The postderef feature is no longer experimental

As proposed by RJBS.

The "5.24" feature bundle (and therefore C<< use v5.24 >>) now enable
postderef and postderef_qq.

I can't find any precedent for what to do with the relevant experimental::*
warnings category when an experimental feature graduates to acceptance. I
have elected to leave the category in place, so that code doing C<< no
warnings "experimental::postderef" >> will continue to work. This means that
C<< use warnings "experimental::postderef" >> is also accepted, but has no
effect.

12 files changed, 61 insertions, 71 deletions

diff --git a/feature.h b/feature.h
index ba796eb8bd..dd98058256 100644
--- a/feature.h
+++ b/feature.h
@@ -13,6 +13,7 @@
 #define FEATURE_BUNDLE_510	1
 #define FEATURE_BUNDLE_511	2
 #define FEATURE_BUNDLE_515	3
+#define FEATURE_BUNDLE_523	4
 #define FEATURE_BUNDLE_CUSTOM	(HINT_FEATURE_MASK >> HINT_FEATURE_SHIFT)
 
 #define CURRENT_HINTS \
@@ -31,7 +32,8 @@
 
 #define FEATURE_FC_IS_ENABLED \
     ( \
-	CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_515 \
+	(CURRENT_FEATURE_BUNDLE >= FEATURE_BUNDLE_515 && \
+	 CURRENT_FEATURE_BUNDLE <= FEATURE_BUNDLE_523) \
      || (CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_CUSTOM && \
 	 FEATURE_IS_ENABLED("fc")) \
     )
@@ -39,7 +41,7 @@
 #define FEATURE_SAY_IS_ENABLED \
     ( \
 	(CURRENT_FEATURE_BUNDLE >= FEATURE_BUNDLE_510 && \
-	 CURRENT_FEATURE_BUNDLE <= FEATURE_BUNDLE_515) \
+	 CURRENT_FEATURE_BUNDLE <= FEATURE_BUNDLE_523) \
      || (CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_CUSTOM && \
 	 FEATURE_IS_ENABLED("say")) \
     )
@@ -47,7 +49,7 @@
 #define FEATURE_STATE_IS_ENABLED \
     ( \
 	(CURRENT_FEATURE_BUNDLE >= FEATURE_BUNDLE_510 && \
-	 CURRENT_FEATURE_BUNDLE <= FEATURE_BUNDLE_515) \
+	 CURRENT_FEATURE_BUNDLE <= FEATURE_BUNDLE_523) \
      || (CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_CUSTOM && \
 	 FEATURE_IS_ENABLED("state")) \
     )
@@ -55,7 +57,7 @@
 #define FEATURE_SWITCH_IS_ENABLED \
     ( \
 	(CURRENT_FEATURE_BUNDLE >= FEATURE_BUNDLE_510 && \
-	 CURRENT_FEATURE_BUNDLE <= FEATURE_BUNDLE_515) \
+	 CURRENT_FEATURE_BUNDLE <= FEATURE_BUNDLE_523) \
      || (CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_CUSTOM && \
 	 FEATURE_IS_ENABLED("switch")) \
     )
@@ -68,15 +70,17 @@
 
 #define FEATURE_EVALBYTES_IS_ENABLED \
     ( \
-	CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_515 \
+	(CURRENT_FEATURE_BUNDLE >= FEATURE_BUNDLE_515 && \
+	 CURRENT_FEATURE_BUNDLE <= FEATURE_BUNDLE_523) \
      || (CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_CUSTOM && \
 	 FEATURE_IS_ENABLED("evalbytes")) \
     )
 
 #define FEATURE_POSTDEREF_IS_ENABLED \
     ( \
-	CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_CUSTOM && \
-	 FEATURE_IS_ENABLED("postderef") \
+	CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_523 \
+     || (CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_CUSTOM && \
+	 FEATURE_IS_ENABLED("postderef")) \
     )
 
 #define FEATURE_ARYBASE_IS_ENABLED \
@@ -94,7 +98,8 @@
 
 #define FEATURE___SUB___IS_ENABLED \
     ( \
-	CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_515 \
+	(CURRENT_FEATURE_BUNDLE >= FEATURE_BUNDLE_515 && \
+	 CURRENT_FEATURE_BUNDLE <= FEATURE_BUNDLE_523) \
      || (CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_CUSTOM && \
 	 FEATURE_IS_ENABLED("__SUB__")) \
     )
@@ -113,13 +118,15 @@
 
