unicode_constants.pl: Generate paired string delimiters

This commit causes several C strings to be generated containing bytes
that match paired string delimiters beyond the four that have
traditionally been used in Perl.  This will allow a future commit to
accept more matching delimiters around strings than those four.

The code explains how the added delimiters are chosen.

2 files changed, 155 insertions, 4 deletions

diff --git a/regen/unicode_constants.pl b/regen/unicode_constants.pl
index 67bc75752d..ed7fa0e60e 100644
--- a/regen/unicode_constants.pl
+++ b/regen/unicode_constants.pl
@@ -1,9 +1,10 @@
 use v5.16.0;
 use strict;
 use warnings;
+no warnings 'experimental::regex_sets';
 require './regen/regen_lib.pl';
 require './regen/charset_translations.pl';
-use Unicode::UCD;
+use Unicode::UCD qw(prop_invlist prop_invmap);
 use charnames qw(:loose);
 
 my $out_fh = open_new('unicode_constants.h', '>',
@@ -85,7 +86,49 @@ print $out_fh <<END;
 
 END
 
-# The data are at __DATA__  in this file.
+# Gather the characters in Unicode that have left/right symmetry suitable for
+# paired string delimiters
+my %paireds = ( ord '<' =>  ord '>' );     # We don't normally use math ones, but
+                                        # this is traditionally included
+
+# This property is the universe of all characters in Unicode which
+# are of some import to the Bidirectional Algorithm, and for which there is
+# another Unicode character that is a mirror of it.
+my ($bmg_invlist, $bmg_invmap, $format, $bmg_default) =
+                                            prop_invmap("Bidi_Mirroring_Glyph");
+
+# The current list of characters that Perl considers to be paired
+# opening/closing delimiters is quite conservative, consisting of those
+# from the above property that other Unicode properties classify as
+# opening/closing.
+
+# Find the ones in the bmg list that Unicode thinks are opening ones.
+for (my $i = 0; $i < $bmg_invlist->@*; $i++) {
+    my $mirror_code_point = $bmg_invmap->[$i];
+    next if $mirror_code_point eq $bmg_default;   # Doesn't map to a character.
+
+    my $code_point = $bmg_invlist->[$i];
+
+    # Bidi_Paired_Bracket_Type=Open and General_Category=Open_Punctuation are
+    # definitely in the list.  It is language-dependent whether members of
+    # General_Category=Initial_Punctuation are considered opening or closing;
+    # we take what Unicode considers the more likely scenario.
+    if (chr($code_point) =~ /(?[ \p{BPT=Open}
+                               | \p{Gc=Open_Punctuation}
+                               | \p{Gc=Initial_Punctuation}
+                            ])/)
+    {
+        $paireds{$code_point} = $mirror_code_point;
+    }
+}
+
+# There are several hundred characters other characters that clearly should be
+# mirrors of each other, like LEFTWARDS ARROW and RIGHTWARDS ARROW.  Unicode
+# did not bother to classify them as mirrors mostly because they aren't of
+# import in the Bidirectional Algorithm.  Most of them are symbols.  These
+# are not considered opening/closing by Perl for now.
+
+# The rest of the data are at __DATA__  in this file.
 
 my @data = <DATA>;
 
@@ -178,6 +221,74 @@ foreach my $charset (get_supported_code_pages()) {
         printf $out_fh "#   define %s%s  %s    /* U+%04X */\n", $name, $suffix, $str, $U_cp;
     }
 
