_bytes,
+                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, $message ) = @$test;
 
     my $length = length $bytes;
-    my $will_overflow = $testname =~ /overflow/;
+    my $will_overflow = $testname =~ /overflow/ ? 'overflow' : "";
 
     {
         use warnings;
@@ -1736,7 +1871,7 @@ foreach my $test (@tests) {
         unless (is(scalar @warnings, 0,
                 "isUTF8_CHAR() and isUTF8_CHAR()_flags $testname: generated no warnings"))
         {
-            diag "The warnings were: " . join(", ", @warnings);
+            output_warnings(@warnings);
         }
 
         undef @warnings;
@@ -1759,7 +1894,7 @@ foreach my $test (@tests) {
         unless (is(scalar @warnings, 0,
                 "isSTRICT_UTF8_CHAR() and isUTF8_CHAR_flags $testname: generated no warnings"))
         {
-            diag "The warnings were: " . join(", ", @warnings);
+            output_warnings(@warnings);
         }
 
         undef @warnings;
@@ -1782,7 +1917,7 @@ foreach my $test (@tests) {
         unless (is(scalar @warnings, 0,
                 "isC9_STRICT_UTF8_CHAR() and isUTF8_CHAR_flags $testname: generated no warnings"))
         {
-            diag "The warnings were: " . join(", ", @warnings);
+            output_warnings(@warnings);
         }
 
         # Test partial character handling, for each byte not a full character
@@ -1845,7 +1980,7 @@ foreach my $test (@tests) {
                 unless (is(scalar @warnings, 0,
                         "$testname: is_utf8_valid_partial_char_flags() generated no warnings"))
                 {
-                    diag "The warnings were: " . join(", ", @warnings);
+                    output_warnings(@warnings);
                 }
             }
         }
@@ -1860,248 +1995,403 @@ foreach my $test (@tests) {
             foreach my $disallow_flag (0, $disallow_flags) {
                 foreach my $do_warning (0, 1) {
 
-                    my $eval_warn = $do_warning
-                                  ? "use warnings '$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)
-                                                        ? 'ABOVE_31_BIT allowed'
-                                                        : 'allowed');
-                    $this_name .= ", $eval_warn";
-                    $this_name .= ", " . (($warn_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)";
-                    eval "$eval_text";
-                    if (! ok ("$@ eq ''", "$this_name: eval succeeded")) {
-                        diag "\$!='$!'; eval'd=\"$call\"";
-                        next;
-                    }
-                    if ($disallowed) {
-                        unless (is($ret_ref->[0], 0, "$this_name: Returns 0"))
-                        {
-                            diag $call;
-                        }
-                    }
-                    else {
-                        unless (is($ret_ref->[0], $allowed_uv,
-                                   "$this_name: Returns expected uv: "
-                                 . sprintf("0x%04X", $allowed_uv)))
-                        {
-                            diag $call;
-                        }
-                    }
-                    unless (is($ret_ref->[1], $expected_len,
-                        "$this_name: Returns expected length: $expected_len"))
+                    # We try each of the above with various combinations of
+                    # malformations that can occur on the same input sequence.
+                    foreach my $short ("",
+                                       "short",
+                                       "unexpected non-continuation")
                     {
-                        diag $call;
-                    }
+                        # The non-characters can't be discerned with a short
+                        # malformation
+                        next if $short && $testname =~ /non-character/;
+
+                        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, $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;
+                            }
 
-                    if (! $do_warning
-                        && ($warning eq 'utf8' || $warning eq $category))
-                    {
-                        if (!is(scalar @warnings, 0,
-                                            "$this_name: No warnings generated"))
-                        {
-                            diag $call;
-                            diag "The warnings were: " . join(", ", @warnings);
-                        }
-                    }
-                    elsif ($will_overflow
-                           && ! $disallow_flag
-                           && $warning eq 'utf8')
-                    {
+                            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 = $expected_len;
+                            if ($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_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, $UTF8_GOT_SHORT;
+                                }
+                                elsif ($malformations_name
+                                                        =~ /non-continuation/)
+                                {
+                                    # Change the final continuation byte into
+                                    # a non one.
+                                    substr($this_bytes, -1, 1) = '?';
+                                    $this_expected_len--;
+                                    push @expected_errors,
+                                                    $UTF8_GOT_NON_CONTINUATION;
+                                }
+                            }
 
