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regcomp.c: Remove invlist_destroy calls
[perl5.git] / regcomp.c
index 31a0b35..a93cc67 100644 (file)
--- a/regcomp.c
+++ b/regcomp.c
@@ -142,6 +142,8 @@ typedef struct RExC_state_t {
     regnode    **recurse;              /* Recurse regops */
     I32                recurse_count;          /* Number of recurse regops */
     I32                in_lookbehind;
+    I32                contains_locale;
+    I32                override_recoding;
 #if ADD_TO_REGEXEC
     char       *starttry;              /* -Dr: where regtry was called. */
 #define RExC_starttry  (pRExC_state->starttry)
@@ -190,6 +192,8 @@ typedef struct RExC_state_t {
 #define RExC_recurse   (pRExC_state->recurse)
 #define RExC_recurse_count     (pRExC_state->recurse_count)
 #define RExC_in_lookbehind     (pRExC_state->in_lookbehind)
+#define RExC_contains_locale   (pRExC_state->contains_locale)
+#define RExC_override_recoding (pRExC_state->override_recoding)
 
 
 #define        ISMULT1(c)      ((c) == '*' || (c) == '+' || (c) == '?')
@@ -509,6 +513,13 @@ static const scan_data_t zero_scan_data =
            (int)offset, RExC_precomp, RExC_precomp + offset);          \
 } STMT_END
 
+#define        ckWARN2regdep(loc,m, a1) STMT_START {                           \
+    const IV offset = loc - RExC_precomp;                              \
+    Perl_ck_warner_d(aTHX_ packWARN2(WARN_DEPRECATED, WARN_REGEXP),    \
+           m REPORT_LOCATION,                                          \
+           a1, (int)offset, RExC_precomp, RExC_precomp + offset);      \
+} STMT_END
+
 #define        ckWARN2reg(loc, m, a1) STMT_START {                             \
     const IV offset = loc - RExC_precomp;                              \
     Perl_ck_warner(aTHX_ packWARN(WARN_REGEXP), m REPORT_LOCATION,     \
@@ -717,11 +728,24 @@ S_cl_anything(const RExC_state_t *pRExC_state, struct regnode_charclass_class *c
 {
     PERL_ARGS_ASSERT_CL_ANYTHING;
 
-    ANYOF_CLASS_ZERO(cl);
     ANYOF_BITMAP_SETALL(cl);
-    cl->flags = ANYOF_EOS|ANYOF_UNICODE_ALL|ANYOF_LOC_NONBITMAP_FOLD|ANYOF_NON_UTF8_LATIN1_ALL;
-    if (LOC)
+    cl->flags = ANYOF_CLASS|ANYOF_EOS|ANYOF_UNICODE_ALL
+               |ANYOF_LOC_NONBITMAP_FOLD|ANYOF_NON_UTF8_LATIN1_ALL;
+
+    /* If any portion of the regex is to operate under locale rules,
+     * initialization includes it.  The reason this isn't done for all regexes
+     * is that the optimizer was written under the assumption that locale was
+     * all-or-nothing.  Given the complexity and lack of documentation in the
+     * optimizer, and that there are inadequate test cases for locale, so many
+     * parts of it may not work properly, it is safest to avoid locale unless
+     * necessary. */
+    if (RExC_contains_locale) {
+       ANYOF_CLASS_SETALL(cl);     /* /l uses class */
        cl->flags |= ANYOF_LOCALE;
+    }
+    else {
+       ANYOF_CLASS_ZERO(cl);       /* Only /l uses class now */
+    }
 }
 
 /* Can match anything (initialization) */
@@ -751,22 +775,15 @@ S_cl_init(const RExC_state_t *pRExC_state, struct regnode_charclass_class *cl)
     Zero(cl, 1, struct regnode_charclass_class);
     cl->type = ANYOF;
     cl_anything(pRExC_state, cl);
+    ARG_SET(cl, ANYOF_NONBITMAP_EMPTY);
 }
 
-STATIC void
-S_cl_init_zero(const RExC_state_t *pRExC_state, struct regnode_charclass_class *cl)
-{
-    PERL_ARGS_ASSERT_CL_INIT_ZERO;
+/* These two functions currently do the exact same thing */
+#define cl_init_zero           S_cl_init
 
-    Zero(cl, 1, struct regnode_charclass_class);
-    cl->type = ANYOF;
-    cl_anything(pRExC_state, cl);
-    if (LOC)
-       cl->flags |= ANYOF_LOCALE;
-}
-
-/* 'And' a given class with another one.  Can create false positives */
-/* We assume that cl is not inverted */
+/* 'AND' a given class with another one.  Can create false positives.  'cl'
+ * should not be inverted.  'and_with->flags & ANYOF_CLASS' should be 0 if
+ * 'and_with' is a regnode_charclass instead of a regnode_charclass_class. */
 STATIC void
 S_cl_and(struct regnode_charclass_class *cl,
        const struct regnode_charclass_class *and_with)
@@ -775,6 +792,7 @@ S_cl_and(struct regnode_charclass_class *cl,
 
     assert(and_with->type == ANYOF);
 
+    /* I (khw) am not sure all these restrictions are necessary XXX */
     if (!(ANYOF_CLASS_TEST_ANY_SET(and_with))
        && !(ANYOF_CLASS_TEST_ANY_SET(cl))
        && (and_with->flags & ANYOF_LOCALE) == (cl->flags & ANYOF_LOCALE)
@@ -789,42 +807,119 @@ S_cl_and(struct regnode_charclass_class *cl,
            for (i = 0; i < ANYOF_BITMAP_SIZE; i++)
                cl->bitmap[i] &= and_with->bitmap[i];
     } /* XXXX: logic is complicated otherwise, leave it along for a moment. */
-    if (!(and_with->flags & ANYOF_EOS))
-       cl->flags &= ~ANYOF_EOS;
 
-    if (!(and_with->flags & ANYOF_LOC_NONBITMAP_FOLD))
-       cl->flags &= ~ANYOF_LOC_NONBITMAP_FOLD;
-    if (!(and_with->flags & ANYOF_NON_UTF8_LATIN1_ALL))
-       cl->flags &= ~ANYOF_NON_UTF8_LATIN1_ALL;
+    if (and_with->flags & ANYOF_INVERT) {
 
-    if (cl->flags & ANYOF_UNICODE_ALL
-       && and_with->flags & ANYOF_NONBITMAP
-       && !(and_with->flags & ANYOF_INVERT))
-    {
-       if (! (and_with->flags & ANYOF_UNICODE_ALL)) {
+        /* Here, the and'ed node is inverted.  Get the AND of the flags that
+         * aren't affected by the inversion.  Those that are affected are
+         * handled individually below */
+       U8 affected_flags = cl->flags & ~INVERSION_UNAFFECTED_FLAGS;
+       cl->flags &= (and_with->flags & INVERSION_UNAFFECTED_FLAGS);
+       cl->flags |= affected_flags;
+
+        /* We currently don't know how to deal with things that aren't in the
+         * bitmap, but we know that the intersection is no greater than what
+         * is already in cl, so let there be false positives that get sorted
+         * out after the synthetic start class succeeds, and the node is
+         * matched for real. */
+
+        /* The inversion of these two flags indicate that the resulting
+         * intersection doesn't have them */
+       if (and_with->flags & ANYOF_UNICODE_ALL) {
            cl->flags &= ~ANYOF_UNICODE_ALL;
        }
-       cl->flags |= and_with->flags & ANYOF_NONBITMAP; /* field is 2 bits; use
-                                                          only the one(s)
-                                                          actually set */
-       ARG_SET(cl, ARG(and_with));
-    }
-    if (!(and_with->flags & ANYOF_UNICODE_ALL) &&
-       !(and_with->flags & ANYOF_INVERT))
-       cl->flags &= ~ANYOF_UNICODE_ALL;
-    if (!(and_with->flags & (ANYOF_NONBITMAP|ANYOF_UNICODE_ALL)) &&
-       !(and_with->flags & ANYOF_INVERT))
-       cl->flags &= ~ANYOF_NONBITMAP;
+       if (and_with->flags & ANYOF_NON_UTF8_LATIN1_ALL) {
+           cl->flags &= ~ANYOF_NON_UTF8_LATIN1_ALL;
+       }
+    }
+    else {   /* and'd node is not inverted */
+       U8 outside_bitmap_but_not_utf8; /* Temp variable */
+
+       if (! ANYOF_NONBITMAP(and_with)) {
+
+            /* Here 'and_with' doesn't match anything outside the bitmap
+             * (except possibly ANYOF_UNICODE_ALL), which means the
+             * intersection can't either, except for ANYOF_UNICODE_ALL, in
+             * which case we don't know what the intersection is, but it's no
+             * greater than what cl already has, so can just leave it alone,
+             * with possible false positives */
+            if (! (and_with->flags & ANYOF_UNICODE_ALL)) {
+                ARG_SET(cl, ANYOF_NONBITMAP_EMPTY);
+               cl->flags &= ~ANYOF_NONBITMAP_NON_UTF8;
+            }
+       }
+       else if (! ANYOF_NONBITMAP(cl)) {
+
+           /* Here, 'and_with' does match something outside the bitmap, and cl
+            * doesn't have a list of things to match outside the bitmap.  If
+             * cl can match all code points above 255, the intersection will
+             * be those above-255 code points that 'and_with' matches.  If cl
+             * can't match all Unicode code points, it means that it can't
+             * match anything outside the bitmap (since the 'if' that got us
+             * into this block tested for that), so we leave the bitmap empty.
+             */
+           if (cl->flags & ANYOF_UNICODE_ALL) {
+               ARG_SET(cl, ARG(and_with));
+
+                /* and_with's ARG may match things that don't require UTF8.
+                 * And now cl's will too, in spite of this being an 'and'.  See
+                 * the comments below about the kludge */
+               cl->flags |= and_with->flags & ANYOF_NONBITMAP_NON_UTF8;
+           }
+       }
+       else {
+            /* Here, both 'and_with' and cl match something outside the
+             * bitmap.  Currently we do not do the intersection, so just match
+             * whatever cl had at the beginning.  */
+       }
+
+
+        /* Take the intersection of the two sets of flags.  However, the
+         * ANYOF_NONBITMAP_NON_UTF8 flag is treated as an 'or'.  This is a
+         * kludge around the fact that this flag is not treated like the others
+         * which are initialized in cl_anything().  The way the optimizer works
+         * is that the synthetic start class (SSC) is initialized to match
+         * anything, and then the first time a real node is encountered, its
+         * values are AND'd with the SSC's with the result being the values of
+         * the real node.  However, there are paths through the optimizer where
+         * the AND never gets called, so those initialized bits are set
+         * inappropriately, which is not usually a big deal, as they just cause
+         * false positives in the SSC, which will just mean a probably
+         * imperceptible slow down in execution.  However this bit has a
+         * higher false positive consequence in that it can cause utf8.pm,
+         * utf8_heavy.pl ... to be loaded when not necessary, which is a much
+         * bigger slowdown and also causes significant extra memory to be used.
+         * In order to prevent this, the code now takes a different tack.  The
+         * bit isn't set unless some part of the regular expression needs it,
+         * but once set it won't get cleared.  This means that these extra
+         * modules won't get loaded unless there was some path through the
+         * pattern that would have required them anyway, and  so any false
+         * positives that occur by not ANDing them out when they could be
+         * aren't as severe as they would be if we treated this bit like all
+         * the others */
+        outside_bitmap_but_not_utf8 = (cl->flags | and_with->flags)
+                                      & ANYOF_NONBITMAP_NON_UTF8;
+       cl->flags &= and_with->flags;
+       cl->flags |= outside_bitmap_but_not_utf8;
+    }
 }
 
-/* 'OR' a given class with another one.  Can create false positives */
-/* We assume that cl is not inverted */
+/* 'OR' a given class with another one.  Can create false positives.  'cl'
+ * should not be inverted.  'or_with->flags & ANYOF_CLASS' should be 0 if
+ * 'or_with' is a regnode_charclass instead of a regnode_charclass_class. */
 STATIC void
 S_cl_or(const RExC_state_t *pRExC_state, struct regnode_charclass_class *cl, const struct regnode_charclass_class *or_with)
 {
     PERL_ARGS_ASSERT_CL_OR;
 
     if (or_with->flags & ANYOF_INVERT) {
+
+        /* Here, the or'd node is to be inverted.  This means we take the
+         * complement of everything not in the bitmap, but currently we don't
+         * know what that is, so give up and match anything */
+       if (ANYOF_NONBITMAP(or_with)) {
+           cl_anything(pRExC_state, cl);
+       }
        /* We do not use
         * (B1 | CL1) | (!B2 & !CL2) = (B1 | !B2 & !CL2) | (CL1 | (!B2 & !CL2))
         *   <= (B1 | !B2) | (CL1 | !CL2)
@@ -834,7 +929,7 @@ S_cl_or(const RExC_state_t *pRExC_state, struct regnode_charclass_class *cl, con
         *   (OK1(i) | OK1(i')) | !(OK1(i) | OK1(i')) =
         *   (OK1(i) | OK1(i')) | (!OK1(i) & !OK1(i'))
         */
-       if ( (or_with->flags & ANYOF_LOCALE) == (cl->flags & ANYOF_LOCALE)
+       else if ( (or_with->flags & ANYOF_LOCALE) == (cl->flags & ANYOF_LOCALE)
             && !(or_with->flags & ANYOF_LOC_NONBITMAP_FOLD)
             && !(cl->flags & ANYOF_LOC_NONBITMAP_FOLD) ) {
            int i;
@@ -845,7 +940,21 @@ S_cl_or(const RExC_state_t *pRExC_state, struct regnode_charclass_class *cl, con
        else {
            cl_anything(pRExC_state, cl);
        }
-    } else {
+
+        /* And, we can just take the union of the flags that aren't affected
+         * by the inversion */
+       cl->flags |= or_with->flags & INVERSION_UNAFFECTED_FLAGS;
+
+        /* For the remaining flags:
+            ANYOF_UNICODE_ALL and inverted means to not match anything above
+                    255, which means that the union with cl should just be
+                    what cl has in it, so can ignore this flag
+            ANYOF_NON_UTF8_LATIN1_ALL and inverted means if not utf8 and ord
+                    is 127-255 to match them, but then invert that, so the
+                    union with cl should just be what cl has in it, so can
+                    ignore this flag
+         */
+    } else {    /* 'or_with' is not inverted */
        /* (B1 | CL1) | (B2 | CL2) = (B1 | B2) | (CL1 | CL2)) */
        if ( (or_with->flags & ANYOF_LOCALE) == (cl->flags & ANYOF_LOCALE)
             && (!(or_with->flags & ANYOF_LOC_NONBITMAP_FOLD)
@@ -864,25 +973,32 @@ S_cl_or(const RExC_state_t *pRExC_state, struct regnode_charclass_class *cl, con
        else { /* XXXX: logic is complicated, leave it along for a moment. */
            cl_anything(pRExC_state, cl);
        }
-    }
-    if (or_with->flags & ANYOF_EOS)
-       cl->flags |= ANYOF_EOS;
-    if (!(or_with->flags & ANYOF_NON_UTF8_LATIN1_ALL))
-       cl->flags |= ANYOF_NON_UTF8_LATIN1_ALL;
 
-    if (or_with->flags & ANYOF_LOC_NONBITMAP_FOLD)
-       cl->flags |= ANYOF_LOC_NONBITMAP_FOLD;
+       if (ANYOF_NONBITMAP(or_with)) {
+
+           /* Use the added node's outside-the-bit-map match if there isn't a
+            * conflict.  If there is a conflict (both nodes match something
+            * outside the bitmap, but what they match outside is not the same
+            * pointer, and hence not easily compared until XXX we extend
+            * inversion lists this far), give up and allow the start class to
+            * match everything outside the bitmap.  If that stuff is all above
+            * 255, can just set UNICODE_ALL, otherwise caould be anything. */
+           if (! ANYOF_NONBITMAP(cl)) {
+               ARG_SET(cl, ARG(or_with));
+           }
+           else if (ARG(cl) != ARG(or_with)) {
 
-    /* If both nodes match something outside the bitmap, but what they match
-     * outside is not the same pointer, and hence not easily compared, give up
-     * and allow the start class to match everything outside the bitmap */
-    if (cl->flags & ANYOF_NONBITMAP && or_with->flags & ANYOF_NONBITMAP &&
-       ARG(cl) != ARG(or_with)) {
-       cl->flags |= ANYOF_UNICODE_ALL;
-    }
+               if ((or_with->flags & ANYOF_NONBITMAP_NON_UTF8)) {
+                   cl_anything(pRExC_state, cl);
+               }
+               else {
+                   cl->flags |= ANYOF_UNICODE_ALL;
+               }
+           }
+       }
 
-    if (or_with->flags & ANYOF_UNICODE_ALL) {
-       cl->flags |= ANYOF_UNICODE_ALL;
+        /* Take the union */
+       cl->flags |= or_with->flags;
     }
 }
 
@@ -2932,9 +3048,9 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
                                 }
                             } else {
 /* 
-    Currently we do not believe that the trie logic can
-    handle case insensitive matching properly when the
-    pattern is not unicode (thus forcing unicode semantics).
+    Currently the trie logic handles case insensitive matching properly only
+    when the pattern is UTF-8 and the node is EXACTFU (thus forcing unicode
+    semantics).
 
