Add 'signatures' to :5.36 feature bundle

pod/perldelta.pod

@@ -31,17 +31,16 @@ here, but most should go in the L</Performance Enhancements> section.
 
 Introduced in Perl version 5.20.0, and modified several times since, the
 subroutine signatures feature (C<use feature 'signatures'>) is now no longer
-considered experimental.
+considered experimental. It is now considered a stable language feature and
+is included in the C<:5.36> feature bundle, enabled automatically by
+C<use v5.36>, and no longer prints a warning.
 
-    use warnings;
-    use feature 'signatures';
+    use v5.36;
 
     sub add ($x, $y) {
       return $x + $y;
     }
 
-No longer prints a warning.
-
 Despite this, certain elements of signatured subroutines remain
 experimental; see below.
 
@@ -58,7 +57,7 @@ argument array or an element thereof (C<@_> or C<$_[INDEX]>), either
 explicitly or implicitly (such as C<shift> or C<pop> with no argument) will
 provoke a warning at compile-time:
 
-    use feature 'signatures';
+    use v5.36;
 
     sub f ($x, $y = 123) {
       say "The first argument is $_[0]";

pod/perlexperiment.pod

@@ -159,7 +159,10 @@ subroutine signatures.
 
 Using the default arguments array (C<@_>) within a subroutine that uses
 signatures will emit a warning in the category
-C<experimental::args_array_with_signatures>.
+C<experimental::args_array_with_signatures>. This includes C<@_> directly,
+elements of it such as C<$_[$index]>, or situations where the default
+arguments array is accessed implicitly such as C<shift> or C<pop> without
+arguments.
 
 =back
 

pod/perlsub.pod

@@ -321,10 +321,12 @@ explicitly.  See L<perlmod/"BEGIN, UNITCHECK, CHECK, INIT and END">
 X<formal parameter> X<parameter, formal>
 
 Perl has a facility to allow a subroutine's formal parameters to be
-introduced by special syntax, separate from the procedural code of the
+declared by special syntax, separate from the procedural code of the
 subroutine body.  The formal parameter list is known as a I<signature>.
-The facility must be enabled first by a pragmatic declaration, 
-C<use feature 'signatures'>.
+
+This facility must be enabled before it can be used. It is enabled
+automatically by a C<use v5.36> (or higher) declaration, or more
+directly by C<use feature 'signatures'>, in the current scope.
 
 The signature is part of a subroutine's body.  Normally the body of a
 subroutine is simply a braced block of code, but when using a signature,

regen/feature.pl

@@ -60,7 +60,7 @@ BEGIN
 use constant V5_35  => sort grep {; $_ ne 'switch'
                                  && $_ ne 'bareword_filehandles'
                                  && $_ ne 'indirect'
-                                 && $_ ne 'multidimensional' } +V5_27, qw{isa};
+                                 && $_ ne 'multidimensional' } +V5_27, qw{isa signatures};
 
 my %feature_bundle = (
     all     => [ sort keys %feature ],
@@ -702,13 +702,15 @@ =head2 The 'postderef' and 'postderef_qq' features
 
 =head2 The 'signatures' feature
 
-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 suroutine:
 
     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. From Perl 5.20 to 5.34,
@@ -719,7 +721,8 @@ =head2 The 'signatures' feature
 
 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).
+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