This is a live mirror of the Perl 5 development currently hosted at https://github.com/perl/perl5
PATCH: [perl #116899]: jump on uninitialised value
[perl5.git] / toke.c
diff --git a/toke.c b/toke.c
index cc123fd..49ff5fa 100644 (file)
--- a/toke.c
+++ b/toke.c
@@ -110,10 +110,7 @@ Individual members of C<PL_parser> have their own documentation.
 #  define PL_nextval           (PL_parser->nextval)
 #endif
 
-#define force_ident_maybe_lex(p) \
-       (PL_bufptr = s, S_force_ident_maybe_lex(aTHX_ p))
-
-static const char ident_too_long[] = "Identifier too long";
+static const char* const ident_too_long = "Identifier too long";
 
 #ifdef PERL_MAD
 #  define CURMAD(slot,sv) if (PL_madskills) { curmad(slot,sv); sv = 0; }
@@ -361,7 +358,7 @@ static struct debug_tokens {
     { GIVEN,           TOKENTYPE_IVAL,         "GIVEN" },
     { HASHBRACK,       TOKENTYPE_NONE,         "HASHBRACK" },
     { IF,              TOKENTYPE_IVAL,         "IF" },
-    { LABEL,           TOKENTYPE_OPVAL,        "LABEL" },
+    { LABEL,           TOKENTYPE_PVAL,         "LABEL" },
     { LOCAL,           TOKENTYPE_IVAL,         "LOCAL" },
     { LOOPEX,          TOKENTYPE_OPNUM,        "LOOPEX" },
     { LSTOP,           TOKENTYPE_OPNUM,        "LSTOP" },
@@ -370,7 +367,6 @@ static struct debug_tokens {
     { METHOD,          TOKENTYPE_OPVAL,        "METHOD" },
     { MULOP,           TOKENTYPE_OPNUM,        "MULOP" },
     { MY,              TOKENTYPE_IVAL,         "MY" },
-    { MYSUB,           TOKENTYPE_NONE,         "MYSUB" },
     { NOAMP,           TOKENTYPE_NONE,         "NOAMP" },
     { NOTOP,           TOKENTYPE_NONE,         "NOTOP" },
     { OROP,            TOKENTYPE_IVAL,         "OROP" },
@@ -548,7 +544,7 @@ S_no_op(pTHX_ const char *const what, char *s)
                    "\t(Missing semicolon on previous line?)\n");
        else if (PL_oldoldbufptr && isIDFIRST_lazy_if(PL_oldoldbufptr,UTF)) {
            const char *t;
-           for (t = PL_oldoldbufptr; (isALNUM_lazy_if(t,UTF) || *t == ':');
+           for (t = PL_oldoldbufptr; (isWORDCHAR_lazy_if(t,UTF) || *t == ':');
                                                             t += UTF ? UTF8SKIP(t) : 1)
                NOOP;
            if (t < PL_bufptr && isSPACE(*t))
@@ -788,6 +784,8 @@ Perl_parser_free(pTHX_  const yy_parser *parser)
                (parser->old_parser && parser->rsfp != parser->old_parser->rsfp)))
        PerlIO_close(parser->rsfp);
     SvREFCNT_dec(parser->rsfp_filters);
+    SvREFCNT_dec(parser->lex_stuff);
+    SvREFCNT_dec(parser->sublex_info.repl);
 
     Safefree(parser->lex_brackstack);
     Safefree(parser->lex_casestack);
@@ -796,6 +794,37 @@ Perl_parser_free(pTHX_  const yy_parser *parser)
     Safefree(parser);
 }
 
+void
+Perl_parser_free_nexttoke_ops(pTHX_  yy_parser *parser, OPSLAB *slab)
+{
+#ifdef PERL_MAD
+    I32 nexttoke = parser->lasttoke;
+#else
+    I32 nexttoke = parser->nexttoke;
+#endif
+    PERL_ARGS_ASSERT_PARSER_FREE_NEXTTOKE_OPS;
+    while (nexttoke--) {
+#ifdef PERL_MAD
+       if (S_is_opval_token(parser->nexttoke[nexttoke].next_type
+                               & 0xffff)
+        && parser->nexttoke[nexttoke].next_val.opval
+        && parser->nexttoke[nexttoke].next_val.opval->op_slabbed
+        && OpSLAB(parser->nexttoke[nexttoke].next_val.opval) == slab) {
+               op_free(parser->nexttoke[nexttoke].next_val.opval);
+               parser->nexttoke[nexttoke].next_val.opval = NULL;
+       }
+#else
+       if (S_is_opval_token(parser->nexttype[nexttoke] & 0xffff)
+        && parser->nextval[nexttoke].opval
+        && parser->nextval[nexttoke].opval->op_slabbed
+        && OpSLAB(parser->nextval[nexttoke].opval) == slab) {
+           op_free(parser->nextval[nexttoke].opval);
+           parser->nextval[nexttoke].opval = NULL;
+       }
+#endif
+    }
+}
+
 