     If/when this is fixed the following define can be swapped
     in below to fully enable trie logic.
@@ -2942,7 +3058,7 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
 #define TRIE_TYPE_IS_SAFE 1
 
 */
-#define TRIE_TYPE_IS_SAFE (UTF || optype==EXACT)
+#define TRIE_TYPE_IS_SAFE ((UTF && optype == EXACTFU) || optype==EXACT)
 
                                 if ( last && TRIE_TYPE_IS_SAFE ) {
                                     make_trie( pRExC_state, 
@@ -3180,6 +3296,9 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
                    data->start_class->flags &= ~ANYOF_EOS;
                    data->start_class->flags |= ANYOF_LOC_NONBITMAP_FOLD;
                    if (OP(scan) == EXACTFL) {
+                       /* XXX This set is probably no longer necessary, and
+                        * probably wrong as LOCALE now is on in the initial
+                        * state */
                        data->start_class->flags |= ANYOF_LOCALE;
                    }
                    else {
@@ -3692,7 +3811,11 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
                    else {
                        if (data->start_class->flags & ANYOF_LOCALE)
                            ANYOF_CLASS_SET(data->start_class,ANYOF_ALNUM);
-                        else if (OP(scan) == ALNUMU) {
+
+                       /* Even if under locale, set the bits for non-locale
+                        * in case it isn't a true locale-node.  This will
+                        * create false positives if it truly is locale */
+                        if (OP(scan) == ALNUMU) {
                             for (value = 0; value < 256; value++) {
                                 if (isWORDCHAR_L1(value)) {
                                     ANYOF_BITMAP_SET(data->start_class, value);
@@ -3729,19 +3852,21 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
                    else {
                        if (data->start_class->flags & ANYOF_LOCALE)
                            ANYOF_CLASS_SET(data->start_class,ANYOF_NALNUM);
-                       else {
-                            if (OP(scan) == NALNUMU) {
-                                for (value = 0; value < 256; value++) {
-                                    if (! isWORDCHAR_L1(value)) {
-                                        ANYOF_BITMAP_SET(data->start_class, value);
-                                    }
-                                }
-                            } else {
-                                for (value = 0; value < 256; value++) {
-                                    if (! isALNUM(value)) {
-                                        ANYOF_BITMAP_SET(data->start_class, value);
-                                    }
-                                }
+
+                       /* Even if under locale, set the bits for non-locale in
+                        * case it isn't a true locale-node.  This will create
+                        * false positives if it truly is locale */
+                       if (OP(scan) == NALNUMU) {
+                           for (value = 0; value < 256; value++) {
+                               if (! isWORDCHAR_L1(value)) {
+                                   ANYOF_BITMAP_SET(data->start_class, value);
+                               }
+                           }
+                       } else {
+                           for (value = 0; value < 256; value++) {
+                               if (! isALNUM(value)) {
+                                   ANYOF_BITMAP_SET(data->start_class, value);
+                               }
                            }
                        }
                    }
@@ -3769,7 +3894,7 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
                         if (data->start_class->flags & ANYOF_LOCALE) {
                            ANYOF_CLASS_SET(data->start_class,ANYOF_SPACE);
                         }
-                        else if (OP(scan) == SPACEU) {
+                        if (OP(scan) == SPACEU) {
                             for (value = 0; value < 256; value++) {
                                 if (isSPACE_L1(value)) {
                                     ANYOF_BITMAP_SET(data->start_class, value);
@@ -3806,7 +3931,7 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
                    else {
                        if (data->start_class->flags & ANYOF_LOCALE)
                            ANYOF_CLASS_SET(data->start_class,ANYOF_NSPACE);
-                        else if (OP(scan) == NSPACEU) {
+                        if (OP(scan) == NSPACEU) {
                             for (value = 0; value < 256; value++) {
                                 if (!isSPACE_L1(value)) {
                                     ANYOF_BITMAP_SET(data->start_class, value);
@@ -3824,24 +3949,25 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
                    break;
                case DIGIT:
                    if (flags & SCF_DO_STCLASS_AND) {
-                       ANYOF_CLASS_CLEAR(data->start_class,ANYOF_NDIGIT);
-                       for (value = 0; value < 256; value++)
-                           if (!isDIGIT(value))
-                               ANYOF_BITMAP_CLEAR(data->start_class, value);
+                       if (!(data->start_class->flags & ANYOF_LOCALE)) {
+                            ANYOF_CLASS_CLEAR(data->start_class,ANYOF_NDIGIT);
+                           for (value = 0; value < 256; value++)
+                               if (!isDIGIT(value))
+                                   ANYOF_BITMAP_CLEAR(data->start_class, value);
+                       }
                    }
                    else {
                        if (data->start_class->flags & ANYOF_LOCALE)
                            ANYOF_CLASS_SET(data->start_class,ANYOF_DIGIT);
-                       else {
-                           for (value = 0; value < 256; value++)
-                               if (isDIGIT(value))
-                                   ANYOF_BITMAP_SET(data->start_class, value);
-                       }
+                       for (value = 0; value < 256; value++)
+                           if (isDIGIT(value))
+                               ANYOF_BITMAP_SET(data->start_class, value);
                    }
                    break;
                case NDIGIT:
                    if (flags & SCF_DO_STCLASS_AND) {
-                       ANYOF_CLASS_CLEAR(data->start_class,ANYOF_DIGIT);
+                       if (!(data->start_class->flags & ANYOF_LOCALE))
+                            ANYOF_CLASS_CLEAR(data->start_class,ANYOF_DIGIT);
                        for (value = 0; value < 256; value++)
                            if (isDIGIT(value))
                                ANYOF_BITMAP_CLEAR(data->start_class, value);
@@ -3849,11 +3975,9 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
                    else {
                        if (data->start_class->flags & ANYOF_LOCALE)
                            ANYOF_CLASS_SET(data->start_class,ANYOF_NDIGIT);
-                       else {
-                           for (value = 0; value < 256; value++)
-                               if (!isDIGIT(value))
-                                   ANYOF_BITMAP_SET(data->start_class, value);
-                       }
+                       for (value = 0; value < 256; value++)
+                           if (!isDIGIT(value))
+                               ANYOF_BITMAP_SET(data->start_class, value);
                    }
                    break;
                CASE_SYNST_FNC(VERTWS);
@@ -4412,6 +4536,7 @@ Perl_re_compile(pTHX_ SV * const pattern, U32 orig_pm_flags)
     I32 sawplus = 0;
     I32 sawopen = 0;
     bool used_setjump = FALSE;
+    regex_charset initial_charset = get_regex_charset(orig_pm_flags);
 
     U8 jump_ret = 0;
     dJMPENV;
@@ -4430,6 +4555,7 @@ Perl_re_compile(pTHX_ SV * const pattern, U32 orig_pm_flags)
 
     RExC_utf8 = RExC_orig_utf8 = SvUTF8(pattern);
     RExC_uni_semantics = 0;
+    RExC_contains_locale = 0;
 
     /****************** LONG JUMP TARGET HERE***********************/
     /* Longjmp back to here if have to switch in midstream to utf8 */
@@ -4486,11 +4612,15 @@ Perl_re_compile(pTHX_ SV * const pattern, U32 orig_pm_flags)
     restudied = 0;
 #endif
 
-    /* Set to use unicode semantics if the pattern is in utf8 and has the
-     * 'depends' charset specified, as it means unicode when utf8  */
     pm_flags = orig_pm_flags;
 
-    if (RExC_utf8 && get_regex_charset(pm_flags) == REGEX_DEPENDS_CHARSET) {
+    if (initial_charset == REGEX_LOCALE_CHARSET) {
+       RExC_contains_locale = 1;
+    }
+    else if (RExC_utf8 && initial_charset == REGEX_DEPENDS_CHARSET) {
+
+       /* Set to use unicode semantics if the pattern is in utf8 and has the
+        * 'depends' charset specified, as it means unicode when utf8  */
        set_regex_charset(&pm_flags, REGEX_UNICODE_CHARSET);
     }
 
@@ -4503,6 +4633,7 @@ Perl_re_compile(pTHX_ SV * const pattern, U32 orig_pm_flags)
     RExC_seen_zerolen = *exp == '^' ? -1 : 0;
     RExC_seen_evals = 0;
     RExC_extralen = 0;
+    RExC_override_recoding = 0;
 
     /* First pass: determine size, legality. */
     RExC_parse = exp;
@@ -5011,14 +5142,13 @@ reStudy:
            && (OP(ri->regstclass) == REG_ANY || OP(ri->regstclass) == SANY))
            ri->regstclass = NULL;
 
-       /* If the synthetic start class were to ever be used when EOS is set,
-        * that bit would have to be cleared, as it is shared with another */
        if ((!(r->anchored_substr || r->anchored_utf8) || r->anchored_offset)
            && stclass_flag
            && !(data.start_class->flags & ANYOF_EOS)
            && !cl_is_anything(data.start_class))
        {
            const U32 n = add_data(pRExC_state, 1, "f");
+           data.start_class->flags |= ANYOF_IS_SYNTHETIC;
 
            Newx(RExC_rxi->data->data[n], 1,
                struct regnode_charclass_class);
@@ -5086,12 +5216,11 @@ reStudy:
        r->check_substr = r->check_utf8 = r->anchored_substr = r->anchored_utf8
                = r->float_substr = r->float_utf8 = NULL;
 
-       /* If the synthetic start class were to ever be used when EOS is set,
-        * that bit would have to be cleared, as it is shared with another */
        if (!(data.start_class->flags & ANYOF_EOS)
            && !cl_is_anything(data.start_class))
        {
            const U32 n = add_data(pRExC_state, 1, "f");
+           data.start_class->flags |= ANYOF_IS_SYNTHETIC;
 
            Newx(RExC_rxi->data->data[n], 1,
                struct regnode_charclass_class);
@@ -5698,101 +5827,60 @@ S_reg_scan_name(pTHX_ RExC_state_t *pRExC_state, U32 flags)
  * this file.  An inversion list is here implemented as a malloc'd C array with
  * some added info.  More will be coming when functionality is added later.
  *
+ * It is currently implemented as an SV pointing to an array of UVs that the SV
+ * thinks are bytes.  This allows us to have an array of UV whose memory
+ * management is automatically handled by the existing facilities for SV's.
+ *
  * Some of the methods should always be private to the implementation, and some
  * should eventually be made public */
 
 #define INVLIST_INITIAL_LEN 10
-#define INVLIST_ARRAY_KEY "array"
-#define INVLIST_MAX_KEY "max"
-#define INVLIST_LEN_KEY "len"
 
 PERL_STATIC_INLINE UV*
-S_invlist_array(pTHX_ HV* const invlist)
+S_invlist_array(pTHX_ SV* const invlist)
 {
     /* Returns the pointer to the inversion list's array.  Every time the
      * length changes, this needs to be called in case malloc or realloc moved
      * it */
 
-    SV** list_ptr = hv_fetchs(invlist, INVLIST_ARRAY_KEY, FALSE);
-
     PERL_ARGS_ASSERT_INVLIST_ARRAY;
 
-    if (list_ptr == NULL) {
-       Perl_croak(aTHX_ "panic: inversion list without a '%s' element",
-                                                           INVLIST_ARRAY_KEY);
-    }
-
-    return INT2PTR(UV *, SvUV(*list_ptr));
-}
-
-PERL_STATIC_INLINE void
-S_invlist_set_array(pTHX_ HV* const invlist, const UV* const array)
-{
-    PERL_ARGS_ASSERT_INVLIST_SET_ARRAY;
-
-    /* Sets the array stored in the inversion list to the memory beginning with
-     * the parameter */
-
-    if (hv_stores(invlist, INVLIST_ARRAY_KEY, newSVuv(PTR2UV(array))) == NULL) {
-       Perl_croak(aTHX_ "panic: can't store '%s' entry in inversion list",
-                                                           INVLIST_ARRAY_KEY);
-    }
+    return (UV *) SvPVX(invlist);
 }
 
 PERL_STATIC_INLINE UV
-S_invlist_len(pTHX_ HV* const invlist)
+S_invlist_len(pTHX_ SV* const invlist)
 {
     /* Returns the current number of elements in the inversion list's array */
 
-    SV** len_ptr = hv_fetchs(invlist, INVLIST_LEN_KEY, FALSE);
-
     PERL_ARGS_ASSERT_INVLIST_LEN;
 
-    if (len_ptr == NULL) {
-       Perl_croak(aTHX_ "panic: inversion list without a '%s' element",
-                                                           INVLIST_LEN_KEY);
-    }
-
-    return SvUV(*len_ptr);
+    return SvCUR(invlist) / sizeof(UV);
 }
 
 PERL_STATIC_INLINE UV
-S_invlist_max(pTHX_ HV* const invlist)
+S_invlist_max(pTHX_ SV* const invlist)
 {
     /* Returns the maximum number of elements storable in the inversion list's
      * array, without having to realloc() */
 
-    SV** max_ptr = hv_fetchs(invlist, INVLIST_MAX_KEY, FALSE);
-
     PERL_ARGS_ASSERT_INVLIST_MAX;
 
-    if (max_ptr == NULL) {
-       Perl_croak(aTHX_ "panic: inversion list without a '%s' element",
-                                                           INVLIST_MAX_KEY);
-    }
-
-    return SvUV(*max_ptr);
+    return SvLEN(invlist) / sizeof(UV);
 }
 
 PERL_STATIC_INLINE void
-S_invlist_set_len(pTHX_ HV* const invlist, const UV len)
+S_invlist_set_len(pTHX_ SV* const invlist, const UV len)
 {
     /* Sets the current number of elements stored in the inversion list */
 
     PERL_ARGS_ASSERT_INVLIST_SET_LEN;
 
-    if (len != 0 && len > invlist_max(invlist)) {
-       Perl_croak(aTHX_ "panic: Can't make '%s=%"UVuf"' more than %s=%"UVuf" in inversion list", INVLIST_LEN_KEY, len, INVLIST_MAX_KEY, invlist_max(invlist));
-    }
-
-    if (hv_stores(invlist, INVLIST_LEN_KEY, newSVuv(len)) == NULL) {
-       Perl_croak(aTHX_ "panic: can't store '%s' entry in inversion list",
-                                                           INVLIST_LEN_KEY);
-    }
+    SvCUR_set(invlist, len * sizeof(UV));
 }
 
 PERL_STATIC_INLINE void
-S_invlist_set_max(pTHX_ HV* const invlist, const UV max)
+S_invlist_set_max(pTHX_ SV* const invlist, const UV max)
 {
 
     /* Sets the maximum number of elements storable in the inversion list
@@ -5801,17 +5889,14 @@ S_invlist_set_max(pTHX_ HV* const invlist, const UV max)
     PERL_ARGS_ASSERT_INVLIST_SET_MAX;
 
     if (max < invlist_len(invlist)) {
-       Perl_croak(aTHX_ "panic: Can't make '%s=%"UVuf"' less than %s=%"UVuf" in inversion list", INVLIST_MAX_KEY, invlist_len(invlist), INVLIST_LEN_KEY, invlist_max(invlist));
+       Perl_croak(aTHX_ "panic: Can't make max size '%"UVuf"' less than current length %"UVuf" in inversion list", invlist_max(invlist), invlist_len(invlist));
     }
 
-    if (hv_stores(invlist, INVLIST_MAX_KEY, newSVuv(max)) == NULL) {
-       Perl_croak(aTHX_ "panic: can't store '%s' entry in inversion list",
-                                                           INVLIST_LEN_KEY);
-    }
+    SvLEN_set(invlist, max * sizeof(UV));
 }
 
 #ifndef PERL_IN_XSUB_RE
-HV*
+SV*
 Perl__new_invlist(pTHX_ IV initial_size)
 {
 
@@ -5819,86 +5904,55 @@ Perl__new_invlist(pTHX_ IV initial_size)
      * space to store 'initial_size' elements.  If that number is negative, a
      * system default is used instead */
 
-    HV* invlist = newHV();
-    UV* list;
-
     if (initial_size < 0) {
        initial_size = INVLIST_INITIAL_LEN;
     }
 
     /* Allocate the initial space */
-    Newx(list, initial_size, UV);
-    invlist_set_array(invlist, list);
-
-    /* set_len has to come before set_max, as the latter inspects the len */
-    invlist_set_len(invlist, 0);
-    invlist_set_max(invlist, initial_size);
-
-    return invlist;
+    return newSV(initial_size * sizeof(UV));
 }
 #endif
 
 PERL_STATIC_INLINE void
-S_invlist_destroy(pTHX_ HV* const invlist)
+S_invlist_destroy(pTHX_ SV* const invlist)
 {
    /* Inversion list destructor */
 
-    SV** list_ptr = hv_fetchs(invlist, INVLIST_ARRAY_KEY, FALSE);
-
     PERL_ARGS_ASSERT_INVLIST_DESTROY;
 