 #define FEATURE_POSTDEREF_QQ_IS_ENABLED \
     ( \
-	CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_CUSTOM && \
-	 FEATURE_IS_ENABLED("postderef_qq") \
+	CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_523 \
+     || (CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_CUSTOM && \
+	 FEATURE_IS_ENABLED("postderef_qq")) \
     )
 
 #define FEATURE_UNIEVAL_IS_ENABLED \
     ( \
-	CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_515 \
+	(CURRENT_FEATURE_BUNDLE >= FEATURE_BUNDLE_515 && \
+	 CURRENT_FEATURE_BUNDLE <= FEATURE_BUNDLE_523) \
      || (CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_CUSTOM && \
 	 FEATURE_IS_ENABLED("unieval")) \
     )
@@ -127,7 +134,7 @@
 #define FEATURE_UNICODE_IS_ENABLED \
     ( \
 	(CURRENT_FEATURE_BUNDLE >= FEATURE_BUNDLE_511 && \
-	 CURRENT_FEATURE_BUNDLE <= FEATURE_BUNDLE_515) \
+	 CURRENT_FEATURE_BUNDLE <= FEATURE_BUNDLE_523) \
      || (CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_CUSTOM && \
 	 FEATURE_IS_ENABLED("unicode")) \
     )
@@ -142,6 +149,9 @@ S_enable_feature_bundle(pTHX_ SV *ver)
     SV *comp_ver = sv_newmortal();
     PL_hints = (PL_hints &~ HINT_FEATURE_MASK)
 	     | (
+		  (sv_setnv(comp_ver, 5.023),
+		   vcmp(ver, upg_version(comp_ver, FALSE)) >= 0)
+			? FEATURE_BUNDLE_523 :
 		  (sv_setnv(comp_ver, 5.015),
 		   vcmp(ver, upg_version(comp_ver, FALSE)) >= 0)
 			? FEATURE_BUNDLE_515 :
diff --git a/lib/feature.pm b/lib/feature.pm
index 4cf11a79da..e2076ed8a6 100644
--- a/lib/feature.pm
+++ b/lib/feature.pm
@@ -5,7 +5,7 @@
 
 package feature;
 
-our $VERSION = '1.41';
+our $VERSION = '1.42';
 
 our %feature = (
     fc              => 'feature_fc',
@@ -29,6 +29,7 @@ our %feature_bundle = (
     "5.10"    => [qw(array_base say state switch)],
     "5.11"    => [qw(array_base say state switch unicode_strings)],
     "5.15"    => [qw(current_sub evalbytes fc say state switch unicode_eval unicode_strings)],
+    "5.23"    => [qw(current_sub evalbytes fc postderef postderef_qq say state switch unicode_eval unicode_strings)],
     "all"     => [qw(array_base bitwise current_sub evalbytes fc lexical_subs postderef postderef_qq refaliasing say signatures state switch unicode_eval unicode_strings)],
     "default" => [qw(array_base)],
 );
@@ -43,13 +44,12 @@ $feature_bundle{"5.19"} = $feature_bundle{"5.15"};
 $feature_bundle{"5.20"} = $feature_bundle{"5.15"};
 $feature_bundle{"5.21"} = $feature_bundle{"5.15"};
 $feature_bundle{"5.22"} = $feature_bundle{"5.15"};
-$feature_bundle{"5.23"} = $feature_bundle{"5.15"};
-$feature_bundle{"5.24"} = $feature_bundle{"5.15"};
+$feature_bundle{"5.24"} = $feature_bundle{"5.23"};
 $feature_bundle{"5.9.5"} = $feature_bundle{"5.10"};
 
 our $hint_shift   = 26;
 our $hint_mask    = 0x1c000000;
-our @hint_bundles = qw( default 5.10 5.11 5.15 );
+our @hint_bundles = qw( default 5.10 5.11 5.15 5.23 );
 
 # This gets set (for now) in $^H as well as in %^H,
 # for runtime speed of the uc/lc/ucfirst/lcfirst functions.
@@ -260,13 +260,6 @@ This feature is available from Perl 5.18 onwards.
 
 =head2 The 'postderef' and 'postderef_qq' features
 
-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::postderef";
-
 The 'postderef' feature allows the use of L<postfix dereference
 syntax|perlref/Postfix Dereference Syntax>.  For example, it will make the
 following two statements equivalent:
@@ -277,7 +270,15 @@ following two statements equivalent:
 The 'postderef_qq' feature extends this, for array and scalar dereference, to
 working inside of double-quotish interpolations.
 
