X-Git-Url: https://perl5.git.perl.org/perl5.git/blobdiff_plain/0b657b1955a40e49c93ca32fe32822f4a8a5205b..6ebc34314145790ccf2ee69fd21fa67f41e4db5e:/regen/feature.pl

diff --git a/regen/feature.pl b/regen/feature.pl
index 667f524..d315253 100755
--- a/regen/feature.pl
+++ b/regen/feature.pl
@@ -11,32 +11,40 @@
 # This script is normally invoked from regen.pl.
 
 BEGIN {
-    require './regen/regen_lib.pl';
     push @INC, './lib';
+    require './regen/regen_lib.pl';
+    require './regen/HeaderParser.pm';
 }
-use strict ;
 
+use strict;
+use warnings;
 
 ###########################################################################
 # Hand-editable data
 
 # (feature name) => (internal name, used in %^H and macro names)
 my %feature = (
-    say             => 'say',
-    state           => 'state',
-    switch          => 'switch',
-    bitwise         => 'bitwise',
-    evalbytes       => 'evalbytes',
-    current_sub     => '__SUB__',
-    refaliasing     => 'refaliasing',
-    postderef_qq    => 'postderef_qq',
-    unicode_eval    => 'unieval',
-    declared_refs   => 'myref',
-    unicode_strings => 'unicode',
-    fc              => 'fc',
-    signatures      => 'signatures',
-    isa             => 'isa',
-    indirect        => 'indirect',
+    say                     => 'say',
+    state                   => 'state',
+    switch                  => 'switch',
+    bitwise                 => 'bitwise',
+    evalbytes               => 'evalbytes',
+    current_sub             => '__SUB__',
+    refaliasing             => 'refaliasing',
+    postderef_qq            => 'postderef_qq',
+    unicode_eval            => 'unieval',
+    declared_refs           => 'myref',
+    unicode_strings         => 'unicode',
+    fc                      => 'fc',
+    signatures              => 'signatures',
+    isa                     => 'isa',
+    indirect                => 'indirect',
+    multidimensional        => 'multidimensional',
+    bareword_filehandles    => 'bareword_filehandles',
+    try                     => 'try',
+    defer                   => 'defer',
+    extra_paired_delimiters => 'more_delims',
+    module_true             => 'module_true',
 );
 
 # NOTE: If a feature is ever enabled in a non-contiguous range of Perl
@@ -44,31 +52,49 @@ my %feature = (
 #       be changed to account.
 
 # 5.odd implies the next 5.even, but an explicit 5.even can override it.
+
+# features bundles
+use constant V5_9_5 => sort qw{say state switch indirect multidimensional bareword_filehandles};
+use constant V5_11  => sort ( +V5_9_5, qw{unicode_strings} );
+use constant V5_15  => sort ( +V5_11, qw{unicode_eval evalbytes current_sub fc} );
+use constant V5_23  => sort ( +V5_15, qw{postderef_qq} );
+use constant V5_27  => sort ( +V5_23, qw{bitwise} );
+
+use constant V5_35  => sort grep {; $_ ne 'switch'
+                                 && $_ ne 'indirect'
+                                 && $_ ne 'multidimensional' } +V5_27, qw{isa signatures};
+
+use constant V5_37  => sort grep {; $_ ne 'bareword_filehandles' } +V5_35, qw{module_true};
+
+#
+# when updating features please also update the Pod entry for L</"FEATURES CHEAT SHEET">
+#
 my %feature_bundle = (
-     all     => [ keys %feature ],
-     default =>	[qw(indirect)],
-    "5.9.5"  =>	[qw(say state switch indirect)],
-    "5.10"   =>	[qw(say state switch indirect)],
-    "5.11"   =>	[qw(say state switch unicode_strings indirect)],
-    "5.13"   =>	[qw(say state switch unicode_strings indirect)],
-    "5.15"   =>	[qw(say state switch unicode_strings unicode_eval
-		    evalbytes current_sub fc indirect)],
-    "5.17"   =>	[qw(say state switch unicode_strings unicode_eval
-		    evalbytes current_sub fc indirect)],
-    "5.19"   =>	[qw(say state switch unicode_strings unicode_eval
-		    evalbytes current_sub fc indirect)],
-    "5.21"   =>	[qw(say state switch unicode_strings unicode_eval
-		    evalbytes current_sub fc indirect)],
-    "5.23"   =>	[qw(say state switch unicode_strings unicode_eval
-		    evalbytes current_sub fc postderef_qq indirect)],
-    "5.25"   =>	[qw(say state switch unicode_strings unicode_eval
-		    evalbytes current_sub fc postderef_qq indirect)],
-    "5.27"   =>	[qw(say state switch unicode_strings unicode_eval
-		    evalbytes current_sub fc postderef_qq bitwise indirect)],
-    "5.29"   =>	[qw(say state switch unicode_strings unicode_eval
-		    evalbytes current_sub fc postderef_qq bitwise indirect)],
-    "5.31"   =>	[qw(say state switch unicode_strings unicode_eval
-		    evalbytes current_sub fc postderef_qq bitwise indirect)],
+    all     => [ sort keys %feature ],
+    default => [ qw{indirect multidimensional bareword_filehandles} ],
+    # using 5.9.5 features bundle
+    "5.9.5" => [ +V5_9_5 ],
+    "5.10"  => [ +V5_9_5 ],
+    # using 5.11 features bundle
+    "5.11"  => [ +V5_11 ],
+    "5.13"  => [ +V5_11 ],
+    # using 5.15 features bundle
+    "5.15"  => [ +V5_15 ],
+    "5.17"  => [ +V5_15 ],
+    "5.19"  => [ +V5_15 ],
+    "5.21"  => [ +V5_15 ],
+    # using 5.23 features bundle
+    "5.23"  => [ +V5_23 ],
+    "5.25"  => [ +V5_23 ],
+    # using 5.27 features bundle
+    "5.27"  => [ +V5_27 ],
+    "5.29"  => [ +V5_27 ],
+    "5.31"  => [ +V5_27 ],
+    "5.33"  => [ +V5_27 ],
+    # using 5.35 features bundle
+    "5.35"  => [ +V5_35 ],
+    # using 5.37 features bundle
+    "5.37"  => [ +V5_37 ],
 );
 
 my @noops = qw( postderef lexical_subs );
@@ -125,12 +151,15 @@ for my $bund (
 my $HintShift;
 my $HintMask;
 my $Uni8Bit;
+my $hp = HeaderParser->new()->read_file("perl.h");
 
-open "perl.h", "<", "perl.h" or die "$0 cannot open perl.h: $!";
-while (readline "perl.h") {
-    next unless /#\s*define\s+(HINT_FEATURE_MASK|HINT_UNI_8_BIT)/;
+foreach my $line_data (@{$hp->lines}) {
+    next unless $line_data->{type} eq "content"
+            and $line_data->{sub_type} eq "#define";
+    my $line = $line_data->{line};
+    next unless $line=~/^\s*#\s*define\s+(HINT_FEATURE_MASK|HINT_UNI_8_BIT)/;
     my $is_u8b = $1 =~ 8;
-    /(0x[A-Fa-f0-9]+)/ or die "No hex number in:\n\n$_\n ";
+    $line=~/(0x[A-Fa-f0-9]+)/ or die "No hex number in:\n\n$line\n ";
     if ($is_u8b) {
 	$Uni8Bit = $1;
     }
@@ -138,21 +167,19 @@ while (readline "perl.h") {
 	my $hex = $HintMask = $1;
 	my $bits = sprintf "%b", oct $1;
 	$bits =~ /^0*1+(0*)\z/
-	 or die "Non-contiguous bits in $bits (binary for $hex):\n\n$_\n ";
+         or die "Non-contiguous bits in $bits (binary for $hex):\n\n$line\n ";
 	$HintShift = length $1;
 	my $bits_needed =
 	    length sprintf "%b", scalar keys %UniqueBundles;
 	$bits =~ /1{$bits_needed}/
 	    or die "Not enough bits (need $bits_needed)"
-		 . " in $bits (binary for $hex):\n\n$_\n ";
+                 . " in $bits (binary for $hex):\n\n$line\n ";
     }
     if ($Uni8Bit && $HintMask) { last }
 }
 die "No HINT_FEATURE_MASK defined in perl.h" unless $HintMask;
 die "No HINT_UNI_8_BIT defined in perl.h"    unless $Uni8Bit;
 
-close "perl.h";
-
 my @HintedBundles =
     ('default', grep !/[^\d.]/, sort values %UniqueBundles);
 
@@ -281,8 +308,13 @@ for (@HintedBundles) {
 print $h <<'EOH';
 #define FEATURE_BUNDLE_CUSTOM	(HINT_FEATURE_MASK >> HINT_FEATURE_SHIFT)
 