-    if (list_ptr != NULL) {
-       UV *list = INT2PTR(UV *, SvUV(*list_ptr)); /* PERL_POISON needs lvalue */
-       Safefree(list);
-    }
+    SvREFCNT_dec(invlist);
 }
 
 STATIC void
-S_invlist_extend(pTHX_ HV* const invlist, const UV new_max)
+S_invlist_extend(pTHX_ SV* const invlist, const UV new_max)
 {
-    /* Change the maximum size of an inversion list (up or down) */
-
-    UV* orig_array;
-    UV* array;
-    const UV old_max = invlist_max(invlist);
+    /* Grow the maximum size of an inversion list */
 
     PERL_ARGS_ASSERT_INVLIST_EXTEND;
 
-    if (old_max == new_max) {  /* If a no-op */
-       return;
-    }
-
-    array = orig_array = invlist_array(invlist);
-    Renew(array, new_max, UV);
-
-    /* If the size change moved the list in memory, set the new one */
-    if (array != orig_array) {
-       invlist_set_array(invlist, array);
-    }
-
-    invlist_set_max(invlist, new_max);
-
+    SvGROW((SV *)invlist, new_max * sizeof(UV));
 }
 
 PERL_STATIC_INLINE void
-S_invlist_trim(pTHX_ HV* const invlist)
+S_invlist_trim(pTHX_ SV* const invlist)
 {
     PERL_ARGS_ASSERT_INVLIST_TRIM;
 
     /* Change the length of the inversion list to how many entries it currently
      * has */
 
-    invlist_extend(invlist, invlist_len(invlist));
+    SvPV_shrink_to_cur((SV *) invlist);
 }
 
 /* An element is in an inversion list iff its index is even numbered: 0, 2, 4,
  * etc */
 
 #define ELEMENT_IN_INVLIST_SET(i) (! ((i) & 1))
+#define PREV_ELEMENT_IN_INVLIST_SET(i) ! ELEMENT_IN_INVLIST_SET(i)
 
 #ifndef PERL_IN_XSUB_RE
 void
-Perl__append_range_to_invlist(pTHX_ HV* const invlist, const UV start, const UV end)
+Perl__append_range_to_invlist(pTHX_ SV* const invlist, const UV start, const UV end)
 {
    /* Subject to change or removal.  Append the range from 'start' to 'end' at
     * the end of the inversion list.  The range must be above any existing
@@ -5969,10 +6023,12 @@ Perl__append_range_to_invlist(pTHX_ HV* const invlist, const UV start, const UV
 }
 #endif
 
-PERL_STATIC_INLINE HV*
-S_invlist_union(pTHX_ HV* const a, HV* const b)
+STATIC void
+S_invlist_union(pTHX_ SV* const a, SV* const b, SV** output)
 {
-    /* Return a new inversion list which is the union of two inversion lists.
+    /* Take the union of two inversion lists and point 'result' to it.  If
+     * 'result' on input points to one of the two lists, the reference count to
+     * that list will be decremented.
      * The basis for this comes from "Unicode Demystified" Chapter 13 by
      * Richard Gillam, published by Addison-Wesley, and explained at some
      * length there.  The preface says to incorporate its examples into your
@@ -5983,14 +6039,15 @@ S_invlist_union(pTHX_ HV* const a, HV* const b)
      * XXX A potential performance improvement is to keep track as we go along
      * if only one of the inputs contributes to the result, meaning the other
      * is a subset of that one.  In that case, we can skip the final copy and
-     * return the larger of the input lists */
+     * return the larger of the input lists, but then outside code might need
+     * to keep track of whether to free the input list or not */
 
     UV* array_a = invlist_array(a);   /* a's array */
     UV* array_b = invlist_array(b);
     UV len_a = invlist_len(a); /* length of a's array */
     UV len_b = invlist_len(b);
 
-    HV* u;                     /* the resulting union */
+    SV* u;                     /* the resulting union */
     UV* array_u;
     UV len_u;
 
@@ -6061,9 +6118,9 @@ S_invlist_union(pTHX_ HV* const a, HV* const b)
     /* Here, we are finished going through at least one of the lists, which
      * means there is something remaining in at most one.  We check if the list
      * that hasn't been exhausted is positioned such that we are in the middle
-     * of a range in its set or not.  (We are in the set if the next item in
-     * the array marks the beginning of something not in the set)   If in the
-     * set, we decrement 'count'; if 0, there is potentially more to output.
+     * of a range in its set or not.  (i_a and i_b point to the element beyond
+     * the one we care about.) If in the set, we decrement 'count'; if 0, there
+     * is potentially more to output.
      * There are four cases:
      * 1) Both weren't in their sets, count is 0, and remains 0.  What's left
      *    in the union is entirely from the non-exhausted set.
@@ -6073,12 +6130,12 @@ S_invlist_union(pTHX_ HV* const a, HV* const b)
      *    that
      * 3) the exhausted was in its set, non-exhausted isn't, count is 1.
      *    Nothing further should be output because the union includes
-     *    everything from the exhausted set.  Not decrementing insures that.
+     *    everything from the exhausted set.  Not decrementing ensures that.
      * 4) the exhausted wasn't in its set, non-exhausted is, count is 1;
      *    decrementing to 0 insures that we look at the remainder of the
      *    non-exhausted set */
-    if ((i_a != len_a && ELEMENT_IN_INVLIST_SET(i_a))
-       || (i_b != len_b && ELEMENT_IN_INVLIST_SET(i_b)))
+    if ((i_a != len_a && PREV_ELEMENT_IN_INVLIST_SET(i_a))
+       || (i_b != len_b && PREV_ELEMENT_IN_INVLIST_SET(i_b)))
     {
        count--;
     }
@@ -6117,16 +6174,25 @@ S_invlist_union(pTHX_ HV* const a, HV* const b)
        }
     }
 
-    return u;
+    /*  We may be removing a reference to one of the inputs */
+    if (&a == output || &b == output) {
+       SvREFCNT_dec(*output);
+    }
+
+    *output = u;
+    return;
 }
 
-PERL_STATIC_INLINE HV*
-S_invlist_intersection(pTHX_ HV* const a, HV* const b)
+STATIC void
+S_invlist_intersection(pTHX_ SV* const a, SV* const b, SV** i)
 {
-    /* Return the intersection of two inversion lists.  The basis for this
-     * comes from "Unicode Demystified" Chapter 13 by Richard Gillam, published
-     * by Addison-Wesley, and explained at some length there.  The preface says
-     * to incorporate its examples into your code at your own risk.
+    /* Take the intersection of two inversion lists and point 'i' to it.  If
+     * 'i' on input points to one of the two lists, the reference count to that
+     * list will be decremented.
+     * The basis for this comes from "Unicode Demystified" Chapter 13 by
+     * Richard Gillam, published by Addison-Wesley, and explained at some
+     * length there.  The preface says to incorporate its examples into your
+     * code at your own risk.  In fact, it had bugs
      *
      * The algorithm is like a merge sort, and is essentially the same as the
      * union above
@@ -6137,7 +6203,7 @@ S_invlist_intersection(pTHX_ HV* const a, HV* const b)
     UV len_a = invlist_len(a); /* length of a's array */
     UV len_b = invlist_len(b);
 
-    HV* r;                  /* the resulting intersection */
+    SV* r;                  /* the resulting intersection */
     UV* array_r;
     UV len_r;
 
@@ -6167,17 +6233,17 @@ S_invlist_intersection(pTHX_ HV* const a, HV* const b)
                       array */
        bool cp_in_set; /* Is it in the input list's set or not */
 
-       /* We need to take one or the other of the two inputs for the union.
-        * Since we are merging two sorted lists, we take the smaller of the
-        * next items.  In case of a tie, we take the one that is not in its
-        * set first (a difference from the union algorithm).  If we took one
-        * in the set first, it would increment the count, possibly to 2 which
-        * would cause it to be output as starting a range in the intersection,
-        * and the next time through we would take that same number, and output
-        * it again as ending the set.  By doing it the opposite of this, we
-        * there is no possibility that the count will be momentarily
-        * incremented to 2.  (In a tie and both are in the set or both not in
-        * the set, it doesn't matter which we take first.) */
+       /* We need to take one or the other of the two inputs for the
+        * intersection.  Since we are merging two sorted lists, we take the
+        * smaller of the next items.  In case of a tie, we take the one that
+        * is not in its set first (a difference from the union algorithm).  If
+        * we took one in the set first, it would increment the count, possibly
+        * to 2 which would cause it to be output as starting a range in the
+        * intersection, and the next time through we would take that same
+        * number, and output it again as ending the set.  By doing it the
+        * opposite of this, there is no possibility that the count will be
+        * momentarily incremented to 2.  (In a tie and both are in the set or
+        * both not in the set, it doesn't matter which we take first.) */
        if (array_a[i_a] < array_b[i_b]
            || (array_a[i_a] == array_b[i_b] && ! ELEMENT_IN_INVLIST_SET(i_a)))
        {
@@ -6206,19 +6272,32 @@ S_invlist_intersection(pTHX_ HV* const a, HV* const b)
        }
     }
 
-    /* Here, we are finished going through at least one of the sets, which
-     * means there is something remaining in at most one.  See the comments in
-     * the union code */
-    if ((i_a != len_a && ! ELEMENT_IN_INVLIST_SET(i_a))
-       || (i_b != len_b && ! ELEMENT_IN_INVLIST_SET(i_b)))
+    /* Here, we are finished going through at least one of the lists, which
+     * means there is something remaining in at most one.  We check if the list
+     * that has been exhausted is positioned such that we are in the middle
+     * of a range in its set or not.  (i_a and i_b point to elements 1 beyond
+     * the ones we care about.)  There are four cases:
+     * 1) Both weren't in their sets, count is 0, and remains 0.  There's
+     *    nothing left in the intersection.
+     * 2) Both were in their sets, count is 2 and perhaps is incremented to
+     *    above 2.  What should be output is exactly that which is in the
+     *    non-exhausted set, as everything it has is also in the intersection
+     *    set, and everything it doesn't have can't be in the intersection
+     * 3) The exhausted was in its set, non-exhausted isn't, count is 1, and
+     *    gets incremented to 2.  Like the previous case, the intersection is
+     *    everything that remains in the non-exhausted set.
+     * 4) the exhausted wasn't in its set, non-exhausted is, count is 1, and
+     *    remains 1.  And the intersection has nothing more. */
+    if ((i_a == len_a && PREV_ELEMENT_IN_INVLIST_SET(i_a))
+       || (i_b == len_b && PREV_ELEMENT_IN_INVLIST_SET(i_b)))
     {
-       count--;
+       count++;
     }
 
     /* The final length is what we've output so far plus what else is in the
-     * intersection.  Only one of the subexpressions below will be non-zero */
+     * intersection.  At most one of the subexpressions below will be non-zero */
     len_r = i_r;
-    if (count == 2) {
+    if (count >= 2) {
        len_r += (len_a - i_a) + (len_b - i_b);
     }
 
@@ -6231,7 +6310,7 @@ S_invlist_intersection(pTHX_ HV* const a, HV* const b)
     }
 
     /* Finish outputting any remaining */
-    if (count == 2) { /* Only one of will have a non-zero copy count */
+    if (count >= 2) { /* At most one will have a non-zero copy count */
        IV copy_count;
        if ((copy_count = len_a - i_a) > 0) {
            Copy(array_a + i_a, array_r + i_r, copy_count, UV);
@@ -6241,22 +6320,34 @@ S_invlist_intersection(pTHX_ HV* const a, HV* const b)
        }
     }
 
-    return r;
+    /*  We may be removing a reference to one of the inputs */
+    if (&a == i || &b == i) {
+       SvREFCNT_dec(*i);
+    }
+
+    *i = r;
+    return;
 }
 
-STATIC HV*
-S_add_range_to_invlist(pTHX_ HV* const invlist, const UV start, const UV end)
+STATIC SV*
+S_add_range_to_invlist(pTHX_ SV* invlist, const UV start, const UV end)
 {
     /* Add the range from 'start' to 'end' inclusive to the inversion list's
      * set.  A pointer to the inversion list is returned.  This may actually be
-     * a new list, in which case the passed in one has been destroyed */
+     * a new list, in which case the passed in one has been destroyed.  The
+     * passed in inversion list can be NULL, in which case a new one is created
+     * with just the one range in it */
 
-    HV* range_invlist;
-    HV* added_invlist;
+    SV* range_invlist;
+    UV len;
 
-    UV len = invlist_len(invlist);
-
-    PERL_ARGS_ASSERT_ADD_RANGE_TO_INVLIST;
+    if (invlist == NULL) {
+       invlist = _new_invlist(2);
+       len = 0;
+    }
+    else {
+       len = invlist_len(invlist);
+    }
 
     /* If comes after the final entry, can just append it to the end */
     if (len == 0
@@ -6272,17 +6363,21 @@ S_add_range_to_invlist(pTHX_ HV* const invlist, const UV start, const UV end)
     range_invlist = _new_invlist(2);
     _append_range_to_invlist(range_invlist, start, end);
 
-    added_invlist = invlist_union(invlist, range_invlist);
+    invlist_union(invlist, range_invlist, &invlist);
 
     /* The passed in list can be freed, as well as our temporary */
-    invlist_destroy(range_invlist);
-    if (invlist != added_invlist) {
-       invlist_destroy(invlist);
-    }
+    SvREFCNT_dec(range_invlist);
 
-    return added_invlist;
+    return invlist;
 }
 
+PERL_STATIC_INLINE SV*
+S_add_cp_to_invlist(pTHX_ SV* invlist, const UV cp) {
+    return add_range_to_invlist(invlist, cp, cp);
+}
+
+#undef INVLIST_INITIAL_LENGTH
+
 /* End of inversion list object */
 
 /*
@@ -6572,6 +6667,7 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp,U32 depth)
                             SvIV_set(sv_dat, 1);
                         }
 #ifdef DEBUGGING
+                       /* Yes this does cause a memory leak in debugging Perls */
                         if (!av_store(RExC_paren_name_list, RExC_npar, SvREFCNT_inc(svname)))
                             SvREFCNT_dec(svname);
 #endif
@@ -6926,8 +7022,10 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp,U32 depth)
            {
                 U32 posflags = 0, negflags = 0;
                U32 *flagsp = &posflags;
-                bool has_charset_modifier = 0;
-               regex_charset cs = REGEX_DEPENDS_CHARSET;
+                char has_charset_modifier = '\0';
+               regex_charset cs = (RExC_utf8 || RExC_uni_semantics)
+                                   ? REGEX_UNICODE_CHARSET
+                                   : REGEX_DEPENDS_CHARSET;
 
                while (*RExC_parse) {
                    /* && strchr("iogcmsx", *RExC_parse) */
@@ -6936,39 +7034,51 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp,U32 depth)
                     switch (*RExC_parse) {
                    CASE_STD_PMMOD_FLAGS_PARSE_SET(flagsp);
                     case LOCALE_PAT_MOD:
-                        if (has_charset_modifier || flagsp == &negflags) {
-                            goto fail_modifiers;
+                        if (has_charset_modifier) {
+                           goto excess_modifier;
+                       }
+                       else if (flagsp == &negflags) {
+                            goto neg_modifier;
                         }
                        cs = REGEX_LOCALE_CHARSET;
-                        has_charset_modifier = 1;
+                        has_charset_modifier = LOCALE_PAT_MOD;
+                       RExC_contains_locale = 1;
                         break;
                     case UNICODE_PAT_MOD:
-                        if (has_charset_modifier || flagsp == &negflags) {
-                            goto fail_modifiers;
+                        if (has_charset_modifier) {
+                           goto excess_modifier;
+                       }
+                       else if (flagsp == &negflags) {
+                            goto neg_modifier;
                         }
                        cs = REGEX_UNICODE_CHARSET;
-                        has_charset_modifier = 1;
+                        has_charset_modifier = UNICODE_PAT_MOD;
                         break;
                     case ASCII_RESTRICT_PAT_MOD:
-                        if (has_charset_modifier || flagsp == &negflags) {
-                            goto fail_modifiers;
+                        if (flagsp == &negflags) {
+                            goto neg_modifier;
                         }
-                       if (*(RExC_parse + 1) == ASCII_RESTRICT_PAT_MOD) {
+                        if (has_charset_modifier) {
+                            if (cs != REGEX_ASCII_RESTRICTED_CHARSET) {
+                                goto excess_modifier;
+                            }
                            /* Doubled modifier implies more restricted */
-                           cs = REGEX_ASCII_MORE_RESTRICTED_CHARSET;
-                           RExC_parse++;
-                       }
+                            cs = REGEX_ASCII_MORE_RESTRICTED_CHARSET;
+                        }
                        else {
                            cs = REGEX_ASCII_RESTRICTED_CHARSET;
                        }
-                        has_charset_modifier = 1;
+                        has_charset_modifier = ASCII_RESTRICT_PAT_MOD;
                         break;
                     case DEPENDS_PAT_MOD:
-                        if (has_use_defaults
-                            || has_charset_modifier
-                            || flagsp == &negflags)
-                        {
+                        if (has_use_defaults) {
                             goto fail_modifiers;
+                       }
+                       else if (flagsp == &negflags) {
+                            goto neg_modifier;
+                       }
+                       else if (has_charset_modifier) {
+                           goto excess_modifier;
                         }
 