 /*
 =for apidoc AmxU|SV *|PL_parser-E<gt>linestr
@@ -980,10 +1009,13 @@ Perl_lex_stuff_pvn(pTHX_ const char *pv, STRLEN len, U32 flags)
        if (flags & LEX_STUFF_UTF8) {
            goto plain_copy;
        } else {
-           STRLEN highhalf = 0;
+           STRLEN highhalf = 0;    /* Count of variants */
            const char *p, *e = pv+len;
-           for (p = pv; p != e; p++)
-               highhalf += !!(((U8)*p) & 0x80);
+           for (p = pv; p != e; p++) {
+               if (! UTF8_IS_INVARIANT(*p)) {
+                    highhalf++;
+                }
+            }
            if (!highhalf)
                goto plain_copy;
            lex_grow_linestr(SvCUR(PL_parser->linestr)+1+len+highhalf);
@@ -994,9 +1026,9 @@ Perl_lex_stuff_pvn(pTHX_ const char *pv, STRLEN len, U32 flags)
            PL_parser->bufend += len+highhalf;
            for (p = pv; p != e; p++) {
                U8 c = (U8)*p;
-               if (c & 0x80) {
-                   *bufptr++ = (char)(0xc0 | (c >> 6));
-                   *bufptr++ = (char)(0x80 | (c & 0x3f));
+               if (! UTF8_IS_INVARIANT(c)) {
+                   *bufptr++ = UTF8_TWO_BYTE_HI(c);
+                   *bufptr++ = UTF8_TWO_BYTE_LO(c);
                } else {
                    *bufptr++ = (char)c;
                }
@@ -1008,14 +1040,13 @@ Perl_lex_stuff_pvn(pTHX_ const char *pv, STRLEN len, U32 flags)
            const char *p, *e = pv+len;
            for (p = pv; p != e; p++) {
                U8 c = (U8)*p;
-               if (c >= 0xc4) {
+               if (UTF8_IS_ABOVE_LATIN1(c)) {
                    Perl_croak(aTHX_ "Lexing code attempted to stuff "
                                "non-Latin-1 character into Latin-1 input");
-               } else if (c >= 0xc2 && p+1 != e &&
-                           (((U8)p[1]) & 0xc0) == 0x80) {
+               } else if (UTF8_IS_NEXT_CHAR_DOWNGRADEABLE(p, e)) {
                    p++;
                    highhalf++;
-               } else if (c >= 0x80) {
+               } else if (! UTF8_IS_INVARIANT(c)) {
                    /* malformed UTF-8 */
                    ENTER;
                    SAVESPTR(PL_warnhook);
@@ -1032,17 +1063,20 @@ Perl_lex_stuff_pvn(pTHX_ const char *pv, STRLEN len, U32 flags)
            SvCUR_set(PL_parser->linestr,
                SvCUR(PL_parser->linestr) + len-highhalf);
            PL_parser->bufend += len-highhalf;
-           for (p = pv; p != e; p++) {
-               U8 c = (U8)*p;
-               if (c & 0x80) {
-                   *bufptr++ = (char)(((c & 0x3) << 6) | (p[1] & 0x3f));
-                   p++;
-               } else {
-                   *bufptr++ = (char)c;
+           p = pv;
+           while (p < e) {
+               if (UTF8_IS_INVARIANT(*p)) {
+                   *bufptr++ = *p;
+                    p++;
                }
+               else {
+                    assert(p < e -1 );
+                   *bufptr++ = TWO_BYTE_UTF8_TO_UNI(*p, *(p+1));
+                   p += 2;
+                }
            }
        } else {
-           plain_copy:
+         plain_copy:
            lex_grow_linestr(SvCUR(PL_parser->linestr)+1+len);
            bufptr = PL_parser->bufptr;
            Move(bufptr, bufptr+len, PL_parser->bufend+1-bufptr, char);
@@ -1390,10 +1424,10 @@ Perl_lex_peek_unichar(pTHX_ U32 flags)
            bufend = PL_parser->bufend;
        }
        head = (U8)*s;
-       if (!(head & 0x80))
+       if (UTF8_IS_INVARIANT(head))
            return head;
-       if (head & 0x40) {
-           len = PL_utf8skip[head];
+       if (UTF8_IS_START(head)) {
+           len = UTF8SKIP(&head);
            while ((STRLEN)(bufend-s) < len) {
                if (!lex_next_chunk(flags | LEX_KEEP_PREVIOUS))
                    break;
@@ -1563,6 +1597,12 @@ S_incline(pTHX_ const char *s)
     PERL_ARGS_ASSERT_INCLINE;
 
     COPLINE_INC_WITH_HERELINES;
+    if (!PL_rsfp && !PL_parser->filtered && PL_lex_state == LEX_NORMAL
+     && s+1 == PL_bufend && *s == ';') {
+       /* fake newline in string eval */
+       CopLINE_dec(PL_curcop);
+       return;
+    }
     if (*s++ != '#')
        return;
     while (SPACE_OR_TAB(*s))
@@ -1695,7 +1735,7 @@ S_incline(pTHX_ const char *s)
 /* skip space before PL_thistoken */
 
 STATIC char *
-S_skipspace0(pTHX_ register char *s)
+S_skipspace0(pTHX_ char *s)
 {
     PERL_ARGS_ASSERT_SKIPSPACE0;
 
@@ -1716,7 +1756,7 @@ S_skipspace0(pTHX_ register char *s)
 /* skip space after PL_thistoken */
 