-#define CURRENT_HINTS \
+/* this is preserved for testing and asserts */
+#define OLD_CURRENT_HINTS \
     (PL_curcop == &PL_compiling ? PL_hints : PL_curcop->cop_hints)
+/* this is the same thing, but simpler (no if) as PL_hints expands
+   to PL_compiling.cop_hints */
+#define CURRENT_HINTS \
+    PL_curcop->cop_hints
 #define CURRENT_FEATURE_BUNDLE \
     ((CURRENT_HINTS & HINT_FEATURE_MASK) >> HINT_FEATURE_SHIFT)
 
@@ -468,32 +500,35 @@ read_only_bottom_close_and_rename($h);
 
 __END__
 package feature;
-
-our $VERSION = '1.58';
+our $VERSION = '1.78';
 
 FEATURES
 
 # TODO:
 # - think about versioned features (use feature switch => 2)
 
+=encoding utf8
+
 =head1 NAME
 
 feature - Perl pragma to enable new features
 
 =head1 SYNOPSIS
 
-    use feature qw(say switch);
-    given ($foo) {
-        when (1)          { say "\$foo == 1" }
-        when ([2,3])      { say "\$foo == 2 || \$foo == 3" }
-        when (/^a[bc]d$/) { say "\$foo eq 'abd' || \$foo eq 'acd'" }
-        when ($_ > 100)   { say "\$foo > 100" }
-        default           { say "None of the above" }
-    }
+    use feature qw(fc say);
+
+    # Without the "use feature" above, this code would not be able to find
+    # the built-ins "say" or "fc":
+    say "The case-folded version of $x is: " . fc $x;
 
-    use feature ':5.10'; # loads all features available in perl 5.10
 
-    use v5.10;           # implicitly loads :5.10 feature bundle
+    # set features to match the :5.36 bundle, which may turn off or on
+    # multiple features (see "FEATURE BUNDLES" below)
+    use feature ':5.36';
+
+
+    # implicitly loads :5.36 feature bundle
+    use v5.36;
 
 =head1 DESCRIPTION
 
@@ -535,9 +570,11 @@ disable I<all> features (an unusual request!) use C<no feature ':all'>.
 
 =head1 AVAILABLE FEATURES
 
+Read L</"FEATURE BUNDLES"> for the feature cheat sheet summary.
+
 =head2 The 'say' feature
 
-C<use feature 'say'> tells the compiler to enable the Perl 6 style
+C<use feature 'say'> tells the compiler to enable the Raku-inspired
 C<say> function.
 
 See L<perlfunc/say> for details.
@@ -555,13 +592,13 @@ This feature is available starting with Perl 5.10.
 
 =head2 The 'switch' feature
 
-B<WARNING>: Because the L<smartmatch operator|perlop/"Smartmatch Operator"> is
-experimental, Perl will warn when you use this feature, unless you have
-explicitly disabled the warning:
+B<WARNING>: This feature is still experimental and the implementation may
+change or be removed in future versions of Perl.  For this reason, Perl will
+warn when you use the feature, unless you have explicitly disabled the warning:
 
     no warnings "experimental::smartmatch";
 
-C<use feature 'switch'> tells the compiler to enable the Perl 6
+C<use feature 'switch'> tells the compiler to enable the Raku
 given/when construct.
 
 See L<perlsyn/"Switch Statements"> for details.
@@ -604,8 +641,8 @@ couldn't be changed without breaking some things that had come to rely on
 them, so the feature can be enabled and disabled.  Details are at
 L<perlfunc/Under the "unicode_eval" feature>.
 
-C<evalbytes> is like string C<eval>, but operating on a byte stream that is
-not UTF-8 encoded.  Details are at L<perlfunc/evalbytes EXPR>.  Without a
+C<evalbytes> is like string C<eval>, but it treats its argument as a byte
+string. Details are at L<perlfunc/evalbytes EXPR>.  Without a
 S<C<use feature 'evalbytes'>> nor a S<C<use v5.16>> (or higher) declaration in
 the current scope, you can still access it by instead writing
 C<CORE::evalbytes>.
@@ -657,9 +694,10 @@ regardless of what feature declarations are in scope.
 =head2 The 'postderef' and 'postderef_qq' features
 
 The 'postderef_qq' feature extends the applicability of L<postfix
-dereference syntax|perlref/Postfix Dereference Syntax> so that postfix array
-and scalar dereference are available in double-quotish interpolations. For
-example, it makes the following two statements equivalent:
+dereference syntax|perlref/Postfix Dereference Syntax> so that
+postfix array dereference, postfix scalar dereference, and
+postfix array highest index access are available in double-quotish interpolations.
+For example, it makes the following two statements equivalent:
 
   my $s = "[@{ $h->{a} }]";
   my $s = "[$h->{a}->@*]";
@@ -683,30 +721,33 @@ regardless of what feature declarations are in scope.
 
 =head2 The 'signatures' feature
 
-B<WARNING>: This feature is still experimental and the implementation may
-change in future versions of Perl.  For this reason, Perl will
-warn when you use the feature, unless you have explicitly disabled the
-warning:
-
-    no warnings "experimental::signatures";
-
-This enables unpacking of subroutine arguments into lexical variables
-by syntax such as
+This enables syntax for declaring subroutine arguments as lexical variables.
+For example, for this subroutine:
 
     sub foo ($left, $right) {
-	return $left + $right;
+        return $left + $right;
     }
 
+Calling C<foo(3, 7)> will assign C<3> into C<$left> and C<7> into C<$right>.
+
 See L<perlsub/Signatures> for details.
 
-This feature is available from Perl 5.20 onwards.
+This feature is available from Perl 5.20 onwards. From Perl 5.20 to 5.34,
+it was classed as experimental, and Perl emitted a warning for its usage,
+except when explicitly disabled:
+
+  no warnings "experimental::signatures";
+
+As of Perl 5.36, use of this feature no longer triggers a warning, though the
+C<experimental::signatures> warning category still exists (for compatibility
+with code that disables it). This feature is now considered stable, and is
+enabled automatically by C<use v5.36> (or higher).
 
 =head2 The 'refaliasing' feature
 
 B<WARNING>: This feature is still experimental and the implementation may
-change in future versions of Perl.  For this reason, Perl will
-warn when you use the feature, unless you have explicitly disabled the
-warning:
+change or be removed in future versions of Perl.  For this reason, Perl will
+warn when you use the feature, unless you have explicitly disabled the warning:
 
     no warnings "experimental::refaliasing";
 
@@ -741,9 +782,8 @@ category.
 =head2 The 'declared_refs' feature
 
 B<WARNING>: This feature is still experimental and the implementation may
-change in future versions of Perl.  For this reason, Perl will
-warn when you use the feature, unless you have explicitly disabled the
-warning:
+change or be removed in future versions of Perl.  For this reason, Perl will
+warn when you use the feature, unless you have explicitly disabled the warning:
 
     no warnings "experimental::declared_refs";
 
@@ -760,7 +800,16 @@ This allows the use of the C<isa> infix operator, which tests whether the
 scalar given by the left operand is an object of the class given by the
 right operand. See L<perlop/Class Instance Operator> for more details.
 
-This feature is available from Perl 5.32 onwards.
+This feature is available from Perl 5.32 onwards.  From Perl 5.32 to 5.34,
+it was classed as experimental, and Perl emitted a warning for its usage,
+except when explicitly disabled:
+
+    no warnings "experimental::isa";
+
+As of Perl 5.36, use of this feature no longer triggers a warning (though the
+C<experimental::isa> warning category stilll exists for compatibility with
+code that disables it). This feature is now considered stable, and is enabled
+automatically by C<use v5.36> (or higher).
 
 =head2 The 'indirect' feature
 
@@ -774,6 +823,481 @@ previous versions, it was simply on all the time.  To disallow (or
 warn on) indirect object syntax on older Perls, see the L<indirect>
 CPAN module.
 