                        /* The dual charset means unicode semantics if the
@@ -6978,8 +7088,24 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp,U32 depth)
                        cs = (RExC_utf8 || RExC_uni_semantics)
                             ? REGEX_UNICODE_CHARSET
                             : REGEX_DEPENDS_CHARSET;
-                        has_charset_modifier = 1;
+                        has_charset_modifier = DEPENDS_PAT_MOD;
                         break;
+                   excess_modifier:
+                       RExC_parse++;
+                       if (has_charset_modifier == ASCII_RESTRICT_PAT_MOD) {
+                           vFAIL2("Regexp modifier \"%c\" may appear a maximum of twice", ASCII_RESTRICT_PAT_MOD);
+                       }
+                       else if (has_charset_modifier == *(RExC_parse - 1)) {
+                           vFAIL2("Regexp modifier \"%c\" may not appear twice", *(RExC_parse - 1));
+                       }
+                       else {
+                           vFAIL3("Regexp modifiers \"%c\" and \"%c\" are mutually exclusive", has_charset_modifier, *(RExC_parse - 1));
+                       }
+                       /*NOTREACHED*/
+                   neg_modifier:
+                       RExC_parse++;
+                       vFAIL2("Regexp modifier \"%c\" may not appear after the \"-\"", *(RExC_parse - 1));
+                       /*NOTREACHED*/
                     case ONCE_PAT_MOD: /* 'o' */
                     case GLOBAL_PAT_MOD: /* 'g' */
                        if (SIZE_ONLY && ckWARN(WARN_REGEXP)) {
@@ -7093,12 +7219,6 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp,U32 depth)
     parse_start = RExC_parse;   /* MJD */
     br = regbranch(pRExC_state, &flags, 1,depth+1);
 
-    if (freeze_paren) {
-        if (RExC_npar > after_freeze)
-            after_freeze = RExC_npar;
-        RExC_npar = freeze_paren;
-    }
-
     /*     branch_len = (paren != 0); */
 
     if (br == NULL)
@@ -7242,7 +7362,7 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp,U32 depth)
     if (RExC_in_lookbehind) {
        RExC_in_lookbehind--;
     }
-    if (after_freeze)
+    if (after_freeze > RExC_npar)
         RExC_npar = after_freeze;
     return(ret);
 }
@@ -7336,7 +7456,9 @@ S_regpiece(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth)
     const char * const origparse = RExC_parse;
     I32 min;
     I32 max = REG_INFTY;
+#ifdef RE_TRACK_PATTERN_OFFSETS
     char *parse_start;
+#endif
     const char *maxpos = NULL;
     GET_RE_DEBUG_FLAGS_DECL;
 
@@ -7355,7 +7477,9 @@ S_regpiece(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth)
 
     if (op == '{' && regcurly(RExC_parse)) {
        maxpos = NULL;
+#ifdef RE_TRACK_PATTERN_OFFSETS
         parse_start = RExC_parse; /* MJD */
+#endif
        next = RExC_parse + 1;
        while (isDIGIT(*next) || *next == ',') {
            if (*next == ',') {
@@ -7451,7 +7575,9 @@ S_regpiece(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth)
       vFAIL("Regexp *+ operand could be empty");
 #endif
 
+#ifdef RE_TRACK_PATTERN_OFFSETS
     parse_start = RExC_parse;
+#endif
     nextchar(pRExC_state);
 
     *flagp = (op != '+') ? (WORST|SPSTART|HASWIDTH) : (WORST|HASWIDTH);
@@ -7515,7 +7641,7 @@ S_regpiece(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth)
 }
 
 
-/* reg_namedseq(pRExC_state,UVp)
+/* reg_namedseq(pRExC_state,UVp, UV depth)
    
    This is expected to be called by a parser routine that has 
    recognized '\N' and needs to handle the rest. RExC_parse is
@@ -7558,13 +7684,10 @@ S_regpiece(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth)
    Parsing failures will generate a fatal error via vFAIL(...)
  */
 STATIC regnode *
-S_reg_namedseq(pTHX_ RExC_state_t *pRExC_state, UV *valuep, I32 *flagp)
+S_reg_namedseq(pTHX_ RExC_state_t *pRExC_state, UV *valuep, I32 *flagp, U32 depth)
 {
     char * endbrace;    /* '}' following the name */
     regnode *ret = NULL;
-#ifdef DEBUGGING
-    char* parse_start = RExC_parse - 2;            /* points to the '\N' */
-#endif
     char* p;
 
     GET_RE_DEBUG_FLAGS_DECL;
@@ -7677,150 +7800,55 @@ S_reg_namedseq(pTHX_ RExC_state_t *pRExC_state, UV *valuep, I32 *flagp)
         ret = (regnode *) &RExC_parse; /* Invalid regnode pointer */
     }
     else {     /* Not a char class */
-       char *s;            /* String to put in generated EXACT node */
-       STRLEN len = 0;     /* Its current byte length */
+
+       /* What is done here is to convert this to a sub-pattern of the form
+        * (?:\x{char1}\x{char2}...)
+        * and then call reg recursively.  That way, it retains its atomicness,
+        * while not having to worry about special handling that some code
+        * points may have.  toke.c has converted the original Unicode values
+        * to native, so that we can just pass on the hex values unchanged.  We
+        * do have to set a flag to keep recoding from happening in the
+        * recursion */
+
+       SV * substitute_parse = newSVpvn_flags("?:", 2, SVf_UTF8|SVs_TEMP);
+       STRLEN len;
        char *endchar;      /* Points to '.' or '}' ending cur char in the input
                               stream */
-       ret = reg_node(pRExC_state,
-                          (U8) ((! FOLD) ? EXACT
-                                         : (LOC)
-                                            ? EXACTFL
-                                            : (MORE_ASCII_RESTRICTED)
-                                              ? EXACTFA
-                                              : (AT_LEAST_UNI_SEMANTICS)
-                                                ? EXACTFU
-                                                : EXACTF));
-       s= STRING(ret);
-
-       /* Exact nodes can hold only a U8 length's of text = 255.  Loop through
-        * the input which is of the form now 'c1.c2.c3...}' until find the
-        * ending brace or exceed length 255.  The characters that exceed this
-        * limit are dropped.  The limit could be relaxed should it become
-        * desirable by reparsing this as (?:\N{NAME}), so could generate
-        * multiple EXACT nodes, as is done for just regular input.  But this
-        * is primarily a named character, and not intended to be a huge long
-        * string, so 255 bytes should be good enough */
-       while (1) {
-           STRLEN length_of_hex;
-           I32 grok_flags = PERL_SCAN_ALLOW_UNDERSCORES
-                           | PERL_SCAN_DISALLOW_PREFIX
-                           | (SIZE_ONLY ? PERL_SCAN_SILENT_ILLDIGIT : 0);
-           UV cp;  /* Ord of current character */
-           bool use_this_char_fold = FOLD;
+       char *orig_end = RExC_end;
+
+       while (RExC_parse < endbrace) {
 
            /* Code points are separated by dots.  If none, there is only one
             * code point, and is terminated by the brace */
            endchar = RExC_parse + strcspn(RExC_parse, ".}");
 
-           /* The values are Unicode even on EBCDIC machines */
-           length_of_hex = (STRLEN)(endchar - RExC_parse);
-           cp = grok_hex(RExC_parse, &length_of_hex, &grok_flags, NULL);
-           if ( length_of_hex == 0 
-               || length_of_hex != (STRLEN)(endchar - RExC_parse) )
-           {
-               RExC_parse += length_of_hex;        /* Includes all the valid */
-               RExC_parse += (RExC_orig_utf8)  /* point to after 1st invalid */
-                               ? UTF8SKIP(RExC_parse)
-                               : 1;
-               /* Guard against malformed utf8 */
-               if (RExC_parse >= endchar) RExC_parse = endchar;
-               vFAIL("Invalid hexadecimal number in \\N{U+...}");
-           }    
-
-           if (FOLD
-               && (cp > 255 || ! MORE_ASCII_RESTRICTED)
-               && is_TRICKYFOLD_cp(cp))
-           {
-           }
-
-           /* Under /aa, we can't mix ASCII with non- in a fold.  If we are
-            * folding, and the source isn't ASCII, look through all the
-            * characters it folds to.  If any one of them is ASCII, forbid
-            * this fold.  (cp is uni, so the 127 below is correct even for
-            * EBCDIC) */
-           if (use_this_char_fold && cp > 127 && MORE_ASCII_RESTRICTED) {
-               U8 tmpbuf[UTF8_MAXBYTES_CASE+1];
-               U8* s = tmpbuf;
-               U8* e;
-               STRLEN foldlen;
-
-               (void) toFOLD_uni(cp, tmpbuf, &foldlen);
-               e = s + foldlen;
-
-               while (s < e) {
-                   if (isASCII(*s)) {
-                       use_this_char_fold = FALSE;
-                       break;
-                   }
-                   s += UTF8SKIP(s);
-               }
-           }
-
-           if (! use_this_char_fold) { /* Not folding, just append to the
-                                          string */
-               STRLEN unilen;
-
-               /* Quit before adding this character if would exceed limit */
-               if (len + UNISKIP(cp) > U8_MAX) break;
-
-               unilen = reguni(pRExC_state, cp, s);
-               if (unilen > 0) {
-                   s   += unilen;
-                   len += unilen;
-               }
-           } else {    /* Folding, output the folded equivalent */
-               STRLEN foldlen,numlen;
-               U8 tmpbuf[UTF8_MAXBYTES_CASE+1], *foldbuf;
-               cp = toFOLD_uni(cp, tmpbuf, &foldlen);
-
-               /* Quit before exceeding size limit */
-               if (len + foldlen > U8_MAX) break;
-               
-               for (foldbuf = tmpbuf;
-                   foldlen;
-                   foldlen -= numlen) 
-               {
-                   cp = utf8_to_uvchr(foldbuf, &numlen);
-                   if (numlen > 0) {
-                       const STRLEN unilen = reguni(pRExC_state, cp, s);
-                       s       += unilen;
-                       len     += unilen;
-                       /* In EBCDIC the numlen and unilen can differ. */
-                       foldbuf += numlen;
-                       if (numlen >= foldlen)
-                           break;
-                   }
-                   else
-                       break; /* "Can't happen." */
-               }                          
-           }
+           /* Convert to notation the rest of the code understands */
+           sv_catpv(substitute_parse, "\\x{");
+           sv_catpvn(substitute_parse, RExC_parse, endchar - RExC_parse);
+           sv_catpv(substitute_parse, "}");
 
            /* Point to the beginning of the next character in the sequence. */
            RExC_parse = endchar + 1;
-
-           /* Quit if no more characters */
-           if (RExC_parse >= endbrace) break;
        }
+       sv_catpv(substitute_parse, ")");
 
+       RExC_parse = SvPV(substitute_parse, len);
 
-       if (SIZE_ONLY) {
-           if (RExC_parse < endbrace) {
-               ckWARNreg(RExC_parse - 1,
-                         "Using just the first characters returned by \\N{}");
-           }
-
-           RExC_size += STR_SZ(len);
-       } else {
-           STR_LEN(ret) = len;
-           RExC_emit += STR_SZ(len);
+       /* Don't allow empty number */
+       if (len < 8) {
+           vFAIL("Invalid hexadecimal number in \\N{U+...}");
        }
+       RExC_end = RExC_parse + len;
 
-       RExC_parse = endbrace + 1;
+       /* The values are Unicode, and therefore not subject to recoding */
+       RExC_override_recoding = 1;
+
+       ret = reg(pRExC_state, 1, flagp, depth+1);
+
+       RExC_parse = endbrace;
+       RExC_end = orig_end;
+       RExC_override_recoding = 0;
 
-       *flagp |= HASWIDTH; /* Not SIMPLE, as that causes the engine to fail
-                              with malformed in t/re/pat_advanced.t */
-       RExC_parse --;
-       Set_Node_Cur_Length(ret); /* MJD */
        nextchar(pRExC_state);
     }
 
@@ -7983,27 +8011,6 @@ tryagain:
        RExC_parse++;
        vFAIL("Quantifier follows nothing");
        break;
-    case LATIN_SMALL_LETTER_SHARP_S:
-    case UTF8_TWO_BYTE_HI_nocast(LATIN_SMALL_LETTER_SHARP_S):
-    case UTF8_TWO_BYTE_HI_nocast(IOTA_D_T):
-#if UTF8_TWO_BYTE_HI_nocast(UPSILON_D_T) != UTF8_TWO_BYTE_HI_nocast(IOTA_D_T)
-#error The beginning utf8 byte of IOTA_D_T and UPSILON_D_T unexpectedly differ.  Other instances in this code should have the case statement below.
-    case UTF8_TWO_BYTE_HI_nocast(UPSILON_D_T):
-#endif
-        do_foldchar:
-        if (!LOC && FOLD) {
-            U32 len,cp;
-           len=0; /* silence a spurious compiler warning */
-            if ((cp = what_len_TRICKYFOLD_safe(RExC_parse,RExC_end,UTF,len))) {
-                *flagp |= HASWIDTH; /* could be SIMPLE too, but needs a handler in regexec.regrepeat */
-                RExC_parse+=len-1; /* we get one from nextchar() as well. :-( */
-                ret = reganode(pRExC_state, FOLDCHAR, cp);
-                Set_Node_Length(ret, 1); /* MJD */
-                nextchar(pRExC_state); /* kill whitespace under /x */
-                return ret;
-            }
-        }
-        goto outer_default;
     case '\\':
        /* Special Escapes
 
@@ -8018,10 +8025,6 @@ tryagain:
           literal text handling code.
        */
        switch ((U8)*++RExC_parse) {
-       case LATIN_SMALL_LETTER_SHARP_S:
-       case UTF8_TWO_BYTE_HI_nocast(LATIN_SMALL_LETTER_SHARP_S):
-       case UTF8_TWO_BYTE_HI_nocast(IOTA_D_T):
-                  goto do_foldchar;        
        /* Special Escapes */
        case 'A':
            RExC_seen_zerolen++;
@@ -8304,7 +8307,7 @@ tryagain:
             Also this makes sure that things like /\N{BLAH}+/ and 
             \N{BLAH} being multi char Just Happen. dmq*/
             ++RExC_parse;
-            ret= reg_namedseq(pRExC_state, NULL, flagp); 
+            ret= reg_namedseq(pRExC_state, NULL, flagp, depth);
             break;
        case 'k':    /* Handle \k<NAME> and \k'NAME' */
        parse_named_seq:
@@ -8442,7 +8445,21 @@ tryagain:
        /* FALL THROUGH */
 
     default:
-        outer_default:{
+
+            parse_start = RExC_parse - 1;
+
+           RExC_parse++;
+
+       defchar: {
+           typedef enum {
+               generic_char = 0,
+               char_s,
+               upsilon_1,
+               upsilon_2,
+               iota_1,
+               iota_2,
+           } char_state;
+           char_state latest_char_state = generic_char;
            register STRLEN len;
            register UV ender;
            register char *p;
@@ -8451,11 +8468,6 @@ tryagain:
            U8 tmpbuf[UTF8_MAXBYTES_CASE+1], *foldbuf;
            regnode * orig_emit;
 
