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Use mnemonics for array indices
[perl5.git] / regcomp.c
index 50e98bd..c7af3fe 100644 (file)
--- a/regcomp.c
+++ b/regcomp.c
@@ -1546,6 +1546,10 @@ S_ssc_is_cp_posixl_init(const RExC_state_t *pRExC_state,
     return TRUE;
 }
 
+#define INVLIST_INDEX 0
+#define ONLY_LOCALE_MATCHES_INDEX 1
+#define DEFERRED_USER_DEFINED_INDEX 2
+
 STATIC SV*
 S_get_ANYOF_cp_list_for_ssc(pTHX_ const RExC_state_t *pRExC_state,
                                const regnode_charclass* const node)
@@ -1571,28 +1575,24 @@ S_get_ANYOF_cp_list_for_ssc(pTHX_ const RExC_state_t *pRExC_state,
         SV **const ary = AvARRAY(av);
         assert(RExC_rxi->data->what[n] == 's');
 
-        if (ary[1] && ary[1] != &PL_sv_undef) { /* Has compile-time swash */
-            invlist = sv_2mortal(invlist_clone(_get_swash_invlist(ary[1]), NULL));
-        }
-        else if (ary[0] && ary[0] != &PL_sv_undef) {
+        if (av_tindex_skip_len_mg(av) >= DEFERRED_USER_DEFINED_INDEX) {
 
-            /* Here, no compile-time swash, and there are things that won't be
-             * known until runtime -- we have to assume it could be anything */
+            /* Here there are things that won't be known until runtime -- we
+             * have to assume it could be anything */
             invlist = sv_2mortal(_new_invlist(1));
             return _add_range_to_invlist(invlist, 0, UV_MAX);
         }
-        else if (ary[3] && ary[3] != &PL_sv_undef) {
+        else if (ary[INVLIST_INDEX]) {
 
-            /* Here no compile-time swash, and no run-time only data.  Use the
-             * node's inversion list */
-            invlist = sv_2mortal(invlist_clone(ary[3], NULL));
+            /* Use the node's inversion list */
+            invlist = sv_2mortal(invlist_clone(ary[INVLIST_INDEX], NULL));
         }
 
         /* Get the code points valid only under UTF-8 locales */
-        if ((ANYOF_FLAGS(node) & ANYOFL_FOLD)
-            && ary[2] && ary[2] != &PL_sv_undef)
+        if (   (ANYOF_FLAGS(node) & ANYOFL_FOLD)
+            &&  av_tindex_skip_len_mg(av) >= ONLY_LOCALE_MATCHES_INDEX)
         {
-            only_utf8_locale_invlist = ary[2];
+            only_utf8_locale_invlist = ary[ONLY_LOCALE_MATCHES_INDEX];
         }
     }
 
@@ -1617,15 +1617,19 @@ S_get_ANYOF_cp_list_for_ssc(pTHX_ const RExC_state_t *pRExC_state,
     }
 
     /* Add in the points from the bit map */
-    for (i = 0; i < NUM_ANYOF_CODE_POINTS; i++) {
-        if (ANYOF_BITMAP_TEST(node, i)) {
-            unsigned int start = i++;
+    if (OP(node) != ANYOFH) {
+        for (i = 0; i < NUM_ANYOF_CODE_POINTS; i++) {
+            if (ANYOF_BITMAP_TEST(node, i)) {
+                unsigned int start = i++;
 
-            for (; i < NUM_ANYOF_CODE_POINTS && ANYOF_BITMAP_TEST(node, i); ++i) {
-                /* empty */
+                for (;    i < NUM_ANYOF_CODE_POINTS
+                       && ANYOF_BITMAP_TEST(node, i); ++i)
+                {
+                    /* empty */
+                }
+                invlist = _add_range_to_invlist(invlist, start, i-1);
+                new_node_has_latin1 = TRUE;
             }
-            invlist = _add_range_to_invlist(invlist, start, i-1);
-            new_node_has_latin1 = TRUE;
         }
     }
 
@@ -1647,11 +1651,26 @@ S_get_ANYOF_cp_list_for_ssc(pTHX_ const RExC_state_t *pRExC_state,
     if (ANYOF_FLAGS(node) & ANYOF_INVERT) {
         _invlist_invert(invlist);
     }
-    else if (new_node_has_latin1 && ANYOF_FLAGS(node) & ANYOFL_FOLD) {
+    else if (ANYOF_FLAGS(node) & ANYOFL_FOLD) {
+        if (new_node_has_latin1) {
 
-        /* Under /li, any 0-255 could fold to any other 0-255, depending on the
-         * locale.  We can skip this if there are no 0-255 at all. */
-        _invlist_union(invlist, PL_Latin1, &invlist);
+            /* Under /li, any 0-255 could fold to any other 0-255, depending on
+             * the locale.  We can skip this if there are no 0-255 at all. */
+            _invlist_union(invlist, PL_Latin1, &invlist);
+
+            invlist = add_cp_to_invlist(invlist, LATIN_SMALL_LETTER_DOTLESS_I);
+            invlist = add_cp_to_invlist(invlist, LATIN_CAPITAL_LETTER_I_WITH_DOT_ABOVE);
+        }
+        else {
+            if (_invlist_contains_cp(invlist, LATIN_SMALL_LETTER_DOTLESS_I)) {
+                invlist = add_cp_to_invlist(invlist, 'I');
+            }
+            if (_invlist_contains_cp(invlist,
+                                        LATIN_CAPITAL_LETTER_I_WITH_DOT_ABOVE))
+            {
+                invlist = add_cp_to_invlist(invlist, 'i');
+            }
+        }
     }
 
     /* Similarly add the UTF-8 locale possible matches.  These have to be
@@ -2038,7 +2057,7 @@ S_is_ssc_worth_it(const RExC_state_t * pRExC_state, const regnode_ssc * ssc)
     U32 count = 0;      /* Running total of number of code points matched by
                            'ssc' */
     UV start, end;      /* Start and end points of current range in inversion
-                           list */
+                           XXX outdated.  UTF-8 locales are common, what about invert? list */
     const U32 max_code_points = (LOC)
                                 ?  256
                                 : ((  ! UNI_SEMANTICS
@@ -4335,6 +4354,23 @@ S_join_exact(pTHX_ RExC_state_t *pRExC_state, regnode *scan,
            }
 #endif
        }
+
+        if (     STR_LEN(scan) == 1
+            &&   isALPHA_A(* STRING(scan))
+            &&  (         OP(scan) == EXACTFAA
+                 || (     OP(scan) == EXACTFU
+                     && ! HAS_NONLATIN1_SIMPLE_FOLD_CLOSURE(* STRING(scan)))))
+        {
+            U8 mask = ~ ('A' ^ 'a'); /* These differ in just one bit */
+
+            /* Replace a length 1 ASCII fold pair node with an ANYOFM node,
+             * with the mask set to the complement of the bit that differs
+             * between upper and lower case, and the lowest code point of the
+             * pair (which the '&' forces) */
+            OP(scan) = ANYOFM;
+            ARG_SET(scan, *STRING(scan) & mask);
+            FLAGS(scan) = mask;
+        }
     }
 
 #ifdef DEBUGGING
@@ -5275,6 +5311,27 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
                     OP(next) = EXACTFU;
                 }
 
+                if (     STR_LEN(next) == 1
+                    &&   isALPHA_A(* STRING(next))
+                    && (         OP(next) == EXACTFAA
+                        || (     OP(next) == EXACTFU
+                            && ! HAS_NONLATIN1_SIMPLE_FOLD_CLOSURE(* STRING(next)))))
+                {
+                    /* These differ in just one bit */
+                    U8 mask = ~ ('A' ^ 'a');
+
+                    assert(isALPHA_A(* STRING(next)));
+
+                    /* Then replace it by an ANYOFM node, with
+                    * the mask set to the complement of the
+                    * bit that differs between upper and lower
+                    * case, and the lowest code point of the
+                    * pair (which the '&' forces) */
+                    OP(next) = ANYOFM;
+                    ARG_SET(next, *STRING(next) & mask);
+                    FLAGS(next) = mask;
+                }
+
                if (flags & SCF_DO_STCLASS) {
                    mincount = 0;
                    maxcount = REG_INFTY;
@@ -5763,6 +5820,7 @@ Perl_re_printf( aTHX_  "LHS=%" UVuf " RHS=%" UVuf "\n",
                 case ANYOFD:
                 case ANYOFL:
                 case ANYOFPOSIXL:
+                case ANYOFH:
                 case ANYOF:
                    if (flags & SCF_DO_STCLASS_AND)
                        ssc_and(pRExC_state, data->start_class,
@@ -8765,7 +8823,6 @@ S_reg_scan_name(pTHX_ RExC_state_t *pRExC_state, U32 flags)
 }
 
 #define DEBUG_PARSE_MSG(funcname)     DEBUG_PARSE_r({           \
-    int num;                                                    \
     if (RExC_lastparse!=RExC_parse) {                           \
         Perl_re_printf( aTHX_  "%s",                            \
             Perl_pv_pretty(aTHX_ RExC_mysv1, RExC_parse,        \
@@ -8781,16 +8838,15 @@ S_reg_scan_name(pTHX_ RExC_state_t *pRExC_state, U32 flags)
     } else                                                      \
         Perl_re_printf( aTHX_ "%16s","");                       \
                                                                 \
-    num=REG_NODE_NUM(REGNODE_p(RExC_emit));                     \
-    if (RExC_lastnum!=num)                                      \
-       Perl_re_printf( aTHX_ "|%4d", num);                      \
+    if (RExC_lastnum!=RExC_emit)                                \
+       Perl_re_printf( aTHX_ "|%4d", RExC_emit);                \
     else                                                        \
        Perl_re_printf( aTHX_ "|%4s","");                        \
     Perl_re_printf( aTHX_ "|%*s%-4s",                           \
         (int)((depth*2)), "",                                   \
         (funcname)                                              \
     );                                                          \
-    RExC_lastnum=num;                                           \
+    RExC_lastnum=RExC_emit;                                     \
     RExC_lastparse=RExC_parse;                                  \
 })
 
@@ -9074,9 +9130,7 @@ Perl__new_invlist(pTHX_ IV initial_size)
        initial_size = 10;
     }
 
-    /* Allocate the initial space */
     new_list = newSV_type(SVt_INVLIST);
-
     initialize_invlist_guts(new_list, initial_size);
 
     return new_list;
@@ -10261,18 +10315,15 @@ Perl__invlist_invert(pTHX_ SV* const invlist)
 SV*
 Perl_invlist_clone(pTHX_ SV* const invlist, SV* new_invlist)
 {
-
     /* Return a new inversion list that is a copy of the input one, which is
      * unchanged.  The new list will not be mortal even if the old one was. */
 
-    const STRLEN nominal_length = _invlist_len(invlist);    /* Why not +1 XXX */
+    const STRLEN nominal_length = _invlist_len(invlist);
     const STRLEN physical_length = SvCUR(invlist);
     const bool offset = *(get_invlist_offset_addr(invlist));
 
     PERL_ARGS_ASSERT_INVLIST_CLONE;
 
-    /* Need to allocate extra space to accommodate Perl's addition of a
-     * trailing NUL to SvPV's, since it thinks they are always strings */
     if (new_invlist == NULL) {
         new_invlist = _new_invlist(nominal_length);
     }
@@ -10563,7 +10614,8 @@ Perl__invlistEQ(pTHX_ SV* const a, SV* const b, const bool complement_b)
 
 /*
  * As best we can, determine the characters that can match the start of
- * the given EXACTF-ish node.
+ * the given EXACTF-ish node.  This is for use in creating ssc nodes, so there
+ * can be false positive matches
  *
  * Returns the invlist as a new SV*; it is the caller's responsibility to
  * call SvREFCNT_dec() when done with it.
@@ -10595,9 +10647,14 @@ S__make_exactf_invlist(pTHX_ RExC_state_t *pRExC_state, regnode *node)
         }
         else {
             /* Any Latin1 range character can potentially match any
-             * other depending on the locale */
+             * other depending on the locale, and in Turkic locales, U+130 and
+             * U+131 */
             if (OP(node) == EXACTFL) {
                 _invlist_union(invlist, PL_Latin1, &invlist);
+                invlist = add_cp_to_invlist(invlist,
+                                                LATIN_SMALL_LETTER_DOTLESS_I);
+                invlist = add_cp_to_invlist(invlist,
+                                        LATIN_CAPITAL_LETTER_I_WITH_DOT_ABOVE);
             }
             else {
                 /* But otherwise, it matches at least itself.  We can
@@ -10701,6 +10758,26 @@ S__make_exactf_invlist(pTHX_ RExC_state_t *pRExC_state, regnode *node)
 
                 invlist = add_cp_to_invlist(invlist, c);
             }
+
+            if (OP(node) == EXACTFL) {
+
+                /* If either [iI] are present in an EXACTFL node the above code
+                 * should have added its normal case pair, but under a Turkish
+                 * locale they could match instead the case pairs from it.  Add
+                 * those as potential matches as well */
+                if (isALPHA_FOLD_EQ(fc, 'I')) {
+                    invlist = add_cp_to_invlist(invlist,
+                                                LATIN_SMALL_LETTER_DOTLESS_I);
+                    invlist = add_cp_to_invlist(invlist,
+                                        LATIN_CAPITAL_LETTER_I_WITH_DOT_ABOVE);
+                }
+                else if (fc == LATIN_SMALL_LETTER_DOTLESS_I) {
+                    invlist = add_cp_to_invlist(invlist, 'I');
+                }
+                else if (fc == LATIN_CAPITAL_LETTER_I_WITH_DOT_ABOVE) {
+                    invlist = add_cp_to_invlist(invlist, 'i');
+                }
+            }
         }
     }
 
@@ -12006,7 +12083,7 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp, U32 depth)
                 DEBUG_OPTIMISE_MORE_r(Perl_re_printf( aTHX_
                     "%*s%*s Setting open paren #%" IVdf " to %d\n",
                     22, "|    |", (int)(depth * 2 + 1), "",
-                    (IV)parno, REG_NODE_NUM(REGNODE_p(ret))));
+                    (IV)parno, ret));
                 RExC_open_parens[parno]= ret;
             }
 
@@ -12095,7 +12172,7 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp, U32 depth)
                 DEBUG_OPTIMISE_MORE_r(Perl_re_printf( aTHX_
                         "%*s%*s Setting close paren #%" IVdf " to %d\n",
                         22, "|    |", (int)(depth * 2 + 1), "",
-                        (IV)parno, REG_NODE_NUM(REGNODE_p(ender))));
+                        (IV)parno, ender));
                 RExC_close_parens[parno]= ender;
                if (RExC_nestroot == parno)
                    RExC_nestroot = 0;
@@ -12129,7 +12206,7 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp, U32 depth)
                 DEBUG_OPTIMISE_MORE_r(Perl_re_printf( aTHX_
                     "%*s%*s Setting close paren #0 (END) to %d\n",
                     22, "|    |", (int)(depth * 2 + 1), "",
-                    REG_NODE_NUM(REGNODE_p(ender))));
+                    ender));
 
                 RExC_close_parens[0]= ender;
             }
@@ -12141,9 +12218,9 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp, U32 depth)
             regprop(RExC_rx, RExC_mysv2, REGNODE_p(ender), NULL, pRExC_state);
             Perl_re_printf( aTHX_  "~ tying lastbr %s (%" IVdf ") to ender %s (%" IVdf ") offset %" IVdf "\n",
                           SvPV_nolen_const(RExC_mysv1),
-                          (IV)REG_NODE_NUM(REGNODE_p(lastbr)),
+                          (IV)lastbr,
                           SvPV_nolen_const(RExC_mysv2),
-                          (IV)REG_NODE_NUM(REGNODE_p(ender)),
+                          (IV)ender,
                           (IV)(ender - lastbr)
             );
         );
@@ -12191,7 +12268,7 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp, U32 depth)
                                   SvPV_nolen_const(RExC_mysv1),
                                   (IV)REG_NODE_NUM(ret_as_regnode),
                                   SvPV_nolen_const(RExC_mysv2),
-                                  (IV)REG_NODE_NUM(REGNODE_p(ender)),
+                                  (IV)ender,
                                   (IV)(ender - ret)
                     );
                 );
@@ -13268,25 +13345,17 @@ S_regatom(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth)
             /* FALLTHROUGH */
        case 'b':
           {
+            U8 flags = 0;
            regex_charset charset = get_regex_charset(RExC_flags);
 