-This feature is available from Perl 5.20 onwards.
+These features are available from Perl 5.20 onwards. In Perl 5.20 and 5.22,
+they were classed as experimental, and Perl emitted a warning for their
+usage, except when explicitly disabled:
+
+  no warnings "experimental::postderef";
+
+As of Perl 5.24, use of these features no longer triggers a warning, though
+the C<experimental::postderef> warning category still exists (for
+compatibility with code that disables it).
 
 =head2 The 'signatures' feature
 
@@ -374,6 +375,7 @@ The following feature bundles are available:
 
   :5.24     say state switch unicode_strings
             unicode_eval evalbytes current_sub fc
+            postderef postderef_qq
 
 The C<:default> bundle represents the feature set that is enabled before
 any C<use feature> or C<no feature> declaration.
diff --git a/lib/overload.t b/lib/overload.t
index e6f4062932..ef4ce4e593 100644
--- a/lib/overload.t
+++ b/lib/overload.t
@@ -2739,7 +2739,6 @@ package refsgalore {
 }
 {
     use feature 'postderef';
-    no warnings 'experimental::postderef';
     tell myio; # vivifies *myio{IO} at compile time
     use constant ioref => bless *myio{IO}, refsgalore::;
     is ioref->$*, 42, '(overloaded constant that is not a scalar ref)->$*';
diff --git a/pod/perldelta.pod b/pod/perldelta.pod
index 58ece4a384..c31893fdb3 100644
--- a/pod/perldelta.pod
+++ b/pod/perldelta.pod
@@ -16,6 +16,12 @@ release.
 For details on what is in this release, see
 L<http://www.unicode.org/versions/Unicode8.0.0/>.
 
+=head2 Postfix dereferencing is no longer experimental
+
+Using the C<postderef> and C<postderef_qq> features no longer emits a warning.
+Existing code that disables that warning category will continue to work. The
+C<5.24> feature bundle now includes those features.
+
 =head1 Incompatible Changes
 
 =head2 The C</\C/> character class has been removed.
diff --git a/pod/perldiag.pod b/pod/perldiag.pod
index 558fd62428..9d048cfda5 100644
--- a/pod/perldiag.pod
+++ b/pod/perldiag.pod
@@ -4748,21 +4748,6 @@ but there was no array C<@foo> in scope at the time.  If you wanted a
 literal @foo, then write it as \@foo; otherwise find out what happened
 to the array you apparently lost track of.
 
-=item Postfix dereference is experimental
-
-(S experimental::postderef) This warning is emitted if you use
-the experimental postfix dereference syntax.  Simply suppress the
-warning if you want to use the feature, but know that in doing
-so you are taking the risk of using an experimental feature which
-may change or be removed in a future Perl version:
-
-    no warnings "experimental::postderef";
-    use feature "postderef", "postderef_qq";
-    $ref->$*;
-    $aref->@*;
-    $aref->@[@indices];
-    ... etc ...
-
 =item Precedence problem: open %s should be open(%s)
 
 (S precedence) The old irregular construct
diff --git a/pod/perlexperiment.pod b/pod/perlexperiment.pod
index 1e7dd27c67..f670147631 100644
--- a/pod/perlexperiment.pod
+++ b/pod/perlexperiment.pod
@@ -97,16 +97,6 @@ C<experimental::signatures>.
 The ticket for this feature is
 L<[perl #121481]|https://rt.perl.org/Ticket/Display.html?id=121481>.
 
-=item Postfix dereference syntax
-
-Introduced in Perl 5.20.0
-
-Using this feature triggers warnings in the category
-C<experimental::postderef>.
-
-The ticket for this feature is
-L<[perl #120162]|https://rt.perl.org:443/rt3/Ticket/Display.html?id=120162>.
-
 =item Aliasing via reference
 
 Introduced in Perl 5.22.0
@@ -270,6 +260,12 @@ Accepted in Perl 5.20.0
 
 Accepted in Perl 5.22.0
 
+=item Postfix dereference syntax
+
+Introduced in Perl 5.20.0
+
+Accepted in Perl 5.24.0
+
 =back
 
 =head2 Removed features
diff --git a/pod/perlop.pod b/pod/perlop.pod
index 018698e89c..d47bcb66e6 100644
--- a/pod/perlop.pod
+++ b/pod/perlop.pod
@@ -154,7 +154,7 @@ and the left side must be either an object (a blessed reference)
 or a class name (that is, a package name).  See L<perlobj>.
 