+    # Now output the strings of opening/closing delimiters.  The Unicode
+    # values were earlier entered into %paireds
+    my $utf8_opening = "";
+    my $utf8_closing = "";
+    my $non_utf8_opening = "";
+    my $non_utf8_closing = "";
+    my $deprecated_if_not_mirrored = "";
+    my $non_utf8_deprecated_if_not_mirrored = "";
+
+    for my $from (sort { $a <=> $b } keys %paireds) {
+        my $to = $paireds{$from};
+        my $utf8_from_backslashed = backslash_x_form($from, $charset);
+        my $utf8_to_backslashed   = backslash_x_form($to, $charset);
+        my $non_utf8_from_backslashed;
+        my $non_utf8_to_backslashed;
+
+        $utf8_opening .= $utf8_from_backslashed;
+        $utf8_closing .= $utf8_to_backslashed;
+
+        if ($from < 256) {
+            $non_utf8_from_backslashed =
+                                  backslash_x_form($from, $charset, 'not_utf8');
+            $non_utf8_to_backslashed =
+                                  backslash_x_form($to, $charset, 'not_utf8');
+
+            $non_utf8_opening .= $non_utf8_from_backslashed;
+            $non_utf8_closing .= $non_utf8_to_backslashed;
+        }
+
+        # Only the ASCII range paired delimiters have traditionally been
+        # accepted.  Until the feature is considered standard, the non-ASCII
+        # opening ones must be deprecated when the feature isn't in effect, so
+        # as to warn about behavior that is planned to change.
+        if ($from > 127) {
+            $deprecated_if_not_mirrored .= $utf8_from_backslashed;
+            $non_utf8_deprecated_if_not_mirrored .=
+                                    $non_utf8_from_backslashed if $from < 256;
+        }
+
+        # The implementing code in toke.c assumes that the byte length of each
+        # opening delimiter is the same as its mirrored closing one.  This
+        # makes sure of that by checking upon each iteration of the loop.
+        if (length $utf8_opening != length $utf8_closing) {
+            die "Byte length of representation of '"
+              .  charnames::viacode($from)
+              . " differs from its mapping '"
+              .  charnames::viacode($to)
+              .  "'";
+        }
+    }
+
+    print $out_fh <<~"EOT";
+
+        #   ifdef PERL_IN_TOKE_C
+               /* Paired characters for quote-like operators, in UTF-8 */
+        #      define EXTRA_OPENING_UTF8_BRACKETS "$utf8_opening"
+        #      define EXTRA_CLOSING_UTF8_BRACKETS "$utf8_closing"
+
+               /* And not in UTF-8 */
+        #      define EXTRA_OPENING_NON_UTF8_BRACKETS "$non_utf8_opening"
+        #      define EXTRA_CLOSING_NON_UTF8_BRACKETS "$non_utf8_closing"
+
+               /* And what's deprecated */
+        #      define DEPRECATED_OPENING_UTF8_BRACKETS "$deprecated_if_not_mirrored"
+        #      define DEPRECATED_OPENING_NON_UTF8_BRACKETS "$non_utf8_deprecated_if_not_mirrored"
+        #   endif
+        EOT
+
     my $max_PRINT_A = 0;
     for my $i (0x20 .. 0x7E) {
         $max_PRINT_A = $a2n[$i] if $a2n[$i] > $max_PRINT_A;
@@ -194,8 +305,6 @@ EOT
 
 }
 
-use Unicode::UCD 'prop_invlist';
-
 my $count = 0;
 my @other_invlist = prop_invlist("Other");
 for (my $i = 0; $i < @other_invlist; $i += 2) {
diff --git a/unicode_constants.h b/unicode_constants.h
index da240236d4..d588d5e8d8 100644
--- a/unicode_constants.h
+++ b/unicode_constants.h
@@ -89,6 +89,20 @@ bytes.
 #   define MICRO_SIGN_NATIVE  0xB5    /* U+00B5 */
 #   define MICRO_SIGN_UTF8  "\xC2\xB5"    /* U+00B5 */
 