+=head2 The 'multidimensional' feature
+
+This feature enables multidimensional array emulation, a perl 4 (or
+earlier) feature that was used to emulate multidimensional arrays with
+hashes.  This works by converting code like C<< $foo{$x, $y} >> into
+C<< $foo{join($;, $x, $y)} >>.  It is enabled by default, but can be
+turned off to disable multidimensional array emulation.
+
+When this feature is disabled the syntax that is normally replaced
+will report a compilation error.
+
+This feature is available under this name from Perl 5.34 onwards. In
+previous versions, it was simply on all the time.
+
+You can use the L<multidimensional> module on CPAN to disable
+multidimensional array emulation for older versions of Perl.
+
+=head2 The 'bareword_filehandles' feature
+
+This feature enables bareword filehandles for builtin functions
+operations, a generally discouraged practice.  It is enabled by
+default, but can be turned off to disable bareword filehandles, except
+for the exceptions listed below.
+
+The perl built-in filehandles C<STDIN>, C<STDOUT>, C<STDERR>, C<DATA>,
+C<ARGV>, C<ARGVOUT> and the special C<_> are always enabled.
+
+This feature is enabled under this name from Perl 5.34 onwards.  In
+previous versions it was simply on all the time.
+
+You can use the L<bareword::filehandles> module on CPAN to disable
+bareword filehandles for older versions of perl.
+
+=head2 The 'try' feature.
+
+B<WARNING>: This feature is still experimental and the implementation may
+change or be removed in future versions of Perl.  For this reason, Perl will
+warn when you use the feature, unless you have explicitly disabled the warning:
+
+    no warnings "experimental::try";
+
+This feature enables the C<try> and C<catch> syntax, which allows exception
+handling, where exceptions thrown from the body of the block introduced with
+C<try> are caught by executing the body of the C<catch> block.
+
+For more information, see L<perlsyn/"Try Catch Exception Handling">.
+
+=head2 The 'defer' feature
+
+B<WARNING>: This feature is still experimental and the implementation may
+change or be removed in future versions of Perl.  For this reason, Perl will
+warn when you use the feature, unless you have explicitly disabled the warning:
+
+    no warnings "experimental::defer";
+
+This feature enables the C<defer> block syntax, which allows a block of code
+to be deferred until when the flow of control leaves the block which contained
+it. For more details, see L<perlsyn/defer>.
+
+=head2 The 'extra_paired_delimiters' feature
+
+B<WARNING>: This feature is still experimental and the implementation may
+change or be removed in future versions of Perl.  For this reason, Perl will
+warn when you use the feature, unless you have explicitly disabled the warning:
+
+    no warnings "experimental::extra_paired_delimiters";
+
+This feature enables the use of more paired string delimiters than the
+traditional four, S<C<< <  > >>>, S<C<( )>>, S<C<{ }>>, and S<C<[ ]>>.  When
+this feature is on, for example, you can say S<C<qrE<171>patE<187>>>.
+
+As with any usage of non-ASCII delimiters in a UTF-8-encoded source file, you
+will want to ensure the parser will decode the source code from UTF-8 bytes
+with a declaration such as C<use utf8>.
+
+This feature is available starting in Perl 5.36.
+
+The complete list of accepted paired delimiters as of Unicode 14.0 is:
+
+ (  )    U+0028, U+0029   LEFT/RIGHT PARENTHESIS
+ <  >    U+003C, U+003E   LESS-THAN/GREATER-THAN SIGN
+ [  ]    U+005B, U+005D   LEFT/RIGHT SQUARE BRACKET
+ {  }    U+007B, U+007D   LEFT/RIGHT CURLY BRACKET
+ «  »    U+00AB, U+00BB   LEFT/RIGHT-POINTING DOUBLE ANGLE QUOTATION MARK
+ »  «    U+00BB, U+00AB   RIGHT/LEFT-POINTING DOUBLE ANGLE QUOTATION MARK
+ ܆  ܇    U+0706, U+0707   SYRIAC COLON SKEWED LEFT/RIGHT
+ ༺  ༻    U+0F3A, U+0F3B   TIBETAN MARK GUG RTAGS GYON,  TIBETAN MARK GUG
+                          RTAGS GYAS
+ ༼  ༽    U+0F3C, U+0F3D   TIBETAN MARK ANG KHANG GYON,  TIBETAN MARK ANG
+                          KHANG GYAS
+ ᚛  ᚜    U+169B, U+169C   OGHAM FEATHER MARK,  OGHAM REVERSED FEATHER MARK
+ ‘  ’    U+2018, U+2019   LEFT/RIGHT SINGLE QUOTATION MARK
+ ’  ‘    U+2019, U+2018   RIGHT/LEFT SINGLE QUOTATION MARK
+ “  ”    U+201C, U+201D   LEFT/RIGHT DOUBLE QUOTATION MARK
+ ”  “    U+201D, U+201C   RIGHT/LEFT DOUBLE QUOTATION MARK
+ ‵  ′    U+2035, U+2032   REVERSED PRIME,  PRIME
+ ‶  ″    U+2036, U+2033   REVERSED DOUBLE PRIME,  DOUBLE PRIME
+ ‷  ‴    U+2037, U+2034   REVERSED TRIPLE PRIME,  TRIPLE PRIME
+ ‹  ›    U+2039, U+203A   SINGLE LEFT/RIGHT-POINTING ANGLE QUOTATION MARK
+ ›  ‹    U+203A, U+2039   SINGLE RIGHT/LEFT-POINTING ANGLE QUOTATION MARK
+ ⁅  ⁆    U+2045, U+2046   LEFT/RIGHT SQUARE BRACKET WITH QUILL
+ ⁍  ⁌    U+204D, U+204C   BLACK RIGHT/LEFTWARDS BULLET
+ ⁽  ⁾    U+207D, U+207E   SUPERSCRIPT LEFT/RIGHT PARENTHESIS
+ ₍  ₎    U+208D, U+208E   SUBSCRIPT LEFT/RIGHT PARENTHESIS
+ →  ←    U+2192, U+2190   RIGHT/LEFTWARDS ARROW
+ ↛  ↚    U+219B, U+219A   RIGHT/LEFTWARDS ARROW WITH STROKE
+ ↝  ↜    U+219D, U+219C   RIGHT/LEFTWARDS WAVE ARROW
+ ↠  ↞    U+21A0, U+219E   RIGHT/LEFTWARDS TWO HEADED ARROW
+ ↣  ↢    U+21A3, U+21A2   RIGHT/LEFTWARDS ARROW WITH TAIL
+ ↦  ↤    U+21A6, U+21A4   RIGHT/LEFTWARDS ARROW FROM BAR
+ ↪  ↩    U+21AA, U+21A9   RIGHT/LEFTWARDS ARROW WITH HOOK
+ ↬  ↫    U+21AC, U+21AB   RIGHT/LEFTWARDS ARROW WITH LOOP
+ ↱  ↰    U+21B1, U+21B0   UPWARDS ARROW WITH TIP RIGHT/LEFTWARDS
+ ↳  ↲    U+21B3, U+21B2   DOWNWARDS ARROW WITH TIP RIGHT/LEFTWARDS