            RExC_seen_zerolen++;
             RExC_seen |= REG_LOOKBEHIND_SEEN;
            op = BOUND + charset;
 
-            if (op == BOUND) {
-                RExC_seen_d_op = TRUE;
-            }
-            else if (op == BOUNDL) {
-                RExC_contains_locale = 1;
-            }
-
-           ret = reg_node(pRExC_state, op);
-           *flagp |= SIMPLE;
            if (RExC_parse >= RExC_end || *(RExC_parse + 1) != '{') {
-                FLAGS(REGNODE_p(ret)) = TRADITIONAL_BOUND;
+                flags = TRADITIONAL_BOUND;
                 if (op > BOUNDA) {  /* /aa is same as /a */
-                    OP(REGNODE_p(ret)) = BOUNDA;
+                    op = BOUNDA;
                 }
             }
             else {
@@ -13322,25 +13391,25 @@ S_regatom(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth)
                         {
                             goto bad_bound_type;
                         }
-                        FLAGS(REGNODE_p(ret)) = GCB_BOUND;
+                        flags = GCB_BOUND;
                         break;
                     case 'l':
                         if (length != 2 || *(RExC_parse + 1) != 'b') {
                             goto bad_bound_type;
                         }
-                        FLAGS(REGNODE_p(ret)) = LB_BOUND;
+                        flags = LB_BOUND;
                         break;
                     case 's':
                         if (length != 2 || *(RExC_parse + 1) != 'b') {
                             goto bad_bound_type;
                         }
-                        FLAGS(REGNODE_p(ret)) = SB_BOUND;
+                        flags = SB_BOUND;
                         break;
                     case 'w':
                         if (length != 2 || *(RExC_parse + 1) != 'b') {
                             goto bad_bound_type;
                         }
-                        FLAGS(REGNODE_p(ret)) = WB_BOUND;
+                        flags = WB_BOUND;
                         break;
                     default:
                       bad_bound_type:
@@ -13353,8 +13422,11 @@ S_regatom(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth)
                 RExC_parse = endbrace;
                 REQUIRE_UNI_RULES(flagp, 0);
 
-                if (op >= BOUNDA) {  /* /aa is same as /a */
-                    OP(REGNODE_p(ret)) = BOUNDU;
+                if (op == BOUND) {
+                    op = BOUNDU;
+                }
+                else if (op >= BOUNDA) {  /* /aa is same as /a */
+                    op = BOUNDU;
                     length += 4;
 
                     /* Don't have to worry about UTF-8, in this message because
@@ -13369,9 +13441,22 @@ S_regatom(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth)
                 }
            }
 
+            if (op == BOUND) {
+                RExC_seen_d_op = TRUE;
+            }
+            else if (op == BOUNDL) {
+                RExC_contains_locale = 1;
+            }
+
             if (invert) {
-                OP(REGNODE_p(ret)) += NBOUND - BOUND;
+                op += NBOUND - BOUND;
             }
+
+           ret = reg_node(pRExC_state, op);
+            FLAGS(REGNODE_p(ret)) = flags;
+
+           *flagp |= SIMPLE;
+
            goto finish_meta_pat;
           }
 
@@ -14328,14 +14413,15 @@ S_regatom(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth)
              * identifies, so when it is set to less than the full node, we can
              * skip the rest of this */
             if (FOLD && p < RExC_end && upper_parse == MAX_NODE_STRING_SIZE) {
+                PERL_UINT_FAST8_T backup_count = 0;
 
                 const STRLEN full_len = len;
 
                assert(len >= MAX_NODE_STRING_SIZE);
 
-                /* Here, <s> points to the final byte of the final character.
-                 * Look backwards through the string until find a non-
-                 * problematic character */
+                /* Here, <s> points to just beyond where we have output the
+                 * final character of the node.  Look backwards through the
+                 * string until find a non- problematic character */
 
                if (! UTF) {
 
@@ -14344,7 +14430,9 @@ S_regatom(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth)
                         goto loopdone;
                     }
 
-                    while (--s >= s0 && IS_NON_FINAL_FOLD(*s)) { }
+                    while (--s >= s0 && IS_NON_FINAL_FOLD(*s)) {
+                        backup_count++;
+                    }
                     len = s - s0 + 1;
                }
                 else {
@@ -14386,6 +14474,7 @@ S_regatom(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth)
                          * special case the very first byte in the string, so
                          * we don't read outside the string */
                         s = (s == s0) ? s -1 : (char *) utf8_hop((U8 *) s, -1);
+                        backup_count++;
                     } /* End of loop backwards through the string */
 
                     /* If there were only problematic characters in the string,
@@ -14409,12 +14498,13 @@ S_regatom(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth)
                 } else {
 
                     /* Here, the node does contain some characters that aren't
-                     * problematic.  If one such is the final character in the
-                     * node, we are done */
-                    if (len == full_len) {
+                     * problematic.  If we didn't have to backup any, then the
+                     * final character in the node is non-problematic, and we
+                     * can take the node as-is */
+                    if (backup_count == 0) {
                         goto loopdone;
                     }
-                    else if (len + ((UTF) ? UTF8SKIP(s) : 1) == full_len) {
+                    else if (backup_count == 1) {
 
                         /* If the final character is problematic, but the
                          * penultimate is not, back-off that last character to
@@ -14584,6 +14674,11 @@ S_populate_ANYOF_from_invlist(pTHX_ regnode *node, SV** invlist_ptr)
     PERL_ARGS_ASSERT_POPULATE_ANYOF_FROM_INVLIST;
     assert(PL_regkind[OP(node)] == ANYOF);
 
+    /* There is no bitmap for this node type */
+    if (OP(node) == ANYOFH) {
+        return;
+    }
+
     ANYOF_BITMAP_ZERO(node);
     if (*invlist_ptr) {
 
@@ -16478,8 +16573,8 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth,
     STRLEN numlen;
     int namedclass = OOB_NAMEDCLASS;
     char *rangebegin = NULL;
-    bool need_class = 0;
-    SV *listsv = NULL;
+    SV *listsv = NULL;      /* List of \p{user-defined} whose definitions
+                               aren't available at the time this was called */
     STRLEN initial_listsv_len = 0; /* Kind of a kludge to see if it is more
                                      than just initialized.  */
     SV* properties = NULL;    /* Code points that match \p{} \P{} */
@@ -16549,7 +16644,6 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth,
     bool warn_super = ALWAYS_WARN_SUPER;
 
     const char * orig_parse = RExC_parse;
-    bool posixl_matches_all = FALSE; /* Does /l class have both e.g. \W,\w ? */
 
     /* This variable is used to mark where the end in the input is of something
      * that looks like a POSIX construct but isn't.  During the parse, when
@@ -16598,7 +16692,9 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth,
     allow_multi_folds = FALSE;
 #endif
 
-    listsv = newSVpvs_flags("# comment\n", SVs_TEMP);
+    /* We include the /i status at the beginning of this so that we can
+     * know it at runtime */
+    listsv = sv_2mortal(Perl_newSVpvf(aTHX_ "#%d\n", cBOOL(FOLD)));
     initial_listsv_len = SvCUR(listsv);
     SvTEMP_off(listsv); /* Grr, TEMPs and mortals are conflated.  */
 
@@ -16837,15 +16933,6 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth,
            case 'P':
                {
                char *e;
-                char *i;
-
-                /* We will handle any undefined properties ourselves */
-                U8 swash_init_flags = _CORE_SWASH_INIT_RETURN_IF_UNDEF
-                                       /* And we actually would prefer to get
-                                        * the straight inversion list of the
-                                        * swash, since we will be accessing it
-                                        * anyway, to save a little time */
-                                      |_CORE_SWASH_INIT_ACCEPT_INVLIST;
 
                 SvREFCNT_dec(swash); /* Free any left-overs */
 
@@ -16903,142 +16990,49 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth,
                }
                {
                     char* name = RExC_parse;
-                    char* base_name;    /* name after any packages are stripped */
-                    char* lookup_name = NULL;
-                    const char * const colon_colon = "::";
-                    bool invert;
-
-                    SV* invlist;
-
-                    /* Temporary workaround for [perl #133136].  For this
-                    * precise input that is in the .t that is failing, load
-                    * utf8.pm, which is what the test wants, so that that
-                    * .t passes */
-                    if (     memEQs(RExC_start, e + 1 - RExC_start,
-                                    "foo\\p{Alnum}")
-                        && ! hv_common(GvHVn(PL_incgv),
-                                       NULL,
-                                       "utf8.pm", sizeof("utf8.pm") - 1,
-                                       0, HV_FETCH_ISEXISTS, NULL, 0))
-                    {
-                        require_pv("utf8.pm");
-                    }
-                    invlist = parse_uniprop_string(name, n, FOLD, &invert);
-                    if (invlist) {
-                        if (invert) {
-                            value ^= 'P' ^ 'p';
-                        }
-                    }
-                    else {
 
-                    /* Try to get the definition of the property into
-                     * <invlist>.  If /i is in effect, the effective property
-                     * will have its name be <__NAME_i>.  The design is
-                     * discussed in commit
-                     * 2f833f5208e26b208886e51e09e2c072b5eabb46 */
-                    name = savepv(Perl_form(aTHX_ "%.*s", (int)n, RExC_parse));
-                    SAVEFREEPV(name);
-
-                    for (i = RExC_parse; i < RExC_parse + n; i++) {
-                        if (isCNTRL(*i) && *i != '\t') {
-                            RExC_parse = e + 1;
-                            vFAIL2("Can't find Unicode property definition \"%s\"", name);
+                    /* Any message returned about expanding the definition */
+                    SV* msg = newSVpvs_flags("", SVs_TEMP);
+
+                    /* If set TRUE, the property is user-defined as opposed to
+                     * official Unicode */
+                    bool user_defined = FALSE;
+
+                    SV * prop_definition = parse_uniprop_string(
+                                            name, n, UTF, FOLD,
+                                            FALSE, /* This is compile-time */
+                                            &user_defined,
+                                            msg,
+                                            0 /* Base level */
+                                           );
+                    if (SvCUR(msg)) {   /* Assumes any error causes a msg */
+                        assert(prop_definition == NULL);
+                        RExC_parse = e + 1;
+                        if (SvUTF8(msg)) {  /* msg being UTF-8 makes the whole
+                                               thing so, or else the display is
+                                               mojibake */
+                            RExC_utf8 = TRUE;
                         }
+                       /* diag_listed_as: Can't find Unicode property definition "%s" in regex; marked by <-- HERE in m/%s/ */
+                        vFAIL2utf8f("%" UTF8f, UTF8fARG(SvUTF8(msg),
+                                    SvCUR(msg), SvPVX(msg)));
                     }
 
-                    if (FOLD) {
-                        lookup_name = savepv(Perl_form(aTHX_ "__%s_i", name));
-
-                        /* The function call just below that uses this can fail
-                         * to return, leaking memory if we don't do this */
-                        SAVEFREEPV(lookup_name);
-                    }
-
-                    /* Look up the property name, and get its swash and
-                     * inversion list, if the property is found  */
-                    swash = _core_swash_init("utf8",
-                                             (lookup_name)
-                                              ? lookup_name
-                                              : name,
-                                             &PL_sv_undef,
-                                             1, /* binary */
-                                             0, /* not tr/// */
-                                             NULL, /* No inversion list */
-                                             &swash_init_flags
-                                            );
-                    if (! swash || ! (invlist = _get_swash_invlist(swash))) {
-                        HV* curpkg = (IN_PERL_COMPILETIME)
-                                      ? PL_curstash
-                                      : CopSTASH(PL_curcop);
-                        UV final_n = n;
-                        bool has_pkg;
-
-                        if (swash) {    /* Got a swash but no inversion list.
-                                           Something is likely wrong that will
-                                           be sorted-out later */
-                            SvREFCNT_dec_NN(swash);
-                            swash = NULL;
-                        }
+                    if (! is_invlist(prop_definition)) {
 
-                        /* Here didn't find it.  It could be a an error (like a
-                         * typo) in specifying a Unicode property, or it could
-                         * be a user-defined property that will be available at
-                         * run-time.  The names of these must begin with 'In'
-                         * or 'Is' (after any packages are stripped off).  So
-                         * if not one of those, or if we accept only
-                         * compile-time properties, is an error; otherwise add
-                         * it to the list for run-time look up. */
-                        if ((base_name = rninstr(name, name + n,
-                                                 colon_colon, colon_colon + 2)))
-                        { /* Has ::.  We know this must be a user-defined
-                             property */
-                            base_name += 2;
-                            final_n -= base_name - name;
-                            has_pkg = TRUE;
+                        /* Here, the definition isn't known, so we have gotten
+                         * returned a string that will be evaluated if and when
+                         * encountered at runtime.  We add it to the list of
+                         * such properties, along with whether it should be
+                         * complemented or not */
+                        if (value == 'P') {
+                            sv_catpvs(listsv, "!");
                         }
                         else {
-                            base_name = name;
-                            has_pkg = FALSE;
-                        }
-
-                        if (   final_n < 3
-                            || base_name[0] != 'I'
-                            || (base_name[1] != 's' && base_name[1] != 'n')
-                            || ret_invlist)
-                        {
-                            const char * const msg
-                                = (has_pkg)
-                                  ? "Illegal user-defined property name"
-                                  : "Can't find Unicode property definition";
-                            RExC_parse = e + 1;
-
-                            /* diag_listed_as: Can't find Unicode property definition "%s" */
-                            vFAIL3utf8f("%s \"%" UTF8f "\"",
-                                msg, UTF8fARG(UTF, n, name));
+                            sv_catpvs(listsv, "+");
                         }
+                        sv_catsv(listsv, prop_definition);
 
-                        /* If the property name doesn't already have a package
-                         * name, add the current one to it so that it can be
-                         * referred to outside it. [perl #121777] */
-                        if (! has_pkg && curpkg) {
-                            char* pkgname = HvNAME(curpkg);
-                            if (memNEs(pkgname, HvNAMELEN(curpkg), "main")) {
-                                char* full_name = Perl_form(aTHX_
-                                                            "%s::%s",
-                                                            pkgname,
-                                                            name);
-                                n = strlen(full_name);
-                                name = savepvn(full_name, n);
-                                SAVEFREEPV(name);
-                            }
-                        }
-                        Perl_sv_catpvf(aTHX_ listsv, "%cutf8::%s%" UTF8f "%s\n",
-                                        (value == 'p' ? '+' : '!'),
-                                        (FOLD) ? "__" : "",
-                                        UTF8fARG(UTF, n, name),
-                                        (FOLD) ? "_i" : "");
-                        optimizable = FALSE;    /* Will have to leave this an
-                                                   ANYOF node */
                         has_runtime_dependency |= HAS_USER_DEFINED_PROPERTY;
 
                         /* We don't know yet what this matches, so have to flag
@@ -17046,27 +17040,32 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth,
                         anyof_flags |= ANYOF_SHARED_d_UPPER_LATIN1_UTF8_STRING_MATCHES_non_d_RUNTIME_USER_PROP;
                     }
                     else {
+                        assert (prop_definition && is_invlist(prop_definition));
 