 STATIC char *
-S_skipspace1(pTHX_ register char *s)
+S_skipspace1(pTHX_ char *s)
 {
     const char *start = s;
     I32 startoff = start - SvPVX(PL_linestr);
@@ -1743,7 +1783,7 @@ S_skipspace1(pTHX_ register char *s)
 }
 
 STATIC char *
-S_skipspace2(pTHX_ register char *s, SV **svp)
+S_skipspace2(pTHX_ char *s, SV **svp)
 {
     char *start;
     const I32 bufptroff = PL_bufptr - SvPVX(PL_linestr);
@@ -1796,7 +1836,7 @@ S_update_debugger_info(pTHX_ SV *orig_sv, const char *const buf, STRLEN len)
  */
 
 STATIC char *
-S_skipspace(pTHX_ register char *s)
+S_skipspace(pTHX_ char *s)
 {
 #ifdef PERL_MAD
     char *start = s;
@@ -1851,7 +1891,7 @@ S_check_uni(pTHX)
     while (isSPACE(*PL_last_uni))
        PL_last_uni++;
     s = PL_last_uni;
-    while (isALNUM_lazy_if(s,UTF) || *s == '-')
+    while (isWORDCHAR_lazy_if(s,UTF) || *s == '-')
        s++;
     if ((t = strchr(s, '(')) && t < PL_bufptr)
        return;
@@ -1998,11 +2038,6 @@ S_force_next(pTHX_ I32 type)
        tokereport(type, &NEXTVAL_NEXTTOKE);
     }
 #endif
-    /* Don’t let opslab_force_free snatch it */
-    if (S_is_opval_token(type & 0xffff) && NEXTVAL_NEXTTOKE.opval) {
-       assert(!NEXTVAL_NEXTTOKE.opval->op_savefree);
-       NEXTVAL_NEXTTOKE.opval->op_savefree = 1;
-    }  
 #ifdef PERL_MAD
     if (PL_curforce < 0)
        start_force(PL_lasttoke);
@@ -2075,7 +2110,7 @@ S_newSV_maybe_utf8(pTHX_ const char *const start, STRLEN len)
  */
 
 STATIC char *
-S_force_word(pTHX_ register char *start, int token, int check_keyword, int allow_pack, int allow_initial_tick)
+S_force_word(pTHX_ char *start, int token, int check_keyword, int allow_pack, int allow_initial_tick)
 {
     dVAR;
     char *s;
@@ -2124,14 +2159,14 @@ S_force_word(pTHX_ register char *start, int token, int check_keyword, int allow
  */
 
 STATIC void
-S_force_ident(pTHX_ register const char *s, int kind)
+S_force_ident(pTHX_ const char *s, int kind)
 {
     dVAR;
 
     PERL_ARGS_ASSERT_FORCE_IDENT;
 
-    if (*s) {
-       const STRLEN len = strlen(s);
+    if (s[0]) {
+       const STRLEN len = s[1] ? strlen(s) : 1; /* s = "\"" see yylex */
        OP* const o = (OP*)newSVOP(OP_CONST, 0, newSVpvn_flags(s, len,
                                                                 UTF ? SVf_UTF8 : 0));
        start_force(PL_curforce);
@@ -2154,6 +2189,14 @@ S_force_ident(pTHX_ register const char *s, int kind)
     }
 }
 
+static void
+S_force_ident_maybe_lex(pTHX_ char pit)
+{
+    start_force(PL_curforce);
+    NEXTVAL_NEXTTOKE.ival = pit;
+    force_next('p');
+}
+
 NV
 Perl_str_to_version(pTHX_ SV *sv)
 {
@@ -2604,6 +2647,201 @@ S_sublex_done(pTHX)
     }
 }
 