-                        # 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.
-                        if (is(scalar @warnings, 1,
-                               "$this_name: Got a single warning "))
-                        {
-                            unless (like($warnings[0], qr/overflow/,
-                                        "$this_name: Got overflow warning"))
+                            my $eval_warn = $do_warning
+                                        ? "use warnings '$warning'"
+                                        : $warning eq "utf8"
+                                            ? "no warnings 'utf8'"
+                                            : ( "use warnings 'utf8';"
+                                              . " no warnings '$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');
+
+                            undef @warnings;
+                            my $ret_ref;
+                            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"))
                             {
-                                diag $call;
+                                diag "\$!='$!'; eval'd=\"$call\"";
+                                next;
                             }
-                        }
-                        else {
-                            diag $call;
-                            if (scalar @warnings) {
-                                diag "The warnings were: "
-                                                        . join(", ", @warnings);
+                            if ($disallowed) {
+                                unless (is($ret_ref->[0], 0,
+                                           "$this_name: Returns 0"))
+                                {
+                                    diag $call;
+                                }
                             }
-                        }
-                    }
-                    elsif ($warn_flag
-                           && ($warning eq 'utf8' || $warning eq $category))
-                    {
-                        if (is(scalar @warnings, 1,
-                               "$this_name: Got a single warning "))
-                        {
-                            unless (like($warnings[0], $message,
-                                        "$this_name: Got expected warning"))
+                            else {
+                                unless (is($ret_ref->[0], $expected_uv,
+                                        "$this_name: Returns expected uv: "
+                                        . sprintf("0x%04X", $expected_uv)))
+                                {
+                                    diag $call;
+                                }
+                            }
+                            unless (is($ret_ref->[1], $this_expected_len,
+                                "$this_name: Returns expected length:"
+                              . " $this_expected_len"))
                             {
                                 diag $call;
                             }
-                        }
-                        else {
-                            diag $call;
-                            if (scalar @warnings) {
-                                diag "The warnings were: "
-                                                        . join(", ", @warnings);
-                            }
-                        }
-                    }
 
-                    # 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 -1 for length"))
-                        {
-                            diag $call;
-                        }
-                        if (! is(scalar @warnings, 0,
-                            "$this_name, CHECK_ONLY: no warnings generated"))
-                        {
-                            diag $call;
-                            diag "The warnings were: " . join(", ", @warnings);
-                        }
-                    }
+                            my $errors = $ret_ref->[2];
 
-                    # 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;
-
-                    # The warning and disallow flags passed in are for
-                    # utf8n_to_uvchr().  Convert them for
-                    # uvchr_to_utf8_flags().
-                    my $uvchr_warn_flag = 0;
-                    my $uvchr_disallow_flag = 0;
-                    if ($warn_flag) {
-                        if ($warn_flag == $UTF8_WARN_SURROGATE) {
-                            $uvchr_warn_flag = $UNICODE_WARN_SURROGATE
-                        }
-                        elsif ($warn_flag == $UTF8_WARN_NONCHAR) {
-                            $uvchr_warn_flag = $UNICODE_WARN_NONCHAR
-                        }
-                        elsif ($warn_flag == $UTF8_WARN_SUPER) {
-                            $uvchr_warn_flag = $UNICODE_WARN_SUPER
-                        }
-                        elsif ($warn_flag == $UTF8_WARN_ABOVE_31_BIT) {
-                            $uvchr_warn_flag = $UNICODE_WARN_ABOVE_31_BIT;
-                        }
-                        else {
-                            fail(sprintf "Unexpected warn flag: %x",
-                                 $warn_flag);
-                            next;
-                        }
-                    }
-                    if ($disallow_flag) {
-                        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_SUPER) {
-                            $uvchr_disallow_flag = $UNICODE_DISALLOW_SUPER
-                        }
-                        elsif ($disallow_flag == $UTF8_DISALLOW_ABOVE_31_BIT) {
-                            $uvchr_disallow_flag =
-                            $UNICODE_DISALLOW_ABOVE_31_BIT;
-                        }
-                        else {
-                            fail(sprintf "Unexpected disallow flag: %x",
-                                 $disallow_flag);
-                            next;
-                        }
-                    }
+                            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"))
+                                {
+                                    $errors &= ~$expected_errors[$i];
+                                }
+                                splice @expected_errors, $i, 1;
+                            }
+                            unless (is(scalar @expected_errors, 0,
+                                    "Got all the expected malformation errors"))
+                            {
+                                diag Dumper \@expected_errors;
+                            }
 
