Add a new regex flag, RXf_RTRIM.

dump.c

@@ -918,6 +918,8 @@ S_pm_description(pTHX_ const PMOP *pm)
             sv_catpvs(desc, ",WHITE");
         if (RX_EXTFLAGS(regex) & RXf_NULL)
             sv_catpvs(desc, ",NULL");
+        if (RX_EXTFLAGS(regex) & RXf_RTRIM)
+            sv_catpvs(desc, ",RTRIM");
     }
 
     append_flags(desc, pmflags, pmflags_flags_names);
@@ -1708,6 +1710,7 @@ const struct flag_to_name regexp_extflags_names[] = {
     {RXf_SKIPWHITE,       "SKIPWHITE,"},
     {RXf_WHITE,           "WHITE,"},
     {RXf_NULL,            "NULL,"},
+    {RXf_RTRIM,           "RTRIM,"},
 };
 
 /* NOTE: this structure is mostly duplicative of one generated by

regexp.h

@@ -450,6 +450,7 @@ and check for NULL.
                                                           /* split " " */
 #  define RXf_WHITE		(1U<<(RXf_BASE_SHIFT+16)) /* Pattern is /\s+/ */
 #  define RXf_NULL		(1U<<(RXf_BASE_SHIFT+17)) /* Pattern is // */
+#  define RXf_RTRIM		(1U<<(RXf_BASE_SHIFT+18)) /* Pattern is /[:space:]\z/u */
 
 /* See comments at the beginning of these defines about adding bits.  The
  * highest bit position should be used, so that if RXf_BASE_SHIFT gets

regnodes.h

@@ -1654,7 +1654,7 @@ EXTCONST char * const PL_reg_name[] = {
 EXTCONST char * PL_reg_extflags_name[];
 #else
 EXTCONST char * const PL_reg_extflags_name[] = {
-	/* Bits in extflags defined: 01111111111111111000111111111111 */
+	/* Bits in extflags defined: 11111111111111111000111111111111 */
 	"MULTILINE",        /* 0x00000001 */
 	"SINGLELINE",       /* 0x00000002 */
 	"FOLD",             /* 0x00000004 */
@@ -1686,7 +1686,7 @@ EXTCONST char * const PL_reg_extflags_name[] = {
 	"SKIPWHITE",        /* 0x10000000 */
 	"WHITE",            /* 0x20000000 */
 	"NULL",             /* 0x40000000 */
-	"UNUSED_BIT_31",    /* 0x80000000 */
+	"RTRIM",            /* 0x80000000 */
 };
 #endif /* DOINIT */