+#   ifdef PERL_IN_TOKE_C
+       /* Paired characters for quote-like operators, in UTF-8 */
+#      define EXTRA_OPENING_UTF8_BRACKETS "\x28\x3C\x5B\x7B\xC2\xAB\xE0\xBC\xBA\xE0\xBC\xBC\xE1\x9A\x9B\xE2\x80\xB9\xE2\x81\x85\xE2\x81\xBD\xE2\x82\x8D\xE2\x8C\x88\xE2\x8C\x8A\xE2\x8C\xA9\xE2\x9D\xA8\xE2\x9D\xAA\xE2\x9D\xAC\xE2\x9D\xAE\xE2\x9D\xB0\xE2\x9D\xB2\xE2\x9D\xB4\xE2\x9F\x85\xE2\x9F\xA6\xE2\x9F\xA8\xE2\x9F\xAA\xE2\x9F\xAC\xE2\x9F\xAE\xE2\xA6\x83\xE2\xA6\x85\xE2\xA6\x87\xE2\xA6\x89\xE2\xA6\x8B\xE2\xA6\x8D\xE2\xA6\x8F\xE2\xA6\x91\xE2\xA6\x93\xE2\xA6\x95\xE2\xA6\x97\xE2\xA7\x98\xE2\xA7\x9A\xE2\xA7\xBC\xE2\xB8\x82\xE2\xB8\x84\xE2\xB8\x89\xE2\xB8\x8C\xE2\xB8\x9C\xE2\xB8\xA0\xE2\xB8\xA2\xE2\xB8\xA4\xE2\xB8\xA6\xE2\xB8\xA8\xE2\xB9\x95\xE2\xB9\x97\xE2\xB9\x99\xE2\xB9\x9B\xE3\x80\x88\xE3\x80\x8A\xE3\x80\x8C\xE3\x80\x8E\xE3\x80\x90\xE3\x80\x94\xE3\x80\x96\xE3\x80\x98\xE3\x80\x9A\xEF\xB9\x99\xEF\xB9\x9B\xEF\xB9\x9D\xEF\xBC\x88\xEF\xBC\xBB\xEF\xBD\x9B\xEF\xBD\x9F\xEF\xBD\xA2"
+#      define EXTRA_CLOSING_UTF8_BRACKETS "\x29\x3E\x5D\x7D\xC2\xBB\xE0\xBC\xBB\xE0\xBC\xBD\xE1\x9A\x9C\xE2\x80\xBA\xE2\x81\x86\xE2\x81\xBE\xE2\x82\x8E\xE2\x8C\x89\xE2\x8C\x8B\xE2\x8C\xAA\xE2\x9D\xA9\xE2\x9D\xAB\xE2\x9D\xAD\xE2\x9D\xAF\xE2\x9D\xB1\xE2\x9D\xB3\xE2\x9D\xB5\xE2\x9F\x86\xE2\x9F\xA7\xE2\x9F\xA9\xE2\x9F\xAB\xE2\x9F\xAD\xE2\x9F\xAF\xE2\xA6\x84\xE2\xA6\x86\xE2\xA6\x88\xE2\xA6\x8A\xE2\xA6\x8C\xE2\xA6\x90\xE2\xA6\x8E\xE2\xA6\x92\xE2\xA6\x94\xE2\xA6\x96\xE2\xA6\x98\xE2\xA7\x99\xE2\xA7\x9B\xE2\xA7\xBD\xE2\xB8\x83\xE2\xB8\x85\xE2\xB8\x8A\xE2\xB8\x8D\xE2\xB8\x9D\xE2\xB8\xA1\xE2\xB8\xA3\xE2\xB8\xA5\xE2\xB8\xA7\xE2\xB8\xA9\xE2\xB9\x96\xE2\xB9\x98\xE2\xB9\x9A\xE2\xB9\x9C\xE3\x80\x89\xE3\x80\x8B\xE3\x80\x8D\xE3\x80\x8F\xE3\x80\x91\xE3\x80\x95\xE3\x80\x97\xE3\x80\x99\xE3\x80\x9B\xEF\xB9\x9A\xEF\xB9\x9C\xEF\xB9\x9E\xEF\xBC\x89\xEF\xBC\xBD\xEF\xBD\x9D\xEF\xBD\xA0\xEF\xBD\xA3"