-                    $disallowed = $uvchr_disallow_flag;
+                            if ($warn_flag || $disallow_flag) {
+                                is($errors, $expected_error_flags,
+                                   "Got the correct error flag");
+                            }
+                            else {
+                                is($errors, 0, "Got no other error flag");
+                            }
 
-                    $this_name = "uvchr_to_utf8_flags() $testname: "
-                                                  . (($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');
+                            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");
+
+                                }
+                            }
 
-                    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)";
-                    eval "$eval_text";
-                    if (! ok ("$@ eq ''", "$this_name: eval succeeded")) {
-                        diag "\$!='$!'; eval'd=\"$eval_text\"";
-                        next;
-                    }
-                    if ($disallowed) {
-                        unless (is($ret, undef, "$this_name: Returns undef")) {
-                            diag $call;
-                        }
-                    }
-                    else {
-                        unless (is($ret, $bytes, "$this_name: Returns expected string")) {
-                            diag $call;
-                        }
-                    }
-                    if (! $do_warning
-                        && ($warning eq 'utf8' || $warning eq $category))
-                    {
-                        if (!is(scalar @warnings, 0,
-                                            "$this_name: No warnings generated"))
-                        {
-                            diag $call;
-                            diag "The warnings were: " . join(", ", @warnings);
-                        }
-                    }
-                    elsif ($uvchr_warn_flag
-                           && ($warning eq 'utf8' || $warning eq $category))
-                    {
-                        if (is(scalar @warnings, 1,
-                               "$this_name: Got a single warning "))
-                        {
-                            unless (like($warnings[0], $message,
+                            # Any overflow will override any super or above-31
+                            # warnings.
+                            goto no_warnings_expected if $will_overflow;
+
+                            if (    ! $do_warning
+                                && (   $warning eq 'utf8'
+                                    || $warning eq $category))
+                            {
+                                goto no_warnings_expected;
+                            }
+                            elsif ($warn_flag) {
+                                if (is(scalar @warnings, 1,
+                                    "$this_name: Got a single warning "))
+                                {
+                                    unless (like($warnings[0], $message,
                                             "$this_name: Got expected warning"))
+                                    {
+                                        diag $call;
+                                    }
+                                }
+                                else {
+                                    diag $call;
+                                    if (scalar @warnings) {
+                                        output_warnings(@warnings);
+                                    }
+                                }
+                            }
+                            else {
+                              no_warnings_expected:
+                                unless (is(scalar @warnings, 0,
+                                        "$this_name: Got no warnings"))
+                                {
+                                    diag $call;
+                                    output_warnings(@warnings);
+                                }
+                            }
+
+                            # Check CHECK_ONLY results when the input is
+                            # disallowed.  Do this when actually disallowed,
+                            # not just when the $disallow_flag is set
+                            if ($disallowed) {
+                                undef @warnings;
+                                $ret_ref = test_utf8n_to_uvchr_error(
+                                               $this_bytes, $this_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 -1 for"
+                                  . " length"))
+                                {
+                                    diag $call;
+                                }
+                                if (! is(scalar @warnings, 0,
+                                    "$this_name, CHECK_ONLY: no warnings"
+                                  . " generated"))
+                                {
+                                    diag $call;
+                                    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, and
+                            # isn't malformed.
+                            next if @malformations;
+
+                            # The warning and disallow flags passed in are for
+                            # utf8n_to_uvchr_error().  Convert them for
+                            # uvchr_to_utf8_flags().
+                            my $uvchr_warn_flag = 0;