-                        /* Here, did get the swash and its inversion list.  If
-                         * the swash is from a user-defined property, then this
-                         * whole character class should be regarded as such */
-                        if (swash_init_flags
-                            & _CORE_SWASH_INIT_USER_DEFINED_PROPERTY)
+                        /* Here we do have the complete property definition
+                         *
+                         * Temporary workaround for [perl #133136].  For this
+                         * precise input that is in the .t that is failing,
+                         * load utf8.pm, which is what the test wants, so that
+                         * that .t passes */
+                        if (     memEQs(RExC_start, e + 1 - RExC_start,
+                                        "foo\\p{Alnum}")
+                            && ! hv_common(GvHVn(PL_incgv),
+                                           NULL,
+                                           "utf8.pm", sizeof("utf8.pm") - 1,
+                                           0, HV_FETCH_ISEXISTS, NULL, 0))
                         {
-                            has_runtime_dependency |= HAS_USER_DEFINED_PROPERTY;
+                            require_pv("utf8.pm");
                         }
-                    }
-                    }
-                    if (invlist) {
-                        if (! (has_runtime_dependency
-                                                & HAS_USER_DEFINED_PROPERTY) &&
+
+                        if (! user_defined &&
                             /* We warn on matching an above-Unicode code point
                              * if the match would return true, except don't
                              * warn for \p{All}, which has exactly one element
                              * = 0 */
-                            (_invlist_contains_cp(invlist, 0x110000)
-                                && (! (_invlist_len(invlist) == 1
-                                       && *invlist_array(invlist) == 0))))
+                            (_invlist_contains_cp(prop_definition, 0x110000)
+                                && (! (_invlist_len(prop_definition) == 1
+                                       && *invlist_array(prop_definition) == 0))))
                         {
                             warn_super = TRUE;
                         }
@@ -17074,23 +17073,17 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth,
                         /* Invert if asking for the complement */
                         if (value == 'P') {
                            _invlist_union_complement_2nd(properties,
-                                                          invlist,
+                                                          prop_definition,
                                                           &properties);
 
                             /* The swash can't be used as-is, because we've
                             * inverted things; delay removing it to here after
                             * have copied its invlist above */
-                            if (! swash) {
-                                SvREFCNT_dec_NN(invlist);
-                            }
                             SvREFCNT_dec(swash);
                             swash = NULL;
                         }
                         else {
-                            _invlist_union(properties, invlist, &properties);
-                            if (! swash) {
-                                SvREFCNT_dec_NN(invlist);
-                            }
+                            _invlist_union(properties, prop_definition, &properties);
                        }
                     }
                 }
@@ -17240,39 +17233,9 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth,
                  * be matched against.  This isn't needed for \p{} and
                  * pseudo-classes, as they are not affected by locale, and
                  * hence are dealt with separately */
-                if (! need_class) {
-                    need_class = 1;
-                    anyof_flags |= ANYOF_MATCHES_POSIXL;
-                    has_runtime_dependency |= HAS_L_RUNTIME_DEPENDENCY;
-
-                    /* We can't change this into some other type of node
-                     * (unless this is the only element, in which case there
-                     * are nodes that mean exactly this) as has runtime
-                     * dependencies */
-                    optimizable = FALSE;
-                }
-
-                /* Coverity thinks it is possible for this to be negative; both
-                 * jhi and khw think it's not, but be safer */
-                assert(! (anyof_flags & ANYOF_MATCHES_POSIXL)
-                       || (namedclass + ((namedclass % 2) ? -1 : 1)) >= 0);
-
-                /* See if it already matches the complement of this POSIX
-                 * class */
-                if (  (anyof_flags & ANYOF_MATCHES_POSIXL)
-                    && POSIXL_TEST(posixl, namedclass + ((namedclass % 2)
-                                                         ? -1
-                                                         : 1)))
-                {
-                    posixl_matches_all = TRUE;
-                    break;  /* No need to continue.  Since it matches both
-                               e.g., \w and \W, it matches everything, and the
-                               bracketed class can be optimized into qr/./s */
-                }
-
-                /* Add this class to those that should be checked at runtime */
                 POSIXL_SET(posixl, namedclass);
                 has_runtime_dependency |= HAS_L_RUNTIME_DEPENDENCY;
+                anyof_flags |= ANYOF_MATCHES_POSIXL;
 
                 /* The above-Latin1 characters are not subject to locale rules.
                  * Just add them to the unconditionally-matched list */
@@ -17801,8 +17764,10 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth,
 
             /* Our calculated list will be for Unicode rules.  For locale
              * matching, we have to keep a separate list that is consulted at
-             * runtime only when the locale indicates Unicode rules.  For
-             * non-locale, we just use the general list */
+             * runtime only when the locale indicates Unicode rules (and we
+             * don't include potential matches in the ASCII/Latin1 range, as
+             * any code point could fold to any other, based on the run-time
+             * locale).   For non-locale, we just use the general list */
             if (LOC) {
                 use_list = &only_utf8_locale_list;
             }
@@ -17834,7 +17799,16 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth,
 
                     if (j < 256) {
 
-                        if (IS_IN_SOME_FOLD_L1(j)) {
+                        /* Under /l, we don't know what code points below 256
+                         * fold to, except we do know the MICRO SIGN folds to
+                         * an above-255 character if the locale is UTF-8, so we
+                         * add it to the special list (in *use_list)  Otherwise
+                         * we know now what things can match, though some folds
+                         * are valid under /d only if the target is UTF-8.
+                         * Those go in a separate list */
+                        if (      IS_IN_SOME_FOLD_L1(j)
+                            && ! (LOC && j != MICRO_SIGN))
+                        {
 
                             /* ASCII is always matched; non-ASCII is matched
                              * only under Unicode rules (which could happen
@@ -18125,7 +18099,10 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth,
                 only_utf8_locale_list = NULL;
             }
         }
-        if (only_utf8_locale_list) {
+        if (    only_utf8_locale_list
+            || (cp_list && (   _invlist_contains_cp(cp_list, LATIN_CAPITAL_LETTER_I_WITH_DOT_ABOVE)
+                            || _invlist_contains_cp(cp_list, LATIN_SMALL_LETTER_DOTLESS_I))))
+        {
             has_runtime_dependency |= HAS_L_RUNTIME_DEPENDENCY;
             anyof_flags
                  |= ANYOFL_FOLD
@@ -18146,7 +18123,6 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth,
                  || (anyof_flags & ANYOF_SHARED_d_MATCHES_ALL_NON_UTF8_NON_ASCII_non_d_WARN_SUPER)))
     {
         RExC_seen_d_op = TRUE;
-        optimizable = FALSE;
         has_runtime_dependency |= HAS_D_RUNTIME_DEPENDENCY;
     }
 
@@ -18179,106 +18155,484 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth,
      * routine) */
     *flagp |= HASWIDTH|SIMPLE;
 
+    if (anyof_flags & ANYOF_LOCALE_FLAGS) {
+        RExC_contains_locale = 1;
+    }
+
     /* Some character classes are equivalent to other nodes.  Such nodes take
      * up less room, and some nodes require fewer operations to execute, than
      * ANYOF nodes.  EXACTish nodes may be joinable with adjacent nodes to
      * improve efficiency. */
 
     if (optimizable) {
-        int posix_class = -1;   /* Illegal value */
-        UV start, end;
+        PERL_UINT_FAST8_T i;
+        Size_t partial_cp_count = 0;
+        UV start[MAX_FOLD_FROMS+1] = { 0 }; /* +1 for the folded-to char */
+        UV   end[MAX_FOLD_FROMS+1] = { 0 };
+
+        if (cp_list) { /* Count the code points in enough ranges that we would
+                          see all the ones possible in any fold in this version
+                          of Unicode */
+
+            invlist_iterinit(cp_list);
+            for (i = 0; i <= MAX_FOLD_FROMS; i++) {
+                if (invlist_iternext(cp_list, &start[i], &end[i])) {
+                    partial_cp_count += end[i] - start[i] + 1;
+                }
+            }
+
+            invlist_iterfinish(cp_list);
+        }
 
-        if (UNLIKELY(posixl_matches_all)) {
-            ret = reg_node(pRExC_state, SANY);
+        /* If we know at compile time that this matches every possible code
+         * point, any run-time dependencies don't matter */
+        if (start[0] == 0 && end[0] == UV_MAX) {
+            if (invert) {
+                ret = reganode(pRExC_state, OPFAIL, 0);
+            }
+            else {
+                ret = reg_node(pRExC_state, SANY);
+                MARK_NAUGHTY(1);
+            }
             goto not_anyof;
         }
 
-        if (cp_list && ! invert) {
-            invlist_iterinit(cp_list);
-            if (! invlist_iternext(cp_list, &start, &end)) {
+        /* Similarly, for /l posix classes, if both a class and its
+         * complement match, any run-time dependencies don't matter */
+        if (posixl) {
+            for (namedclass = 0; namedclass < ANYOF_POSIXL_MAX;
+                                                        namedclass += 2)
+            {
+                if (   POSIXL_TEST(posixl, namedclass)      /* class */
+                    && POSIXL_TEST(posixl, namedclass + 1)) /* its complement */
+                {
+                    if (invert) {
+                        ret = reganode(pRExC_state, OPFAIL, 0);
+                    }
+                    else {
+                        ret = reg_node(pRExC_state, SANY);
+                        MARK_NAUGHTY(1);
+                    }
+                    goto not_anyof;
+                }
+            }
+            /* For well-behaved locales, some classes are subsets of others,
+             * so complementing the subset and including the non-complemented
+             * superset should match everything, like [\D[:alnum:]], and
+             * [[:^alpha:][:alnum:]], but some implementations of locales are
+             * buggy, and khw thinks its a bad idea to have optimization change
+             * behavior, even if it avoids an OS bug in a given case */
+
+#define isSINGLE_BIT_SET(n) isPOWER_OF_2(n)
+
+            /* If is a single posix /l class, can optimize to just that op.
+             * Such a node will not match anything in the Latin1 range, as that
+             * is not determinable until runtime, but will match whatever the
+             * class does outside that range.  (Note that some classes won't
+             * match anything outside the range, like [:ascii:]) */
+            if (    isSINGLE_BIT_SET(posixl)
+                && (partial_cp_count == 0 || start[0] > 255))
+            {
+                U8 classnum;
+                SV * class_above_latin1 = NULL;
+                bool already_inverted;
+                bool are_equivalent;
+
+                /* Compute which bit is set, which is the same thing as, e.g.,
+                 * ANYOF_CNTRL.  From
+                 * https://graphics.stanford.edu/~seander/bithacks.html#IntegerLogDeBruijn
+                 * */
+                static const int MultiplyDeBruijnBitPosition2[32] =
+                    {
+                    0, 1, 28, 2, 29, 14, 24, 3, 30, 22, 20, 15, 25, 17, 4, 8,
+                    31, 27, 13, 23, 21, 19, 16, 7, 26, 12, 18, 6, 11, 5, 10, 9
+                    };
+
+                namedclass = MultiplyDeBruijnBitPosition2[(posixl
+                                                          * 0x077CB531U) >> 27];
+                classnum = namedclass_to_classnum(namedclass);
+
+                /* The named classes are such that the inverted number is one
+                 * larger than the non-inverted one */
+                already_inverted = namedclass
+                                 - classnum_to_namedclass(classnum);
+
+                /* Create an inversion list of the official property, inverted
+                 * if the constructed node list is inverted, and restricted to
+                 * only the above latin1 code points, which are the only ones
+                 * known at compile time */
+                _invlist_intersection_maybe_complement_2nd(
+                                                    PL_AboveLatin1,
+                                                    PL_XPosix_ptrs[classnum],
+                                                    already_inverted,
+                                                    &class_above_latin1);
+                are_equivalent = _invlistEQ(class_above_latin1, cp_list,
+                                                                        FALSE);
+                SvREFCNT_dec_NN(class_above_latin1);
+
+                if (are_equivalent) {
+
+                    /* Resolve the run-time inversion flag with this possibly
+                     * inverted class */
+                    invert = invert ^ already_inverted;
+
+                    ret = reg_node(pRExC_state,
+                                   POSIXL + invert * (NPOSIXL - POSIXL));
+                    FLAGS(REGNODE_p(ret)) = classnum;
+                    goto not_anyof;
+                }
+            }
+        }
+
+        /* khw can't think of any other possible transformation involving
+         * these. */
+        if (has_runtime_dependency & HAS_USER_DEFINED_PROPERTY) {
+            goto is_anyof;
+        }
+
+        if (! has_runtime_dependency) {
 
             /* If the list is empty, nothing matches.  This happens, for
              * example, when a Unicode property that doesn't match anything is
              * the only element in the character class (perluniprops.pod notes
              * such properties). */
+            if (partial_cp_count == 0) {
+                assert (! invert);
                 ret = reganode(pRExC_state, OPFAIL, 0);
                 goto not_anyof;
             }
 
-            if (start == end) {    /* The range is a single code point */
-                if (! invlist_iternext(cp_list, &start, &end)
+            /* If matches everything but \n */
+            if (   start[0] == 0 && end[0] == '\n' - 1
+                && start[1] == '\n' + 1 && end[1] == UV_MAX)
+            {
+                assert (! invert);
+                ret = reg_node(pRExC_state, REG_ANY);
+                MARK_NAUGHTY(1);
+                goto not_anyof;
+            }
+        }
 
-                        /* Don't do this optimization if it would require
-                         * changing the pattern to UTF-8 */
-                    && (start < 256 || UTF))
-                {
-                    /* Here, the list contains a single code point.  Can
-                     * optimize into an EXACTish node */
+        /* Next see if can optimize classes that contain just a few code points
+         * into an EXACTish node.  The reason to do this is to let the
+         * optimizer join this node with adjacent EXACTish ones.
+         *
+         * An EXACTFish node can be generated even if not under /i, and vice
+         * versa.  But care must be taken.  An EXACTFish node has to be such
+         * that it only matches precisely the code points in the class, but we
+         * want to generate the least restrictive one that does that, to
+         * increase the odds of being able to join with an adjacent node.  For
+         * example, if the class contains [kK], we have to make it an EXACTFAA
+         * node to prevent the KELVIN SIGN from matching.  Whether we are under
+         * /i or not is irrelevant in this case.  Less obvious is the pattern
+         * qr/[\x{02BC}]n/i.  U+02BC is MODIFIER LETTER APOSTROPHE. That is
+         * supposed to match the single character U+0149 LATIN SMALL LETTER N
+         * PRECEDED BY APOSTROPHE.  And so even though there is no simple fold
+         * that includes \X{02BC}, there is a multi-char fold that does, and so
+         * the node generated for it must be an EXACTFish one.  On the other
+         * hand qr/:/i should generate a plain EXACT node since the colon
+         * participates in no fold whatsoever, and having it EXACT tells the
+         * optimizer the target string cannot match unless it has a colon in
+         * it.
+         *
+         * We don't typically generate an EXACTish node if doing so would
+         * require changing the pattern to UTF-8, as that affects /d and
+         * otherwise is slower.  However, under /i, not changing to UTF-8 can
+         * miss some potential multi-character folds.  We calculate the
+         * EXACTish node, and then decide if something would be missed if we
+         * don't upgrade */
+        if (   ! posixl
+            && ! invert
+
+                /* Only try if there are no more code points in the class than
+                 * in the max possible fold */
+            &&   partial_cp_count > 0 && partial_cp_count <= MAX_FOLD_FROMS + 1
+
+            && (start[0] < 256 || UTF || FOLD))
+        {
+            if (partial_cp_count == 1 && ! upper_latin1_only_utf8_matches)
+            {
+                /* We can always make a single code point class into an
+                 * EXACTish node. */
+
+                if (LOC) {
+
+                    /* Here is /l:  Use EXACTL, except /li indicates EXACTFL,
+                     * as that means there is a fold not known until runtime so
+                     * shows as only a single code point here. */
+                    op = (FOLD) ? EXACTFL : EXACTL;
+                }
+                else if (! FOLD) { /* Not /l and not /i */
+                    op = (start[0] < 256) ? EXACT : EXACT_ONLY8;
+                }
+                else if (start[0] < 256) { /* /i, not /l, and the code point is
+                                              small */
+
+                    /* Under /i, it gets a little tricky.  A code point that
+                     * doesn't participate in a fold should be an EXACT node.
+                     * We know this one isn't the result of a simple fold, or
+                     * there'd be more than one code point in the list, but it
+                     * could be part of a multi- character fold.  In that case
+                     * we better not create an EXACT node, as we would wrongly
+                     * be telling the optimizer that this code point must be in
+                     * the target string, and that is wrong.  This is because
+                     * if the sequence around this code point forms a
+                     * multi-char fold, what needs to be in the string could be
+                     * the code point that folds to the sequence.
+                     *
+                     * This handles the case of below-255 code points, as we
+                     * have an easy look up for those.  The next clause handles
+                     * the above-256 one */
+                    op = IS_IN_SOME_FOLD_L1(start[0])
+                         ? EXACTFU
+                         : EXACT;
+                }
+                else {  /* /i, larger code point.  Since we are under /i, and
+                           have just this code point, we know that it can't
+                           fold to something else, so PL_InMultiCharFold
+                           applies to it */
+                    op = _invlist_contains_cp(PL_InMultiCharFold,
+                                              start[0])
+                         ? EXACTFU_ONLY8
+                         : EXACT_ONLY8;
+                }
+
+                value = start[0];
+            }
+            else if (  ! (has_runtime_dependency & ~HAS_D_RUNTIME_DEPENDENCY)
+                     && _invlist_contains_cp(PL_in_some_fold, start[0]))
+            {
+                /* Here, the only runtime dependency, if any, is from /d, and
+                 * the class matches more than one code point, and the lowest
+                 * code point participates in some fold.  It might be that the
+                 * other code points are /i equivalent to this one, and hence
+                 * they would representable by an EXACTFish node.  Above, we
+                 * eliminated classes that contain too many code points to be
+                 * EXACTFish, with the test for MAX_FOLD_FROMS
+                 *
+                 * First, special case the ASCII fold pairs, like 'B' and 'b'.
+                 * We do this because we have EXACTFAA at our disposal for the
+                 * ASCII range */
+                if (partial_cp_count == 2 && isASCII(start[0])) {
+
+                    /* The only ASCII characters that participate in folds are
+                     * alphabetics */
+                    assert(isALPHA(start[0]));
+                    if (   end[0] == start[0]   /* First range is a single
+                                                   character, so 2nd exists */
+                        && isALPHA_FOLD_EQ(start[0], start[1]))
+                    {
+
+                        /* Here, is part of an ASCII fold pair */
 