+ ⇀  ↼    U+21C0, U+21BC   RIGHT/LEFTWARDS HARPOON WITH BARB UPWARDS
+ ⇁  ↽    U+21C1, U+21BD   RIGHT/LEFTWARDS HARPOON WITH BARB DOWNWARDS
+ ⇉  ⇇    U+21C9, U+21C7   RIGHT/LEFTWARDS PAIRED ARROWS
+ ⇏  ⇍    U+21CF, U+21CD   RIGHT/LEFTWARDS DOUBLE ARROW WITH STROKE
+ ⇒  ⇐    U+21D2, U+21D0   RIGHT/LEFTWARDS DOUBLE ARROW
+ ⇛  ⇚    U+21DB, U+21DA   RIGHT/LEFTWARDS TRIPLE ARROW
+ ⇝  ⇜    U+21DD, U+21DC   RIGHT/LEFTWARDS SQUIGGLE ARROW
+ ⇢  ⇠    U+21E2, U+21E0   RIGHT/LEFTWARDS DASHED ARROW
+ ⇥  ⇤    U+21E5, U+21E4   RIGHT/LEFTWARDS ARROW TO BAR
+ ⇨  ⇦    U+21E8, U+21E6   RIGHT/LEFTWARDS WHITE ARROW
+ ⇴  ⬰    U+21F4, U+2B30   RIGHT/LEFT ARROW WITH SMALL CIRCLE
+ ⇶  ⬱    U+21F6, U+2B31   THREE RIGHT/LEFTWARDS ARROWS
+ ⇸  ⇷    U+21F8, U+21F7   RIGHT/LEFTWARDS ARROW WITH VERTICAL STROKE
+ ⇻  ⇺    U+21FB, U+21FA   RIGHT/LEFTWARDS ARROW WITH DOUBLE VERTICAL
+                          STROKE
+ ⇾  ⇽    U+21FE, U+21FD   RIGHT/LEFTWARDS OPEN-HEADED ARROW
+ ∈  ∋    U+2208, U+220B   ELEMENT OF,  CONTAINS AS MEMBER
+ ∉  ∌    U+2209, U+220C   NOT AN ELEMENT OF,  DOES NOT CONTAIN AS MEMBER
+ ∊  ∍    U+220A, U+220D   SMALL ELEMENT OF,  SMALL CONTAINS AS MEMBER
+ ≤  ≥    U+2264, U+2265   LESS-THAN/GREATER-THAN OR EQUAL TO
+ ≦  ≧    U+2266, U+2267   LESS-THAN/GREATER-THAN OVER EQUAL TO
+ ≨  ≩    U+2268, U+2269   LESS-THAN/GREATER-THAN BUT NOT EQUAL TO
+ ≪  ≫    U+226A, U+226B   MUCH LESS-THAN/GREATER-THAN
+ ≮  ≯    U+226E, U+226F   NOT LESS-THAN/GREATER-THAN
+ ≰  ≱    U+2270, U+2271   NEITHER LESS-THAN/GREATER-THAN NOR EQUAL TO
+ ≲  ≳    U+2272, U+2273   LESS-THAN/GREATER-THAN OR EQUIVALENT TO
+ ≴  ≵    U+2274, U+2275   NEITHER LESS-THAN/GREATER-THAN NOR EQUIVALENT TO
+ ≺  ≻    U+227A, U+227B   PRECEDES/SUCCEEDS
+ ≼  ≽    U+227C, U+227D   PRECEDES/SUCCEEDS OR EQUAL TO
+ ≾  ≿    U+227E, U+227F   PRECEDES/SUCCEEDS OR EQUIVALENT TO
+ ⊀  ⊁    U+2280, U+2281   DOES NOT PRECEDE/SUCCEED
+ ⊂  ⊃    U+2282, U+2283   SUBSET/SUPERSET OF
+ ⊄  ⊅    U+2284, U+2285   NOT A SUBSET/SUPERSET OF
+ ⊆  ⊇    U+2286, U+2287   SUBSET/SUPERSET OF OR EQUAL TO
+ ⊈  ⊉    U+2288, U+2289   NEITHER A SUBSET/SUPERSET OF NOR EQUAL TO
+ ⊊  ⊋    U+228A, U+228B   SUBSET/SUPERSET OF WITH NOT EQUAL TO
+ ⊣  ⊢    U+22A3, U+22A2   LEFT/RIGHT TACK
+ ⊦  ⫞    U+22A6, U+2ADE   ASSERTION,  SHORT LEFT TACK
+ ⊨  ⫤    U+22A8, U+2AE4   TRUE,  VERTICAL BAR DOUBLE LEFT TURNSTILE
+ ⊩  ⫣    U+22A9, U+2AE3   FORCES,  DOUBLE VERTICAL BAR LEFT TURNSTILE
+ ⊰  ⊱    U+22B0, U+22B1   PRECEDES/SUCCEEDS UNDER RELATION
+ ⋐  ⋑    U+22D0, U+22D1   DOUBLE SUBSET/SUPERSET
+ ⋖  ⋗    U+22D6, U+22D7   LESS-THAN/GREATER-THAN WITH DOT
+ ⋘  ⋙    U+22D8, U+22D9   VERY MUCH LESS-THAN/GREATER-THAN
+ ⋜  ⋝    U+22DC, U+22DD   EQUAL TO OR LESS-THAN/GREATER-THAN
+ ⋞  ⋟    U+22DE, U+22DF   EQUAL TO OR PRECEDES/SUCCEEDS
+ ⋠  ⋡    U+22E0, U+22E1   DOES NOT PRECEDE/SUCCEED OR EQUAL
+ ⋦  ⋧    U+22E6, U+22E7   LESS-THAN/GREATER-THAN BUT NOT EQUIVALENT TO
+ ⋨  ⋩    U+22E8, U+22E9   PRECEDES/SUCCEEDS BUT NOT EQUIVALENT TO
+ ⋲  ⋺    U+22F2, U+22FA   ELEMENT OF/CONTAINS WITH LONG HORIZONTAL STROKE
+ ⋳  ⋻    U+22F3, U+22FB   ELEMENT OF/CONTAINS WITH VERTICAL BAR AT END OF
+                          HORIZONTAL STROKE
+ ⋴  ⋼    U+22F4, U+22FC   SMALL ELEMENT OF/CONTAINS WITH VERTICAL BAR AT
+                          END OF HORIZONTAL STROKE
+ ⋶  ⋽    U+22F6, U+22FD   ELEMENT OF/CONTAINS WITH OVERBAR
+ ⋷  ⋾    U+22F7, U+22FE   SMALL ELEMENT OF/CONTAINS WITH OVERBAR
+ ⌈  ⌉    U+2308, U+2309   LEFT/RIGHT CEILING
+ ⌊  ⌋    U+230A, U+230B   LEFT/RIGHT FLOOR
+ ⌦  ⌫    U+2326, U+232B   ERASE TO THE RIGHT/LEFT
+ 〈 〉   U+2329, U+232A   LEFT/RIGHT-POINTING ANGLE BRACKET
+ ⍈  ⍇    U+2348, U+2347   APL FUNCTIONAL SYMBOL QUAD RIGHT/LEFTWARDS ARROW
+ ⏩ ⏪   U+23E9, U+23EA   BLACK RIGHT/LEFT-POINTING DOUBLE TRIANGLE
+ ⏭  ⏮    U+23ED, U+23EE   BLACK RIGHT/LEFT-POINTING DOUBLE TRIANGLE WITH
+                          VERTICAL BAR
+ ☛  ☚    U+261B, U+261A   BLACK RIGHT/LEFT POINTING INDEX
+ ☞  ☜    U+261E, U+261C   WHITE RIGHT/LEFT POINTING INDEX
+ ⚞  ⚟    U+269E, U+269F   THREE LINES CONVERGING RIGHT/LEFT
+ ❨  ❩    U+2768, U+2769   MEDIUM LEFT/RIGHT PARENTHESIS ORNAMENT
+ ❪  ❫    U+276A, U+276B   MEDIUM FLATTENED LEFT/RIGHT PARENTHESIS ORNAMENT
+ ❬  ❭    U+276C, U+276D   MEDIUM LEFT/RIGHT-POINTING ANGLE BRACKET
+                          ORNAMENT
+ ❮  ❯    U+276E, U+276F   HEAVY LEFT/RIGHT-POINTING ANGLE QUOTATION MARK
+                          ORNAMENT
+ ❰  ❱    U+2770, U+2771   HEAVY LEFT/RIGHT-POINTING ANGLE BRACKET ORNAMENT
+ ❲  ❳    U+2772, U+2773   LIGHT LEFT/RIGHT TORTOISE SHELL BRACKET ORNAMENT
+ ❴  ❵    U+2774, U+2775   MEDIUM LEFT/RIGHT CURLY BRACKET ORNAMENT
+ ⟃  ⟄    U+27C3, U+27C4   OPEN SUBSET/SUPERSET
+ ⟅  ⟆    U+27C5, U+27C6   LEFT/RIGHT S-SHAPED BAG DELIMITER
+ ⟈  ⟉    U+27C8, U+27C9   REVERSE SOLIDUS PRECEDING SUBSET,  SUPERSET
+                          PRECEDING SOLIDUS
+ ⟞  ⟝    U+27DE, U+27DD   LONG LEFT/RIGHT TACK
+ ⟦  ⟧    U+27E6, U+27E7   MATHEMATICAL LEFT/RIGHT WHITE SQUARE BRACKET
+ ⟨  ⟩    U+27E8, U+27E9   MATHEMATICAL LEFT/RIGHT ANGLE BRACKET
+ ⟪  ⟫    U+27EA, U+27EB   MATHEMATICAL LEFT/RIGHT DOUBLE ANGLE BRACKET
+ ⟬  ⟭    U+27EC, U+27ED   MATHEMATICAL LEFT/RIGHT WHITE TORTOISE SHELL
+                          BRACKET
+ ⟮  ⟯    U+27EE, U+27EF   MATHEMATICAL LEFT/RIGHT FLATTENED PARENTHESIS
+ ⟴  ⬲    U+27F4, U+2B32   RIGHT/LEFT ARROW WITH CIRCLED PLUS
+ ⟶  ⟵    U+27F6, U+27F5   LONG RIGHT/LEFTWARDS ARROW
+ ⟹  ⟸    U+27F9, U+27F8   LONG RIGHT/LEFTWARDS DOUBLE ARROW