-            parse_start = RExC_parse - 1;
-
-           RExC_parse++;
-
-       defchar:
            ender = 0;
            orig_emit = RExC_emit; /* Save the original output node position in
                                      case we need to output a different node
@@ -8480,11 +8492,6 @@ tryagain:
                if (RExC_flags & RXf_PMf_EXTENDED)
                    p = regwhite( pRExC_state, p );
                switch ((U8)*p) {
-               case LATIN_SMALL_LETTER_SHARP_S:
-               case UTF8_TWO_BYTE_HI_nocast(LATIN_SMALL_LETTER_SHARP_S):
-               case UTF8_TWO_BYTE_HI_nocast(IOTA_D_T):
-                          if (LOC || !FOLD || !is_TRICKYFOLD_safe(p,RExC_end,UTF))
-                               goto normal_default;
                case '^':
                case '$':
                case '.':
@@ -8509,11 +8516,6 @@ tryagain:
 
                    switch ((U8)*++p) {
                    /* These are all the special escapes. */
-                    case LATIN_SMALL_LETTER_SHARP_S:
-                    case UTF8_TWO_BYTE_HI_nocast(LATIN_SMALL_LETTER_SHARP_S):
-                    case UTF8_TWO_BYTE_HI_nocast(IOTA_D_T):
-                          if (LOC || !FOLD || !is_TRICKYFOLD_safe(p,RExC_end,UTF))
-                               goto normal_default;                
                    case 'A':             /* Start assertion */
                    case 'b': case 'B':   /* Word-boundary assertion*/
                    case 'C':             /* Single char !DANGEROUS! */
@@ -8640,7 +8642,7 @@ tryagain:
                            goto recode_encoding;
                        break;
                    recode_encoding:
-                       {
+                       if (! RExC_override_recoding) {
                            SV* enc = PL_encoding;
                            ender = reg_recode((const char)(U8)ender, &enc);
                            if (!enc && SIZE_ONLY)
@@ -8684,75 +8686,244 @@ tryagain:
                 * putting it in a special node keeps regexec from having to
                 * deal with a non-utf8 multi-char fold */
                if (FOLD
-                   && (ender > 255 || ! MORE_ASCII_RESTRICTED)
-                   && is_TRICKYFOLD_cp(ender))
+                   && (ender > 255 || (! MORE_ASCII_RESTRICTED && ! LOC)))
                {
-                   /* If is in middle of outputting characters into an
-                    * EXACTish node, go output what we have so far, and
-                    * position the parse so that this will be called again
-                    * immediately */
-                   if (len) {
-                       p  = RExC_parse + len - 1;
-                       goto loopdone;
-                   }
-                   else {
+                   /* We look for either side of the fold.  For example \xDF
+                    * folds to 'ss'.  We look for both the single character
+                    * \xDF and the sequence 'ss'.  When we find something that
+                    * could be one of those, we stop and flush whatever we
+                    * have output so far into the EXACTish node that was being
+                    * built.  Then restore the input pointer to what it was.
+                    * regatom will return that EXACT node, and will be called
+                    * again, positioned so the first character is the one in
+                    * question, which we return in a different node type.
+                    * The multi-char folds are a sequence, so the occurrence
+                    * of the first character in that sequence doesn't
+                    * necessarily mean that what follows is the rest of the
+                    * sequence.  We keep track of that with a state machine,
+                    * with the state being set to the latest character
+                    * processed before the current one.  Most characters will
+                    * set the state to 0, but if one occurs that is part of a
+                    * potential tricky fold sequence, the state is set to that
+                    * character, and the next loop iteration sees if the state
+                    * should progress towards the final folded-from character,
+                    * or if it was a false alarm.  If it turns out to be a
+                    * false alarm, the character(s) will be output in a new
+                    * EXACTish node, and join_exact() will later combine them.
+                    * In the case of the 'ss' sequence, which is more common
+                    * and more easily checked, some look-ahead is done to
+                    * save time by ruling-out some false alarms */
+                   switch (ender) {
+                       default:
+                           latest_char_state = generic_char;
+                           break;
+                       case 's':
+                       case 'S':
+                       case 0x17F: /* LATIN SMALL LETTER LONG S */
+                            if (AT_LEAST_UNI_SEMANTICS) {
+                               if (latest_char_state == char_s) {  /* 'ss' */
+                                   ender = LATIN_SMALL_LETTER_SHARP_S;
+                                   goto do_tricky;
+                               }
+                               else if (p < RExC_end) {
+
+                                   /* Look-ahead at the next character.  If it
+                                    * is also an s, we handle as a sharp s
+                                    * tricky regnode.  */
+                                   if (*p == 's' || *p == 'S') {
+
+                                       /* But first flush anything in the
+                                        * EXACTish buffer */
+                                       if (len != 0) {
+                                           p = oldp;
+                                           goto loopdone;
+                                       }
+                                       p++;    /* Account for swallowing this
+                                                  's' up */
+                                       ender = LATIN_SMALL_LETTER_SHARP_S;
+                                       goto do_tricky;
+                                   }
+                                       /* Here, the next character is not a
+                                        * literal 's', but still could
+                                        * evaluate to one if part of a \o{},
+                                        * \x or \OCTAL-DIGIT.  The minimum
+                                        * length required for that is 4, eg
+                                        * \x53 or \123 */
+                                   else if (*p == '\\'
+                                            && p < RExC_end - 4
+                                            && (isDIGIT(*(p + 1))
+                                                || *(p + 1) == 'x'
+                                                || *(p + 1) == 'o' ))
+                                   {
 
-                       /* Here we are ready to output our tricky fold
-                        * character.  What's done is to pretend it's in a
-                        * [bracketed] class, and let the code that deals with
-                        * those handle it, as that code has all the
-                        * intelligence necessary.  First save the current
-                        * parse state, get rid of the already allocated EXACT
-                        * node that the ANYOFV node will replace, and point
-                        * the parse to a buffer which we fill with the
-                        * character we want the regclass code to think is
-                        * being parsed */
-                       char* const oldregxend = RExC_end;
-                       char tmpbuf[2];
-                       RExC_emit = orig_emit;
-                       RExC_parse = tmpbuf;
-                       if (UTF) {
-                           tmpbuf[0] = UTF8_TWO_BYTE_HI(ender);
-                           tmpbuf[1] = UTF8_TWO_BYTE_LO(ender);
-                           RExC_end = RExC_parse + 2;
-                       }
-                       else {
-                           tmpbuf[0] = (char) ender;
-                           RExC_end = RExC_parse + 1;
-                       }
+                                       /* Here, it could be an 's', too much
+                                        * bother to figure it out here.  Flush
+                                        * the buffer if any; when come back
+                                        * here, set the state so know that the
+                                        * previous char was an 's' */
+                                       if (len != 0) {
+                                           latest_char_state = generic_char;
+                                           p = oldp;
+                                           goto loopdone;
+                                       }
+                                       latest_char_state = char_s;
+                                       break;
+                                   }
+                               }
+                           }
 
-                       ret = regclass(pRExC_state,depth+1);
+                           /* Here, can't be an 'ss' sequence, or at least not
+                            * one that could fold to/from the sharp ss */
+                           latest_char_state = generic_char;
+                           break;
+                       case 0x03C5:    /* First char in upsilon series */
+                       case 0x03A5:    /* Also capital UPSILON, which folds to
+                                          03C5, and hence exhibits the same
+                                          problem */
+                           if (p < RExC_end - 4) { /* Need >= 4 bytes left */
+                               latest_char_state = upsilon_1;
+                               if (len != 0) {
+                                   p = oldp;
+                                   goto loopdone;
+                               }
+                           }
+                           else {
+                               latest_char_state = generic_char;
+                           }
+                           break;
+                       case 0x03B9:    /* First char in iota series */
+                       case 0x0399:    /* Also capital IOTA */
+                       case 0x1FBE:    /* GREEK PROSGEGRAMMENI folds to 3B9 */
+                       case 0x0345:    /* COMBINING GREEK YPOGEGRAMMENI folds
+                                          to 3B9 */
+                           if (p < RExC_end - 4) {
+                               latest_char_state = iota_1;
+                               if (len != 0) {
+                                   p = oldp;
+                                   goto loopdone;
+                               }
+                           }
+                           else {
+                               latest_char_state = generic_char;
+                           }
+                           break;
+                       case 0x0308:
+                           if (latest_char_state == upsilon_1) {
+                               latest_char_state = upsilon_2;
+                           }
+                           else if (latest_char_state == iota_1) {
+                               latest_char_state = iota_2;
+                           }
+                           else {
+                               latest_char_state = generic_char;
+                           }
+                           break;
+                       case 0x301:
+                           if (latest_char_state == upsilon_2) {
+                               ender = GREEK_SMALL_LETTER_UPSILON_WITH_DIALYTIKA_AND_TONOS;
+                               goto do_tricky;
+                           }
+                           else if (latest_char_state == iota_2) {
+                               ender = GREEK_SMALL_LETTER_IOTA_WITH_DIALYTIKA_AND_TONOS;
+                               goto do_tricky;
+                           }
+                           latest_char_state = generic_char;
+                           break;
 
-                       /* Here, have parsed the buffer.  Reset the parse to
-                        * the actual input, and return */
-                       RExC_end = oldregxend;
-                       RExC_parse = p - 1;
+                       /* These are the tricky fold characters.  Flush any
+                        * buffer first. (When adding to this list, also should
+                        * add them to fold_grind.t to make sure get tested) */
+                       case GREEK_SMALL_LETTER_UPSILON_WITH_DIALYTIKA_AND_TONOS:
+                       case GREEK_SMALL_LETTER_IOTA_WITH_DIALYTIKA_AND_TONOS:
+                       case LATIN_SMALL_LETTER_SHARP_S:
+                       case LATIN_CAPITAL_LETTER_SHARP_S:
+                       case 0x1FD3: /* GREEK SMALL LETTER IOTA WITH DIALYTIKA AND OXIA */
+                       case 0x1FE3: /* GREEK SMALL LETTER UPSILON WITH DIALYTIKA AND OXIA */
+                           if (len != 0) {
+                               p = oldp;
+                               goto loopdone;
+                           }
+                           /* FALL THROUGH */
+                       do_tricky: {
+                           char* const oldregxend = RExC_end;
+                           U8 tmpbuf[UTF8_MAXBYTES+1];
+
+                           /* Here, we know we need to generate a special
+                            * regnode, and 'ender' contains the tricky
+                            * character.  What's done is to pretend it's in a
+                            * [bracketed] class, and let the code that deals
+                            * with those handle it, as that code has all the
+                            * intelligence necessary.  First save the current
+                            * parse state, get rid of the already allocated
+                            * but empty EXACT node that the ANYOFV node will
+                            * replace, and point the parse to a buffer which
+                            * we fill with the character we want the regclass
+                            * code to think is being parsed */
+                           RExC_emit = orig_emit;
+                           RExC_parse = (char *) tmpbuf;
+                           if (UTF) {
+                               U8 *d = uvchr_to_utf8(tmpbuf, ender);
+                               *d = '\0';
+                               RExC_end = (char *) d;
+                           }
+                           else {  /* ender above 255 already excluded */
+                               tmpbuf[0] = (U8) ender;
+                               tmpbuf[1] = '\0';
+                               RExC_end = RExC_parse + 1;
+                           }
 
-                       Set_Node_Offset(ret, RExC_parse);
-                       Set_Node_Cur_Length(ret);
-                       nextchar(pRExC_state);
-                       *flagp |= HASWIDTH|SIMPLE;
-                       return ret;
+                           ret = regclass(pRExC_state,depth+1);
+
+                           /* Here, have parsed the buffer.  Reset the parse to
+                            * the actual input, and return */
+                           RExC_end = oldregxend;
+                           RExC_parse = p - 1;
+
+                           Set_Node_Offset(ret, RExC_parse);
+                           Set_Node_Cur_Length(ret);
+                           nextchar(pRExC_state);
+                           *flagp |= HASWIDTH|SIMPLE;
+                           return ret;
+                       }
                    }
                }
 
                if ( RExC_flags & RXf_PMf_EXTENDED)
                    p = regwhite( pRExC_state, p );
                if (UTF && FOLD) {
-                   /* Prime the casefolded buffer. */
-                   if (isASCII(ender)) {
+                   /* Prime the casefolded buffer.  Locale rules, which apply
+                    * only to code points < 256, aren't known until execution,
+                    * so for them, just output the original character using
+                    * utf8 */
+                   if (LOC && ender < 256) {
+                       if (UNI_IS_INVARIANT(ender)) {
+                           *tmpbuf = (U8) ender;
+                           foldlen = 1;
+                       } else {
+                           *tmpbuf = UTF8_TWO_BYTE_HI(ender);
+                           *(tmpbuf + 1) = UTF8_TWO_BYTE_LO(ender);
+                           foldlen = 2;
+                       }
+                   }
+                   else if (isASCII(ender)) {  /* Note: Here can't also be LOC
+                                                */
                        ender = toLOWER(ender);
                        *tmpbuf = (U8) ender;
                        foldlen = 1;
                    }
-                   else if (! MORE_ASCII_RESTRICTED) {
+                   else if (! MORE_ASCII_RESTRICTED && ! LOC) {
+
+                       /* Locale and /aa require more selectivity about the
+                        * fold, so are handled below.  Otherwise, here, just
+                        * use the fold */
                        ender = toFOLD_uni(ender, tmpbuf, &foldlen);
                    }
                    else {
-                       /* When not to mix ASCII with non-, reject folds that
-                        * mix them, using only the non-folded code point.  So
-                        * do the fold to a temporary, and inspect each
-                        * character in it. */
+                       /* Under locale rules or /aa we are not to mix,
+                        * respectively, ords < 256 or ASCII with non-.  So
+                        * reject folds that mix them, using only the
+                        * non-folded code point.  So do the fold to a
+                        * temporary, and inspect each character in it. */
                        U8 trialbuf[UTF8_MAXBYTES_CASE+1];
                        U8* s = trialbuf;
                        UV tmpender = toFOLD_uni(ender, trialbuf, &foldlen);
@@ -8760,7 +8931,10 @@ tryagain:
                        bool fold_ok = TRUE;
 
                        while (s < e) {
-                           if (isASCII(*s)) {
+                           if (isASCII(*s)
+                               || (LOC && (UTF8_IS_INVARIANT(*s)
+                                          || UTF8_IS_DOWNGRADEABLE_START(*s))))
+                           {
                                fold_ok = FALSE;
                                break;
                            }
@@ -8846,8 +9020,9 @@ tryagain:
                     }
                     len--;
                }
-               else
+               else {
                    REGC((char)ender, s++);
+               }
            }
        loopdone:   /* Jumped to when encounters something that shouldn't be in
                       the node */
@@ -9073,14 +9248,14 @@ S_checkposixcc(pTHX_ RExC_state_t *pRExC_state)
 ANYOF_##NAME:                                                                  \
        for (value = 0; value < 256; value++)                                  \
            if (TEST)                                                          \
-           stored += set_regclass_bit(pRExC_state, ret, (U8) value, &nonbitmap);  \
+           stored += set_regclass_bit(pRExC_state, ret, (U8) value, &l1_fold_invlist, &unicode_alternate);  \
     yesno = '+';                                                               \
     what = WORD;                                                               \
     break;                                                                     \
 case ANYOF_N##NAME:                                                            \
        for (value = 0; value < 256; value++)                                  \
            if (!TEST)                                                         \
-           stored += set_regclass_bit(pRExC_state, ret, (U8) value, &nonbitmap);  \
+           stored += set_regclass_bit(pRExC_state, ret, (U8) value, &l1_fold_invlist, &unicode_alternate);  \
     yesno = '!';                                                               \
     what = WORD;                                                               \
     break
@@ -9095,14 +9270,14 @@ ANYOF_##NAME:                                                                  \
     else if (UNI_SEMANTICS) {                                                  \
         for (value = 0; value < 256; value++) {                                \
             if (TEST_8(value)) stored +=                                       \
-                      set_regclass_bit(pRExC_state, ret, (U8) value, &nonbitmap);  \
+                      set_regclass_bit(pRExC_state, ret, (U8) value, &l1_fold_invlist, &unicode_alternate);  \
         }                                                                      \
     }                                                                          \
     else {                                                                     \
         for (value = 0; value < 128; value++) {                                \
             if (TEST_7(UNI_TO_NATIVE(value))) stored +=                        \
                set_regclass_bit(pRExC_state, ret,                     \
-                                  (U8) UNI_TO_NATIVE(value), &nonbitmap);                 \
+                                  (U8) UNI_TO_NATIVE(value), &l1_fold_invlist, &unicode_alternate);                 \
         }                                                                      \
     }                                                                          \
     yesno = '+';                                                               \
@@ -9113,20 +9288,20 @@ case ANYOF_N##NAME:                                                            \
     else if (UNI_SEMANTICS) {                                                  \
         for (value = 0; value < 256; value++) {                                \
             if (! TEST_8(value)) stored +=                                     \
-                   set_regclass_bit(pRExC_state, ret, (U8) value, &nonbitmap);    \
+                   set_regclass_bit(pRExC_state, ret, (U8) value, &l1_fold_invlist, &unicode_alternate);    \
         }                                                                      \
     }                                                                          \
     else {                                                                     \
         for (value = 0; value < 128; value++) {                                \
             if (! TEST_7(UNI_TO_NATIVE(value))) stored += set_regclass_bit(  \
-                       pRExC_state, ret, (U8) UNI_TO_NATIVE(value), &nonbitmap);    \
+                       pRExC_state, ret, (U8) UNI_TO_NATIVE(value), &l1_fold_invlist, &unicode_alternate);    \
         }                                                                      \
        if (AT_LEAST_ASCII_RESTRICTED) {                                       \
            for (value = 128; value < 256; value++) {                          \
              stored += set_regclass_bit(                                     \
-                          pRExC_state, ret, (U8) UNI_TO_NATIVE(value), &nonbitmap); \
+                          pRExC_state, ret, (U8) UNI_TO_NATIVE(value), &l1_fold_invlist, &unicode_alternate); \
            }                                                                  \
-           ANYOF_FLAGS(ret) |= ANYOF_UNICODE_ALL|ANYOF_UTF8;                  \
+           ANYOF_FLAGS(ret) |= ANYOF_UNICODE_ALL;                             \
        }                                                                      \
        else {                                                                 \
            /* For a non-ut8 target string with DEPENDS semantics, all above   \
@@ -9134,43 +9309,30 @@ case ANYOF_N##NAME:                                                            \
             * classes.  But in utf8, they have their Unicode semantics, so    \
             * can't just set them in the bitmap, or else regexec.c will think \
             * they matched when they shouldn't. */                            \
-           ANYOF_FLAGS(ret) |= ANYOF_NON_UTF8_LATIN1_ALL|ANYOF_UTF8;          \
+           ANYOF_FLAGS(ret) |= ANYOF_NON_UTF8_LATIN1_ALL;                     \
        }                                                                      \
     }                                                                          \
     yesno = '!';                                                               \
     what = WORD;                                                               \
     break
 