+PERL_STATIC_INLINE SV*
+S_get_and_check_backslash_N_name(pTHX_ const char* s, const char* const e)
+{
+    /* <s> points to first character of interior of \N{}, <e> to one beyond the
+     * interior, hence to the "}".  Finds what the name resolves to, returning
+     * an SV* containing it; NULL if no valid one found */
+
+    SV* res = newSVpvn_flags(s, e - s, UTF ? SVf_UTF8 : 0);
+
+    HV * table;
+    SV **cvp;
+    SV *cv;
+    SV *rv;
+    HV *stash;
+    const U8* first_bad_char_loc;
+    const char* backslash_ptr = s - 3; /* Points to the <\> of \N{... */
+
+    PERL_ARGS_ASSERT_GET_AND_CHECK_BACKSLASH_N_NAME;
+
+    if (UTF && ! is_utf8_string_loc((U8 *) backslash_ptr,
+                                     e - backslash_ptr,
+                                     &first_bad_char_loc))
+    {
+        /* If warnings are on, this will print a more detailed analysis of what
+         * is wrong than the error message below */
+        utf8n_to_uvuni(first_bad_char_loc,
+                       e - ((char *) first_bad_char_loc),
+                       NULL, 0);
+
+        /* We deliberately don't try to print the malformed character, which
+         * might not print very well; it also may be just the first of many
+         * malformations, so don't print what comes after it */
+        yyerror(Perl_form(aTHX_
+            "Malformed UTF-8 character immediately after '%.*s'",
+            (int) (first_bad_char_loc - (U8 *) backslash_ptr), backslash_ptr));
+       return NULL;
+    }
+
+    res = new_constant( NULL, 0, "charnames", res, NULL, backslash_ptr,
+                        /* include the <}> */
+                        e - backslash_ptr + 1);
+    if (! SvPOK(res)) {
+        SvREFCNT_dec_NN(res);
+        return NULL;
+    }
+
+    /* See if the charnames handler is the Perl core's, and if so, we can skip
+     * the validation needed for a user-supplied one, as Perl's does its own
+     * validation. */
+    table = GvHV(PL_hintgv);            /* ^H */
+    cvp = hv_fetchs(table, "charnames", FALSE);
+    if (cvp && (cv = *cvp) && SvROK(cv) && ((rv = SvRV(cv)) != NULL)
+        && SvTYPE(rv) == SVt_PVCV && ((stash = CvSTASH(rv)) != NULL))
+    {
+        const char * const name = HvNAME(stash);
+        if strEQ(name, "_charnames") {
+           return res;
+       }
+    }
+
+    /* Here, it isn't Perl's charname handler.  We can't rely on a
+     * user-supplied handler to validate the input name.  For non-ut8 input,
+     * look to see that the first character is legal.  Then loop through the
+     * rest checking that each is a continuation */
+
+    /* This code needs to be sync'ed with a regex in _charnames.pm which does
+     * the same thing */
+
+    if (! UTF) {
+        if (! isALPHAU(*s)) {
+            goto bad_charname;
+        }
+        s++;
+        while (s < e) {
+            if (! isCHARNAME_CONT(*s)) {
+                goto bad_charname;
+            }
+           if (*s == ' ' && *(s-1) == ' ' && ckWARN(WARN_DEPRECATED)) {
+                Perl_warn(aTHX_ "A sequence of multiple spaces in a charnames alias definition is deprecated");
+            }
+            s++;
+        }
+        if (*(s-1) == ' ' && ckWARN(WARN_DEPRECATED)) {
+            Perl_warn(aTHX_ "Trailing white-space in a charnames alias definition is deprecated");
+        }
+    }
+    else {
+        /* Similarly for utf8.  For invariants can check directly; for other
+         * Latin1, can calculate their code point and check; otherwise  use a
+         * swash */
+        if (UTF8_IS_INVARIANT(*s)) {
+            if (! isALPHAU(*s)) {
+                goto bad_charname;
+            }
+            s++;
+        } else if (UTF8_IS_DOWNGRADEABLE_START(*s)) {
+            if (! isALPHAU(UNI_TO_NATIVE(TWO_BYTE_UTF8_TO_UNI(*s, *(s+1))))) {
+                goto bad_charname;
+            }
+            s += 2;
+        }
+        else {
+            if (! PL_utf8_charname_begin) {
+                U8 flags = _CORE_SWASH_INIT_ACCEPT_INVLIST;
+                PL_utf8_charname_begin = _core_swash_init("utf8",
+                                                        "_Perl_Charname_Begin",
+                                                        &PL_sv_undef,
+                                                        1, 0, NULL, &flags);
+            }
+            if (! swash_fetch(PL_utf8_charname_begin, (U8 *) s, TRUE)) {
+                goto bad_charname;
+            }
+            s += UTF8SKIP(s);
+        }
+
+        while (s < e) {
+            if (UTF8_IS_INVARIANT(*s)) {
+                if (! isCHARNAME_CONT(*s)) {
+                    goto bad_charname;
+                }
+                if (*s == ' ' && *(s-1) == ' ' && ckWARN(WARN_DEPRECATED)) {
+                    Perl_warn(aTHX_ "A sequence of multiple spaces in a charnames alias definition is deprecated");
+                }
+                s++;
+            }
+            else if (UTF8_IS_DOWNGRADEABLE_START(*s)) {
+                if (! isCHARNAME_CONT(UNI_TO_NATIVE(TWO_BYTE_UTF8_TO_UNI(*s,
+                                                                    *(s+1)))))
+                {
+                    goto bad_charname;
+                }
+                s += 2;
+            }
+            else {
+                if (! PL_utf8_charname_continue) {
+                    U8 flags = _CORE_SWASH_INIT_ACCEPT_INVLIST;
+                    PL_utf8_charname_continue = _core_swash_init("utf8",
+                                                "_Perl_Charname_Continue",
+                                                &PL_sv_undef,
+                                                1, 0, NULL, &flags);
+                }
+                if (! swash_fetch(PL_utf8_charname_continue, (U8 *) s, TRUE)) {
+                    goto bad_charname;
+                }
+                s += UTF8SKIP(s);
+            }
+        }
+        if (*(s-1) == ' ' && ckWARN(WARN_DEPRECATED)) {
+            Perl_warn(aTHX_ "Trailing white-space in a charnames alias definition is deprecated");
+        }
+    }
+
+    if (SvUTF8(res)) { /* Don't accept malformed input */
+        const U8* first_bad_char_loc;
+        STRLEN len;
+        const char* const str = SvPV_const(res, len);
+        if (! is_utf8_string_loc((U8 *) str, len, &first_bad_char_loc)) {
+            /* If warnings are on, this will print a more detailed analysis of
+             * what is wrong than the error message below */
+            utf8n_to_uvuni(first_bad_char_loc,
+                           (char *) first_bad_char_loc - str,
+                           NULL, 0);
+
+            /* We deliberately don't try to print the malformed character,
+             * which might not print very well; it also may be just the first
+             * of many malformations, so don't print what comes after it */
+            yyerror_pv(
+              Perl_form(aTHX_
+                "Malformed UTF-8 returned by %.*s immediately after '%.*s'",
+                 (int) (e - backslash_ptr + 1), backslash_ptr,
+                 (int) ((char *) first_bad_char_loc - str), str
+              ),
+              SVf_UTF8);
+            return NULL;
+        }
+    }
+
+    return res;
+
+  bad_charname: {
+        int bad_char_size = ((UTF) ? UTF8SKIP(s) : 1);
+
+        /* The final %.*s makes sure that should the trailing NUL be missing
+         * that this print won't run off the end of the string */
+        yyerror_pv(
+          Perl_form(aTHX_
+            "Invalid character in \\N{...}; marked by <-- HERE in %.*s<-- HERE %.*s",
+            (int)(s - backslash_ptr + bad_char_size), backslash_ptr,
+            (int)(e - s + bad_char_size), s + bad_char_size
+          ),
+          UTF ? SVf_UTF8 : 0);
+        return NULL;
+    }
+}
+
 /*
   scan_const
 