+
+       /* And not in UTF-8 */
+#      define EXTRA_OPENING_NON_UTF8_BRACKETS "\x28\x3C\x5B\x7B\xAB"
+#      define EXTRA_CLOSING_NON_UTF8_BRACKETS "\x29\x3E\x5D\x7D\xBB"
+
+       /* And what's deprecated */
+#      define DEPRECATED_OPENING_UTF8_BRACKETS "\xC2\xAB\xE0\xBC\xBA\xE0\xBC\xBC\xE1\x9A\x9B\xE2\x80\xB9\xE2\x81\x85\xE2\x81\xBD\xE2\x82\x8D\xE2\x8C\x88\xE2\x8C\x8A\xE2\x8C\xA9\xE2\x9D\xA8\xE2\x9D\xAA\xE2\x9D\xAC\xE2\x9D\xAE\xE2\x9D\xB0\xE2\x9D\xB2\xE2\x9D\xB4\xE2\x9F\x85\xE2\x9F\xA6\xE2\x9F\xA8\xE2\x9F\xAA\xE2\x9F\xAC\xE2\x9F\xAE\xE2\xA6\x83\xE2\xA6\x85\xE2\xA6\x87\xE2\xA6\x89\xE2\xA6\x8B\xE2\xA6\x8D\xE2\xA6\x8F\xE2\xA6\x91\xE2\xA6\x93\xE2\xA6\x95\xE2\xA6\x97\xE2\xA7\x98\xE2\xA7\x9A\xE2\xA7\xBC\xE2\xB8\x82\xE2\xB8\x84\xE2\xB8\x89\xE2\xB8\x8C\xE2\xB8\x9C\xE2\xB8\xA0\xE2\xB8\xA2\xE2\xB8\xA4\xE2\xB8\xA6\xE2\xB8\xA8\xE2\xB9\x95\xE2\xB9\x97\xE2\xB9\x99\xE2\xB9\x9B\xE3\x80\x88\xE3\x80\x8A\xE3\x80\x8C\xE3\x80\x8E\xE3\x80\x90\xE3\x80\x94\xE3\x80\x96\xE3\x80\x98\xE3\x80\x9A\xEF\xB9\x99\xEF\xB9\x9B\xEF\xB9\x9D\xEF\xBC\x88\xEF\xBC\xBB\xEF\xBD\x9B\xEF\xBD\x9F\xEF\xBD\xA2"
+#      define DEPRECATED_OPENING_NON_UTF8_BRACKETS "\xAB"
+#   endif
+
 #   ifdef PERL_IN_REGCOMP_C
 #     define MAX_PRINT_A  0x7E   /* The max code point that isPRINT_A */
 #   endif
@@ -136,6 +150,20 @@ bytes.
 #   define MICRO_SIGN_NATIVE  0xA0    /* U+00B5 */
 #   define MICRO_SIGN_UTF8  "\x80\x64"    /* U+00B5 */
 