-/* 
-   We dont use PERL_LEGACY_UNICODE_CHARCLASS_MAPPINGS as the direct test
-   so that it is possible to override the option here without having to 
-   rebuild the entire core. as we are required to do if we change regcomp.h
-   which is where PERL_LEGACY_UNICODE_CHARCLASS_MAPPINGS is defined.
-*/
-#if PERL_LEGACY_UNICODE_CHARCLASS_MAPPINGS
-#define BROKEN_UNICODE_CHARCLASS_MAPPINGS
-#endif
-
-#ifdef BROKEN_UNICODE_CHARCLASS_MAPPINGS
-#define POSIX_CC_UNI_NAME(CCNAME) CCNAME
-#else
-#define POSIX_CC_UNI_NAME(CCNAME) "Posix" CCNAME
-#endif
-
 STATIC U8
-S_set_regclass_bit_fold(pTHX_ RExC_state_t *pRExC_state, regnode* node, const U8 value, HV** nonbitmap_ptr)
+S_set_regclass_bit_fold(pTHX_ RExC_state_t *pRExC_state, regnode* node, const U8 value, SV** invlist_ptr, AV** alternate_ptr)
 {
 
     /* Handle the setting of folds in the bitmap for non-locale ANYOF nodes.
      * Locale folding is done at run-time, so this function should not be
      * called for nodes that are for locales.
      *
-     * This function simply sets the bit corresponding to the fold of the input
+     * This function sets the bit corresponding to the fold of the input
      * 'value', if not already set.  The fold of 'f' is 'F', and the fold of
      * 'F' is 'f'.
      *
-     * It also sets any necessary flags, and returns the number of bits that
-     * actually changed from 0 to 1 */
+     * It also knows about the characters that are in the bitmap that have
+     * folds that are matchable only outside it, and sets the appropriate lists
+     * and flags.
+     *
+     * It returns the number of bits that actually changed from 0 to 1 */
 
     U8 stored = 0;
     U8 fold;
@@ -9185,20 +9347,109 @@ S_set_regclass_bit_fold(pTHX_ RExC_state_t *pRExC_state, regnode* node, const U8
         ANYOF_BITMAP_SET(node, fold);
         stored++;
     }
-    if ((_HAS_NONLATIN1_FOLD_CLOSURE_ONLY_FOR_USE_BY_REGCOMP_DOT_C_AND_REGEXEC_DOT_C(value) && (! isASCII(value) || ! MORE_ASCII_RESTRICTED))
-       || (! UNI_SEMANTICS
-           && ! isASCII(value)
-           && PL_fold_latin1[value] != value))
-    {   /* A character that has a fold outside of Latin1 matches outside the
-           bitmap, but only when the target string is utf8.  Similarly when we
-           don't have unicode semantics for the above ASCII Latin-1 characters,
-           and they have a fold, they should match if the target is utf8, and
-           not otherwise */
-       if (! *nonbitmap_ptr) {
-           *nonbitmap_ptr = _new_invlist(2);
+    if (_HAS_NONLATIN1_FOLD_CLOSURE_ONLY_FOR_USE_BY_REGCOMP_DOT_C_AND_REGEXEC_DOT_C(value) && (! isASCII(value) || ! MORE_ASCII_RESTRICTED)) {
+       /* Certain Latin1 characters have matches outside the bitmap.  To get
+        * here, 'value' is one of those characters.   None of these matches is
+        * valid for ASCII characters under /aa, which have been excluded by
+        * the 'if' above.  The matches fall into three categories:
+        * 1) They are singly folded-to or -from an above 255 character, as
+        *    LATIN SMALL LETTER Y WITH DIAERESIS and LATIN CAPITAL LETTER Y
+        *    WITH DIAERESIS;
+        * 2) They are part of a multi-char fold with another character in the
+        *    bitmap, only LATIN SMALL LETTER SHARP S => "ss" fits that bill;
+        * 3) They are part of a multi-char fold with a character not in the
+        *    bitmap, such as various ligatures.
+        * We aren't dealing fully with multi-char folds, except we do deal
+        * with the pattern containing a character that has a multi-char fold
+        * (not so much the inverse).
+        * For types 1) and 3), the matches only happen when the target string
+        * is utf8; that's not true for 2), and we set a flag for it.
+        *
+        * The code below adds to the passed in inversion list the single fold
+        * closures for 'value'.  The values are hard-coded here so that an
+        * innocent-looking character class, like /[ks]/i won't have to go out
+        * to disk to find the possible matches.  XXX It would be better to
+        * generate these via regen, in case a new version of the Unicode
+        * standard adds new mappings, though that is not really likely. */
+       switch (value) {
+           case 'k':
+           case 'K':
+               /* KELVIN SIGN */
+               *invlist_ptr = add_cp_to_invlist(*invlist_ptr, 0x212A);
+               break;
+           case 's':
+           case 'S':
+               /* LATIN SMALL LETTER LONG S */
+               *invlist_ptr = add_cp_to_invlist(*invlist_ptr, 0x017F);
+               break;
+           case MICRO_SIGN:
+               *invlist_ptr = add_cp_to_invlist(*invlist_ptr,
+                                                GREEK_SMALL_LETTER_MU);
+               *invlist_ptr = add_cp_to_invlist(*invlist_ptr,
+                                                GREEK_CAPITAL_LETTER_MU);
+               break;
+           case LATIN_CAPITAL_LETTER_A_WITH_RING_ABOVE:
+           case LATIN_SMALL_LETTER_A_WITH_RING_ABOVE:
+               /* ANGSTROM SIGN */
+               *invlist_ptr = add_cp_to_invlist(*invlist_ptr, 0x212B);
+               if (DEPENDS_SEMANTICS) {    /* See DEPENDS comment below */
+                   *invlist_ptr = add_cp_to_invlist(*invlist_ptr,
+                                                    PL_fold_latin1[value]);
+               }
+               break;
+           case LATIN_SMALL_LETTER_Y_WITH_DIAERESIS:
+               *invlist_ptr = add_cp_to_invlist(*invlist_ptr,
+                                       LATIN_CAPITAL_LETTER_Y_WITH_DIAERESIS);
+               break;
+           case LATIN_SMALL_LETTER_SHARP_S:
+               *invlist_ptr = add_cp_to_invlist(*invlist_ptr,
+                                       LATIN_CAPITAL_LETTER_SHARP_S);
+
+               /* Under /a, /d, and /u, this can match the two chars "ss" */
+               if (! MORE_ASCII_RESTRICTED) {
+                   add_alternate(alternate_ptr, (U8 *) "ss", 2);
+
+                   /* And under /u or /a, it can match even if the target is
+                    * not utf8 */
+                   if (AT_LEAST_UNI_SEMANTICS) {
+                       ANYOF_FLAGS(node) |= ANYOF_NONBITMAP_NON_UTF8;
+                   }
+               }
+               break;
+           case 'F': case 'f':
+           case 'I': case 'i':
+           case 'L': case 'l':
+           case 'T': case 't':
+           case 'A': case 'a':
+           case 'H': case 'h':
+           case 'J': case 'j':
+           case 'N': case 'n':
+           case 'W': case 'w':
+           case 'Y': case 'y':
+                /* These all are targets of multi-character folds from code
+                 * points that require UTF8 to express, so they can't match
+                 * unless the target string is in UTF-8, so no action here is
+                 * necessary, as regexec.c properly handles the general case
+                 * for UTF-8 matching */
+               break;
+           default:
+               /* Use deprecated warning to increase the chances of this
+                * being output */
+               ckWARN2regdep(RExC_parse, "Perl folding rules are not up-to-date for 0x%x; please use the perlbug utility to report;", value);
+               break;
        }
-       *nonbitmap_ptr = add_range_to_invlist(*nonbitmap_ptr, value, value);
-       ANYOF_FLAGS(node) |= ANYOF_UTF8;
+    }
+    else if (DEPENDS_SEMANTICS
+           && ! isASCII(value)
+           && PL_fold_latin1[value] != value)
+    {
+          /* Under DEPENDS rules, non-ASCII Latin1 characters match their
+           * folds only when the target string is in UTF-8.  We add the fold
+           * here to the list of things to match outside the bitmap, which
+           * won't be looked at unless it is UTF8 (or else if something else
+           * says to look even if not utf8, but those things better not happen
+           * under DEPENDS semantics. */
+       *invlist_ptr = add_cp_to_invlist(*invlist_ptr, PL_fold_latin1[value]);
     }
 
     return stored;
@@ -9206,7 +9457,7 @@ S_set_regclass_bit_fold(pTHX_ RExC_state_t *pRExC_state, regnode* node, const U8
 
 
 PERL_STATIC_INLINE U8
-S_set_regclass_bit(pTHX_ RExC_state_t *pRExC_state, regnode* node, const U8 value, HV** nonbitmap_ptr)
+S_set_regclass_bit(pTHX_ RExC_state_t *pRExC_state, regnode* node, const U8 value, SV** invlist_ptr, AV** alternate_ptr)
 {
     /* This inline function sets a bit in the bitmap if not already set, and if
      * appropriate, its fold, returning the number of bits that actually
@@ -9224,16 +9475,36 @@ S_set_regclass_bit(pTHX_ RExC_state_t *pRExC_state, regnode* node, const U8 valu
     stored = 1;
 
     if (FOLD && ! LOC) {       /* Locale folds aren't known until runtime */
-       stored += set_regclass_bit_fold(pRExC_state, node, value, nonbitmap_ptr);
+       stored += set_regclass_bit_fold(pRExC_state, node, value, invlist_ptr, alternate_ptr);
     }
 
     return stored;
 }
 
+STATIC void
+S_add_alternate(pTHX_ AV** alternate_ptr, U8* string, STRLEN len)
+{
+    /* Adds input 'string' with length 'len' to the ANYOF node's unicode
+     * alternate list, pointed to by 'alternate_ptr'.  This is an array of
+     * the multi-character folds of characters in the node */
+    SV *sv;
+
+    PERL_ARGS_ASSERT_ADD_ALTERNATE;
+
+    if (! *alternate_ptr) {
+       *alternate_ptr = newAV();
+    }
+    sv = newSVpvn_utf8((char*)string, len, TRUE);
+    av_push(*alternate_ptr, sv);
+    return;
+}
+
 /*
    parse a class specification and produce either an ANYOF node that
    matches the pattern or perhaps will be optimized into an EXACTish node
-   instead. */
+   instead. The node contains a bit map for the first 256 characters, with the
+   corresponding bit set if that character is in the list.  For characters
+   above 255, a range list is used */
 
 STATIC regnode *
 S_regclass(pTHX_ RExC_state_t *pRExC_state, U32 depth)
@@ -9248,9 +9519,32 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state, U32 depth)
     IV namedclass;
     char *rangebegin = NULL;
     bool need_class = 0;
+    bool allow_full_fold = TRUE;   /* Assume wants multi-char folding */
     SV *listsv = NULL;
+    STRLEN initial_listsv_len = 0; /* Kind of a kludge to see if it is more
+                                     than just initialized.  */
     UV n;
-    HV* nonbitmap = NULL;
+
+    /* code points this node matches that can't be stored in the bitmap */
+    SV* nonbitmap = NULL;
+
+    /* The items that are to match that aren't stored in the bitmap, but are a
+     * result of things that are stored there.  This is the fold closure of
+     * such a character, either because it has DEPENDS semantics and shouldn't
+     * be matched unless the target string is utf8, or is a code point that is
+     * too large for the bit map, as for example, the fold of the MICRO SIGN is
+     * above 255.  This all is solely for performance reasons.  By having this
+     * code know the outside-the-bitmap folds that the bitmapped characters are
+     * involved with, we don't have to go out to disk to find the list of
+     * matches, unless the character class includes code points that aren't
+     * storable in the bit map.  That means that a character class with an 's'
+     * in it, for example, doesn't need to go out to disk to find everything
+     * that matches.  A 2nd list is used so that the 'nonbitmap' list is kept
+     * empty unless there is something whose fold we don't know about, and will
+     * have to go out to the disk to find. */
+    SV* l1_fold_invlist = NULL;
+
+    /* List of multi-character folds that are matched by this node */
     AV* unicode_alternate  = NULL;
 #ifdef EBCDIC
     UV literal_endpoint = 0;
@@ -9282,27 +9576,30 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state, U32 depth)
        RExC_parse++;
        if (!SIZE_ONLY)
            ANYOF_FLAGS(ret) |= ANYOF_INVERT;
+
+        /* We have decided to not allow multi-char folds in inverted character
+        * classes, due to the confusion that can happen, especially with
+        * classes that are designed for a non-Unicode world:  You have the
+        * peculiar case that:
+            "s s" =~ /^[^\xDF]+$/i => Y
+            "ss"  =~ /^[^\xDF]+$/i => N
+         *
+         * See [perl #89750] */
+        allow_full_fold = FALSE;
     }
 
     if (SIZE_ONLY) {
        RExC_size += ANYOF_SKIP;
-#ifdef ANYOF_ADD_LOC_SKIP
-       if (LOC) {
-           RExC_size += ANYOF_ADD_LOC_SKIP;
-       }
-#endif
        listsv = &PL_sv_undef; /* For code scanners: listsv always non-NULL. */
     }
     else {
        RExC_emit += ANYOF_SKIP;
        if (LOC) {
            ANYOF_FLAGS(ret) |= ANYOF_LOCALE;
-#ifdef ANYOF_ADD_LOC_SKIP
-           RExC_emit += ANYOF_ADD_LOC_SKIP;
-#endif
        }
        ANYOF_BITMAP_ZERO(ret);
        listsv = newSVpvs("# comment\n");
+       initial_listsv_len = SvCUR(listsv);
     }
 
     nextvalue = RExC_parse < RExC_end ? UCHARAT(RExC_parse) : 0;
@@ -9368,7 +9665,7 @@ parseit:
                     from earlier versions, OTOH that behaviour was broken
                     as well. */
                     UV v; /* value is register so we cant & it /grrr */
-                    if (reg_namedseq(pRExC_state, &v, NULL)) {
+                    if (reg_namedseq(pRExC_state, &v, NULL, depth)) {
                         goto parseit;
                     }
                     value= v; 
@@ -9397,14 +9694,7 @@ parseit:
                    e = RExC_parse;
                    n = 1;
                }
-               if (SIZE_ONLY) {
-                   if (LOC) {
-                       ckWARN2reg(RExC_parse,
-                               "\\%c uses Unicode rules, not locale rules",
-                               (int) value);
-                   }
-               }
-               else {
+               if (!SIZE_ONLY) {
                    if (UCHARAT(RExC_parse) == '^') {
                         RExC_parse++;
                         n--;
@@ -9431,7 +9721,7 @@ parseit:
 
                /* The \p could match something in the Latin1 range, hence
                 * something that isn't utf8 */
-               ANYOF_FLAGS(ret) |= ANYOF_NONBITMAP;
+               ANYOF_FLAGS(ret) |= ANYOF_NONBITMAP_NON_UTF8;
                namedclass = ANYOF_MAX;  /* no official name, but it's named */
 
                /* \p means they want Unicode semantics */
@@ -9500,7 +9790,7 @@ parseit:
                    break;
                }
            recode_encoding:
-               {
+               if (! RExC_override_recoding) {
                    SV* enc = PL_encoding;
                    value = reg_recode((const char)(U8)value, &enc);
                    if (!enc && SIZE_ONLY)
@@ -9534,21 +9824,18 @@ parseit:
            if (LOC && namedclass < ANYOF_MAX && ! need_class) {
                need_class = 1;
                if (SIZE_ONLY) {
-#ifdef ANYOF_CLASS_ADD_SKIP
-                   RExC_size += ANYOF_CLASS_ADD_SKIP;
-#endif
+                   RExC_size += ANYOF_CLASS_SKIP - ANYOF_SKIP;
                }
                else {
-#ifdef ANYOF_CLASS_ADD_SKIP
-                   RExC_emit += ANYOF_CLASS_ADD_SKIP;
-#endif
+                   RExC_emit += ANYOF_CLASS_SKIP - ANYOF_SKIP;
                    ANYOF_CLASS_ZERO(ret);
                }
                ANYOF_FLAGS(ret) |= ANYOF_CLASS;
            }
 
            /* a bad range like a-\d, a-[:digit:].  The '-' is taken as a
-            * literal */
+            * literal, as is the character that began the false range, i.e.
+            * the 'a' in the examples */
            if (range) {
                if (!SIZE_ONLY) {
                    const int w =
@@ -9558,16 +9845,14 @@ parseit:
                               "False [] range \"%*.*s\"",
                               w, w, rangebegin);
 
