Add require_false feature flag

feature.h

@@ -29,7 +29,7 @@
 	   & HINT_LOCALIZE_HH)						  \
 	    ? Perl_feature_is_enabled(aTHX_ STR_WITH_LEN(name)) : FALSE)
 /* The longest string we pass in.  */
-#define MAX_FEATURE_LEN (sizeof("postderef_qq")-1)
+#define MAX_FEATURE_LEN (sizeof("require_false")-1)
 
 #define FEATURE_FC_IS_ENABLED \
     ( \
@@ -127,6 +127,12 @@
 	 FEATURE_IS_ENABLED("myref") \
     )
 
+#define FEATURE_REQUIRE_FALSE_IS_ENABLED \
+    ( \
+	CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_CUSTOM && \
+	 FEATURE_IS_ENABLED("require_false") \
+    )
+
 #define FEATURE_UNICODE_IS_ENABLED \
     ( \
 	(CURRENT_FEATURE_BUNDLE >= FEATURE_BUNDLE_511 && \

lib/feature.pm

@@ -21,6 +21,7 @@ our %feature = (
     postderef_qq    => 'feature_postderef_qq',
     unicode_eval    => 'feature_unieval',
     declared_refs   => 'feature_myref',
+    require_false   => 'feature_require_false',
     unicode_strings => 'feature_unicode',
 );
 
@@ -30,7 +31,7 @@ our %feature_bundle = (
     "5.15"    => [qw(current_sub evalbytes fc say state switch unicode_eval unicode_strings)],
     "5.23"    => [qw(current_sub evalbytes fc postderef_qq say state switch unicode_eval unicode_strings)],
     "5.27"    => [qw(bitwise current_sub evalbytes fc postderef_qq say state switch unicode_eval unicode_strings)],
-    "all"     => [qw(array_base bitwise current_sub declared_refs evalbytes fc postderef_qq refaliasing say signatures state switch unicode_eval unicode_strings)],
+    "all"     => [qw(array_base bitwise current_sub declared_refs evalbytes fc postderef_qq refaliasing require_false say signatures state switch unicode_eval unicode_strings)],
     "default" => [qw(array_base)],
 );
 

regen/feature.pl

@@ -36,6 +36,7 @@ BEGIN
     unicode_strings => 'unicode',
     fc              => 'fc',
     signatures      => 'signatures',
+    require_false   => 'require_false',
 );
 
 # NOTE: If a feature is ever enabled in a non-contiguous range of Perl