-                    value = start;
+                        if (   ASCII_FOLD_RESTRICTED
+                            || HAS_NONLATIN1_SIMPLE_FOLD_CLOSURE(start[0]))
+                        {
+                            /* If the second clause just above was true, it
+                             * means we can't be under /i, or else the list
+                             * would have included more than this fold pair.
+                             * Therefore we have to exclude the possibility of
+                             * whatever else it is that folds to these, by
+                             * using EXACTFAA */
+                            op = EXACTFAA;
+                        }
+                        else if (HAS_NONLATIN1_FOLD_CLOSURE(start[0])) {
 
-                    if (! FOLD) {
-                        op = (LOC)
-                             ? EXACTL
-                             : EXACT;
+                            /* Here, there's no simple fold that start[0] is part
+                             * of, but there is a multi-character one.  If we
+                             * are not under /i, we want to exclude that
+                             * possibility; if under /i, we want to include it
+                             * */
+                            op = (FOLD) ? EXACTFU : EXACTFAA;
+                        }
+                        else {
+
+                            /* Here, the only possible fold start[0] particpates in
+                             * is with start[1].  /i or not isn't relevant */
+                            op = EXACTFU;
+                        }
+
+                        value = toFOLD(start[0]);
+                    }
+                }
+                else if (  ! upper_latin1_only_utf8_matches
+                         || (   _invlist_len(upper_latin1_only_utf8_matches)
+                                                                          == 2
+                             && PL_fold_latin1[
+                               invlist_highest(upper_latin1_only_utf8_matches)]
+                             == start[0]))
+                {
+                    /* Here, the smallest character is non-ascii or there are
+                     * more than 2 code points matched by this node.  Also, we
+                     * either don't have /d UTF-8 dependent matches, or if we
+                     * do, they look like they could be a single character that
+                     * is the fold of the lowest one in the always-match list.
+                     * This test quickly excludes most of the false positives
+                     * when there are /d UTF-8 depdendent matches.  These are
+                     * like LATIN CAPITAL LETTER A WITH GRAVE matching LATIN
+                     * SMALL LETTER A WITH GRAVE iff the target string is
+                     * UTF-8.  (We don't have to worry above about exceeding
+                     * the array bounds of PL_fold_latin1[] because any code
+                     * point in 'upper_latin1_only_utf8_matches' is below 256.)
+                     *
+                     * EXACTFAA would apply only to pairs (hence exactly 2 code
+                     * points) in the ASCII range, so we can't use it here to
+                     * artificially restrict the fold domain, so we check if
+                     * the class does or does not match some EXACTFish node.
+                     * Further, if we aren't under /i, and and the folded-to
+                     * character is part of a multi-character fold, we can't do
+                     * this optimization, as the sequence around it could be
+                     * that multi-character fold, and we don't here know the
+                     * context, so we have to assume it is that multi-char
+                     * fold, to prevent potential bugs.
+                     *
+                     * To do the general case, we first find the fold of the
+                     * lowest code point (which may be higher than the lowest
+                     * one), then find everything that folds to it.  (The data
+                     * structure we have only maps from the folded code points,
+                     * so we have to do the earlier step.) */
+
+                    Size_t foldlen;
+                    U8 foldbuf[UTF8_MAXBYTES_CASE];
+                    UV folded = _to_uni_fold_flags(start[0],
+                                                        foldbuf, &foldlen, 0);
+                    unsigned int first_fold;
+                    const unsigned int * remaining_folds;
+                    Size_t folds_to_this_cp_count = _inverse_folds(
+                                                            folded,
+                                                            &first_fold,
+                                                            &remaining_folds);
+                    Size_t folds_count = folds_to_this_cp_count + 1;
+                    SV * fold_list = _new_invlist(folds_count);
+                    unsigned int i;
+
+                    /* If there are UTF-8 dependent matches, create a temporary
+                     * list of what this node matches, including them. */
+                    SV * all_cp_list = NULL;
+                    SV ** use_this_list = &cp_list;
+
+                    if (upper_latin1_only_utf8_matches) {
+                        all_cp_list = _new_invlist(0);
+                        use_this_list = &all_cp_list;
+                        _invlist_union(cp_list,
+                                       upper_latin1_only_utf8_matches,
+                                       use_this_list);
                     }
-                    else if (LOC) {
 
-                        /* A locale node under folding with one code point can
-                         * be an EXACTFL, as its fold won't be calculated until
-                         * runtime */
-                        op = EXACTFL;
+                    /* Having gotten everything that participates in the fold
+                     * containing the lowest code point, we turn that into an
+                     * inversion list, making sure everything is included. */
+                    fold_list = add_cp_to_invlist(fold_list, start[0]);
+                    fold_list = add_cp_to_invlist(fold_list, folded);
+                    fold_list = add_cp_to_invlist(fold_list, first_fold);
+                    for (i = 0; i < folds_to_this_cp_count - 1; i++) {
+                        fold_list = add_cp_to_invlist(fold_list,
+                                                        remaining_folds[i]);
                     }
-                    else {
 
-                        /* Here, we are generally folding, but there is only
-                         * one code point to match.  If we have to, we use an
-                         * EXACT node, but it would be better for joining with
-                         * adjacent nodes in the optimization phase if we used
-                         * the same EXACTFish node that any such are likely to
-                         * be.  We can do this iff the code point doesn't
-                         * participate in any folds.  For example, an EXACTF of
-                         * a colon is the same as an EXACT one, since nothing
-                         * folds to or from a colon. */
-                        if (value < 256) {
-                            if (IS_IN_SOME_FOLD_L1(value)) {
-                                op = EXACT;
-                            }
-                        }
-                        else {
-                            if (_invlist_contains_cp(PL_in_some_fold, value)) {
-                                op = EXACT;
+                    /* If the fold list is identical to what's in this ANYOF
+                     * node, the node can be represented by an EXACTFish one
+                     * instead */
+                    if (_invlistEQ(*use_this_list, fold_list,
+                                   0 /* Don't complement */ )
+                    ) {
+
+                        /* But, we have to be careful, as mentioned above.
+                         * Just the right sequence of characters could match
+                         * this if it is part of a multi-character fold.  That
+                         * IS what we want if we are under /i.  But it ISN'T
+                         * what we want if not under /i, as it could match when
+                         * it shouldn't.  So, when we aren't under /i and this
+                         * character participates in a multi-char fold, we
+                         * don't optimize into an EXACTFish node.  So, for each
+                         * case below we have to check if we are folding
+                         * and if not, if it is not part of a multi-char fold.
+                         * */
+                        if (start[0] > 255) {    /* Highish code point */
+                            if (FOLD || ! _invlist_contains_cp(
+                                            PL_InMultiCharFold, folded))
+                            {
+                                op = (LOC)
+                                     ? EXACTFLU8
+                                     : (ASCII_FOLD_RESTRICTED)
+                                       ? EXACTFAA
+                                       : EXACTFU_ONLY8;
+                                value = folded;
                             }
+                        }   /* Below, the lowest code point < 256 */
+                        else if (    FOLD
+                                 &&  folded == 's'
+                                 &&  DEPENDS_SEMANTICS)
+                        {   /* An EXACTF node containing a single character
+                                's', can be an EXACTFU if it doesn't get
+                                joined with an adjacent 's' */
+                            op = EXACTFU_S_EDGE;
+                            value = folded;
                         }
+                        else if (    FOLD
+                                || ! HAS_NONLATIN1_FOLD_CLOSURE(start[0]))
+                        {
+                            if (upper_latin1_only_utf8_matches) {
+                                op = EXACTF;
 
-                        /* If we haven't found the node type, above, it means
-                         * we can use the prevailing one */
-                        if (op == END) {
-                            op = compute_EXACTish(pRExC_state);
+                                /* We can't use the fold, as that only matches
+                                 * under UTF-8 */
+                                value = start[0];
+                            }
+                            else if (     UNLIKELY(start[0] == MICRO_SIGN)
+                                     && ! UTF)
+                            {   /* EXACTFUP is a special node for this
+                                   character */
+                                op = (ASCII_FOLD_RESTRICTED)
+                                     ? EXACTFAA
+                                     : EXACTFUP;
+                                value = MICRO_SIGN;
+                            }
+                            else if (     ASCII_FOLD_RESTRICTED
+                                     && ! isASCII(start[0]))
+                            {   /* For ASCII under /iaa, we can use EXACTFU
+                                   below */
+                                op = EXACTFAA;
+                                value = folded;
+                            }
+                            else {
+                                op = EXACTFU;
+                                value = folded;
+                            }
                         }
                     }
-                }
-            }   /* End of first range contains just a single code point */
-            else if (start == 0) {
-                if (end == UV_MAX) {
-                    op = SANY;
-                    MARK_NAUGHTY(1);
-                }
-                else if (end == '\n' - 1
-                        && invlist_iternext(cp_list, &start, &end)
-                        && start == '\n' + 1 && end == UV_MAX)
-                {
-                    op = REG_ANY;
-                    MARK_NAUGHTY(1);
+
+                    SvREFCNT_dec_NN(fold_list);
+                    SvREFCNT_dec(all_cp_list);
                 }
             }
-            invlist_iterfinish(cp_list);
 
             if (op != END) {
-                if (PL_regkind[op] != EXACT) {
-                    ret = reg_node(pRExC_state, op);
+
+                /* Here, we have calculated what EXACTish node we would use.
+                 * But we don't use it if it would require converting the
+                 * pattern to UTF-8, unless not using it could cause us to miss
+                 * some folds (hence be buggy) */
+
+                if (! UTF && value > 255) {
+                    SV * in_multis = NULL;
+
+                    assert(FOLD);
+
+                    /* If there is no code point that is part of a multi-char
+                     * fold, then there aren't any matches, so we don't do this
+                     * optimization.  Otherwise, it could match depending on
+                     * the context around us, so we do upgrade */
+                    _invlist_intersection(PL_InMultiCharFold, cp_list, &in_multis);
+                    if (UNLIKELY(_invlist_len(in_multis) != 0)) {
+                        REQUIRE_UTF8(flagp);
+                    }
+                    else {
+                        op = END;
+                    }
                 }
-                else {
+
+                if (op != END) {
                     U8 len = (UTF) ? UVCHR_SKIP(value) : 1;
 
                     ret = regnode_guts(pRExC_state, op, len, "exact");
@@ -18291,11 +18645,12 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth,
                     else {
                         uvchr_to_utf8((U8 *) STRING(REGNODE_p(ret)), value);
                     }
+                    goto not_anyof;
                 }
-                goto not_anyof;
             }
+        }
 
-            {
+        if (! has_runtime_dependency) {
 
             /* See if this can be turned into an ANYOFM node.  Think about the
              * bit patterns in two different bytes.  In some positions, the
@@ -18333,7 +18688,8 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth,
             }
 
             if (invlist_highest(cp_list) <= max_permissible) {
-                UV this_start, this_end, lowest_cp;
+                UV this_start, this_end;
+                UV lowest_cp = UV_MAX;  /* inited to suppress compiler warn */
                 U8 bits_differing = 0;
                 Size_t full_cp_count = 0;
                 bool first_time = TRUE;
@@ -18409,18 +18765,24 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth,
             if (op != END) {
                 goto not_anyof;
             }
-            }
+        }
 
-        {
+        if (! (anyof_flags & ANYOF_LOCALE_FLAGS)) {
             PERL_UINT_FAST8_T type;
+            SV * intersection = NULL;
+            SV* d_invlist = NULL;
 
-            /* Here, didn't find an optimization.  See if this matches any
-             * of the POSIX classes.  The POSIXA ones are about the same speed
-             * as ANYOF ops, but take less room; the ones that have
-             * above-Latin1 code point matches are somewhat faster than ANYOF.
-             * */
+            /* See if this matches any of the POSIX classes.  The POSIXA and
+             * POSIXD ones are about the same speed as ANYOF ops, but take less
+             * room; the ones that have above-Latin1 code point matches are
+             * somewhat faster than ANYOF.  */
 
-            for (type = POSIXU; type <= POSIXA; type++) {
+            for (type = POSIXA; type >= POSIXD; type--) {
+                int posix_class;
+
+                if (type == POSIXL) {   /* But not /l posix classes */
+                    continue;
+                }
 
                 for (posix_class = 0;
                      posix_class <= _HIGHEST_REGCOMP_DOT_H_SYNC;
@@ -18437,37 +18799,109 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth,
                         official_code_points = &PL_XPosix_ptrs[posix_class];
                     }
 
+                    /* Skip non-existent classes of this type.  e.g. \v only
+                     * has an entry in PL_XPosix_ptrs */
+                    if (! *official_code_points) {
+                        continue;
+                    }
+
                     /* Try both the regular class, and its inversion */
                     for (try_inverted = 0; try_inverted < 2; try_inverted++) {
-                        /* Check if matches, normal or inverted */
-                        if (*official_code_points) {
-                            if (_invlistEQ(*our_code_points,
-                                        *official_code_points,
-                                        try_inverted))
+                        bool this_inverted = invert ^ try_inverted;
+
+                        if (type != POSIXD) {
+
+                            /* This class that isn't /d can't match if we have
+                             * /d dependencies */
+                            if (has_runtime_dependency
+                                                    & HAS_D_RUNTIME_DEPENDENCY)
                             {
-                                ret = reg_node(pRExC_state, (try_inverted)
-                                                            ? type + NPOSIXA
-                                                                   - POSIXA
-                                                            : type);
-                                FLAGS(REGNODE_p(ret)) = posix_class;
-                                goto not_anyof;
+                                continue;
                             }
                         }
+                        else /* is /d */ if (! this_inverted) {
+
+                            /* /d classes don't match anything non-ASCII below
+                             * 256 unconditionally (which cp_list contains) */
+                            _invlist_intersection(cp_list, PL_UpperLatin1,
+                                                           &intersection);
+                            if (_invlist_len(intersection) != 0) {
+                                continue;
+                            }
+
+                            SvREFCNT_dec(d_invlist);
+                            d_invlist = invlist_clone(cp_list, NULL);
+
+                            /* But under UTF-8 it turns into using /u rules.
+                             * Add the things it matches under these conditions
+                             * so that we check below that these are identical
+                             * to what the tested class should match */
+                            if (upper_latin1_only_utf8_matches) {
+                                _invlist_union(
+                                            d_invlist,
+                                            upper_latin1_only_utf8_matches,
+                                            &d_invlist);
+                            }
+                            our_code_points = &d_invlist;
+                        }
+                        else {  /* POSIXD, inverted.  If this doesn't have this
+                                   flag set, it isn't /d. */
+                            if (! (anyof_flags & ANYOF_SHARED_d_MATCHES_ALL_NON_UTF8_NON_ASCII_non_d_WARN_SUPER))
+                            {
+                                continue;
+                            }
+                            our_code_points = &cp_list;
+                        }
+
+                        /* Here, have weeded out some things.  We want to see
+                         * if the list of characters this node contains
+                         * ('*our_code_points') precisely matches those of the
+                         * class we are currently checking against
+                         * ('*official_code_points'). */
+                        if (_invlistEQ(*our_code_points,
+                                       *official_code_points,
+                                       try_inverted))
+                        {
+                            /* Here, they precisely match.  Optimize this ANYOF
+                             * node into its equivalent POSIX one of the
+                             * correct type, possibly inverted */
+                            ret = reg_node(pRExC_state, (try_inverted)
+                                                        ? type + NPOSIXA
+                                                                - POSIXA
+                                                        : type);
+                            FLAGS(REGNODE_p(ret)) = posix_class;
+                            SvREFCNT_dec(d_invlist);
+                            SvREFCNT_dec(intersection);
+                            goto not_anyof;
+                        }
                     }
                 }
             }
+            SvREFCNT_dec(d_invlist);
+            SvREFCNT_dec(intersection);
         }
+
+        /* If didn't find an optimization and there is no need for a
+        * bitmap, optimize to indicate that */
+        if (     start[0] >= NUM_ANYOF_CODE_POINTS
+            && ! LOC
+            && ! upper_latin1_only_utf8_matches)
+        {
+            op = ANYOFH;
         }
     }   /* End of seeing if can optimize it into a different node */
 