+                   stored +=
+                         set_regclass_bit(pRExC_state, ret, '-', &l1_fold_invlist, &unicode_alternate);
                    if (prevvalue < 256) {
                        stored +=
-                         set_regclass_bit(pRExC_state, ret, (U8) prevvalue, &nonbitmap);
-                       stored +=
-                         set_regclass_bit(pRExC_state, ret, '-', &nonbitmap);
+                         set_regclass_bit(pRExC_state, ret, (U8) prevvalue, &l1_fold_invlist, &unicode_alternate);
                    }
                    else {
-                       ANYOF_FLAGS(ret) |= ANYOF_UTF8;
-                       Perl_sv_catpvf(aTHX_ listsv,
-                          "%04"UVxf"\n%04"UVxf"\n", (UV)prevvalue, (UV) '-');
+                       nonbitmap = add_cp_to_invlist(nonbitmap, prevvalue);
                    }
                }
 
@@ -9596,15 +9881,9 @@ parseit:
                case _C_C_T_(PSXSPC, isPSXSPC_L1, isPSXSPC, "XPosixSpace");
                case _C_C_T_(PUNCT, isPUNCT_L1, isPUNCT, "XPosixPunct");
                case _C_C_T_(UPPER, isUPPER_L1, isUPPER, "XPosixUpper");
-#ifdef BROKEN_UNICODE_CHARCLASS_MAPPINGS
                 /* \s, \w match all unicode if utf8. */
                 case _C_C_T_(SPACE, isSPACE_L1, isSPACE, "SpacePerl");
                 case _C_C_T_(ALNUM, isWORDCHAR_L1, isALNUM, "Word");
-#else
-                /* \s, \w match ascii and locale only */
-                case _C_C_T_(SPACE, isSPACE_L1, isSPACE, "PerlSpace");
-                case _C_C_T_(ALNUM, isWORDCHAR_L1, isALNUM, "PerlWord");
-#endif         
                case _C_C_T_(XDIGIT, isXDIGIT_L1, isXDIGIT, "XPosixXDigit");
                case _C_C_T_NOLOC_(VERTWS, is_VERTWS_latin1(&value), "VertSpace");
                case _C_C_T_NOLOC_(HORIZWS, is_HORIZWS_latin1(&value), "HorizSpace");
@@ -9614,7 +9893,7 @@ parseit:
                    else {
                        for (value = 0; value < 128; value++)
                            stored +=
-                              set_regclass_bit(pRExC_state, ret, (U8) ASCII_TO_NATIVE(value), &nonbitmap);
+                              set_regclass_bit(pRExC_state, ret, (U8) ASCII_TO_NATIVE(value), &l1_fold_invlist, &unicode_alternate);
                    }
                    yesno = '+';
                    what = NULL;        /* Doesn't match outside ascii, so
@@ -9626,7 +9905,7 @@ parseit:
                    else {
                        for (value = 128; value < 256; value++)
                            stored +=
-                              set_regclass_bit(pRExC_state, ret, (U8) ASCII_TO_NATIVE(value), &nonbitmap);
+                              set_regclass_bit(pRExC_state, ret, (U8) ASCII_TO_NATIVE(value), &l1_fold_invlist, &unicode_alternate);
                    }
                    ANYOF_FLAGS(ret) |= ANYOF_UNICODE_ALL;
                    yesno = '!';
@@ -9639,10 +9918,10 @@ parseit:
                        /* consecutive digits assumed */
                        for (value = '0'; value <= '9'; value++)
                            stored +=
-                              set_regclass_bit(pRExC_state, ret, (U8) value, &nonbitmap);
+                              set_regclass_bit(pRExC_state, ret, (U8) value, &l1_fold_invlist, &unicode_alternate);
                    }
                    yesno = '+';
-                   what = POSIX_CC_UNI_NAME("Digit");
+                   what = "Digit";
                    break;
                case ANYOF_NDIGIT:
                    if (LOC)
@@ -9651,13 +9930,13 @@ parseit:
                        /* consecutive digits assumed */
                        for (value = 0; value < '0'; value++)
                            stored +=
-                              set_regclass_bit(pRExC_state, ret, (U8) value, &nonbitmap);
+                              set_regclass_bit(pRExC_state, ret, (U8) value, &l1_fold_invlist, &unicode_alternate);
                        for (value = '9' + 1; value < 256; value++)
                            stored +=
-                              set_regclass_bit(pRExC_state, ret, (U8) value, &nonbitmap);
+                              set_regclass_bit(pRExC_state, ret, (U8) value, &l1_fold_invlist, &unicode_alternate);
                    }
                    yesno = '!';
-                   what = POSIX_CC_UNI_NAME("Digit");
+                   what = "Digit";
                    if (AT_LEAST_ASCII_RESTRICTED ) {
                        ANYOF_FLAGS(ret) |= ANYOF_UNICODE_ALL;
                    }
@@ -9672,7 +9951,6 @@ parseit:
                if (what && ! (AT_LEAST_ASCII_RESTRICTED)) {
                    /* Strings such as "+utf8::isWord\n" */
                    Perl_sv_catpvf(aTHX_ listsv, "%cutf8::Is%s\n", yesno, what);
-                   ANYOF_FLAGS(ret) |= ANYOF_UTF8;
                }
 
                continue;
@@ -9688,8 +9966,10 @@ parseit:
        }
        else {
            prevvalue = value; /* save the beginning of the range */
-           if (*RExC_parse == '-' && RExC_parse+1 < RExC_end &&
-               RExC_parse[1] != ']') {
+           if (RExC_parse+1 < RExC_end
+               && *RExC_parse == '-'
+               && RExC_parse[1] != ']')
+           {
                RExC_parse++;
 
                /* a bad range like \w-, [:word:]- ? */
@@ -9704,7 +9984,7 @@ parseit:
                    }
                    if (!SIZE_ONLY)
                        stored +=
-                            set_regclass_bit(pRExC_state, ret, '-', &nonbitmap);
+                            set_regclass_bit(pRExC_state, ret, '-', &l1_fold_invlist, &unicode_alternate);
                } else
                    range = 1;  /* yeah, it's a range! */
                continue;       /* but do it the next time */
@@ -9733,129 +10013,27 @@ parseit:
                        for (i = prevvalue; i <= ceilvalue; i++)
                            if (isLOWER(i) && !ANYOF_BITMAP_TEST(ret,i)) {
                                stored +=
-                                  set_regclass_bit(pRExC_state, ret, (U8) i, &nonbitmap);
+                                  set_regclass_bit(pRExC_state, ret, (U8) i, &l1_fold_invlist, &unicode_alternate);
                            }
                    } else {
                        for (i = prevvalue; i <= ceilvalue; i++)
                            if (isUPPER(i) && !ANYOF_BITMAP_TEST(ret,i)) {
                                stored +=
-                                  set_regclass_bit(pRExC_state, ret, (U8) i, &nonbitmap);
+                                  set_regclass_bit(pRExC_state, ret, (U8) i, &l1_fold_invlist, &unicode_alternate);
                            }
                    }
                }
                else
 #endif
                      for (i = prevvalue; i <= ceilvalue; i++) {
-                       stored += set_regclass_bit(pRExC_state, ret, (U8) i, &nonbitmap);
+                       stored += set_regclass_bit(pRExC_state, ret, (U8) i, &l1_fold_invlist, &unicode_alternate);
                      }
          }
          if (value > 255) {
            const UV prevnatvalue  = NATIVE_TO_UNI(prevvalue);
            const UV natvalue      = NATIVE_TO_UNI(value);
-           if (! nonbitmap) {
-               nonbitmap = _new_invlist(2);
-           }
            nonbitmap = add_range_to_invlist(nonbitmap, prevnatvalue, natvalue);
-           ANYOF_FLAGS(ret) |= ANYOF_UTF8;
        }
-#if 0
-
-               /* If the code point requires utf8 to represent, and we are not
-                * folding, it can't match unless the target is in utf8.  Only
-                * a few code points above 255 fold to below it, so XXX an
-                * optimization would be to know which ones and set the flag
-                * appropriately. */
-               ANYOF_FLAGS(ret) |= (FOLD || value < 256)
-                                   ? ANYOF_NONBITMAP
-                                   : ANYOF_UTF8;
-               if (prevnatvalue < natvalue) { /* '>' case is fatal error above */
-
-                   /* The \t sets the whole range */
-                   Perl_sv_catpvf(aTHX_ listsv, "%04"UVxf"\t%04"UVxf"\n",
-                                  prevnatvalue, natvalue);
-
-                   /* Currently, we don't look at every value in the range.
-                    * Therefore we have to assume the worst case: that if
-                    * folding, it will match more than one character.  But in
-                    * lookbehind patterns, can only be single character
-                    * length, so disallow those folds */
-                   if (FOLD && ! RExC_in_lookbehind) {
-                     OP(ret) = ANYOFV;
-                   }
-               }
-               else if (prevnatvalue == natvalue) {
-                   Perl_sv_catpvf(aTHX_ listsv, "%04"UVxf"\n", natvalue);
-                   if (FOLD) {
-                        U8 foldbuf[UTF8_MAXBYTES_CASE+1];
-                        STRLEN foldlen;
-                        const UV f = to_uni_fold(natvalue, foldbuf, &foldlen);
-
-#ifdef EBCDIC /* RD t/uni/fold ff and 6b */
-                        if (RExC_precomp[0] == ':' &&
-                            RExC_precomp[1] == '[' &&
-                            (f == 0xDF || f == 0x92)) {
-                            f = NATIVE_TO_UNI(f);
-                        }
-#endif
-                        /* If folding and foldable and a single
-                         * character, insert also the folded version
-                         * to the charclass. */
-                        if (f != value) {
-#ifdef EBCDIC /* RD tunifold ligatures s,t fb05, fb06 */
-                            if ((RExC_precomp[0] == ':' &&
-                                 RExC_precomp[1] == '[' &&
-                                 (f == 0xA2 &&
-                                  (value == 0xFB05 || value == 0xFB06))) ?
-                                foldlen == ((STRLEN)UNISKIP(f) - 1) :
-                                foldlen == (STRLEN)UNISKIP(f) )
-#else
-                             if (foldlen == (STRLEN)UNISKIP(f))
-#endif
-                                 Perl_sv_catpvf(aTHX_ listsv,
-                                                "%04"UVxf"\n", f);
-                             else if (! RExC_in_lookbehind) {
-                                 /* Any multicharacter foldings
-                                  * (disallowed in lookbehind patterns)
-                                  * require the following transform:
-                                  * [ABCDEF] -> (?:[ABCabcDEFd]|pq|rst)
-                                  * where E folds into "pq" and F folds
-                                  * into "rst", all other characters
-                                  * fold to single characters.  We save
-                                  * away these multicharacter foldings,
-                                  * to be later saved as part of the
-                                  * additional "s" data. */
-                                 SV *sv;
-
-                                 if (!unicode_alternate)
-                                     unicode_alternate = newAV();
-                                 sv = newSVpvn_utf8((char*)foldbuf, foldlen,
-                                                    TRUE);
-                                 av_push(unicode_alternate, sv);
-                                 OP(ret) = ANYOFV;
-                             }
-                        }
-
-                        /* If folding and the value is one of the Greek
-                         * sigmas insert a few more sigmas to make the
-                         * folding rules of the sigmas to work right.
-                         * Note that not all the possible combinations
-                         * are handled here: some of them are handled
-                         * by the standard folding rules, and some of
-                         * them (literal or EXACTF cases) are handled
-                         * during runtime in regexec.c:S_find_byclass(). */
-                        if (value == UNICODE_GREEK_SMALL_LETTER_FINAL_SIGMA) {
-                             Perl_sv_catpvf(aTHX_ listsv, "%04"UVxf"\n",
-                                            (UV)UNICODE_GREEK_CAPITAL_LETTER_SIGMA);
-                             Perl_sv_catpvf(aTHX_ listsv, "%04"UVxf"\n",
-                                            (UV)UNICODE_GREEK_SMALL_LETTER_SIGMA);
-                        }
-                        else if (value == UNICODE_GREEK_CAPITAL_LETTER_SIGMA)
-                             Perl_sv_catpvf(aTHX_ listsv, "%04"UVxf"\n",
-                                            (UV)UNICODE_GREEK_SMALL_LETTER_SIGMA);
-                   }
-               }
-           }
-#endif
 #ifdef EBCDIC
            literal_endpoint = 0;
 #endif
@@ -9870,204 +10048,199 @@ parseit:
         return ret;
     /****** !SIZE_ONLY AFTER HERE *********/
 
-    /* Finish up the non-bitmap entries */
-    if (nonbitmap) {
-       UV* nonbitmap_array;
+    /* If folding and there are code points above 255, we calculate all
+     * characters that could fold to or from the ones already on the list */
+    if (FOLD && nonbitmap) {
        UV i;
 
-       /* If folding, we add to the list all characters that could fold to or
-        * from the ones already on the list */
-       if (FOLD) {
-           HV* fold_intersection;
-           UV* fold_list;
-
-           /* This is a list of all the characters that participate in folds
-            * (except marks, etc in multi-char folds */
-           if (! PL_utf8_foldable) {
-               SV* swash = swash_init("utf8", "Cased", &PL_sv_undef, 1, 0);
-               PL_utf8_foldable = _swash_to_invlist(swash);
-           }
+       SV* fold_intersection;
+       UV* fold_list;
 
-           /* This is a hash that for a particular fold gives all characters
-            * that are involved in it */
-           if (! PL_utf8_foldclosures) {
-
-               /* If we were unable to find any folds, then we likely won't be
-                * able to find the closures.  So just create an empty list.
-                * Folding will effectively be restricted to the non-Unicode
-                * rules hard-coded into Perl.  (This case happens legitimately
-                * during compilation of Perl itself before the Unicode tables
-                * are generated) */
-               if (invlist_len(PL_utf8_foldable) == 0) {
-                   PL_utf8_foldclosures = _new_invlist(0);
-               } else {
-                   /* If the folds haven't been read in, call a fold function
-                    * to force that */
-                   if (! PL_utf8_tofold) {
-                       U8 dummy[UTF8_MAXBYTES+1];
-                       STRLEN dummy_len;
-                       to_utf8_fold((U8*) "A", dummy, &dummy_len);
-                   }
-                   PL_utf8_foldclosures = _swash_inversion_hash(PL_utf8_tofold);
+       /* This is a list of all the characters that participate in folds
+           * (except marks, etc in multi-char folds */
+       if (! PL_utf8_foldable) {
+           SV* swash = swash_init("utf8", "Cased", &PL_sv_undef, 1, 0);
+           PL_utf8_foldable = _swash_to_invlist(swash);
+       }
+
+       /* This is a hash that for a particular fold gives all characters
+           * that are involved in it */
+       if (! PL_utf8_foldclosures) {
+
+           /* If we were unable to find any folds, then we likely won't be
+            * able to find the closures.  So just create an empty list.
+            * Folding will effectively be restricted to the non-Unicode rules
+            * hard-coded into Perl.  (This case happens legitimately during
+            * compilation of Perl itself before the Unicode tables are
+            * generated) */
+           if (invlist_len(PL_utf8_foldable) == 0) {
+               PL_utf8_foldclosures = newHV();
+           } else {
+               /* If the folds haven't been read in, call a fold function
+                   * to force that */
+               if (! PL_utf8_tofold) {
+                   U8 dummy[UTF8_MAXBYTES+1];
+                   STRLEN dummy_len;
+                   to_utf8_fold((U8*) "A", dummy, &dummy_len);
                }
+               PL_utf8_foldclosures = _swash_inversion_hash(PL_utf8_tofold);
            }
+       }
+
+       /* Only the characters in this class that participate in folds need
+           * be checked.  Get the intersection of this class and all the
+           * possible characters that are foldable.  This can quickly narrow
+           * down a large class */
+       invlist_intersection(PL_utf8_foldable, nonbitmap, &fold_intersection);
+
+       /* Now look at the foldable characters in this class individually */
+       fold_list = invlist_array(fold_intersection);
+       for (i = 0; i < invlist_len(fold_intersection); i++) {
+           UV j;
 
