Initial attempt at feature 'try'

 * Add feature, experimental warning, keyword
 * Basic parsing
 * Basic implementation as optree fragment

See also
  https://github.com/Perl/perl5/issues/18504

1 files changed, 17 insertions, 2 deletions

diff --git a/feature.h b/feature.h
index 173719f2b9..501bc3a3b1 100644
--- a/feature.h
+++ b/feature.h
@@ -27,8 +27,9 @@
 #define FEATURE_SIGNATURES_BIT           0x1000
 #define FEATURE_STATE_BIT                0x2000
 #define FEATURE_SWITCH_BIT               0x4000
-#define FEATURE_UNIEVAL_BIT              0x8000
-#define FEATURE_UNICODE_BIT              0x10000
+#define FEATURE_TRY_BIT                  0x8000
+#define FEATURE_UNIEVAL_BIT              0x10000
+#define FEATURE_UNICODE_BIT              0x20000
 
 #define FEATURE_BUNDLE_DEFAULT	0
 #define FEATURE_BUNDLE_510	1
@@ -72,6 +73,12 @@
 	 FEATURE_IS_ENABLED_MASK(FEATURE_SAY_BIT)) \
     )
 
+#define FEATURE_TRY_IS_ENABLED \
+    ( \
+	CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_CUSTOM && \
+	 FEATURE_IS_ENABLED_MASK(FEATURE_TRY_BIT) \
+    )
+
 #define FEATURE_STATE_IS_ENABLED \
     ( \
 	(CURRENT_FEATURE_BUNDLE >= FEATURE_BUNDLE_510 && \
@@ -337,6 +344,14 @@ S_magic_sethint_feature(pTHX_ SV *keysv, const char *keypv, STRLEN keylen,
             }
             return;
 
+        case 't':
+            if (keylen == sizeof("feature_try")-1
+                 && memcmp(subf+1, "ry", keylen - sizeof("feature_")) == 0) {
+                mask = FEATURE_TRY_BIT;
+                break;
+            }
+            return;
+
         case 'u':
             if (keylen == sizeof("feature_unicode")-1
                  && memcmp(subf+1, "nicode", keylen - sizeof("feature_")) == 0) {