 The dereferencing cases (as opposed to method-calling cases) are
-somewhat extended by the experimental C<postderef> feature.  For the
+somewhat extended by the C<postderef> feature.  For the
 details of that feature, consult L<perlref/Postfix Dereference Syntax>.
 
 =head2 Auto-increment and Auto-decrement
diff --git a/pod/perlref.pod b/pod/perlref.pod
index 86ecfdd404..8956be5750 100644
--- a/pod/perlref.pod
+++ b/pod/perlref.pod
@@ -758,9 +758,7 @@ For example:
     $r = [ 1, [ 2, 3 ], 4 ];
     $r->[1]->@*;  # equivalent to @{ $r->[1] }
 
-This syntax must be enabled with C<use feature 'postderef'>.  It is
-experimental, and will warn by default unless C<no warnings
-'experimental::postderef'> is in effect.
+This syntax must be enabled with C<use feature 'postderef'>.
 
 Postfix dereference should work in all circumstances where block
 (circumfix) dereference worked, and should be entirely equivalent.  This
diff --git a/regen/feature.pl b/regen/feature.pl
index 115c5a5c32..48363041f4 100755
--- a/regen/feature.pl
+++ b/regen/feature.pl
@@ -60,7 +60,7 @@ my %feature_bundle = (
     "5.21"   =>	[qw(say state switch unicode_strings unicode_eval
 		    evalbytes current_sub fc)],
     "5.23"   =>	[qw(say state switch unicode_strings unicode_eval
-		    evalbytes current_sub fc)],
+		    evalbytes current_sub fc postderef postderef_qq)],
 );
 
 # not actually used currently
@@ -367,7 +367,7 @@ read_only_bottom_close_and_rename($h);
 __END__
 package feature;
 
-our $VERSION = '1.41';
+our $VERSION = '1.42';
 
 FEATURES
 
@@ -575,13 +575,6 @@ This feature is available from Perl 5.18 onwards.
 
 =head2 The 'postderef' and 'postderef_qq' features
 
-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::postderef";
-
 The 'postderef' feature allows the use of L<postfix dereference
 syntax|perlref/Postfix Dereference Syntax>.  For example, it will make the
 following two statements equivalent:
@@ -592,7 +585,15 @@ following two statements equivalent:
 The 'postderef_qq' feature extends this, for array and scalar dereference, to
 working inside of double-quotish interpolations.
 
-This feature is available from Perl 5.20 onwards.
+These features are available from Perl 5.20 onwards. In Perl 5.20 and 5.22,
+they were classed as experimental, and Perl emitted a warning for their
+usage, except when explicitly disabled:
+
+  no warnings "experimental::postderef";
+
+As of Perl 5.24, use of these features no longer triggers a warning, though
+the C<experimental::postderef> warning category still exists (for
+compatibility with code that disables it).
 
 =head2 The 'signatures' feature
 
diff --git a/t/lib/warnings/toke b/t/lib/warnings/toke
index dab8451484..d65467c218 100644
--- a/t/lib/warnings/toke
+++ b/t/lib/warnings/toke
@@ -1047,8 +1047,6 @@ no warnings 'experimental::postderef';
 (\$_)->$*;
 "$_->$*";
 EXPECT
-Postfix dereference is experimental at - line 3.
-Postfix dereference is experimental at - line 4.
 ########
 # toke.c
 use warnings 'portable' ;
diff --git a/t/op/postfixderef.t b/t/op/postfixderef.t
index 79b66dea4b..920bc2db23 100644
--- a/t/op/postfixderef.t
+++ b/t/op/postfixderef.t
@@ -43,7 +43,6 @@ plan(125);
 }
 
 use feature 'postderef';
-no warnings 'experimental::postderef';
 
 {
     no strict 'refs';
diff --git a/toke.c b/toke.c
index 71938bd879..763baa5eb0 100644
--- a/toke.c
+++ b/toke.c
@@ -5140,10 +5140,6 @@ Perl_yylex(pTHX)
 		  ||(*s == '*' && (s[1] == '*' || s[1] == '{'))
 		 ))
 		{
-		    Perl_ck_warner_d(aTHX_
-			packWARN(WARN_EXPERIMENTAL__POSTDEREF),
-			"Postfix dereference is experimental"
-		    );
 		    PL_expect = XPOSTDEREF;
 		    TOKEN(ARROW);
 		}