+ ⟼  ⟻    U+27FC, U+27FB   LONG RIGHT/LEFTWARDS ARROW FROM BAR
+ ⟾  ⟽    U+27FE, U+27FD   LONG RIGHT/LEFTWARDS DOUBLE ARROW FROM BAR
+ ⟿  ⬳    U+27FF, U+2B33   LONG RIGHT/LEFTWARDS SQUIGGLE ARROW
+ ⤀  ⬴    U+2900, U+2B34   RIGHT/LEFTWARDS TWO-HEADED ARROW WITH VERTICAL
+                          STROKE
+ ⤁  ⬵    U+2901, U+2B35   RIGHT/LEFTWARDS TWO-HEADED ARROW WITH DOUBLE
+                          VERTICAL STROKE
+ ⤃  ⤂    U+2903, U+2902   RIGHT/LEFTWARDS DOUBLE ARROW WITH VERTICAL
+                          STROKE
+ ⤅  ⬶    U+2905, U+2B36   RIGHT/LEFTWARDS TWO-HEADED ARROW FROM BAR
+ ⤇  ⤆    U+2907, U+2906   RIGHT/LEFTWARDS DOUBLE ARROW FROM BAR
+ ⤍  ⤌    U+290D, U+290C   RIGHT/LEFTWARDS DOUBLE DASH ARROW
+ ⤏  ⤎    U+290F, U+290E   RIGHT/LEFTWARDS TRIPLE DASH ARROW
+ ⤐  ⬷    U+2910, U+2B37   RIGHT/LEFTWARDS TWO-HEADED TRIPLE DASH ARROW
+ ⤑  ⬸    U+2911, U+2B38   RIGHT/LEFTWARDS ARROW WITH DOTTED STEM
+ ⤔  ⬹    U+2914, U+2B39   RIGHT/LEFTWARDS ARROW WITH TAIL WITH VERTICAL
+                          STROKE
+ ⤕  ⬺    U+2915, U+2B3A   RIGHT/LEFTWARDS ARROW WITH TAIL WITH DOUBLE
+                          VERTICAL STROKE
+ ⤖  ⬻    U+2916, U+2B3B   RIGHT/LEFTWARDS TWO-HEADED ARROW WITH TAIL
+ ⤗  ⬼    U+2917, U+2B3C   RIGHT/LEFTWARDS TWO-HEADED ARROW WITH TAIL WITH
+                          VERTICAL STROKE
+ ⤘  ⬽    U+2918, U+2B3D   RIGHT/LEFTWARDS TWO-HEADED ARROW WITH TAIL WITH
+                          DOUBLE VERTICAL STROKE
+ ⤚  ⤙    U+291A, U+2919   RIGHT/LEFTWARDS ARROW-TAIL
+ ⤜  ⤛    U+291C, U+291B   RIGHT/LEFTWARDS DOUBLE ARROW-TAIL
+ ⤞  ⤝    U+291E, U+291D   RIGHT/LEFTWARDS ARROW TO BLACK DIAMOND
+ ⤠  ⤟    U+2920, U+291F   RIGHT/LEFTWARDS ARROW FROM BAR TO BLACK DIAMOND
+ ⤳  ⬿    U+2933, U+2B3F   WAVE ARROW POINTING DIRECTLY RIGHT/LEFT
+ ⤷  ⤶    U+2937, U+2936   ARROW POINTING DOWNWARDS THEN CURVING RIGHT/
+                          LEFTWARDS
+ ⥅  ⥆    U+2945, U+2946   RIGHT/LEFTWARDS ARROW WITH PLUS BELOW
+ ⥇  ⬾    U+2947, U+2B3E   RIGHT/LEFTWARDS ARROW THROUGH X
+ ⥓  ⥒    U+2953, U+2952   RIGHT/LEFTWARDS HARPOON WITH BARB UP TO BAR
+ ⥗  ⥖    U+2957, U+2956   RIGHT/LEFTWARDS HARPOON WITH BARB DOWN TO BAR
+ ⥛  ⥚    U+295B, U+295A   RIGHT/LEFTWARDS HARPOON WITH BARB UP FROM BAR
+ ⥟  ⥞    U+295F, U+295E   RIGHT/LEFTWARDS HARPOON WITH BARB DOWN FROM BAR
+ ⥤  ⥢    U+2964, U+2962   RIGHT/LEFTWARDS HARPOON WITH BARB UP ABOVE
+                          RIGHT/LEFTWARDS HARPOON WITH BARB DOWN
+ ⥬  ⥪    U+296C, U+296A   RIGHT/LEFTWARDS HARPOON WITH BARB UP ABOVE LONG
+                          DASH
+ ⥭  ⥫    U+296D, U+296B   RIGHT/LEFTWARDS HARPOON WITH BARB DOWN BELOW
+                          LONG DASH
+ ⥱  ⭀    U+2971, U+2B40   EQUALS SIGN ABOVE RIGHT/LEFTWARDS ARROW
+ ⥲  ⭁    U+2972, U+2B41   TILDE OPERATOR ABOVE RIGHTWARDS ARROW,  REVERSE
+                          TILDE OPERATOR ABOVE LEFTWARDS ARROW
+ ⥴  ⭋    U+2974, U+2B4B   RIGHTWARDS ARROW ABOVE TILDE OPERATOR,
+                          LEFTWARDS ARROW ABOVE REVERSE TILDE OPERATOR
+ ⥵  ⭂    U+2975, U+2B42   RIGHTWARDS ARROW ABOVE ALMOST EQUAL TO,
+                          LEFTWARDS ARROW ABOVE REVERSE ALMOST EQUAL TO
+ ⥹  ⥻    U+2979, U+297B   SUBSET/SUPERSET ABOVE RIGHT/LEFTWARDS ARROW
+ ⦃  ⦄    U+2983, U+2984   LEFT/RIGHT WHITE CURLY BRACKET
+ ⦅  ⦆    U+2985, U+2986   LEFT/RIGHT WHITE PARENTHESIS
+ ⦇  ⦈    U+2987, U+2988   Z NOTATION LEFT/RIGHT IMAGE BRACKET
+ ⦉  ⦊    U+2989, U+298A   Z NOTATION LEFT/RIGHT BINDING BRACKET
+ ⦋  ⦌    U+298B, U+298C   LEFT/RIGHT SQUARE BRACKET WITH UNDERBAR
+ ⦍  ⦐    U+298D, U+2990   LEFT/RIGHT SQUARE BRACKET WITH TICK IN TOP
+                          CORNER
+ ⦏  ⦎    U+298F, U+298E   LEFT/RIGHT SQUARE BRACKET WITH TICK IN BOTTOM
+                          CORNER
+ ⦑  ⦒    U+2991, U+2992   LEFT/RIGHT ANGLE BRACKET WITH DOT
+ ⦓  ⦔    U+2993, U+2994   LEFT/RIGHT ARC LESS-THAN/GREATER-THAN BRACKET
+ ⦕  ⦖    U+2995, U+2996   DOUBLE LEFT/RIGHT ARC GREATER-THAN/LESS-THAN
+                          BRACKET
+ ⦗  ⦘    U+2997, U+2998   LEFT/RIGHT BLACK TORTOISE SHELL BRACKET
+ ⦨  ⦩    U+29A8, U+29A9   MEASURED ANGLE WITH OPEN ARM ENDING IN ARROW
+                          POINTING UP AND RIGHT/LEFT
+ ⦪  ⦫    U+29AA, U+29AB   MEASURED ANGLE WITH OPEN ARM ENDING IN ARROW
+                          POINTING DOWN AND RIGHT/LEFT
+ ⦳  ⦴    U+29B3, U+29B4   EMPTY SET WITH RIGHT/LEFT ARROW ABOVE
+ ⧀  ⧁    U+29C0, U+29C1   CIRCLED LESS-THAN/GREATER-THAN
+ ⧘  ⧙    U+29D8, U+29D9   LEFT/RIGHT WIGGLY FENCE
+ ⧚  ⧛    U+29DA, U+29DB   LEFT/RIGHT DOUBLE WIGGLY FENCE
+ ⧼  ⧽    U+29FC, U+29FD   LEFT/RIGHT-POINTING CURVED ANGLE BRACKET
+ ⩹  ⩺    U+2A79, U+2A7A   LESS-THAN/GREATER-THAN WITH CIRCLE INSIDE
+ ⩻  ⩼    U+2A7B, U+2A7C   LESS-THAN/GREATER-THAN WITH QUESTION MARK ABOVE
+ ⩽  ⩾    U+2A7D, U+2A7E   LESS-THAN/GREATER-THAN OR SLANTED EQUAL TO
+ ⩿  ⪀    U+2A7F, U+2A80   LESS-THAN/GREATER-THAN OR SLANTED EQUAL TO WITH
+                          DOT INSIDE
+ ⪁  ⪂    U+2A81, U+2A82   LESS-THAN/GREATER-THAN OR SLANTED EQUAL TO WITH
+                          DOT ABOVE
+ ⪃  ⪄    U+2A83, U+2A84   LESS-THAN/GREATER-THAN OR SLANTED EQUAL TO WITH
+                          DOT ABOVE RIGHT/LEFT
+ ⪅  ⪆    U+2A85, U+2A86   LESS-THAN/GREATER-THAN OR APPROXIMATE
+ ⪇  ⪈    U+2A87, U+2A88   LESS-THAN/GREATER-THAN AND SINGLE-LINE NOT
+                          EQUAL TO
+ ⪉  ⪊    U+2A89, U+2A8A   LESS-THAN/GREATER-THAN AND NOT APPROXIMATE
+ ⪍  ⪎    U+2A8D, U+2A8E   LESS-THAN/GREATER-THAN ABOVE SIMILAR OR EQUAL
+ ⪕  ⪖    U+2A95, U+2A96   SLANTED EQUAL TO OR LESS-THAN/GREATER-THAN