-    /* It's going to be an ANYOF node. */
-    op = (has_runtime_dependency & HAS_D_RUNTIME_DEPENDENCY)
-         ? ANYOFD
-         : ((posixl)
-            ? ANYOFPOSIXL
-            : ((LOC)
-               ? ANYOFL
-               : ANYOF));
+  is_anyof: /* It's going to be an ANYOF node. */
+    if (op != ANYOFH) {
+        op = (has_runtime_dependency & HAS_D_RUNTIME_DEPENDENCY)
+             ? ANYOFD
+             : ((posixl)
+                ? ANYOFPOSIXL
+                : ((LOC)
+                   ? ANYOFL
+                   : ANYOF));
+    }
+
     ret = regnode_guts(pRExC_state, op, regarglen[op], "anyof");
     FILL_NODE(ret, op);        /* We set the argument later */
     RExC_emit += 1 + regarglen[op];
@@ -18523,11 +18957,6 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth,
                   only_utf8_locale_list,
                   swash, cBOOL(has_runtime_dependency
                                                 & HAS_USER_DEFINED_PROPERTY));
-
-    if (ANYOF_FLAGS(REGNODE_p(ret)) & ANYOF_LOCALE_FLAGS) {
-        RExC_contains_locale = 1;
-    }
-
     return ret;
 
   not_anyof:
@@ -18537,7 +18966,7 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth,
 
     Set_Node_Offset_Length(REGNODE_p(ret), orig_parse - RExC_start,
                                            RExC_parse - orig_parse);;
-    SvREFCNT_dec_NN(cp_list);;
+    SvREFCNT_dec(cp_list);;
     return ret;
 }
 
@@ -18556,23 +18985,15 @@ S_set_ANYOF_arg(pTHX_ RExC_state_t* const pRExC_state,
      * the node passed-in.  If there is nothing outside the node's bitmap, the
      * arg is set to ANYOF_ONLY_HAS_BITMAP.  Otherwise, it sets the argument to
      * the count returned by add_data(), having allocated and stored an array,
-     * av, that that count references, as follows:
-     *  av[0] stores the character class description in its textual form.
-     *        This is used later (regexec.c:Perl_regclass_swash()) to
-     *        initialize the appropriate swash, and is also useful for dumping
-     *        the regnode.  This is set to &PL_sv_undef if the textual
-     *        description is not needed at run-time (as happens if the other
-     *        elements completely define the class)
-     *  av[1] if &PL_sv_undef, is a placeholder to later contain the swash
-     *        computed from av[0].  But if no further computation need be done,
-     *        the swash is stored here now (and av[0] is &PL_sv_undef).
-     *  av[2] stores the inversion list of code points that match only if the
-     *        current locale is UTF-8
-     *  av[3] stores the cp_list inversion list for use in addition or instead
-     *        of av[0]; used only if cp_list exists and av[1] is &PL_sv_undef.
-     *        (Otherwise everything needed is already in av[0] and av[1])
-     *  av[4] is set if any component of the class is from a user-defined
-     *        property; used only if av[3] exists */
+     * av, as follows:
+     *
+     *  av[0] stores the inversion list defining this class as far as known at
+     *        this time, or PL_sv_undef if nothing definite is now known.
+     *  av[1] stores the inversion list of code points that match only if the
+     *        current locale is UTF-8, or if none, PL_sv_undef if there is an
+     *        av[2], or no entry otherwise.
+     *  av[2] stores the list of user-defined properties whose subroutine
+     *        definitions aren't known at this time, or no entry if none. */
 
     UV n;
 
@@ -18587,26 +19008,16 @@ S_set_ANYOF_arg(pTHX_ RExC_state_t* const pRExC_state,
        AV * const av = newAV();
        SV *rv;
 
-       av_store(av, 0, (runtime_defns)
-                       ? SvREFCNT_inc(runtime_defns) : &PL_sv_undef);
-       if (swash) {
-           assert(cp_list);
-           av_store(av, 1, swash);
-           SvREFCNT_dec_NN(cp_list);
-       }
-       else {
-           av_store(av, 1, &PL_sv_undef);
-           if (cp_list) {
-               av_store(av, 3, cp_list);
-               av_store(av, 4, newSVuv(has_user_defined_property));
-           }
-       }
+        if (cp_list) {
+            av_store(av, INVLIST_INDEX, cp_list);
+        }
 
         if (only_utf8_locale_list) {
-           av_store(av, 2, only_utf8_locale_list);
+            av_store(av, ONLY_LOCALE_MATCHES_INDEX, only_utf8_locale_list);
         }
-        else {
-           av_store(av, 2, &PL_sv_undef);
+
+        if (runtime_defns) {
+            av_store(av, DEFERRED_USER_DEFINED_INDEX, SvREFCNT_inc(runtime_defns));
         }
 
        rv = newRV_noinc(MUTABLE_SV(av));
@@ -18652,7 +19063,6 @@ Perl__get_regclass_nonbitmap_data(pTHX_ const regexp *prog,
      * that, in spite of this function's name, the swash it returns may include
      * the bitmap data as well */
 
-    SV *sw  = NULL;
     SV *si  = NULL;         /* Input swash initialization string */
     SV* invlist = NULL;
 
@@ -18669,53 +19079,59 @@ Perl__get_regclass_nonbitmap_data(pTHX_ const regexp *prog,
            SV * const rv = MUTABLE_SV(data->data[n]);
            AV * const av = MUTABLE_AV(SvRV(rv));
            SV **const ary = AvARRAY(av);
-           U8 swash_init_flags = _CORE_SWASH_INIT_ACCEPT_INVLIST;
 
-           si = *ary;  /* ary[0] = the string to initialize the swash with */
+            invlist = ary[INVLIST_INDEX];
 
-            if (av_tindex_skip_len_mg(av) >= 2) {
-                if (only_utf8_locale_ptr
-                    && ary[2]
-                    && ary[2] != &PL_sv_undef)
-                {
-                    *only_utf8_locale_ptr = ary[2];
-                }
-                else {
-                    assert(only_utf8_locale_ptr);
-                    *only_utf8_locale_ptr = NULL;
-                }
-
-                /* Elements 3 and 4 are either both present or both absent. [3]
-                 * is any inversion list generated at compile time; [4]
-                 * indicates if that inversion list has any user-defined
-                 * properties in it. */
-                if (av_tindex_skip_len_mg(av) >= 3) {
-                    invlist = ary[3];
-                    if (SvUV(ary[4])) {
-                        swash_init_flags |= _CORE_SWASH_INIT_USER_DEFINED_PROPERTY;
+            if (av_tindex_skip_len_mg(av) >= ONLY_LOCALE_MATCHES_INDEX) {
+                *only_utf8_locale_ptr = ary[ONLY_LOCALE_MATCHES_INDEX];
+            }
+
+            if (av_tindex_skip_len_mg(av) >= DEFERRED_USER_DEFINED_INDEX) {
+                si = ary[DEFERRED_USER_DEFINED_INDEX];
+            }
+
+           if (doinit && (si || invlist)) {
+                if (si) {
+                    bool user_defined;
+                    SV * msg = newSVpvs_flags("", SVs_TEMP);
+
+                    SV * prop_definition = handle_user_defined_property(
+                            "", 0, FALSE,   /* There is no \p{}, \P{} */
+                            SvPVX_const(si)[1] - '0',   /* /i or not has been
+                                                           stored here for just
+                                                           this occasion */
+                            TRUE,           /* run time */
+                            si,             /* The property definition  */
+                            &user_defined,
+                            msg,
+                            0               /* base level call */
+                           );
+
+                    if (SvCUR(msg)) {
+                        assert(prop_definition == NULL);
+
+                        Perl_croak(aTHX_ "%" UTF8f,
+                                UTF8fARG(SvUTF8(msg), SvCUR(msg), SvPVX(msg)));
                     }
-                }
-                else {
-                    invlist = NULL;
-                }
-           }
 
-           /* Element [1] is reserved for the set-up swash.  If already there,
-            * return it; if not, create it and store it there */
-           if (ary[1] && SvROK(ary[1])) {
-               sw = ary[1];
-           }
-           else if (doinit && ((si && si != &PL_sv_undef)
-                                 || (invlist && invlist != &PL_sv_undef))) {
-               assert(si);
-               sw = _core_swash_init("utf8", /* the utf8 package */
-                                     "", /* nameless */
-                                     si,
-                                     1, /* binary */
-                                     0, /* not from tr/// */
-                                     invlist,
-                                     &swash_init_flags);
-               (void)av_store(av, 1, sw);
+                    if (invlist) {
+                        _invlist_union(invlist, prop_definition, &invlist);
+                        SvREFCNT_dec_NN(prop_definition);
+                    }
+                    else {
+                        invlist = prop_definition;
+                    }
+
+                    assert(ONLY_LOCALE_MATCHES_INDEX == 1 + INVLIST_INDEX);
+                    assert(DEFERRED_USER_DEFINED_INDEX == 1
+                                                + ONLY_LOCALE_MATCHES_INDEX);
+
+                    av_store(av, INVLIST_INDEX, invlist);
+                    av_fill(av, (ary[ONLY_LOCALE_MATCHES_INDEX])
+                                 ? ONLY_LOCALE_MATCHES_INDEX:
+                                 INVLIST_INDEX);
+                    si = NULL;
+                }
            }
        }
     }
@@ -18729,9 +19145,7 @@ Perl__get_regclass_nonbitmap_data(pTHX_ const regexp *prog,
          * compile-time, before everything gets resolved, in which case we
          * return the currently best available information, which is the string
          * that will eventually be used to do that resolving, 'si' */
-       if ((! sw || (invlist = _get_swash_invlist(sw)) == NULL)
-            && (si && si != &PL_sv_undef))
-        {
+       if (si) {
             /* Here, we only have 'si' (and possibly some passed-in data in
              * 'invlist', which is handled below)  If the caller only wants
              * 'si', use that.  */
@@ -18853,7 +19267,7 @@ Perl__get_regclass_nonbitmap_data(pTHX_ const regexp *prog,
        *listsvp = matches_string;
     }
 
-    return sw;
+    return invlist;
 }
 #endif /* !defined(PERL_IN_XSUB_RE) || defined(PLUGGABLE_RE_EXTENSION) */
 
@@ -19234,7 +19648,7 @@ S_regtail(pTHX_ RExC_state_t * pRExC_state,
             DEBUG_PARSE_MSG((scan==p ? "tail" : ""));
             regprop(RExC_rx, RExC_mysv, REGNODE_p(scan), NULL, pRExC_state);
             Perl_re_printf( aTHX_  "~ %s (%d) %s %s\n",
-                SvPV_nolen_const(RExC_mysv), REG_NODE_NUM(REGNODE_p(scan)),
+                SvPV_nolen_const(RExC_mysv), scan,
                     (temp == NULL ? "->" : ""),
                     (temp == NULL ? PL_reg_name[OP(REGNODE_p(val))] : "")
             );
@@ -19325,7 +19739,7 @@ S_regtail_study(pTHX_ RExC_state_t *pRExC_state, regnode_offset p,
             regprop(RExC_rx, RExC_mysv, REGNODE_p(scan), NULL, pRExC_state);
             Perl_re_printf( aTHX_  "~ %s (%d) -> %s\n",
                 SvPV_nolen_const(RExC_mysv),
-                REG_NODE_NUM(REGNODE_p(scan)),
+                scan,
                 PL_reg_name[exact]);
         });
        if (temp == NULL)
@@ -19338,7 +19752,7 @@ S_regtail_study(pTHX_ RExC_state_t *pRExC_state, regnode_offset p,
         Perl_re_printf( aTHX_
                       "~ attach to %s (%" IVdf ") offset to %" IVdf "\n",
                      SvPV_nolen_const(RExC_mysv),
-                     (IV)REG_NODE_NUM(REGNODE_p(val)),
+                     (IV)val,
                      (IV)(val - scan)
         );
     });
@@ -19816,42 +20230,46 @@ Perl_regprop(pTHX_ const regexp *prog, SV *sv, const regnode *o, const regmatch_
         /* Ready to start outputting.  First, the initial left bracket */
        Perl_sv_catpvf(aTHX_ sv, "[%s", PL_colors[0]);
 
-        /* Then all the things that could fit in the bitmap */
-        do_sep = put_charclass_bitmap_innards(sv,
-                                              ANYOF_BITMAP(o),
-                                              bitmap_range_not_in_bitmap,
-                                              only_utf8_locale_invlist,
-                                              o,
-
-                                              /* Can't try inverting for a
-                                               * better display if there are
-                                               * things that haven't been
-                                               * resolved */
-                                              unresolved != NULL);
-        SvREFCNT_dec(bitmap_range_not_in_bitmap);
-
-        /* If there are user-defined properties which haven't been defined yet,
-         * output them.  If the result is not to be inverted, it is clearest to
-         * output them in a separate [] from the bitmap range stuff.  If the
-         * result is to be complemented, we have to show everything in one [],
-         * as the inversion applies to the whole thing.  Use {braces} to
-         * separate them from anything in the bitmap and anything above the
-         * bitmap. */
-        if (unresolved) {
-            if (inverted) {
-                if (! do_sep) { /* If didn't output anything in the bitmap */
-                    sv_catpvs(sv, "^");
+        if (OP(o) != ANYOFH) {
+            /* Then all the things that could fit in the bitmap */
+            do_sep = put_charclass_bitmap_innards(sv,
+                                                  ANYOF_BITMAP(o),
+                                                  bitmap_range_not_in_bitmap,
+                                                  only_utf8_locale_invlist,
+                                                  o,
+
+                                                  /* Can't try inverting for a
+                                                   * better display if there
+                                                   * are things that haven't
+                                                   * been resolved */
+                                                  unresolved != NULL);
+            SvREFCNT_dec(bitmap_range_not_in_bitmap);
+
+            /* If there are user-defined properties which haven't been defined
+             * yet, output them.  If the result is not to be inverted, it is
+             * clearest to output them in a separate [] from the bitmap range
+             * stuff.  If the result is to be complemented, we have to show
+             * everything in one [], as the inversion applies to the whole
+             * thing.  Use {braces} to separate them from anything in the
+             * bitmap and anything above the bitmap. */
+            if (unresolved) {
+                if (inverted) {
+                    if (! do_sep) { /* If didn't output anything in the bitmap
+                                     */
+                        sv_catpvs(sv, "^");
+                    }
+                    sv_catpvs(sv, "{");
                 }
-                sv_catpvs(sv, "{");
-            }
-            else if (do_sep) {
-                Perl_sv_catpvf(aTHX_ sv,"%s][%s", PL_colors[1], PL_colors[0]);
-            }
-            sv_catsv(sv, unresolved);
-            if (inverted) {
-                sv_catpvs(sv, "}");
+                else if (do_sep) {
+                    Perl_sv_catpvf(aTHX_ sv,"%s][%s", PL_colors[1],
+                                                      PL_colors[0]);
+                }
+                sv_catsv(sv, unresolved);
+                if (inverted) {
+                    sv_catpvs(sv, "}");
+                }
+                do_sep = ! inverted;
             }
-            do_sep = ! inverted;
         }
 