+#   ifdef PERL_IN_TOKE_C
+       /* Paired characters for quote-like operators, in UTF-8 */
+#      define EXTRA_OPENING_UTF8_BRACKETS "\x4D\x4C\xAD\xC0\x80\x52\xBA\x68\x69\xBA\x68\x70\xBC\x63\x6A\xCA\x42\x68\xCA\x43\x46\xCA\x44\x71\xCA\x45\x54\xCA\x67\x49\xCA\x67\x51\xCA\x68\x4A\xCB\x6A\x49\xCB\x6A\x51\xCB\x6A\x53\xCB\x6A\x55\xCB\x6A\x57\xCB\x6A\x59\xCB\x6A\x63\xCB\x72\x46\xCB\x73\x47\xCB\x73\x49\xCB\x73\x51\xCB\x73\x53\xCB\x73\x55\xCC\x53\x44\xCC\x53\x46\xCC\x53\x48\xCC\x53\x4A\xCC\x53\x52\xCC\x53\x54\xCC\x53\x56\xCC\x53\x58\xCC\x53\x62\xCC\x53\x64\xCC\x53\x66\xCC\x55\x67\xCC\x55\x69\xCC\x56\x70\xCD\x57\x43\xCD\x57\x45\xCD\x57\x4A\xCD\x57\x53\xCD\x57\x70\xCD\x58\x41\xCD\x58\x43\xCD\x58\x45\xCD\x58\x47\xCD\x58\x49\xCD\x59\x64\xCD\x59\x66\xCD\x59\x68\xCD\x59\x6A\xCE\x41\x49\xCE\x41\x51\xCE\x41\x53\xCE\x41\x55\xCE\x41\x57\xCE\x41\x63\xCE\x41\x65\xCE\x41\x67\xCE\x41\x69\xDD\x73\x59\x68\xDD\x73\x59\x6A\xDD\x73\x59\x71\xDD\x73\x67\x49\xDD\x73\x68\x6A\xDD\x73\x69\x6A\xDD\x73\x69\x73\xDD\x73\x6A\x43"
+#      define EXTRA_CLOSING_UTF8_BRACKETS "\x5D\x6E\xBD\xD0\x80\x6A\xBA\x68\x6A\xBA\x68\x71\xBC\x63\x70\xCA\x42\x69\xCA\x43\x47\xCA\x44\x72\xCA\x45\x55\xCA\x67\x4A\xCA\x67\x52\xCA\x68\x51\xCB\x6A\x4A\xCB\x6A\x52\xCB\x6A\x54\xCB\x6A\x56\xCB\x6A\x58\xCB\x6A\x62\xCB\x6A\x64\xCB\x72\x47\xCB\x73\x48\xCB\x73\x4A\xCB\x73\x52\xCB\x73\x54\xCB\x73\x56\xCC\x53\x45\xCC\x53\x47\xCC\x53\x49\xCC\x53\x51\xCC\x53\x53\xCC\x53\x57\xCC\x53\x55\xCC\x53\x59\xCC\x53\x63\xCC\x53\x65\xCC\x53\x67\xCC\x55\x68\xCC\x55\x6A\xCC\x56\x71\xCD\x57\x44\xCD\x57\x46\xCD\x57\x51\xCD\x57\x54\xCD\x57\x71\xCD\x58\x42\xCD\x58\x44\xCD\x58\x46\xCD\x58\x48\xCD\x58\x4A\xCD\x59\x65\xCD\x59\x67\xCD\x59\x69\xCD\x59\x70\xCE\x41\x4A\xCE\x41\x52\xCE\x41\x54\xCE\x41\x56\xCE\x41\x58\xCE\x41\x64\xCE\x41\x66\xCE\x41\x68\xCE\x41\x6A\xDD\x73\x59\x69\xDD\x73\x59\x70\xDD\x73\x59\x72\xDD\x73\x67\x4A\xDD\x73\x68\x71\xDD\x73\x69\x71\xDD\x73\x6A\x41\xDD\x73\x6A\x44"