@@ -2711,6 +2949,7 @@ S_scan_const(pTHX_ char *start)
                                                   isn't utf8, as for example
                                                   when it is entirely composed
                                                   of hex constants */
+    SV *res;                           /* result from charnames */
 
     /* Note on sizing:  The scanned constant is placed into sv, which is
      * initialized by newSV() assuming one byte of output for every byte of
@@ -2724,7 +2963,8 @@ S_scan_const(pTHX_ char *start)
      * far, plus the length the current construct will occupy, plus room for
      * the trailing NUL, plus one byte for every input byte still unscanned */ 
 
-    UV uv;
+    UV uv = UV_MAX; /* Initialize to weird value to try to catch any uses
+                       before set */
 #ifdef EBCDIC
     UV literal_endpoint = 0;
     bool native_range = TRUE; /* turned to FALSE if the first endpoint is Unicode. */
@@ -2739,6 +2979,9 @@ S_scan_const(pTHX_ char *start)
        this_utf8  = PL_sublex_info.sub_op->op_private & (PL_lex_repl ? OPpTRANS_FROM_UTF : OPpTRANS_TO_UTF);
     }
 
+    /* Protect sv from errors and fatal warnings. */
+    ENTER_with_name("scan_const");
+    SAVEFREESV(sv);
 
     while (s < send || dorange) {
 
@@ -2758,7 +3001,7 @@ S_scan_const(pTHX_ char *start)
 #ifdef EBCDIC
                    && !native_range
 #endif
-                   ) {
+                ) {
                    char * const c = (char*)utf8_hop((U8*)d, -1);
                    char *e = d++;
                    while (e-- > c)
@@ -2810,7 +3053,6 @@ S_scan_const(pTHX_ char *start)
 #endif
 
                 if (min > max) {
-                   SvREFCNT_dec(sv);
                    Perl_croak(aTHX_
                               "Invalid range \"%c-%c\" in transliteration operator",
                               (char)min, (char)max);
@@ -2869,7 +3111,6 @@ S_scan_const(pTHX_ char *start)
            /* range begins (ignore - as first or last char) */
            else if (*s == '-' && s+1 < send  && s != start) {
                if (didrange) {
-                   SvREFCNT_dec(sv);
                    Perl_croak(aTHX_ "Ambiguous range in transliteration operator");
                }
                if (has_utf8
@@ -2945,7 +3186,7 @@ S_scan_const(pTHX_ char *start)
           (@foo, @::foo, @'foo, @{foo}, @$foo, @+, @-)
           */
        else if (*s == '@' && s[1]) {
-           if (isALNUM_lazy_if(s+1,UTF))
+           if (isWORDCHAR_lazy_if(s+1,UTF))
                break;
            if (strchr(":'{$", s[1]))
                break;
@@ -3007,7 +3248,7 @@ S_scan_const(pTHX_ char *start)
            else if (PL_lex_inpat
                    && (*s != 'N'
                        || s[1] != '{'
-                       || regcurly(s + 1)))
+                       || regcurly(s + 1, FALSE)))
            {
                *d++ = NATIVE_TO_NEED(has_utf8,'\\');
                goto default_action;
@@ -3024,7 +3265,7 @@ S_scan_const(pTHX_ char *start)
                /* FALL THROUGH */
            default:
                {
-                   if ((isALNUMC(*s)))
+                   if ((isALPHANUMERIC(*s)))
                        Perl_ck_warner(aTHX_ packWARN(WARN_MISC),
                                       "Unrecognized escape \\%c passed through",
                                       *s);
@@ -3036,21 +3277,30 @@ S_scan_const(pTHX_ char *start)
            case '0': case '1': case '2': case '3':
            case '4': case '5': case '6': case '7':
                {
-                    I32 flags = 0;
+                    I32 flags = PERL_SCAN_SILENT_ILLDIGIT;
                     STRLEN len = 3;
                    uv = NATIVE_TO_UNI(grok_oct(s, &len, &flags, NULL));
                    s += len;
+                    if (len < 3 && s < send && isDIGIT(*s)
+                        && ckWARN(WARN_MISC))
+                    {
+                        Perl_warner(aTHX_ packWARN(WARN_MISC),
+                                    "%s", form_short_octal_warning(s, len));
+                    }
                }
                goto NUM_ESCAPE_INSERT;
 