         /* And, finally, add the above-the-bitmap stuff */
@@ -21396,6 +21814,15 @@ S_dumpuntil(pTHX_ const regexp *r, const regnode *start, const regnode *node,
 void
 Perl_init_uniprops(pTHX)
 {
+    PL_user_def_props = newHV();
+
+#ifdef USE_ITHREADS
+
+    HvSHAREKEYS_off(PL_user_def_props);
+    PL_user_def_props_aTHX = aTHX;
+
+#endif
+
     /* Set up the inversion list global variables */
 
     PL_XPosix_ptrs[_CC_ASCII] = _new_invlist_C_array(uni_prop_ptrs[UNI_ASCII]);
@@ -21453,8 +21880,10 @@ Perl_init_uniprops(pTHX)
     PL_in_some_fold = _new_invlist_C_array(uni_prop_ptrs[UNI__PERL_ANY_FOLDS]);
     PL_HasMultiCharFold = _new_invlist_C_array(uni_prop_ptrs[
                                             UNI__PERL_FOLDS_TO_MULTI_CHAR]);
-    PL_InMultiCharFold = _new_invlist_C_array(UNI__PERL_IS_IN_MULTI_CHAR_FOLD_invlist);
-    PL_NonFinalFold = _new_invlist_C_array(UNI__PERL_NON_FINAL_FOLDS_invlist);
+    PL_InMultiCharFold = _new_invlist_C_array(uni_prop_ptrs[
+                                            UNI__PERL_IS_IN_MULTI_CHAR_FOLD]);
+    PL_NonFinalFold = _new_invlist_C_array(uni_prop_ptrs[
+                                            UNI__PERL_NON_FINAL_FOLDS]);
 
     PL_utf8_toupper = _new_invlist_C_array(Uppercase_Mapping_invlist);
     PL_utf8_tolower = _new_invlist_C_array(Lowercase_Mapping_invlist);
@@ -21463,6 +21892,7 @@ Perl_init_uniprops(pTHX)
     PL_utf8_tosimplefold = _new_invlist_C_array(Simple_Case_Folding_invlist);
     PL_utf8_foldclosures = _new_invlist_C_array(_Perl_IVCF_invlist);
     PL_utf8_mark = _new_invlist_C_array(uni_prop_ptrs[UNI_M]);
+    PL_CCC_non0_non230 = _new_invlist_C_array(_Perl_CCC_non0_non230_invlist);
 
 #ifdef UNI_XIDC
     /* The below are used only by deprecated functions.  They could be removed */
@@ -21472,39 +21902,444 @@ Perl_init_uniprops(pTHX)
 #endif
 }
 
-SV *
-Perl_parse_uniprop_string(pTHX_ const char * const name, const Size_t name_len,
-                                const bool to_fold, bool * invert)
+#if 0
+
+This code was mainly added for backcompat to give a warning for non-portable
+code points in user-defined properties.  But experiments showed that the
+warning in earlier perls were only omitted on overflow, which should be an
+error, so there really isnt a backcompat issue, and actually adding the
+warning when none was present before might cause breakage, for little gain.  So
+khw left this code in, but not enabled.  Tests were never added.
+
+embed.fnc entry:
+Ei     |const char *|get_extended_utf8_msg|const UV cp
+
+PERL_STATIC_INLINE const char *
+S_get_extended_utf8_msg(pTHX_ const UV cp)
 {
-    /* Parse the interior meat of \p{} passed to this in 'name' with length
-     * 'name_len', and return an inversion list if a property with 'name' is
-     * found, or NULL if not.  'name' point to the input with leading and
-     * trailing space trimmed.  'to_fold' indicates if /i is in effect.
+    U8 dummy[UTF8_MAXBYTES + 1];
+    HV *msgs;
+    SV **msg;
+
+    uvchr_to_utf8_flags_msgs(dummy, cp, UNICODE_WARN_PERL_EXTENDED,
+                             &msgs);
+
+    msg = hv_fetchs(msgs, "text", 0);
+    assert(msg);
+
+    (void) sv_2mortal((SV *) msgs);
+
+    return SvPVX(*msg);
+}
+
+#endif
+
+SV *
+Perl_handle_user_defined_property(pTHX_
+
+    /* Parses the contents of a user-defined property definition; returning the
+     * expanded definition if possible.  If so, the return is an inversion
+     * list.
      *
-     * When the return is an inversion list, '*invert' will be set to a boolean
-     * indicating if it should be inverted or not
+     * If there are subroutines that are part of the expansion and which aren't
+     * known at the time of the call to this function, this returns what
+     * parse_uniprop_string() returned for the first one encountered.
      *
-     * This currently doesn't handle all cases.  A NULL return indicates the
-     * caller should try a different approach
-     */
+     * If an error was found, NULL is returned, and 'msg' gets a suitable
+     * message appended to it.  (Appending allows the back trace of how we got
+     * to the faulty definition to be displayed through nested calls of
+     * user-defined subs.)
+     *
+     * The caller IS responsible for freeing any returned SV.
+     *
+     * The syntax of the contents is pretty much described in perlunicode.pod,
+     * but we also allow comments on each line */
+
+    const char * name,          /* Name of property */
+    const STRLEN name_len,      /* The name's length in bytes */
+    const bool is_utf8,         /* ? Is 'name' encoded in UTF-8 */
+    const bool to_fold,         /* ? Is this under /i */
+    const bool runtime,         /* ? Are we in compile- or run-time */
+    SV* contents,               /* The property's definition */
+    bool *user_defined_ptr,     /* This will be set TRUE as we wouldn't be
+                                   getting called unless this is thought to be
+                                   a user-defined property */
+    SV * msg,                   /* Any error or warning msg(s) are appended to
+                                   this */
+    const STRLEN level)         /* Recursion level of this call */
+{
+    STRLEN len;
+    const char * string         = SvPV_const(contents, len);
+    const char * const e        = string + len;
+    const bool is_contents_utf8 = cBOOL(SvUTF8(contents));
+    const STRLEN msgs_length_on_entry = SvCUR(msg);
+
+    const char * s0 = string;   /* Points to first byte in the current line
+                                   being parsed in 'string' */
+    const char overflow_msg[] = "Code point too large in \"";
+    SV* running_definition = NULL;
+
+    PERL_ARGS_ASSERT_HANDLE_USER_DEFINED_PROPERTY;
+
+    *user_defined_ptr = TRUE;
+
+    /* Look at each line */
+    while (s0 < e) {
+        const char * s;     /* Current byte */
+        char op = '+';      /* Default operation is 'union' */
+        IV   min = 0;       /* range begin code point */
+        IV   max = -1;      /* and range end */
+        SV* this_definition;
+
+        /* Skip comment lines */
+        if (*s0 == '#') {
+            s0 = strchr(s0, '\n');
+            if (s0 == NULL) {
+                break;
+            }
+            s0++;
+            continue;
+        }
 
-    char* lookup_name;
-    bool stricter = FALSE;
-    bool is_nv_type = FALSE;         /* nv= or numeric_value=, or possibly one
-                                        of the cjk numeric properties (though
-                                        it requires extra effort to compile
-                                        them) */
-    unsigned int i;
-    unsigned int j = 0, lookup_len;
-    int equals_pos = -1;        /* Where the '=' is found, or negative if none */
-    int slash_pos = -1;        /* Where the '/' is found, or negative if none */
-    int table_index = 0;
-    bool starts_with_In_or_Is = FALSE;
-    Size_t lookup_offset = 0;
+        /* For backcompat, allow an empty first line */
+        if (*s0 == '\n') {
+            s0++;
+            continue;
+        }
+
+        /* First character in the line may optionally be the operation */
+        if (   *s0 == '+'
+            || *s0 == '!'
+            || *s0 == '-'
+            || *s0 == '&')
+        {
+            op = *s0++;
+        }
+
+        /* If the line is one or two hex digits separated by blank space, its
+         * a range; otherwise it is either another user-defined property or an
+         * error */
+
+        s = s0;
+
+        if (! isXDIGIT(*s)) {
+            goto check_if_property;
+        }
+
+        do { /* Each new hex digit will add 4 bits. */
+            if (min > ( (IV) MAX_LEGAL_CP >> 4)) {
+                s = strchr(s, '\n');
+                if (s == NULL) {
+                    s = e;
+                }
+                if (SvCUR(msg) > 0) sv_catpvs(msg, "; ");
+                sv_catpv(msg, overflow_msg);
+                Perl_sv_catpvf(aTHX_ msg, "%" UTF8f,
+                                     UTF8fARG(is_contents_utf8, s - s0, s0));
+                sv_catpvs(msg, "\"");
+                goto return_msg;
+            }
+
+            /* Accumulate this digit into the value */
+            min = (min << 4) + READ_XDIGIT(s);
+        } while (isXDIGIT(*s));
+
+        while (isBLANK(*s)) { s++; }
+
+        /* We allow comments at the end of the line */
+        if (*s == '#') {
+            s = strchr(s, '\n');
+            if (s == NULL) {
+                s = e;
+            }
+            s++;
+        }
+        else if (s < e && *s != '\n') {
+            if (! isXDIGIT(*s)) {
+                goto check_if_property;
+            }
+
+            /* Look for the high point of the range */
+            max = 0;
+            do {
+                if (max > ( (IV) MAX_LEGAL_CP >> 4)) {
+                    s = strchr(s, '\n');
+                    if (s == NULL) {
+                        s = e;
+                    }
+                    if (SvCUR(msg) > 0) sv_catpvs(msg, "; ");
+                    sv_catpv(msg, overflow_msg);
+                    Perl_sv_catpvf(aTHX_ msg, "%" UTF8f,
+                                      UTF8fARG(is_contents_utf8, s - s0, s0));
+                    sv_catpvs(msg, "\"");
+                    goto return_msg;
+                }
+
+                max = (max << 4) + READ_XDIGIT(s);
+            } while (isXDIGIT(*s));
+
+            while (isBLANK(*s)) { s++; }
+
+            if (*s == '#') {
+                s = strchr(s, '\n');
+                if (s == NULL) {
+                    s = e;
+                }
+            }
+            else if (s < e && *s != '\n') {
+                goto check_if_property;
+            }
+        }
+
+        if (max == -1) {    /* The line only had one entry */
+            max = min;
+        }
+        else if (max < min) {
+            if (SvCUR(msg) > 0) sv_catpvs(msg, "; ");
+            sv_catpvs(msg, "Illegal range in \"");
+            Perl_sv_catpvf(aTHX_ msg, "%" UTF8f,
+                                UTF8fARG(is_contents_utf8, s - s0, s0));
+            sv_catpvs(msg, "\"");
+            goto return_msg;
+        }
+
+#if 0   /* See explanation at definition above of get_extended_utf8_msg() */
+
+        if (   UNICODE_IS_PERL_EXTENDED(min)
+            || UNICODE_IS_PERL_EXTENDED(max))
+        {
+            if (SvCUR(msg) > 0) sv_catpvs(msg, "; ");
+
+            /* If both code points are non-portable, warn only on the lower
+             * one. */
+            sv_catpv(msg, get_extended_utf8_msg(
+                                            (UNICODE_IS_PERL_EXTENDED(min))
+                                            ? min : max));
+            sv_catpvs(msg, " in \"");
+            Perl_sv_catpvf(aTHX_ msg, "%" UTF8f,
+                                 UTF8fARG(is_contents_utf8, s - s0, s0));
+            sv_catpvs(msg, "\"");
+        }
+
+#endif
+
+        /* Here, this line contains a legal range */
+        this_definition = sv_2mortal(_new_invlist(2));
+        this_definition = _add_range_to_invlist(this_definition, min, max);
+        goto calculate;
+
+      check_if_property:
+
+        /* Here it isn't a legal range line.  See if it is a legal property
+         * line.  First find the end of the meat of the line */
+        s = strpbrk(s, "#\n");
+        if (s == NULL) {
+            s = e;
+        }
+
+        /* Ignore trailing blanks in keeping with the requirements of
+         * parse_uniprop_string() */
+        s--;
+        while (s > s0 && isBLANK_A(*s)) {
+            s--;
+        }
+        s++;
+
+        this_definition = parse_uniprop_string(s0, s - s0,
+                                               is_utf8, to_fold, runtime,
+                                               user_defined_ptr, msg,
+                                               (name_len == 0)
+                                                ? level /* Don't increase level
+                                                           if input is empty */
+                                                : level + 1
+                                              );
+        if (this_definition == NULL) {
+            goto return_msg;    /* 'msg' should have had the reason appended to
+                                   it by the above call */
+        }
+
+        if (! is_invlist(this_definition)) {    /* Unknown at this time */
+            return newSVsv(this_definition);
+        }
+
+        if (*s != '\n') {
+            s = strchr(s, '\n');
+            if (s == NULL) {
+                s = e;
+            }
+        }
+
+      calculate:
+
+        switch (op) {
+            case '+':
+                _invlist_union(running_definition, this_definition,
+                                                        &running_definition);
+                break;
+            case '-':
+                _invlist_subtract(running_definition, this_definition,
+                                                        &running_definition);
+                break;
+            case '&':
+                _invlist_intersection(running_definition, this_definition,
+                                                        &running_definition);
+                break;
+            case '!':
+                _invlist_union_complement_2nd(running_definition,
+                                        this_definition, &running_definition);
+                break;
+            default:
+                Perl_croak(aTHX_ "panic: %s: %d: Unexpected operation %d",
+                                 __FILE__, __LINE__, op);
+                break;
+        }
+
+        /* Position past the '\n' */
+        s0 = s + 1;
+    }   /* End of loop through the lines of 'contents' */
+
+    /* Here, we processed all the lines in 'contents' without error.  If we
+     * didn't add any warnings, simply return success */
+    if (msgs_length_on_entry == SvCUR(msg)) {
+
+        /* If the expansion was empty, the answer isn't nothing: its an empty
+         * inversion list */
+        if (running_definition == NULL) {
+            running_definition = _new_invlist(1);
+        }
+
+        return running_definition;
+    }
+
+    /* Otherwise, add some explanatory text, but we will return success */
+
+  return_msg:
+
+    if (name_len > 0) {
+        sv_catpvs(msg, " in expansion of ");
+        Perl_sv_catpvf(aTHX_ msg, "%" UTF8f, UTF8fARG(is_utf8, name_len, name));
+    }
+
+    return running_definition;
+}
+
+/* As explained below, certain operations need to take place in the first
+ * thread created.  These macros switch contexts */
+#ifdef USE_ITHREADS
+#  define DECLARATION_FOR_GLOBAL_CONTEXT                                    \
+                                        PerlInterpreter * save_aTHX = aTHX;
+#  define SWITCH_TO_GLOBAL_CONTEXT                                          \
+                           PERL_SET_CONTEXT((aTHX = PL_user_def_props_aTHX))
+#  define RESTORE_CONTEXT  PERL_SET_CONTEXT((aTHX = save_aTHX));
+#  define CUR_CONTEXT      aTHX
+#  define ORIGINAL_CONTEXT save_aTHX
+#else
+#  define DECLARATION_FOR_GLOBAL_CONTEXT
+#  define SWITCH_TO_GLOBAL_CONTEXT          NOOP
+#  define RESTORE_CONTEXT                   NOOP
+#  define CUR_CONTEXT                       NULL
+#  define ORIGINAL_CONTEXT                  NULL
+#endif
+
+STATIC void
+S_delete_recursion_entry(pTHX_ void *key)
+{
+    /* Deletes the entry used to detect recursion when expanding user-defined
+     * properties.  This is a function so it can be set up to be called even if
+     * the program unexpectedly quits */
+
+    SV ** current_entry;
+    const STRLEN key_len = strlen((const char *) key);
+    DECLARATION_FOR_GLOBAL_CONTEXT;
+
+    SWITCH_TO_GLOBAL_CONTEXT;
+
+    /* If the entry is one of these types, it is a permanent entry, and not the
+     * one used to detect recursions.  This function should delete only the
+     * recursion entry */
+    current_entry = hv_fetch(PL_user_def_props, (const char *) key, key_len, 0);
+    if (     current_entry
+        && ! is_invlist(*current_entry)
+        && ! SvPOK(*current_entry))
+    {
+        (void) hv_delete(PL_user_def_props, (const char *) key, key_len,
+                                                                    G_DISCARD);
+    }
+
+    RESTORE_CONTEXT;
+}
+
+SV *
+Perl_parse_uniprop_string(pTHX_
+
+    /* Parse the interior of a \p{}, \P{}.  Returns its definition if knowable
+     * now.  If so, the return is an inversion list.
+     *
+     * If the property is user-defined, it is a subroutine, which in turn
+     * may call other subroutines.  This function will call the whole nest of
+     * them to get the definition they return; if some aren't known at the time
+     * of the call to this function, the fully qualified name of the highest
+     * level sub is returned.  It is an error to call this function at runtime
+     * without every sub defined.
+     *
+     * If an error was found, NULL is returned, and 'msg' gets a suitable
+     * message appended to it.  (Appending allows the back trace of how we got
+     * to the faulty definition to be displayed through nested calls of
+     * user-defined subs.)
+     *
+     * The caller should NOT try to free any returned inversion list.
+     *
+     * Other parameters will be set on return as described below */
+
+    const char * const name,    /* The first non-blank in the \p{}, \P{} */
+    const Size_t name_len,      /* Its length in bytes, not including any
+                                   trailing space */
+    const bool is_utf8,         /* ? Is 'name' encoded in UTF-8 */
+    const bool to_fold,         /* ? Is this under /i */
+    const bool runtime,         /* TRUE if this is being called at run time */
+    bool *user_defined_ptr,     /* Upon return from this function it will be
+                                   set to TRUE if any component is a
+                                   user-defined property */
+    SV * msg,                   /* Any error or warning msg(s) are appended to
+                                   this */
+   const STRLEN level)          /* Recursion level of this call */
+{
+    char* lookup_name;          /* normalized name for lookup in our tables */
+    unsigned lookup_len;        /* Its length */
+    bool stricter = FALSE;      /* Some properties have stricter name
+                                   normalization rules, which we decide upon
+                                   based on parsing */
+
+    /* nv= or numeric_value=, or possibly one of the cjk numeric properties
+     * (though it requires extra effort to download them from Unicode and
+     * compile perl to know about them) */
+    bool is_nv_type = FALSE;
+
+    unsigned int i, j = 0;
+    int equals_pos = -1;    /* Where the '=' is found, or negative if none */
+    int slash_pos  = -1;    /* Where the '/' is found, or negative if none */
+    int table_index = 0;    /* The entry number for this property in the table
+                               of all Unicode property names */
+    bool starts_with_In_or_Is = FALSE;  /* ? Does the name start with 'In' or
+                                             'Is' */
+    Size_t lookup_offset = 0;   /* Used to ignore the first few characters of
+                                   the normalized name in certain situations */
+    Size_t non_pkg_begin = 0;   /* Offset of first byte in 'name' that isn't
+                                   part of a package name */
+    bool could_be_user_defined = TRUE;  /* ? Could this be a user-defined
+                                             property rather than a Unicode
+                                             one. */
+    SV * prop_definition = NULL;  /* The returned definition of 'name' or NULL
+                                     if an error.  If it is an inversion list,
+                                     it is the definition.  Otherwise it is a
+                                     string containing the fully qualified sub
+                                     name of 'name' */
+    bool invert_return = FALSE; /* ? Do we need to complement the result before
+                                     returning it */
 