-           /* Only the characters in this class that participate in folds need
-            * be checked.  Get the intersection of this class and all the
-            * possible characters that are foldable.  This can quickly narrow
-            * down a large class */
-           fold_intersection = invlist_intersection(PL_utf8_foldable, nonbitmap);
-
-           /* Now look at the foldable characters in this class individually */
-           fold_list = invlist_array(fold_intersection);
-           for (i = 0; i < invlist_len(fold_intersection); i++) {
-               UV j;
-
-               /* The next entry is the beginning of the range that is in the
-                * class */
-               UV start = fold_list[i++];
-
-
-               /* The next entry is the beginning of the next range, which
-                * isn't in the class, so the end of the current range is one
-                * less than that */
-               UV end = fold_list[i] - 1;
-
-               /* Look at every character in the range */
-               for (j = start; j <= end; j++) {
-
-                   /* Get its fold */
-                   U8 foldbuf[UTF8_MAXBYTES_CASE+1];
-                   STRLEN foldlen;
-                   const UV f = to_uni_fold(j, foldbuf, &foldlen);
-
-                   if (foldlen > (STRLEN)UNISKIP(f)) {
-
-                       /* Any multicharacter foldings (disallowed in
-                        * lookbehind patterns) require the following
-                        * transform: [ABCDEF] -> (?:[ABCabcDEFd]|pq|rst) where
-                        * E folds into "pq" and F folds into "rst", all other
-                        * characters fold to single characters.  We save away
-                        * these multicharacter foldings, to be later saved as
-                        * part of the additional "s" data. */
-                       if (! RExC_in_lookbehind) {
-                           SV *sv;
-                           U8* loc = foldbuf;
-                           U8* e = foldbuf + foldlen;
-
-                           /* If any of the folded characters of this are in
-                            * the Latin1 range, tell the regex engine that
-                            * this can match a non-utf8 target string.  The
-                            * multi-byte fold whose source is in the
-                            * Latin1 range (U+00DF) applies only when the
-                            * target string is utf8, or under unicode rules */
-                           if (j > 255 || AT_LEAST_UNI_SEMANTICS) {
-                               while (loc < e) {
-                                   if (MORE_ASCII_RESTRICTED && (isASCII(*loc) != isASCII(j))) {
+           /* The next entry is the beginning of the range that is in the
+            * class */
+           UV start = fold_list[i++];
+
+
+           /* The next entry is the beginning of the next range, which
+               * isn't in the class, so the end of the current range is one
+               * less than that */
+           UV end = fold_list[i] - 1;
+
+           /* Look at every character in the range */
+           for (j = start; j <= end; j++) {
+
+               /* Get its fold */
+               U8 foldbuf[UTF8_MAXBYTES_CASE+1];
+               STRLEN foldlen;
+               const UV f =
+                    _to_uni_fold_flags(j, foldbuf, &foldlen, allow_full_fold);
+
+               if (foldlen > (STRLEN)UNISKIP(f)) {
+
+                   /* Any multicharacter foldings (disallowed in
+                       * lookbehind patterns) require the following
+                       * transform: [ABCDEF] -> (?:[ABCabcDEFd]|pq|rst) where
+                       * E folds into "pq" and F folds into "rst", all other
+                       * characters fold to single characters.  We save away
+                       * these multicharacter foldings, to be later saved as
+                       * part of the additional "s" data. */
+                   if (! RExC_in_lookbehind) {
+                       U8* loc = foldbuf;
+                       U8* e = foldbuf + foldlen;
+
+                       /* If any of the folded characters of this are in
+                           * the Latin1 range, tell the regex engine that
+                           * this can match a non-utf8 target string.  The
+                           * only multi-byte fold whose source is in the
+                           * Latin1 range (U+00DF) applies only when the
+                           * target string is utf8, or under unicode rules */
+                       if (j > 255 || AT_LEAST_UNI_SEMANTICS) {
+                           while (loc < e) {
+
+                               /* Can't mix ascii with non- under /aa */
+                               if (MORE_ASCII_RESTRICTED
+                                   && (isASCII(*loc) != isASCII(j)))
+                               {
+                                   goto end_multi_fold;
+                               }
+                               if (UTF8_IS_INVARIANT(*loc)
+                                   || UTF8_IS_DOWNGRADEABLE_START(*loc))
+                               {
+                                   /* Can't mix above and below 256 under
+                                       * LOC */
+                                   if (LOC) {
                                        goto end_multi_fold;
                                    }
-                                   /* XXX Discard this fold if any are latin1
-                                    * and LOC */
-                                   if (UTF8_IS_INVARIANT(*loc)
-                                       || UTF8_IS_DOWNGRADEABLE_START(*loc))
-                                   {
-                                       ANYOF_FLAGS(ret)
-                                               |= ANYOF_NONBITMAP_NON_UTF8;
-                                       break;
-                                   }
-                                   loc += UTF8SKIP(loc);
+                                   ANYOF_FLAGS(ret)
+                                           |= ANYOF_NONBITMAP_NON_UTF8;
+                                   break;
                                }
+                               loc += UTF8SKIP(loc);
                            }
-                           ANYOF_FLAGS(ret) |= ANYOF_UTF8;
+                       }
 
-                           if (!unicode_alternate) {
-                               unicode_alternate = newAV();
-                           }
-                           sv = newSVpvn_utf8((char*)foldbuf, foldlen, TRUE);
-                           av_push(unicode_alternate, sv);
+                       add_alternate(&unicode_alternate, foldbuf, foldlen);
+                   end_multi_fold: ;
+                   }
 
-                           /* This node is variable length */
-                           OP(ret) = ANYOFV;
-                       end_multi_fold: ;
-                       }
+                   /* This is special-cased, as it is the only letter which
+                    * has both a multi-fold and single-fold in Latin1.  All
+                    * the other chars that have single and multi-folds are
+                    * always in utf8, and the utf8 folding algorithm catches
+                    * them */
+                   if (! LOC && j == LATIN_CAPITAL_LETTER_SHARP_S) {
+                       stored += set_regclass_bit(pRExC_state,
+                                       ret,
+                                       LATIN_SMALL_LETTER_SHARP_S,
+                                       &l1_fold_invlist, &unicode_alternate);
                    }
-                   else { /* Single character fold */
-                       SV** listp;
-
-                       /* Consider "k" =~ /[K]/i.  The line above would have
-                        * just folded the 'k' to itself, and that isn't going
-                        * to match 'K'.  So we look through the closure of
-                        * everything that folds to 'k'.  That will find the
-                        * 'K'.  Initialize the list, if necessary */
-
-                       /* The data structure is a hash with the keys every
-                        * character that is folded to, like 'k', and the
-                        * values each an array of everything that folds to its
-                        * key.  e.g. [ 'k', 'K', KELVIN_SIGN ] */
-                       if ((listp = hv_fetch(PL_utf8_foldclosures,
-                                     (char *) foldbuf, foldlen, FALSE)))
-                       {
-                           AV* list = (AV*) *listp;
-                           IV k;
-                           for (k = 0; k <= av_len(list); k++) {
-                               SV** c_p = av_fetch(list, k, FALSE);
-                               UV c;
-                               if (c_p == NULL) {
-                                   Perl_croak(aTHX_ "panic: invalid PL_utf8_foldclosures structure");
-                               }
-                               c = SvUV(*c_p);
-                               if (MORE_ASCII_RESTRICTED && (isASCII(c) != isASCII(j))) {
-                                   continue;
-                               }
+               }
+               else {
+                   /* Single character fold.  Add everything in its fold
+                       * closure to the list that this node should match */
+                   SV** listp;
+
+                   /* The fold closures data structure is a hash with the
+                       * keys being every character that is folded to, like
+                       * 'k', and the values each an array of everything that
+                       * folds to its key.  e.g. [ 'k', 'K', KELVIN_SIGN ] */
+                   if ((listp = hv_fetch(PL_utf8_foldclosures,
+                                   (char *) foldbuf, foldlen, FALSE)))
+                   {
+                       AV* list = (AV*) *listp;
+                       IV k;
+                       for (k = 0; k <= av_len(list); k++) {
+                           SV** c_p = av_fetch(list, k, FALSE);
+                           UV c;
+                           if (c_p == NULL) {
+                               Perl_croak(aTHX_ "panic: invalid PL_utf8_foldclosures structure");
+                           }
+                           c = SvUV(*c_p);
+
+                           /* /aa doesn't allow folds between ASCII and
+                               * non-; /l doesn't allow them between above
+                               * and below 256 */
+                           if ((MORE_ASCII_RESTRICTED
+                                && (isASCII(c) != isASCII(j)))
+                                   || (LOC && ((c < 256) != (j < 256))))
+                           {
+                               continue;
+                           }
 
-                               if (c < 256 && AT_LEAST_UNI_SEMANTICS) {
-                                   stored += set_regclass_bit(pRExC_state, ret, (U8) c, &nonbitmap);
-                               }
-                                   /* It may be that the code point is already
-                                    * in this range or already in the bitmap,
-                                    * XXX THink about LOC
-                                    * in which case we need do nothing */
-                               else if ((c < start || c > end)
-                                        && (c > 255
-                                            || ! ANYOF_BITMAP_TEST(ret, c)))
-                               {
-                                   nonbitmap = add_range_to_invlist(nonbitmap, c, c);
-                               }
+                           if (c < 256 && AT_LEAST_UNI_SEMANTICS) {
+                               stored += set_regclass_bit(pRExC_state,
+                                       ret,
+                                       (U8) c,
+                                       &l1_fold_invlist, &unicode_alternate);
+                           }
+                               /* It may be that the code point is already
+                                   * in this range or already in the bitmap,
+                                   * in which case we need do nothing */
+                           else if ((c < start || c > end)
+                                       && (c > 255
+                                           || ! ANYOF_BITMAP_TEST(ret, c)))
+                           {
+                               nonbitmap = add_cp_to_invlist(nonbitmap, c);
                            }
                        }
                    }
                }
            }
-           invlist_destroy(fold_intersection);
-       } /* End of processing all the folds */
-
-       /*  Here have the full list of items to match that aren't in the
-        *  bitmap.  Convert to the structure that the rest of the code is
-        *  expecting.   XXX That rest of the code should convert to this
-        *  structure */
-       nonbitmap_array = invlist_array(nonbitmap);
-       for (i = 0; i < invlist_len(nonbitmap); i++) {
-
-           /* The next entry is the beginning of the range that is in the
-            * class */
-           UV start = nonbitmap_array[i++];
-
-           /* The next entry is the beginning of the next range, which isn't
-            * in the class, so the end of the current range is one less than
-            * that */
-           UV end = nonbitmap_array[i] - 1;
+       }
+       SvREFCNT_dec(fold_intersection);
+    }
 
-           if (start == end) {
-               Perl_sv_catpvf(aTHX_ listsv, "%04"UVxf"\n", start);
-           }
-           else {
-               /* The \t sets the whole range */
-               Perl_sv_catpvf(aTHX_ listsv, "%04"UVxf"\t%04"UVxf"\n",
-                       /* XXX EBCDIC */
-                                  start, end);
-           }
+    /* Combine the two lists into one. */
+    if (l1_fold_invlist) {
+       if (nonbitmap) {
+           invlist_union(nonbitmap, l1_fold_invlist, &nonbitmap);
+           SvREFCNT_dec(l1_fold_invlist);
+       }
+       else {
+           nonbitmap = l1_fold_invlist;
        }
-       invlist_destroy(nonbitmap);
     }
 
     /* Here, we have calculated what code points should be in the character
@@ -10080,20 +10253,25 @@ parseit:
      * optimize locale.  Doing so perhaps could be done as long as there is
      * nothing like \w in it; some thought also would have to be given to the
      * interaction with above 0x100 chars */
-    if (! LOC && (ANYOF_FLAGS(ret) & ANYOF_FLAGS_ALL) == ANYOF_INVERT) {
+    if (! LOC
+       && (ANYOF_FLAGS(ret) & ANYOF_FLAGS_ALL) == ANYOF_INVERT
+       && ! unicode_alternate
+       && ! nonbitmap
+       && SvCUR(listsv) == initial_listsv_len)
+    {
        for (value = 0; value < ANYOF_BITMAP_SIZE; ++value)
            ANYOF_BITMAP(ret)[value] ^= 0xFF;
        stored = 256 - stored;
 
        /* The inversion means that everything above 255 is matched; and at the
         * same time we clear the invert flag */
-       ANYOF_FLAGS(ret) = ANYOF_UTF8|ANYOF_UNICODE_ALL;
+       ANYOF_FLAGS(ret) = ANYOF_UNICODE_ALL;
     }
 
     /* Folding in the bitmap is taken care of above, but not for locale (for
      * which we have to wait to see what folding is in effect at runtime), and
      * for things not in the bitmap.  Set run-time fold flag for these */
-    if (FOLD && (LOC || (ANYOF_FLAGS(ret) & ANYOF_NONBITMAP))) {
+    if (FOLD && (LOC || nonbitmap || unicode_alternate)) {
        ANYOF_FLAGS(ret) |= ANYOF_LOC_NONBITMAP_FOLD;
     }
 
@@ -10111,7 +10289,10 @@ parseit:
      * characters which only have the two folds; so things like 'fF' and 'Ii'
      * wouldn't work because they are part of the fold of 'LATIN SMALL LIGATURE
      * FI'. */
-    if (! (ANYOF_FLAGS(ret) & (ANYOF_NONBITMAP|ANYOF_INVERT|ANYOF_UNICODE_ALL))
+    if (! nonbitmap
+       && ! unicode_alternate
+       && SvCUR(listsv) == initial_listsv_len
+       && ! (ANYOF_FLAGS(ret) & (ANYOF_INVERT|ANYOF_UNICODE_ALL))
         && (((stored == 1 && ((! (ANYOF_FLAGS(ret) & ANYOF_LOCALE))
                               || (! ANYOF_CLASS_TEST_ANY_SET(ret)))))
            || (stored == 2 && ((! (ANYOF_FLAGS(ret) & ANYOF_LOCALE))
@@ -10178,7 +10359,54 @@ parseit:
         return ret;
     }
 
-    {
+    if (nonbitmap) {
+       UV* nonbitmap_array = invlist_array(nonbitmap);
+       UV nonbitmap_len = invlist_len(nonbitmap);
+       UV i;
+
+       /*  Here have the full list of items to match that aren't in the
+        *  bitmap.  Convert to the structure that the rest of the code is
+        *  expecting.   XXX That rest of the code should convert to this
+        *  structure */
+       for (i = 0; i < nonbitmap_len; i++) {
+
+           /* The next entry is the beginning of the range that is in the
+            * class */
+           UV start = nonbitmap_array[i++];
+           UV end;
+
+           /* The next entry is the beginning of the next range, which isn't
+            * in the class, so the end of the current range is one less than
+            * that.  But if there is no next range, it means that the range
+            * begun by 'start' extends to infinity, which for this platform
+            * ends at UV_MAX */
+           if (i == nonbitmap_len) {
+               end = UV_MAX;
+           }
+           else {
+               end = nonbitmap_array[i] - 1;
+           }
+
+           if (start == end) {
+               Perl_sv_catpvf(aTHX_ listsv, "%04"UVxf"\n", start);
+           }
+           else {
+               /* The \t sets the whole range */
+               Perl_sv_catpvf(aTHX_ listsv, "%04"UVxf"\t%04"UVxf"\n",
+                       /* XXX EBCDIC */
+                                  start, end);
+           }
+       }
+       SvREFCNT_dec(nonbitmap);
+    }
+
+    if (SvCUR(listsv) == initial_listsv_len && ! unicode_alternate) {
+       ARG_SET(ret, ANYOF_NONBITMAP_EMPTY);
+       SvREFCNT_dec(listsv);
+       SvREFCNT_dec(unicode_alternate);
+    }
+    else {
+
        AV * const av = newAV();
        SV *rv;
        /* The 0th element stores the character class description
@@ -10189,7 +10417,18 @@ parseit:
         * used later (regexec.c:S_reginclass()). */
        av_store(av, 0, listsv);
        av_store(av, 1, NULL);
-       av_store(av, 2, MUTABLE_SV(unicode_alternate));
+
+        /* Store any computed multi-char folds only if we are allowing
+         * them */
+        if (allow_full_fold) {
+            av_store(av, 2, MUTABLE_SV(unicode_alternate));
+            if (unicode_alternate) { /* This node is variable length */
+                OP(ret) = ANYOFV;
+            }
+        }
+        else {
+            av_store(av, 2, NULL);
+        }
        rv = newRV_noinc(MUTABLE_SV(av));
        n = add_data(pRExC_state, 1, "s");
        RExC_rxi->data->data[n] = (void*)rv;
@@ -10983,12 +11222,12 @@ Perl_regprop(pTHX_ const regexp *prog, SV *sv, const regnode *o)
         /* output information about the unicode matching */
        if (flags & ANYOF_UNICODE_ALL)
            sv_catpvs(sv, "{unicode_all}");
-       else if (flags & ANYOF_UTF8)
+       else if (ANYOF_NONBITMAP(o))
            sv_catpvs(sv, "{unicode}");
        if (flags & ANYOF_NONBITMAP_NON_UTF8)
            sv_catpvs(sv, "{outside bitmap}");
 
-       {
+       if (ANYOF_NONBITMAP(o)) {
            SV *lv;
            SV * const sw = regclass_swash(prog, o, FALSE, &lv, 0);
        
@@ -11461,12 +11700,11 @@ Perl_regdupe_internal(pTHX_ REGEXP * const rx, CLONE_PARAMS *param)
     dVAR;
     struct regexp *const r = (struct regexp *)SvANY(rx);
     regexp_internal *reti;
-    int len, npar;
+    int len;
     RXi_GET_DECL(r,ri);
 
     PERL_ARGS_ASSERT_REGDUPE_INTERNAL;
     
-    npar = r->nparens+1;
     len = ProgLen(ri);
     
     Newxc(reti, sizeof(regexp_internal) + len*sizeof(regnode), char, regexp_internal);