+ ⪗  ⪘    U+2A97, U+2A98   SLANTED EQUAL TO OR LESS-THAN/GREATER-THAN WITH
+                          DOT INSIDE
+ ⪙  ⪚    U+2A99, U+2A9A   DOUBLE-LINE EQUAL TO OR LESS-THAN/GREATER-THAN
+ ⪛  ⪜    U+2A9B, U+2A9C   DOUBLE-LINE SLANTED EQUAL TO OR LESS-THAN/
+                          GREATER-THAN
+ ⪝  ⪞    U+2A9D, U+2A9E   SIMILAR OR LESS-THAN/GREATER-THAN
+ ⪟  ⪠    U+2A9F, U+2AA0   SIMILAR ABOVE LESS-THAN/GREATER-THAN ABOVE
+                          EQUALS SIGN
+ ⪡  ⪢    U+2AA1, U+2AA2   DOUBLE NESTED LESS-THAN/GREATER-THAN
+ ⪦  ⪧    U+2AA6, U+2AA7   LESS-THAN/GREATER-THAN CLOSED BY CURVE
+ ⪨  ⪩    U+2AA8, U+2AA9   LESS-THAN/GREATER-THAN CLOSED BY CURVE ABOVE
+                          SLANTED EQUAL
+ ⪪  ⪫    U+2AAA, U+2AAB   SMALLER THAN/LARGER THAN
+ ⪬  ⪭    U+2AAC, U+2AAD   SMALLER THAN/LARGER THAN OR EQUAL TO
+ ⪯  ⪰    U+2AAF, U+2AB0   PRECEDES/SUCCEEDS ABOVE SINGLE-LINE EQUALS SIGN
+ ⪱  ⪲    U+2AB1, U+2AB2   PRECEDES/SUCCEEDS ABOVE SINGLE-LINE NOT EQUAL TO
+ ⪳  ⪴    U+2AB3, U+2AB4   PRECEDES/SUCCEEDS ABOVE EQUALS SIGN
+ ⪵  ⪶    U+2AB5, U+2AB6   PRECEDES/SUCCEEDS ABOVE NOT EQUAL TO
+ ⪷  ⪸    U+2AB7, U+2AB8   PRECEDES/SUCCEEDS ABOVE ALMOST EQUAL TO
+ ⪹  ⪺    U+2AB9, U+2ABA   PRECEDES/SUCCEEDS ABOVE NOT ALMOST EQUAL TO
+ ⪻  ⪼    U+2ABB, U+2ABC   DOUBLE PRECEDES/SUCCEEDS
+ ⪽  ⪾    U+2ABD, U+2ABE   SUBSET/SUPERSET WITH DOT
+ ⪿  ⫀    U+2ABF, U+2AC0   SUBSET/SUPERSET WITH PLUS SIGN BELOW
+ ⫁  ⫂    U+2AC1, U+2AC2   SUBSET/SUPERSET WITH MULTIPLICATION SIGN BELOW
+ ⫃  ⫄    U+2AC3, U+2AC4   SUBSET/SUPERSET OF OR EQUAL TO WITH DOT ABOVE
+ ⫅  ⫆    U+2AC5, U+2AC6   SUBSET/SUPERSET OF ABOVE EQUALS SIGN
+ ⫇  ⫈    U+2AC7, U+2AC8   SUBSET/SUPERSET OF ABOVE TILDE OPERATOR
+ ⫉  ⫊    U+2AC9, U+2ACA   SUBSET/SUPERSET OF ABOVE ALMOST EQUAL TO
+ ⫋  ⫌    U+2ACB, U+2ACC   SUBSET/SUPERSET OF ABOVE NOT EQUAL TO
+ ⫏  ⫐    U+2ACF, U+2AD0   CLOSED SUBSET/SUPERSET
+ ⫑  ⫒    U+2AD1, U+2AD2   CLOSED SUBSET/SUPERSET OR EQUAL TO
+ ⫕  ⫖    U+2AD5, U+2AD6   SUBSET/SUPERSET ABOVE SUBSET/SUPERSET
+ ⫥  ⊫    U+2AE5, U+22AB   DOUBLE VERTICAL BAR DOUBLE LEFT/RIGHT TURNSTILE
+ ⫷  ⫸    U+2AF7, U+2AF8   TRIPLE NESTED LESS-THAN/GREATER-THAN
+ ⫹  ⫺    U+2AF9, U+2AFA   DOUBLE-LINE SLANTED LESS-THAN/GREATER-THAN OR
+                          EQUAL TO
+ ⭆  ⭅    U+2B46, U+2B45   RIGHT/LEFTWARDS QUADRUPLE ARROW
+ ⭇  ⭉    U+2B47, U+2B49   REVERSE TILDE OPERATOR ABOVE RIGHTWARDS ARROW,
+                          TILDE OPERATOR ABOVE LEFTWARDS ARROW
+ ⭈  ⭊    U+2B48, U+2B4A   RIGHTWARDS ARROW ABOVE REVERSE ALMOST EQUAL
+                          TO,  LEFTWARDS ARROW ABOVE ALMOST EQUAL TO
+ ⭌  ⥳    U+2B4C, U+2973   RIGHTWARDS ARROW ABOVE REVERSE TILDE OPERATOR,
+                          LEFTWARDS ARROW ABOVE TILDE OPERATOR
+ â­¢  â­     U+2B62, U+2B60   RIGHT/LEFTWARDS TRIANGLE-HEADED ARROW
+ â­¬  â­ª    U+2B6C, U+2B6A   RIGHT/LEFTWARDS TRIANGLE-HEADED DASHED ARROW
+ â­²  â­°    U+2B72, U+2B70   RIGHT/LEFTWARDS TRIANGLE-HEADED ARROW TO BAR
+ â­¼  â­º    U+2B7C, U+2B7A   RIGHT/LEFTWARDS TRIANGLE-HEADED ARROW WITH
+                          DOUBLE VERTICAL STROKE
+ ⮆  ⮄    U+2B86, U+2B84   RIGHT/LEFTWARDS TRIANGLE-HEADED PAIRED ARROWS
+ ⮊  ⮈    U+2B8A, U+2B88   RIGHT/LEFTWARDS BLACK CIRCLED WHITE ARROW
+ ⮕  ⬅    U+2B95, U+2B05   RIGHT/LEFTWARDS BLACK ARROW
+ ⮚  ⮘    U+2B9A, U+2B98   THREE-D TOP-LIGHTED RIGHT/LEFTWARDS EQUILATERAL
+                          ARROWHEAD
+ ⮞  ⮜    U+2B9E, U+2B9C   BLACK RIGHT/LEFTWARDS EQUILATERAL ARROWHEAD
+ ⮡  ⮠    U+2BA1, U+2BA0   DOWNWARDS TRIANGLE-HEADED ARROW WITH LONG TIP
+                          RIGHT/LEFTWARDS
+ ⮣  ⮢    U+2BA3, U+2BA2   UPWARDS TRIANGLE-HEADED ARROW WITH LONG TIP
+                          RIGHT/LEFTWARDS
+ ⮩  ⮨    U+2BA9, U+2BA8   BLACK CURVED DOWNWARDS AND RIGHT/LEFTWARDS ARROW
+ ⮫  ⮪    U+2BAB, U+2BAA   BLACK CURVED UPWARDS AND RIGHT/LEFTWARDS ARROW
+ â®±  â®°    U+2BB1, U+2BB0   RIBBON ARROW DOWN RIGHT/LEFT
+ ⮳  ⮲    U+2BB3, U+2BB2   RIBBON ARROW UP RIGHT/LEFT
+ ⯮  ⯬    U+2BEE, U+2BEC   RIGHT/LEFTWARDS TWO-HEADED ARROW WITH TRIANGLE
+                          ARROWHEADS
+ ⸂  ⸃    U+2E02, U+2E03   LEFT/RIGHT SUBSTITUTION BRACKET
+ ⸃  ⸂    U+2E03, U+2E02   RIGHT/LEFT SUBSTITUTION BRACKET
+ ⸄  ⸅    U+2E04, U+2E05   LEFT/RIGHT DOTTED SUBSTITUTION BRACKET
+ ⸅  ⸄    U+2E05, U+2E04   RIGHT/LEFT DOTTED SUBSTITUTION BRACKET
+ ⸉  ⸊    U+2E09, U+2E0A   LEFT/RIGHT TRANSPOSITION BRACKET
+ ⸊  ⸉    U+2E0A, U+2E09   RIGHT/LEFT TRANSPOSITION BRACKET
+ ⸌  ⸍    U+2E0C, U+2E0D   LEFT/RIGHT RAISED OMISSION BRACKET
+ ⸍  ⸌    U+2E0D, U+2E0C   RIGHT/LEFT RAISED OMISSION BRACKET
+ ⸑  ⸐    U+2E11, U+2E10   REVERSED FORKED PARAGRAPHOS,  FORKED PARAGRAPHOS
+ ⸜  ⸝    U+2E1C, U+2E1D   LEFT/RIGHT LOW PARAPHRASE BRACKET
+ ⸝  ⸜    U+2E1D, U+2E1C   RIGHT/LEFT LOW PARAPHRASE BRACKET
+ ⸠  ⸡    U+2E20, U+2E21   LEFT/RIGHT VERTICAL BAR WITH QUILL
+ ⸡  ⸠    U+2E21, U+2E20   RIGHT/LEFT VERTICAL BAR WITH QUILL
+ ⸢  ⸣    U+2E22, U+2E23   TOP LEFT/RIGHT HALF BRACKET
+ ⸤  ⸥    U+2E24, U+2E25   BOTTOM LEFT/RIGHT HALF BRACKET
+ ⸦  ⸧    U+2E26, U+2E27   LEFT/RIGHT SIDEWAYS U BRACKET
+ ⸨  ⸩    U+2E28, U+2E29   LEFT/RIGHT DOUBLE PARENTHESIS
+ ⸶  ⸷    U+2E36, U+2E37   DAGGER WITH LEFT/RIGHT GUARD
+ ⹂  „    U+2E42, U+201E   DOUBLE LOW-REVERSED-9 QUOTATION MARK,  DOUBLE
+                          LOW-9 QUOTATION MARK
+ ⹕  ⹖    U+2E55, U+2E56   LEFT/RIGHT SQUARE BRACKET WITH STROKE
+ ⹗  ⹘    U+2E57, U+2E58   LEFT/RIGHT SQUARE BRACKET WITH DOUBLE STROKE
+ ⹙  ⹚    U+2E59, U+2E5A   TOP HALF LEFT/RIGHT PARENTHESIS