     PERL_ARGS_ASSERT_PARSE_UNIPROP_STRING;
 
-    /* The input will be modified into 'lookup_name' */
+    /* The input will be normalized into 'lookup_name' */
     Newx(lookup_name, name_len, char);
     SAVEFREEPV(lookup_name);
 
@@ -21512,40 +22347,86 @@ Perl_parse_uniprop_string(pTHX_ const char * const name, const Size_t name_len,
     for (i = 0; i < name_len; i++) {
         char cur = name[i];
 
-        /* These characters can be freely ignored in most situations.  Later it
-         * may turn out we shouldn't have ignored them, and we have to reparse,
-         * but we don't have enough information yet to make that decision */
-        if (cur == '-' || cur == '_' || isSPACE_A(cur)) {
+        /* Most of the characters in the input will be of this ilk, being parts
+         * of a name */
+        if (isIDCONT_A(cur)) {
+
+            /* Case differences are ignored.  Our lookup routine assumes
+             * everything is lowercase, so normalize to that */
+            if (isUPPER_A(cur)) {
+                lookup_name[j++] = toLOWER_A(cur);
+                continue;
+            }
+
+            if (cur == '_') { /* Don't include these in the normalized name */
+                continue;
+            }
+
+            lookup_name[j++] = cur;
+
+            /* The first character in a user-defined name must be of this type.
+             * */
+            if (i - non_pkg_begin == 0 && ! isIDFIRST_A(cur)) {
+                could_be_user_defined = FALSE;
+            }
+
             continue;
         }
 
-        /* Case differences are also ignored.  Our lookup routine assumes
-         * everything is lowercase */
-        if (isUPPER_A(cur)) {
-            lookup_name[j++] = toLOWER(cur);
+        /* Here, the character is not something typically in a name,  But these
+         * two types of characters (and the '_' above) can be freely ignored in
+         * most situations.  Later it may turn out we shouldn't have ignored
+         * them, and we have to reparse, but we don't have enough information
+         * yet to make that decision */
+        if (cur == '-' || isSPACE_A(cur)) {
+            could_be_user_defined = FALSE;
             continue;
         }
 
-        /* A double colon is either an error, or a package qualifier to a
-         * subroutine user-defined property; neither of which do we currently
-         * handle
-         *
-         * But a single colon is a synonym for '=' */
-        if (cur == ':') {
-            if (i < name_len - 1 && name[i+1] == ':') {
-                return NULL;
-            }
-            cur = '=';
+        /* An equals sign or single colon mark the end of the first part of
+         * the property name */
+        if (    cur == '='
+            || (cur == ':' && (i >= name_len - 1 || name[i+1] != ':')))
+        {
+            lookup_name[j++] = '='; /* Treat the colon as an '=' */
+            equals_pos = j; /* Note where it occurred in the input */
+            could_be_user_defined = FALSE;
+            break;
         }
 
         /* Otherwise, this character is part of the name. */
         lookup_name[j++] = cur;
 
-        /* Only the equals sign needs further processing */
-        if (cur == '=') {
-            equals_pos = j; /* Note where it occurred in the input */
-            break;
+        /* Here it isn't a single colon, so if it is a colon, it must be a
+         * double colon */
+        if (cur == ':') {
+
+            /* A double colon should be a package qualifier.  We note its
+             * position and continue.  Note that one could have
+             *      pkg1::pkg2::...::foo
+             * so that the position at the end of the loop will be just after
+             * the final qualifier */
+
+            i++;
+            non_pkg_begin = i + 1;
+            lookup_name[j++] = ':';
+        }
+        else { /* Only word chars (and '::') can be in a user-defined name */
+            could_be_user_defined = FALSE;
         }
+    } /* End of parsing through the lhs of the property name (or all of it if
+         no rhs) */
+
+#define STRLENs(s)  (sizeof("" s "") - 1)
+
+    /* If there is a single package name 'utf8::', it is ambiguous.  It could
+     * be for a user-defined property, or it could be a Unicode property, as
+     * all of them are considered to be for that package.  For the purposes of
+     * parsing the rest of the property, strip it off */
+    if (non_pkg_begin == STRLENs("utf8::") && memBEGINPs(name, name_len, "utf8::")) {
+        lookup_name +=  STRLENs("utf8::");
+        j -=  STRLENs("utf8::");
+        equals_pos -=  STRLENs("utf8::");
     }
 
     /* Here, we are either done with the whole property name, if it was simple;
@@ -21562,17 +22443,22 @@ Perl_parse_uniprop_string(pTHX_ const char * const name, const Size_t name_len,
             }
         }
 
-        /* Certain properties need special handling.  They may optionally be
-         * prefixed by 'is'.  Ignore that prefix for the purposes of checking
-         * if this is one of those properties */
+        /* Certain properties whose values are numeric need special handling.
+         * They may optionally be prefixed by 'is'.  Ignore that prefix for the
+         * purposes of checking if this is one of those properties */
         if (memBEGINPs(lookup_name, name_len, "is")) {
             lookup_offset = 2;
         }
 
-        /* Then check if it is one of these properties.  This is hard-coded
-         * because easier this way, and the list is unlikely to change.  There
-         * are several properties like this in the Unihan DB, which is unlikely
-         * to be compiled, and they all end with 'numeric'.  The interiors
+        /* Then check if it is one of these specially-handled properties.  The
+         * possibilities are hard-coded because easier this way, and the list
+         * is unlikely to change.
+         *
+         * All numeric value type properties are of this ilk, and are also
+         * special in a different way later on.  So find those first.  There
+         * are several numeric value type properties in the Unihan DB (which is
+         * unlikely to be compiled with perl, but we handle it here in case it
+         * does get compiled).  They all end with 'numeric'.  The interiors
          * aren't checked for the precise property.  This would stop working if
          * a cjk property were to be created that ended with 'numeric' and
          * wasn't a numeric type */
@@ -21600,15 +22486,14 @@ Perl_parse_uniprop_string(pTHX_ const char * const name, const Size_t name_len,
         {
             unsigned int k;
 
-            /* What makes these properties special is that the stuff after the
-             * '=' is a number.  Therefore, we can't throw away '-'
-             * willy-nilly, as those could be a minus sign.  Other stricter
+            /* Since the stuff after the '=' is a number, we can't throw away
+             * '-' willy-nilly, as those could be a minus sign.  Other stricter
              * rules also apply.  However, these properties all can have the
              * rhs not be a number, in which case they contain at least one
              * alphabetic.  In those cases, the stricter rules don't apply.
              * But the numeric type properties can have the alphas [Ee] to
              * signify an exponent, and it is still a number with stricter
-             * rules.  So look for an alpha that signifys not-strict */
+             * rules.  So look for an alpha that signifies not-strict */
             stricter = TRUE;
             for (k = i; k < name_len; k++) {
                 if (   isALPHA_A(name[k])
@@ -21636,7 +22521,7 @@ Perl_parse_uniprop_string(pTHX_ const char * const name, const Size_t name_len,
              * zeros, or between the final leading zero and the first other
              * digit */
             for (; i < name_len - 1; i++) {
-                if (   name[i] != '0'
+                if (    name[i] != '0'
                     && (name[i] != '_' || ! isDIGIT_A(name[i+1])))
                 {
                     break;
@@ -21646,9 +22531,8 @@ Perl_parse_uniprop_string(pTHX_ const char * const name, const Size_t name_len,
     }
     else {  /* No '=' */
 
-       /* We are now in a position to determine if this property should have
-        * been parsed using stricter rules.  Only a few are like that, and
-        * unlikely to change. */
+       /* Only a few properties without an '=' should be parsed with stricter
+        * rules.  The list is unlikely to change. */
         if (   memBEGINPs(lookup_name, j, "perl")
             && memNEs(lookup_name + 4, j - 4, "space")
             && memNEs(lookup_name + 4, j - 4, "word"))
@@ -21743,33 +22627,308 @@ Perl_parse_uniprop_string(pTHX_ const char * const name, const Size_t name_len,
     {
         lookup_name[j++] = '&';
     }
-    else if (name_len > 2 && name[0] == 'I' && (   name[1] == 'n'
-                                                || name[1] == 's'))
-    {
-
-        /* Also, if the original input began with 'In' or 'Is', it could be a
-         * subroutine call instead of a property names, which currently isn't
-         * handled by this function.  Subroutine calls can't happen if there is
-         * an '=' in the name */
-        if (equals_pos < 0 && get_cvn_flags(name, name_len, GV_NOTQUAL) != NULL)
-        {
-            return NULL;
-        }
 
+    /* If the original input began with 'In' or 'Is', it could be a subroutine
+     * call to a user-defined property instead of a Unicode property name. */
+    if (    non_pkg_begin + name_len > 2
+        &&  name[non_pkg_begin+0] == 'I'
+        && (name[non_pkg_begin+1] == 'n' || name[non_pkg_begin+1] == 's'))
+    {
         starts_with_In_or_Is = TRUE;
     }
+    else {
+        could_be_user_defined = FALSE;
+    }
+
+    if (could_be_user_defined) {
+        CV* user_sub;
+
+        /* Here, the name could be for a user defined property, which are
+         * implemented as subs. */
+        user_sub = get_cvn_flags(name, name_len, 0);
+        if (user_sub) {
+
+            /* Here, there is a sub by the correct name.  Normally we call it
+             * to get the property definition */
+            dSP;
+            SV * user_sub_sv = MUTABLE_SV(user_sub);
+            SV * error;     /* Any error returned by calling 'user_sub' */
+            SV * fq_name;   /* Fully qualified property name */
+            SV * placeholder;
+            char to_fold_string[] = "0:";   /* The 0 gets overwritten with the
+                                               actual value */
+            SV ** saved_user_prop_ptr;      /* Hash entry for this property */
+
+            /* How many times to retry when another thread is in the middle of
+             * expanding the same definition we want */
+            PERL_INT_FAST8_T retry_countdown = 10;
+
+            DECLARATION_FOR_GLOBAL_CONTEXT;
+
+            /* If we get here, we know this property is user-defined */
+            *user_defined_ptr = TRUE;
+
+            /* We refuse to call a tainted subroutine; returning an error
+             * instead */
+            if (TAINT_get) {
+                if (SvCUR(msg) > 0) sv_catpvs(msg, "; ");
+                sv_catpvs(msg, "Insecure user-defined property");
+                goto append_name_to_msg;
+            }
+
+            /* In principal, we only call each subroutine property definition
+             * once during the life of the program.  This guarantees that the
+             * property definition never changes.  The results of the single
+             * sub call are stored in a hash, which is used instead for future
+             * references to this property.  The property definition is thus
+             * immutable.  But, to allow the user to have a /i-dependent
+             * definition, we call the sub once for non-/i, and once for /i,
+             * should the need arise, passing the /i status as a parameter.
+             *
+             * We start by constructing the hash key name, consisting of the
+             * fully qualified subroutine name */
+            fq_name = sv_2mortal(newSV(10));    /* 10 is just a guess */
+            (void) cv_name(user_sub, fq_name, 0);
+
+            /* But precede the sub name in the key with the /i status, so that
+             * there is a key for /i and a different key for non-/i */
+            to_fold_string[0] = to_fold + '0';
+            sv_insert(fq_name, 0, 0, to_fold_string, 2);
+
+            /* We only call the sub once throughout the life of the program
+             * (with the /i, non-/i exception noted above).  That means the
+             * hash must be global and accessible to all threads.  It is
+             * created at program start-up, before any threads are created, so
+             * is accessible to all children.  But this creates some
+             * complications.
+             *
+             * 1) The keys can't be shared, or else problems arise; sharing is
+             *    turned off at hash creation time
+             * 2) All SVs in it are there for the remainder of the life of the
+             *    program, and must be created in the same interpreter context
+             *    as the hash, or else they will be freed from the wrong pool
+             *    at global destruction time.  This is handled by switching to
+             *    the hash's context to create each SV going into it, and then
+             *    immediately switching back
+             * 3) All accesses to the hash must be controlled by a mutex, to
+             *    prevent two threads from getting an unstable state should
+             *    they simultaneously be accessing it.  The code below is
+             *    crafted so that the mutex is locked whenever there is an
+             *    access and unlocked only when the next stable state is
+             *    achieved.
+             *
+             * The hash stores either the definition of the property if it was
+             * valid, or, if invalid, the error message that was raised.  We
+             * use the type of SV to distinguish.
+             *
+             * There's also the need to guard against the definition expansion
+             * from infinitely recursing.  This is handled by storing the aTHX
+             * of the expanding thread during the expansion.  Again the SV type
+             * is used to distinguish this from the other two cases.  If we
+             * come to here and the hash entry for this property is our aTHX,
+             * it means we have recursed, and the code assumes that we would
+             * infinitely recurse, so instead stops and raises an error.
+             * (Any recursion has always been treated as infinite recursion in
+             * this feature.)
+             *
+             * If instead, the entry is for a different aTHX, it means that
+             * that thread has gotten here first, and hasn't finished expanding
+             * the definition yet.  We just have to wait until it is done.  We
+             * sleep and retry a few times, returning an error if the other
+             * thread doesn't complete. */
+
+          re_fetch:
+            USER_PROP_MUTEX_LOCK;
+
+            /* If we have an entry for this key, the subroutine has already
+             * been called once with this /i status. */
+            saved_user_prop_ptr = hv_fetch(PL_user_def_props,
+                                           SvPVX(fq_name), SvCUR(fq_name), 0);
+            if (saved_user_prop_ptr) {
+
+                /* If the saved result is an inversion list, it is the valid
+                 * definition of this property */
+                if (is_invlist(*saved_user_prop_ptr)) {
+                    prop_definition = *saved_user_prop_ptr;
+
+                    /* The SV in the hash won't be removed until global
+                     * destruction, so it is stable and we can unlock */
+                    USER_PROP_MUTEX_UNLOCK;
+
+                    /* The caller shouldn't try to free this SV */
+                    return prop_definition;
+                }
+
+                /* Otherwise, if it is a string, it is the error message
+                 * that was returned when we first tried to evaluate this
+                 * property.  Fail, and append the message */
+                if (SvPOK(*saved_user_prop_ptr)) {
+                    if (SvCUR(msg) > 0) sv_catpvs(msg, "; ");
+                    sv_catsv(msg, *saved_user_prop_ptr);
+
+                    /* The SV in the hash won't be removed until global
+                     * destruction, so it is stable and we can unlock */
+                    USER_PROP_MUTEX_UNLOCK;
+
+                    return NULL;
+                }
+
+                assert(SvIOK(*saved_user_prop_ptr));
+
+                /* Here, we have an unstable entry in the hash.  Either another
+                 * thread is in the middle of expanding the property's
+                 * definition, or we are ourselves recursing.  We use the aTHX
+                 * in it to distinguish */
+                if (SvIV(*saved_user_prop_ptr) != PTR2IV(CUR_CONTEXT)) {
 