            /* eg. \o{24} indicates the octal constant \024 */
            case 'o':
                {
-                   STRLEN len;
                    const char* error;
 
-                   bool valid = grok_bslash_o(s, &uv, &len, &error, 1);
-                   s += len;
+                   bool valid = grok_bslash_o(&s, &uv, &error,
+                                               TRUE, /* Output warning */
+                                               FALSE, /* Not strict */
+                                               TRUE, /* Output warnings for
+                                                         non-portables */
+                                               UTF);
                    if (! valid) {
                        yyerror(error);
                        continue;
@@ -3061,11 +3311,14 @@ S_scan_const(pTHX_ char *start)
            /* eg. \x24 indicates the hex constant 0x24 */
            case 'x':
                {
-                   STRLEN len;
                    const char* error;
 
-                   bool valid = grok_bslash_x(s, &uv, &len, &error, 1);
-                   s += len;
+                   bool valid = grok_bslash_x(&s, &uv, &error,
+                                               TRUE, /* Output warning */
+                                               FALSE, /* Not strict */
+                                               TRUE,  /* Output warnings for
+                                                         non-portables */
+                                               UTF);
                    if (! valid) {
                        yyerror(error);
                        continue;
@@ -3174,31 +3427,6 @@ S_scan_const(pTHX_ char *start)
 
                /* Here it looks like a named character */
 
-               if (PL_lex_inpat) {
-
-                   /* XXX This block is temporary code.  \N{} implies that the
-                    * pattern is to have Unicode semantics, and therefore
-                    * currently has to be encoded in utf8.  By putting it in
-                    * utf8 now, we save a whole pass in the regular expression
-                    * compiler.  Once that code is changed so Unicode
-                    * semantics doesn't necessarily have to be in utf8, this
-                    * block should be removed.  However, the code that parses
-                    * the output of this would have to be changed to not
-                    * necessarily expect utf8 */
-                   if (!has_utf8) {
-                       SvCUR_set(sv, d - SvPVX_const(sv));
-                       SvPOK_on(sv);
-                       *d = '\0';
-                       /* See Note on sizing above.  */
-                       sv_utf8_upgrade_flags_grow(sv,
-                                       SV_GMAGIC|SV_FORCE_UTF8_UPGRADE,
-                                       /* 5 = '\N{' + cur char + NUL */
-                                       (STRLEN)(send - s) + 5);
-                       d = SvPVX(sv) + SvCUR(sv);
-                       has_utf8 = TRUE;
-                   }
-               }
-
                if (*s == 'U' && s[1] == '+') { /* \N{U+...} */
                    I32 flags = PERL_SCAN_ALLOW_UNDERSCORES
                                | PERL_SCAN_DISALLOW_PREFIX;
@@ -3260,32 +3488,12 @@ S_scan_const(pTHX_ char *start)
                        else d = (char*)uvuni_to_utf8((U8*)d, uv);
                    }
                }
-               else { /* Here is \N{NAME} but not \N{U+...}. */
-
-                   SV *res;            /* result from charnames */
-                   const char *str;    /* the string in 'res' */
-                   STRLEN len;         /* its length */
-
-                   /* Get the value for NAME */
-                   res = newSVpvn(s, e - s);
-                   res = new_constant( NULL, 0, "charnames",
-                                       /* includes all of: \N{...} */
-                                       res, NULL, s - 3, e - s + 4 );
-
-                   /* Most likely res will be in utf8 already since the
-                    * standard charnames uses pack U, but a custom translator
-                    * can leave it otherwise, so make sure.  XXX This can be
-                    * revisited to not have charnames use utf8 for characters
-                    * that don't need it when regexes don't have to be in utf8
-                    * for Unicode semantics.  If doing so, remember EBCDIC */
-                   sv_utf8_upgrade(res);
-                   str = SvPV_const(res, len);
-
-                   /* Don't accept malformed input */
-                   if (! is_utf8_string((U8 *) str, len)) {
-                       yyerror("Malformed UTF-8 returned by \\N");
-                   }
-                   else if (PL_lex_inpat) {
+               else /* Here is \N{NAME} but not \N{U+...}. */
+                     if ((res = get_and_check_backslash_N_name(s, e)))
+                {
+                    STRLEN len;
+                    const char *str = SvPV_const(res, len);
+                    if (PL_lex_inpat) {
 
                        if (! len) { /* The name resolved to an empty string */
                            Copy("\\N{}", d, 4, char);
@@ -3299,73 +3507,88 @@ S_scan_const(pTHX_ char *start)
                            * returned by charnames */
 
                            const char *str_end = str + len;
-                           STRLEN char_length;     /* cur char's byte length */
-                           STRLEN output_length;   /* and the number of bytes
-                                                      after this is translated
-                                                      into hex digits */
                            const STRLEN off = d - SvPVX_const(sv);
 