+                            my $uvchr_disallow_flag = 0;
+                            if ($warn_flag) {
+                                if ($warn_flag == $UTF8_WARN_SURROGATE) {
+                                    $uvchr_warn_flag = $UNICODE_WARN_SURROGATE
+                                }
+                                elsif ($warn_flag == $UTF8_WARN_NONCHAR) {
+                                    $uvchr_warn_flag = $UNICODE_WARN_NONCHAR
+                                }
+                                elsif ($warn_flag == $UTF8_WARN_SUPER) {
+                                    $uvchr_warn_flag = $UNICODE_WARN_SUPER
+                                }
+                                elsif ($warn_flag == $UTF8_WARN_ABOVE_31_BIT) {
+                                    $uvchr_warn_flag
+                                                   = $UNICODE_WARN_ABOVE_31_BIT;
+                                }
+                                else {
+                                    fail(sprintf "Unexpected warn flag: %x",
+                                        $warn_flag);
+                                    next;
+                                }
+                            }
+                            if ($disallow_flag) {
+                                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_SUPER) {
+                                    $uvchr_disallow_flag
+                                                  = $UNICODE_DISALLOW_SUPER;
+                                }
+                                elsif ($disallow_flag
+                                                == $UTF8_DISALLOW_ABOVE_31_BIT)
+                                {
+                                    $uvchr_disallow_flag =
+                                                $UNICODE_DISALLOW_ABOVE_31_BIT;
+                                }
+                                else {
+                                    fail(sprintf "Unexpected disallow flag: %x",
+                                        $disallow_flag);
+                                    next;
+                                }
+                            }
+
+                            $disallowed = $uvchr_disallow_flag;
+
+                            $this_name = "uvchr_to_utf8_flags() $testname: "
+                                                    . (($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');
+
+                            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)";
+                            eval "$eval_text";
+                            if (! ok ("$@ eq ''", "$this_name: eval succeeded"))
                             {
-                                diag $call;
+                                diag "\$!='$!'; eval'd=\"$eval_text\"";
+                                next;
                             }
-                        }
-                        else {
-                            diag $call;
-                            if (scalar @warnings) {
-                                diag "The warnings were: "
-                                                        . join(", ", @warnings);
+                            if ($disallowed) {
+                                unless (is($ret, undef,
+                                        "$this_name: Returns undef"))
+                                {
+                                    diag $call;
+                                }
+                            }
+                            else {
+                                unless (is($ret, $bytes,
+                                        "$this_name: Returns expected string"))
+                                {
+                                    diag $call;
+                                }
+                            }
+                            if (! $do_warning
+                                && ($warning eq 'utf8' || $warning eq $category))
+                            {
+                                if (!is(scalar @warnings, 0,
+                                        "$this_name: No warnings generated"))
+                                {
+                                    diag $call;
+                                    output_warnings(@warnings);
+                                }
+                            }
+                            elsif (       $uvchr_warn_flag
+                                   && (   $warning eq 'utf8'
+                                       || $warning eq $category))
+                            {
+                                if (is(scalar @warnings, 1,
+                                    "$this_name: Got a single warning "))
+                                {
+                                    unless (like($warnings[0], $message,
+                                            "$this_name: Got expected warning"))
+                                    {
+                                        diag $call;
+                                    }
+                                }
+                                else {
+                                    diag $call;
+                                    output_warnings(@warnings)
+                                                        if scalar @warnings;
+                                }
                             }
                         }
                     }
@@ -2111,4 +2401,50 @@ foreach my $test (@tests) {
     }
 }
 
+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");
+    }
+}
+
 done_testing;