-    lookup_len = j;     /* Use a more mnemonic name starting here */
+                    /* Here, it's another thread doing the expanding.  We've
+                     * looked as much as we are going to at the contents of the
+                     * hash entry.  It's safe to unlock. */
+                    USER_PROP_MUTEX_UNLOCK;
+
+                    /* Retry a few times */
+                    if (retry_countdown-- > 0) {
+                        PerlProc_sleep(1);
+                        goto re_fetch;
+                    }
+
+                    if (SvCUR(msg) > 0) sv_catpvs(msg, "; ");
+                    sv_catpvs(msg, "Timeout waiting for another thread to "
+                                   "define");
+                    goto append_name_to_msg;
+                }
+
+                /* Here, we are recursing; don't dig any deeper */
+                USER_PROP_MUTEX_UNLOCK;
+
+                if (SvCUR(msg) > 0) sv_catpvs(msg, "; ");
+                sv_catpvs(msg,
+                          "Infinite recursion in user-defined property");
+                goto append_name_to_msg;
+            }
+
+            /* Here, this thread has exclusive control, and there is no entry
+             * for this property in the hash.  So we have the go ahead to
+             * expand the definition ourselves. */
+
+            ENTER;
+
+            /* Create a temporary placeholder in the hash to detect recursion
+             * */
+            SWITCH_TO_GLOBAL_CONTEXT;
+            placeholder= newSVuv(PTR2IV(ORIGINAL_CONTEXT));
+            (void) hv_store_ent(PL_user_def_props, fq_name, placeholder, 0);
+            RESTORE_CONTEXT;
+
+            /* Now that we have a placeholder, we can let other threads
+             * continue */
+            USER_PROP_MUTEX_UNLOCK;
+
+            /* Make sure the placeholder always gets destroyed */
+            SAVEDESTRUCTOR_X(S_delete_recursion_entry, SvPVX(fq_name));
+
+            PUSHMARK(SP);
+            SAVETMPS;
+
+            /* Call the user's function, with the /i status as a parameter.
+             * Note that we have gone to a lot of trouble to keep this call
+             * from being within the locked mutex region. */
+            XPUSHs(boolSV(to_fold));
+            PUTBACK;
+
+            (void) call_sv(user_sub_sv, G_EVAL|G_SCALAR);
+
+            SPAGAIN;
+
+            error = ERRSV;
+            if (SvTRUE(error)) {
+                if (SvCUR(msg) > 0) sv_catpvs(msg, "; ");
+                sv_catpvs(msg, "Error \"");
+                sv_catsv(msg, error);
+                sv_catpvs(msg, "\"");
+                if (name_len > 0) {
+                    sv_catpvs(msg, " in expansion of ");
+                    Perl_sv_catpvf(aTHX_ msg, "%" UTF8f, UTF8fARG(is_utf8,
+                                                                  name_len,
+                                                                  name));
+                }
+
+                (void) POPs;
+                prop_definition = NULL;
+            }
+            else {  /* G_SCALAR guarantees a single return value */
+
+                /* The contents is supposed to be the expansion of the property
+                 * definition.  Call a function to check for valid syntax and
+                 * handle it */
+                prop_definition = handle_user_defined_property(name, name_len,
+                                                    is_utf8, to_fold, runtime,
+                                                    POPs, user_defined_ptr,
+                                                    msg,
+                                                    level);
+            }
+
+            /* Here, we have the results of the expansion.  Replace the
+             * placeholder with them.  We need exclusive access to the hash,
+             * and we can't let anyone else in, between when we delete the
+             * placeholder and add the permanent entry */
+            USER_PROP_MUTEX_LOCK;
+
+            S_delete_recursion_entry(aTHX_ SvPVX(fq_name));
+
+            if (! prop_definition || is_invlist(prop_definition)) {
+
+                /* If we got success we use the inversion list defining the
+                 * property; otherwise use the error message */
+                SWITCH_TO_GLOBAL_CONTEXT;
+                (void) hv_store_ent(PL_user_def_props,
+                                    fq_name,
+                                    ((prop_definition)
+                                     ? newSVsv(prop_definition)
+                                     : newSVsv(msg)),
+                                    0);
+                RESTORE_CONTEXT;
+            }
+
+            /* All done, and the hash now has a permanent entry for this
+             * property.  Give up exclusive control */
+            USER_PROP_MUTEX_UNLOCK;
+
+            FREETMPS;
+            LEAVE;
+
+            if (prop_definition) {
+
+                /* If the definition is for something not known at this time,
+                 * we toss it, and go return the main property name, as that's
+                 * the one the user will be aware of */
+                if (! is_invlist(prop_definition)) {
+                    SvREFCNT_dec_NN(prop_definition);
+                    goto definition_deferred;
+                }
+
+                sv_2mortal(prop_definition);
+            }
+
+            /* And return */
+            return prop_definition;
+
+        }   /* End of calling the subroutine for the user-defined property */
+    }       /* End of it could be a user-defined property */
+
+    /* Here it wasn't a user-defined property that is known at this time.  See
+     * if it is a Unicode property */
+
+    lookup_len = j;     /* This is a more mnemonic name than 'j' */
 
     /* Get the index into our pointer table of the inversion list corresponding
      * to the property */
     table_index = match_uniprop((U8 *) lookup_name, lookup_len);
 
-    /* If it didn't find the property */
+    /* If it didn't find the property ... */
     if (table_index == 0) {
 
-        /* If didn't find the property, we try again stripping off any initial
-         * 'In' or 'Is' */
+        /* Try again stripping off any initial 'In' or 'Is' */
         if (starts_with_In_or_Is) {
             lookup_name += 2;
             lookup_len -= 2;
@@ -21782,14 +22941,28 @@ Perl_parse_uniprop_string(pTHX_ const char * const name, const Size_t name_len,
         if (table_index == 0) {
             char * canonical;
 
-            /* If not found, and not a numeric type property, isn't a legal
-             * property */
+            /* Here, we didn't find it.  If not a numeric type property, and
+             * can't be a user-defined one, it isn't a legal property */
             if (! is_nv_type) {
-                return NULL;
-            }
+                if (! could_be_user_defined) {
+                    goto failed;
+                }
+
+                /* Here, the property name is legal as a user-defined one.   At
+                 * compile time, it might just be that the subroutine for that
+                 * property hasn't been encountered yet, but at runtime, it's
+                 * an error to try to use an undefined one */
+                if (runtime) {
+                    if (SvCUR(msg) > 0) sv_catpvs(msg, "; ");
+                    sv_catpvs(msg, "Unknown user-defined property name");
+                    goto append_name_to_msg;
+                }
+
+                goto definition_deferred;
+            } /* End of isn't a numeric type property */
 
-            /* But the numeric type properties need more work to decide.  What
-             * we do is make sure we have the number in canonical form and look
+            /* The numeric type properties need more work to decide.  What we
+             * do is make sure we have the number in canonical form and look
              * that up. */
 
             if (slash_pos < 0) {    /* No slash */
@@ -21805,13 +22978,14 @@ Perl_parse_uniprop_string(pTHX_ const char * const name, const Size_t name_len,
                              lookup_len - equals_pos)
                           != lookup_name + lookup_len)
                 {
-                    return NULL;
+                    goto failed;
                 }
 
-                /* If the value is an integer, the canonical value is integral */
+                /* If the value is an integer, the canonical value is integral
+                 * */
                 if (Perl_ceil(value) == value) {
                     canonical = Perl_form(aTHX_ "%.*s%.0" NVff,
-                                                equals_pos, lookup_name, value);
+                                            equals_pos, lookup_name, value);
                 }
                 else {  /* Otherwise, it is %e with a known precision */
                     char * exp_ptr;
@@ -21873,12 +23047,12 @@ Perl_parse_uniprop_string(pTHX_ const char * const name, const Size_t name_len,
                 /* Convert the numerator to numeric */
                 end_ptr = this_lookup_name + slash_pos;
                 if (! grok_atoUV(this_lookup_name, &numerator, &end_ptr)) {
-                    return NULL;
+                    goto failed;
                 }
 
                 /* It better have included all characters before the slash */
                 if (*end_ptr != '/') {
-                    return NULL;
+                    goto failed;
                 }
 
                 /* Set to look at just the denominator */
@@ -21888,7 +23062,7 @@ Perl_parse_uniprop_string(pTHX_ const char * const name, const Size_t name_len,
 
                 /* Convert the denominator to numeric */
                 if (! grok_atoUV(this_lookup_name, &denominator, &end_ptr)) {
-                    return NULL;
+                    goto failed;
                 }
 
                 /* It better be the rest of the characters, and don't divide by
@@ -21896,7 +23070,7 @@ Perl_parse_uniprop_string(pTHX_ const char * const name, const Size_t name_len,
                 if (   end_ptr != this_lookup_name + lookup_len
                     || denominator == 0)
                 {
-                    return NULL;
+                    goto failed;
                 }
 
                 /* Get the greatest common denominator using
@@ -21912,11 +23086,11 @@ Perl_parse_uniprop_string(pTHX_ const char * const name, const Size_t name_len,
                 /* If already in lowest possible terms, we have already tried
                  * looking this up */
                 if (gcd == 1) {
-                    return NULL;
+                    goto failed;
                 }
 
-                /* Reduce the rational, which should put it in canonical form.
-                 * Then look it up */
+                /* Reduce the rational, which should put it in canonical form
+                 * */
                 numerator /= gcd;
                 denominator /= gcd;
 
@@ -21927,26 +23101,23 @@ Perl_parse_uniprop_string(pTHX_ const char * const name, const Size_t name_len,
             /* Here, we have the number in canonical form.  Try that */
             table_index = match_uniprop((U8 *) canonical, strlen(canonical));
             if (table_index == 0) {
-                return NULL;
+                goto failed;
             }
-        }
-    }
+        }   /* End of still didn't find the property in our table */
+    }       /* End of       didn't find the property in our table */
 
-    /* The return is an index into a table of ptrs.  A negative return
-     * signifies that the real index is the absolute value, but the result
-     * needs to be inverted */
+    /* Here, we have a non-zero return, which is an index into a table of ptrs.
+     * A negative return signifies that the real index is the absolute value,
+     * but the result needs to be inverted */
     if (table_index < 0) {
-        *invert = TRUE;
+        invert_return = TRUE;
         table_index = -table_index;
     }
-    else {
-        *invert = FALSE;
-    }
 
     /* Out-of band indices indicate a deprecated property.  The proper index is
      * modulo it with the table size.  And dividing by the table size yields
-     * an offset into a table constructed to contain the corresponding warning
-     * message */
+     * an offset into a table constructed by regen/mk_invlists.pl to contain
+     * the corresponding warning message */
     if (table_index > MAX_UNI_KEYWORD_INDEX) {
         Size_t warning_offset = table_index / MAX_UNI_KEYWORD_INDEX;
         table_index %= MAX_UNI_KEYWORD_INDEX;
@@ -21980,7 +23151,62 @@ Perl_parse_uniprop_string(pTHX_ const char * const name, const Size_t name_len,
     }
 
     /* Create and return the inversion list */
-    return _new_invlist_C_array(uni_prop_ptrs[table_index]);
+    prop_definition =_new_invlist_C_array(uni_prop_ptrs[table_index]);
+    if (invert_return) {
+        _invlist_invert(prop_definition);
+    }
+    sv_2mortal(prop_definition);
+    return prop_definition;
+
+
+  failed:
+    if (non_pkg_begin != 0) {
+        if (SvCUR(msg) > 0) sv_catpvs(msg, "; ");
+        sv_catpvs(msg, "Illegal user-defined property name");
+    }
+    else {
+        if (SvCUR(msg) > 0) sv_catpvs(msg, "; ");
+        sv_catpvs(msg, "Can't find Unicode property definition");
+    }
+    /* FALLTHROUGH */
+
+  append_name_to_msg:
+    {
+        const char * prefix = (runtime && level == 0) ?  " \\p{" : " \"";
+        const char * suffix = (runtime && level == 0) ?  "}" : "\"";
+
+        sv_catpv(msg, prefix);
+        Perl_sv_catpvf(aTHX_ msg, "%" UTF8f, UTF8fARG(is_utf8, name_len, name));
+        sv_catpv(msg, suffix);
+    }
+
+    return NULL;
+
+  definition_deferred:
+
+    /* Here it could yet to be defined, so defer evaluation of this
+     * until its needed at runtime. */
+    prop_definition = newSVpvs_flags("", SVs_TEMP);
+
+    /* To avoid any ambiguity, the package is always specified.
+     * Use the current one if it wasn't included in our input */
+    if (non_pkg_begin == 0) {
+        const HV * pkg = (IN_PERL_COMPILETIME)
+                         ? PL_curstash
+                         : CopSTASH(PL_curcop);
+        const char* pkgname = HvNAME(pkg);
+
+        Perl_sv_catpvf(aTHX_ prop_definition, "%" UTF8f,
+                      UTF8fARG(is_utf8, strlen(pkgname), pkgname));
+        sv_catpvs(prop_definition, "::");
+    }
+
+    Perl_sv_catpvf(aTHX_ prop_definition, "%" UTF8f,
+                         UTF8fARG(is_utf8, name_len, name));
+    sv_catpvs(prop_definition, "\n");
+
+    *user_defined_ptr = TRUE;
+    return prop_definition;
 }
 
 #endif