+
+       /* And not in UTF-8 */
+#      define EXTRA_OPENING_NON_UTF8_BRACKETS "\x4D\x4C\xAD\xC0\x8A"
+#      define EXTRA_CLOSING_NON_UTF8_BRACKETS "\x5D\x6E\xBD\xD0\x8B"
+
+       /* And what's deprecated */
+#      define DEPRECATED_OPENING_UTF8_BRACKETS "\x80\x52\xBA\x68\x69\xBA\x68\x70\xBC\x63\x6A\xCA\x42\x68\xCA\x43\x46\xCA\x44\x71\xCA\x45\x54\xCA\x67\x49\xCA\x67\x51\xCA\x68\x4A\xCB\x6A\x49\xCB\x6A\x51\xCB\x6A\x53\xCB\x6A\x55\xCB\x6A\x57\xCB\x6A\x59\xCB\x6A\x63\xCB\x72\x46\xCB\x73\x47\xCB\x73\x49\xCB\x73\x51\xCB\x73\x53\xCB\x73\x55\xCC\x53\x44\xCC\x53\x46\xCC\x53\x48\xCC\x53\x4A\xCC\x53\x52\xCC\x53\x54\xCC\x53\x56\xCC\x53\x58\xCC\x53\x62\xCC\x53\x64\xCC\x53\x66\xCC\x55\x67\xCC\x55\x69\xCC\x56\x70\xCD\x57\x43\xCD\x57\x45\xCD\x57\x4A\xCD\x57\x53\xCD\x57\x70\xCD\x58\x41\xCD\x58\x43\xCD\x58\x45\xCD\x58\x47\xCD\x58\x49\xCD\x59\x64\xCD\x59\x66\xCD\x59\x68\xCD\x59\x6A\xCE\x41\x49\xCE\x41\x51\xCE\x41\x53\xCE\x41\x55\xCE\x41\x57\xCE\x41\x63\xCE\x41\x65\xCE\x41\x67\xCE\x41\x69\xDD\x73\x59\x68\xDD\x73\x59\x6A\xDD\x73\x59\x71\xDD\x73\x67\x49\xDD\x73\x68\x6A\xDD\x73\x69\x6A\xDD\x73\x69\x73\xDD\x73\x6A\x43"
+#      define DEPRECATED_OPENING_NON_UTF8_BRACKETS "\x8A"
+#   endif
+
 #   ifdef PERL_IN_REGCOMP_C
 #     define MAX_PRINT_A  0xF9   /* The max code point that isPRINT_A */
 #   endif
@@ -183,6 +211,20 @@ bytes.
 #   define MICRO_SIGN_NATIVE  0xA0    /* U+00B5 */
 #   define MICRO_SIGN_UTF8  "\x78\x63"    /* U+00B5 */
 