-                           /* 2 hex per byte; 2 chars for '\N'; 2 chars for
-                            * max('U+', '.'); and 1 for NUL */
-                           char hex_string[2 * UTF8_MAXBYTES + 5];
-
-                           /* Get the first character of the result. */
-                           U32 uv = utf8n_to_uvuni((U8 *) str,
-                                                   len,
-                                                   &char_length,
-                                                   UTF8_ALLOW_ANYUV);
-
-                           /* The call to is_utf8_string() above hopefully
-                            * guarantees that there won't be an error.  But
-                            * it's easy here to make sure.  The function just
-                            * above warns and returns 0 if invalid utf8, but
-                            * it can also return 0 if the input is validly a
-                            * NUL. Disambiguate */
-                           if (uv == 0 && NATIVE_TO_ASCII(*str) != '\0') {
-                               uv = UNICODE_REPLACEMENT;
-                           }
-
-                           /* Convert first code point to hex, including the
-                            * boiler plate before it.  For all these, we
-                            * convert to native format so that downstream code
-                            * can continue to assume the input is native */
-                           output_length =
-                               my_snprintf(hex_string, sizeof(hex_string),
-                                           "\\N{U+%X",
-                                           (unsigned int) UNI_TO_NATIVE(uv));
-
-                           /* Make sure there is enough space to hold it */
-                           d = off + SvGROW(sv, off
-                                                + output_length
-                                                + (STRLEN)(send - e)
-                                                + 2);  /* '}' + NUL */
-                           /* And output it */
-                           Copy(hex_string, d, output_length, char);
-                           d += output_length;
-
-                           /* For each subsequent character, append dot and
-                            * its ordinal in hex */
-                           while ((str += char_length) < str_end) {
-                               const STRLEN off = d - SvPVX_const(sv);
-                               U32 uv = utf8n_to_uvuni((U8 *) str,
-                                                       str_end - str,
-                                                       &char_length,
-                                                       UTF8_ALLOW_ANYUV);
-                               if (uv == 0 && NATIVE_TO_ASCII(*str) != '\0') {
-                                   uv = UNICODE_REPLACEMENT;
-                               }
-
-                               output_length =
-                                   my_snprintf(hex_string, sizeof(hex_string),
-                                           ".%X",
-                                           (unsigned int) UNI_TO_NATIVE(uv));
-
-                               d = off + SvGROW(sv, off
-                                                    + output_length
-                                                    + (STRLEN)(send - e)
-                                                    + 2);      /* '}' +  NUL */
-                               Copy(hex_string, d, output_length, char);
-                               d += output_length;
+                            if (! SvUTF8(res)) {
+                                /* For the non-UTF-8 case, we can determine the
+                                 * exact length needed without having to parse
+                                 * through the string.  Each character takes up
+                                 * 2 hex digits plus either a trailing dot or
+                                 * the "}" */
+                                d = off + SvGROW(sv, off
+                                                    + 3 * len
+                                                    + 6 /* For the "\N{U+", and
+                                                           trailing NUL */
+                                                    + (STRLEN)(send - e));
+                                Copy("\\N{U+", d, 5, char);
+                                d += 5;
+                                while (str < str_end) {
+                                    char hex_string[4];
+                                    my_snprintf(hex_string, sizeof(hex_string),
+                                                "%02X.", (U8) *str);
+                                    Copy(hex_string, d, 3, char);
+                                    d += 3;
+                                    str++;
+                                }
+                                d--;    /* We will overwrite below the final
+                                           dot with a right brace */
+                            }
+                            else {
+                                STRLEN char_length; /* cur char's byte length */
+
+                                /* and the number of bytes after this is
+                                 * translated into hex digits */
+                                STRLEN output_length;
+
+                                /* 2 hex per byte; 2 chars for '\N'; 2 chars
+                                 * for max('U+', '.'); and 1 for NUL */
+                                char hex_string[2 * UTF8_MAXBYTES + 5];
+
+                                /* Get the first character of the result. */
+                                U32 uv = utf8n_to_uvuni((U8 *) str,
+                                                        len,
+                                                        &char_length,
+                                                        UTF8_ALLOW_ANYUV);
+                                /* Convert first code point to hex, including
+                                 * the boiler plate before it.  For all these,
+                                 * we convert to native format so that
+                                 * downstream code can continue to assume the
+                                 * input is native */
+                                output_length =
+                                    my_snprintf(hex_string, sizeof(hex_string),
+                                            "\\N{U+%X",
+                                            (unsigned int) UNI_TO_NATIVE(uv));
+
+                                /* Make sure there is enough space to hold it */
+                                d = off + SvGROW(sv, off
+                                                    + output_length
+                                                    + (STRLEN)(send - e)
+                                                    + 2);      /* '}' + NUL */
+                                /* And output it */
+                                Copy(hex_string, d, output_length, char);
+                                d += output_length;
+
+                                /* For each subsequent character, append dot and
+                                * its ordinal in hex */
+                                while ((str += char_length) < str_end) {
+                                    const STRLEN off = d - SvPVX_const(sv);
+                                    U32 uv = utf8n_to_uvuni((U8 *) str,
+                                                            str_end - str,
+                                                            &char_length,
+                                                            UTF8_ALLOW_ANYUV);
+                                    output_length =
+                                        my_snprintf(hex_string,
+                                            sizeof(hex_string),
+                                            ".%X",
+                                            (unsigned int) UNI_TO_NATIVE(uv));
+
+                                    d = off + SvGROW(sv, off
+                                                        + output_length
+                                                        + (STRLEN)(send - e)
+                                                        + 2);  /* '}' +  NUL */
+                                    Copy(hex_string, d, output_length, char);
+                                    d += output_length;
+                                }
                            }
 