+ ⹛  ⹜    U+2E5B, U+2E5C   BOTTOM HALF LEFT/RIGHT PARENTHESIS
+ 〈 〉   U+3008, U+3009   LEFT/RIGHT ANGLE BRACKET
+ 《 》   U+300A, U+300B   LEFT/RIGHT DOUBLE ANGLE BRACKET
+ 「 」   U+300C, U+300D   LEFT/RIGHT CORNER BRACKET
+ 『 』   U+300E, U+300F   LEFT/RIGHT WHITE CORNER BRACKET
+ 【 】   U+3010, U+3011   LEFT/RIGHT BLACK LENTICULAR BRACKET
+ 〔 〕   U+3014, U+3015   LEFT/RIGHT TORTOISE SHELL BRACKET
+ 〖 〗   U+3016, U+3017   LEFT/RIGHT WHITE LENTICULAR BRACKET
+ 〘 〙   U+3018, U+3019   LEFT/RIGHT WHITE TORTOISE SHELL BRACKET
+ 〚 〛   U+301A, U+301B   LEFT/RIGHT WHITE SQUARE BRACKET
+ 〝 〞   U+301D, U+301E   REVERSED DOUBLE PRIME QUOTATION MARK,  DOUBLE
+                          PRIME QUOTATION MARK
+ ꧁  ꧂    U+A9C1, U+A9C2   JAVANESE LEFT/RIGHT RERENGGAN
+ ï´¾  ï´¿    U+FD3E, U+FD3F   ORNATE LEFT/RIGHT PARENTHESIS
+ ﹙ ﹚   U+FE59, U+FE5A   SMALL LEFT/RIGHT PARENTHESIS
+ ﹛ ﹜   U+FE5B, U+FE5C   SMALL LEFT/RIGHT CURLY BRACKET
+ ﹝ ﹞   U+FE5D, U+FE5E   SMALL LEFT/RIGHT TORTOISE SHELL BRACKET
+ ﹤ ﹥   U+FE64, U+FE65   SMALL LESS-THAN/GREATER-THAN SIGN
+ （ ）   U+FF08, U+FF09   FULLWIDTH LEFT/RIGHT PARENTHESIS
+ ＜ ＞   U+FF1C, U+FF1E   FULLWIDTH LESS-THAN/GREATER-THAN SIGN
+ ï¼» ï¼½   U+FF3B, U+FF3D   FULLWIDTH LEFT/RIGHT SQUARE BRACKET
+ ｛ ｝   U+FF5B, U+FF5D   FULLWIDTH LEFT/RIGHT CURLY BRACKET
+ ｟ ｠   U+FF5F, U+FF60   FULLWIDTH LEFT/RIGHT WHITE PARENTHESIS
+ ï½¢  ï½£    U+FF62, U+FF63   HALFWIDTH LEFT/RIGHT CORNER BRACKET
+ ï¿«  ï¿©    U+FFEB, U+FFE9   HALFWIDTH RIGHT/LEFTWARDS ARROW
+ 𝄃  𝄂    U+1D103, U+1D102 MUSICAL SYMBOL REVERSE FINAL BARLINE,  MUSICAL
+                          SYMBOL FINAL BARLINE
+ 𝄆  𝄇    U+1D106, U+1D107 MUSICAL SYMBOL LEFT/RIGHT REPEAT SIGN
+ 👉 👈   U+1F449, U+1F448 WHITE RIGHT/LEFT POINTING BACKHAND INDEX
+ 🔈 🕨    U+1F508, U+1F568 SPEAKER,  RIGHT SPEAKER
+ 🔉 🕩    U+1F509, U+1F569 SPEAKER WITH ONE SOUND WAVE,  RIGHT SPEAKER WITH
+                          ONE SOUND WAVE
+ 🔊 🕪    U+1F50A, U+1F56A SPEAKER WITH THREE SOUND WAVES,  RIGHT SPEAKER
+                          WITH THREE SOUND WAVES
+ 🕻  🕽    U+1F57B, U+1F57D LEFT/RIGHT HAND TELEPHONE RECEIVER
+ 🖙  🖘    U+1F599, U+1F598 SIDEWAYS WHITE RIGHT/LEFT POINTING INDEX
+ 🖛  🖚    U+1F59B, U+1F59A SIDEWAYS BLACK RIGHT/LEFT POINTING INDEX
+ 🖝  🖜    U+1F59D, U+1F59C BLACK RIGHT/LEFT POINTING BACKHAND INDEX
+ 🗦  🗧    U+1F5E6, U+1F5E7 THREE RAYS LEFT/RIGHT
+ 🠂  🠀    U+1F802, U+1F800 RIGHT/LEFTWARDS ARROW WITH SMALL TRIANGLE
+                          ARROWHEAD
+ 🠆  🠄    U+1F806, U+1F804 RIGHT/LEFTWARDS ARROW WITH MEDIUM TRIANGLE
+                          ARROWHEAD
+ 🠊  🠈    U+1F80A, U+1F808 RIGHT/LEFTWARDS ARROW WITH LARGE TRIANGLE
+                          ARROWHEAD
+ 🠒  🠐    U+1F812, U+1F810 RIGHT/LEFTWARDS ARROW WITH SMALL EQUILATERAL
+                          ARROWHEAD
+ 🠖  🠔    U+1F816, U+1F814 RIGHT/LEFTWARDS ARROW WITH EQUILATERAL ARROWHEAD
+ 🠚  🠘    U+1F81A, U+1F818 HEAVY RIGHT/LEFTWARDS ARROW WITH EQUILATERAL
+                          ARROWHEAD
+ 🠞  🠜    U+1F81E, U+1F81C HEAVY RIGHT/LEFTWARDS ARROW WITH LARGE
+                          EQUILATERAL ARROWHEAD
+ 🠢  🠠    U+1F822, U+1F820 RIGHT/LEFTWARDS TRIANGLE-HEADED ARROW WITH
+                          NARROW SHAFT
+ 🠦  🠤    U+1F826, U+1F824 RIGHT/LEFTWARDS TRIANGLE-HEADED ARROW WITH
+                          MEDIUM SHAFT
+ 🠪  🠨    U+1F82A, U+1F828 RIGHT/LEFTWARDS TRIANGLE-HEADED ARROW WITH BOLD
+                          SHAFT
+ 🠮  🠬    U+1F82E, U+1F82C RIGHT/LEFTWARDS TRIANGLE-HEADED ARROW WITH
+                          HEAVY SHAFT
+ 🠲  🠰    U+1F832, U+1F830 RIGHT/LEFTWARDS TRIANGLE-HEADED ARROW WITH VERY
+                          HEAVY SHAFT
+ 🠶  🠴    U+1F836, U+1F834 RIGHT/LEFTWARDS FINGER-POST ARROW
+ 🠺  🠸    U+1F83A, U+1F838 RIGHT/LEFTWARDS SQUARED ARROW
+ 🠾  🠼    U+1F83E, U+1F83C RIGHT/LEFTWARDS COMPRESSED ARROW
+ 🡂  🡀    U+1F842, U+1F840 RIGHT/LEFTWARDS HEAVY COMPRESSED ARROW
+ 🡆  🡄    U+1F846, U+1F844 RIGHT/LEFTWARDS HEAVY ARROW
+ 🡒  🡐    U+1F852, U+1F850 RIGHT/LEFTWARDS SANS-SERIF ARROW
+ 🡢  🡠    U+1F862, U+1F860 WIDE-HEADED RIGHT/LEFTWARDS LIGHT BARB ARROW
+ 🡪  🡨    U+1F86A, U+1F868 WIDE-HEADED RIGHT/LEFTWARDS BARB ARROW
+ 🡲  🡰    U+1F872, U+1F870 WIDE-HEADED RIGHT/LEFTWARDS MEDIUM BARB ARROW
+ 🡺  🡸    U+1F87A, U+1F878 WIDE-HEADED RIGHT/LEFTWARDS HEAVY BARB ARROW
+ 🢂  🢀    U+1F882, U+1F880 WIDE-HEADED RIGHT/LEFTWARDS VERY HEAVY BARB
+                          ARROW
+ 🢒  🢐    U+1F892, U+1F890 RIGHT/LEFTWARDS TRIANGLE ARROWHEAD
+ 🢖  🢔    U+1F896, U+1F894 RIGHT/LEFTWARDS WHITE ARROW WITHIN TRIANGLE
+                          ARROWHEAD
+ 🢚  🢘    U+1F89A, U+1F898 RIGHT/LEFTWARDS ARROW WITH NOTCHED TAIL
+ 🢡  🢠    U+1F8A1, U+1F8A0 RIGHTWARDS BOTTOM SHADED WHITE ARROW,
+                          LEFTWARDS BOTTOM-SHADED WHITE ARROW
+ 🢣  🢢    U+1F8A3, U+1F8A2 RIGHT/LEFTWARDS TOP SHADED WHITE ARROW
+ 🢥  🢦    U+1F8A5, U+1F8A6 RIGHT/LEFTWARDS RIGHT-SHADED WHITE ARROW
+ 🢧  🢤    U+1F8A7, U+1F8A4 RIGHT/LEFTWARDS LEFT-SHADED WHITE ARROW
+ 🢩  🢨    U+1F8A9, U+1F8A8 RIGHT/LEFTWARDS BACK-TILTED SHADOWED WHITE ARROW
+ 🢫  🢪    U+1F8AB, U+1F8AA RIGHT/LEFTWARDS FRONT-TILTED SHADOWED WHITE
+                          ARROW
+
+=head2 The 'module_true' feature
+
+This feature removes the need to return a true value at the end of a module
+loaded with C<require> or C<use>. Any errors during compilation will cause
+failures, but reaching the end of the module when this feature is in effect
+will prevent C<perl> from throwing an exception that the module "did not return
+a true value".
+
 =head1 FEATURE BUNDLES
 