+#   ifdef PERL_IN_TOKE_C
+       /* Paired characters for quote-like operators, in UTF-8 */
+#      define EXTRA_OPENING_UTF8_BRACKETS "\x4D\x4C\xBA\xC0\x78\x52\xB9\x67\x68\xB9\x67\x6A\xBD\x62\x69\xCA\x42\x67\xCA\x43\x46\xCA\x44\x70\xCA\x45\x54\xCA\x66\x49\xCA\x66\x51\xCA\x67\x4A\xCB\x69\x49\xCB\x69\x51\xCB\x69\x53\xCB\x69\x55\xCB\x69\x57\xCB\x69\x59\xCB\x69\x62\xCB\x71\x46\xCB\x72\x47\xCB\x72\x49\xCB\x72\x51\xCB\x72\x53\xCB\x72\x55\xCC\x53\x44\xCC\x53\x46\xCC\x53\x48\xCC\x53\x4A\xCC\x53\x52\xCC\x53\x54\xCC\x53\x56\xCC\x53\x58\xCC\x53\x5F\xCC\x53\x63\xCC\x53\x65\xCC\x55\x66\xCC\x55\x68\xCC\x56\x6A\xCD\x57\x43\xCD\x57\x45\xCD\x57\x4A\xCD\x57\x53\xCD\x57\x6A\xCD\x58\x41\xCD\x58\x43\xCD\x58\x45\xCD\x58\x47\xCD\x58\x49\xCD\x59\x63\xCD\x59\x65\xCD\x59\x67\xCD\x59\x69\xCE\x41\x49\xCE\x41\x51\xCE\x41\x53\xCE\x41\x55\xCE\x41\x57\xCE\x41\x62\xCE\x41\x64\xCE\x41\x66\xCE\x41\x68\xDD\x72\x59\x67\xDD\x72\x59\x69\xDD\x72\x59\x70\xDD\x72\x66\x49\xDD\x72\x67\x69\xDD\x72\x68\x69\xDD\x72\x68\x72\xDD\x72\x69\x43"
+#      define EXTRA_CLOSING_UTF8_BRACKETS "\x5D\x6E\xBB\xD0\x78\x69\xB9\x67\x69\xB9\x67\x70\xBD\x62\x6A\xCA\x42\x68\xCA\x43\x47\xCA\x44\x71\xCA\x45\x55\xCA\x66\x4A\xCA\x66\x52\xCA\x67\x51\xCB\x69\x4A\xCB\x69\x52\xCB\x69\x54\xCB\x69\x56\xCB\x69\x58\xCB\x69\x5F\xCB\x69\x63\xCB\x71\x47\xCB\x72\x48\xCB\x72\x4A\xCB\x72\x52\xCB\x72\x54\xCB\x72\x56\xCC\x53\x45\xCC\x53\x47\xCC\x53\x49\xCC\x53\x51\xCC\x53\x53\xCC\x53\x57\xCC\x53\x55\xCC\x53\x59\xCC\x53\x62\xCC\x53\x64\xCC\x53\x66\xCC\x55\x67\xCC\x55\x69\xCC\x56\x70\xCD\x57\x44\xCD\x57\x46\xCD\x57\x51\xCD\x57\x54\xCD\x57\x70\xCD\x58\x42\xCD\x58\x44\xCD\x58\x46\xCD\x58\x48\xCD\x58\x4A\xCD\x59\x64\xCD\x59\x66\xCD\x59\x68\xCD\x59\x6A\xCE\x41\x4A\xCE\x41\x52\xCE\x41\x54\xCE\x41\x56\xCE\x41\x58\xCE\x41\x63\xCE\x41\x65\xCE\x41\x67\xCE\x41\x69\xDD\x72\x59\x68\xDD\x72\x59\x6A\xDD\x72\x59\x71\xDD\x72\x66\x4A\xDD\x72\x67\x70\xDD\x72\x68\x70\xDD\x72\x69\x41\xDD\x72\x69\x44"
+
+       /* And not in UTF-8 */
+#      define EXTRA_OPENING_NON_UTF8_BRACKETS "\x4D\x4C\xBA\xC0\x8A"
+#      define EXTRA_CLOSING_NON_UTF8_BRACKETS "\x5D\x6E\xBB\xD0\x8B"
+
+       /* And what's deprecated */
+#      define DEPRECATED_OPENING_UTF8_BRACKETS "\x78\x52\xB9\x67\x68\xB9\x67\x6A\xBD\x62\x69\xCA\x42\x67\xCA\x43\x46\xCA\x44\x70\xCA\x45\x54\xCA\x66\x49\xCA\x66\x51\xCA\x67\x4A\xCB\x69\x49\xCB\x69\x51\xCB\x69\x53\xCB\x69\x55\xCB\x69\x57\xCB\x69\x59\xCB\x69\x62\xCB\x71\x46\xCB\x72\x47\xCB\x72\x49\xCB\x72\x51\xCB\x72\x53\xCB\x72\x55\xCC\x53\x44\xCC\x53\x46\xCC\x53\x48\xCC\x53\x4A\xCC\x53\x52\xCC\x53\x54\xCC\x53\x56\xCC\x53\x58\xCC\x53\x5F\xCC\x53\x63\xCC\x53\x65\xCC\x55\x66\xCC\x55\x68\xCC\x56\x6A\xCD\x57\x43\xCD\x57\x45\xCD\x57\x4A\xCD\x57\x53\xCD\x57\x6A\xCD\x58\x41\xCD\x58\x43\xCD\x58\x45\xCD\x58\x47\xCD\x58\x49\xCD\x59\x63\xCD\x59\x65\xCD\x59\x67\xCD\x59\x69\xCE\x41\x49\xCE\x41\x51\xCE\x41\x53\xCE\x41\x55\xCE\x41\x57\xCE\x41\x62\xCE\x41\x64\xCE\x41\x66\xCE\x41\x68\xDD\x72\x59\x67\xDD\x72\x59\x69\xDD\x72\x59\x70\xDD\x72\x66\x49\xDD\x72\x67\x69\xDD\x72\x68\x69\xDD\x72\x68\x72\xDD\x72\x69\x43"
+#      define DEPRECATED_OPENING_NON_UTF8_BRACKETS "\x8A"
+#   endif
+
 #   ifdef PERL_IN_REGCOMP_C
 #     define MAX_PRINT_A  0xF9   /* The max code point that isPRINT_A */
 #   endif