 It's possible to load multiple features together, using
@@ -816,12 +1340,12 @@ main compilation unit (that is, the one-liner that follows C<-E>).
 By explicitly requiring a minimum Perl version number for your program, with
 the C<use VERSION> construct.  That is,
 
-    use v5.10.0;
+    use v5.36.0;
 
 will do an implicit
 
     no feature ':all';
-    use feature ':5.10';
+    use feature ':5.36';
 
 and so on.  Note how the trailing sub-version
 is automatically stripped from the
@@ -829,7 +1353,7 @@ version.
 
 But to avoid portability warnings (see L<perlfunc/use>), you may prefer:
 
-    use 5.010;
+    use 5.036;
 
 with the same effect.
 
@@ -841,6 +1365,76 @@ also does the equivalent of C<use strict>; see L<perlfunc/use> for details.
 
 =back
 
+=head1 CHECKING FEATURES
+
+C<feature> provides some simple APIs to check which features are enabled.
+
+These functions cannot be imported and must be called by their fully
+qualified names.  If you don't otherwise need to set a feature you will
+need to ensure C<feature> is loaded with:
+
+  use feature ();
+
+=over
+
+=item feature_enabled($feature)
+
+=item feature_enabled($feature, $depth)
+
+  package MyStandardEnforcer;
+  use feature ();
+  use Carp "croak";
+  sub import {
+    croak "disable indirect!" if feature::feature_enabled("indirect");
+  }
+
+Test whether a named feature is enabled at a given level in the call
+stack, returning a true value if it is.  C<$depth> defaults to 1,
+which checks the scope that called the scope calling
+feature::feature_enabled().
+
+croaks for an unknown feature name.
+
+=item features_enabled()
+
+=item features_enabled($depth)
+
+  package ReportEnabledFeatures;
+  use feature "say";
+  sub import {
+    say STDERR join " ", feature::features_enabled();
+  }
+
+Returns a list of the features enabled at a given level in the call
+stack.  C<$depth> defaults to 1, which checks the scope that called
+the scope calling feature::features_enabled().
+
+=item feature_bundle()
+
+=item feature_bundle($depth)
+
+Returns the feature bundle, if any, selected at a given level in the
+call stack.  C<$depth> defaults to 1, which checks the scope that called
+the scope calling feature::feature_bundle().
+
+Returns an undefined value if no feature bundle is selected in the
+scope.
+
+The bundle name returned will be for the earliest bundle matching the
+selected bundle, so:
+
+  use feature ();
+  use v5.12;
+  BEGIN { print feature::feature_bundle(0); }
+
+will print C<5.11>.
+
+This returns internal state, at this point C<use v5.12;> sets the
+feature bundle, but C< use feature ":5.12"; > does not set the feature
+bundle.  This may change in a future release of perl.
+
+=back
+
 =cut
 
 sub import {
@@ -930,4 +1524,65 @@ sub croak {
     Carp::croak(@_);
 }
 
+sub features_enabled {
+    my ($depth) = @_;
+
+    $depth //= 1;
+    my @frame = caller($depth+1)
+      or return;
+    my ($hints, $hinthash) = @frame[8, 10];
+
+    my $bundle_number = $hints & $hint_mask;
+    if ($bundle_number != $hint_mask) {
+        return $feature_bundle{$hint_bundles[$bundle_number >> $hint_shift]}->@*;
+    }
+    else {
+        my @features;
+        for my $feature (sort keys %feature) {
+            if ($hinthash->{$feature{$feature}}) {
+                push @features, $feature;
+            }
+        }
+        return @features;
+    }
+}
+
+sub feature_enabled {
+    my ($feature, $depth) = @_;
+
+    $depth //= 1;
+    my @frame = caller($depth+1)
+      or return;
+    my ($hints, $hinthash) = @frame[8, 10];
+
+    my $hint_feature = $feature{$feature}
+      or croak "Unknown feature $feature";
+    my $bundle_number = $hints & $hint_mask;
+    if ($bundle_number != $hint_mask) {
+        my $bundle = $hint_bundles[$bundle_number >> $hint_shift];
+        for my $bundle_feature ($feature_bundle{$bundle}->@*) {
+            return 1 if $bundle_feature eq $feature;
+        }
+        return 0;
+    }
+    else {
+        return $hinthash->{$hint_feature} // 0;
+    }
+}
+
+sub feature_bundle {
+    my $depth = shift;
+
+    $depth //= 1;
+    my @frame = caller($depth+1)
+      or return;
+    my $bundle_number = $frame[8] & $hint_mask;
+    if ($bundle_number != $hint_mask) {
+        return $hint_bundles[$bundle_number >> $hint_shift];
+    }
+    else {
+        return undef;
+    }
+}
+
 1;