                            *d++ = '}'; /* Done.  Add the trailing brace */
@@ -3398,68 +3621,9 @@ S_scan_const(pTHX_ char *start)
                        Copy(str, d, len, char);
                        d += len;
                    }
+
                    SvREFCNT_dec(res);
 
-                   /* Deprecate non-approved name syntax */
-                   if (ckWARN_d(WARN_DEPRECATED)) {
-                       bool problematic = FALSE;
-                       char* i = s;
-
-                       /* For non-ut8 input, look to see that the first
-                        * character is an alpha, then loop through the rest
-                        * checking that each is a continuation */
-                       if (! this_utf8) {
-                           if (! isALPHAU(*i)) problematic = TRUE;
-                           else for (i = s + 1; i < e; i++) {
-                               if (isCHARNAME_CONT(*i)) continue;
-                               problematic = TRUE;
-                               break;
-                           }
-                       }
-                       else {
-                           /* Similarly for utf8.  For invariants can check
-                            * directly.  We accept anything above the latin1
-                            * range because it is immaterial to Perl if it is
-                            * correct or not, and is expensive to check.  But
-                            * it is fairly easy in the latin1 range to convert
-                            * the variants into a single character and check
-                            * those */
-                           if (UTF8_IS_INVARIANT(*i)) {
-                               if (! isALPHAU(*i)) problematic = TRUE;
-                           } else if (UTF8_IS_DOWNGRADEABLE_START(*i)) {
-                               if (! isALPHAU(UNI_TO_NATIVE(TWO_BYTE_UTF8_TO_UNI(*i,
-                                                                           *(i+1)))))
-                               {
-                                   problematic = TRUE;
-                               }
-                           }
-                           if (! problematic) for (i = s + UTF8SKIP(s);
-                                                   i < e;
-                                                   i+= UTF8SKIP(i))
-                           {
-                               if (UTF8_IS_INVARIANT(*i)) {
-                                   if (isCHARNAME_CONT(*i)) continue;
-                               } else if (! UTF8_IS_DOWNGRADEABLE_START(*i)) {
-                                   continue;
-                               } else if (isCHARNAME_CONT(
-                                           UNI_TO_NATIVE(
-                                           TWO_BYTE_UTF8_TO_UNI(*i, *(i+1)))))
-                               {
-                                   continue;
-                               }
-                               problematic = TRUE;
-                               break;
-                           }
-                       }
-                       if (problematic) {
-                           /* The e-i passed to the final %.*s makes sure that
-                            * should the trailing NUL be missing that this
-                            * print won't run off the end of the string */
-                           Perl_warner(aTHX_ packWARN(WARN_DEPRECATED),
-                                       "Deprecated character in \\N{...}; marked by <-- HERE  in \\N{%.*s<-- HERE %.*s",
-                                       (int)(i - s + 1), s, (int)(e - i), i + 1);
-                       }
-                   }
                } /* End \N{NAME} */
 #ifdef EBCDIC
                if (!dorange) 
@@ -3585,6 +3749,7 @@ S_scan_const(pTHX_ char *start)
 
     /* return the substring (via pl_yylval) only if we parsed anything */
     if (s > PL_bufptr) {
+       SvREFCNT_inc_simple_void_NN(sv);
        if ( PL_hints & ( PL_lex_inpat ? HINT_NEW_RE : HINT_NEW_STRING ) ) {
            const char *const key = PL_lex_inpat ? "qr" : "q";
            const STRLEN keylen = PL_lex_inpat ? 2 : 1;
@@ -3609,8 +3774,8 @@ S_scan_const(pTHX_ char *start)
                                type, typelen);
        }
        pl_yylval.opval = (OP*)newSVOP(OP_CONST, 0, sv);
-    } else
-       SvREFCNT_dec(sv);
+    }
+    LEAVE_with_name("scan_const");
     return s;
 }
 
@@ -3636,7 +3801,7 @@ S_scan_const(pTHX_ char *start)
 /* This is the one truly awful dwimmer necessary to conflate C and sed. */
 
 STATIC int
-S_intuit_more(pTHX_ register char *s)
+S_intuit_more(pTHX_ char *s)
 {
     dVAR;
 
@@ -3653,7 +3818,7 @@ S_intuit_more(pTHX_ register char *s)
 
     /* In a pattern, so maybe we have {n,m}. */
     if (*s == '{') {
-       if (regcurly(s)) {
+       if (regcurly(s, FALSE)) {
            return FALSE;
        }
        return TRUE;
@@ -3666,16 +3831,16 @@ S_intuit_more(pTHX_ register char *s)
        return FALSE;
     else {
         /* this is terrifying, and it works */
-       int weight = 2;         /* let's weigh the evidence */
+       int weight;
        char seen[256];
-       unsigned char un_char = 255, last_un_char;
        const char * const send = strchr(s,']');
+       unsigned char un_char, last_un_char;
        char tmpbuf[sizeof PL_tokenbuf * 4];
 
        if (!send)              /* has to be an expression */
            return TRUE;
+       weight = 2;             /* let's weigh the evidence */
 
-       Zero(seen,256,char);
        if (*s == '$')
            weight -= 3;
        else if (isDIGIT(*s)) {
@@ -3686,6 +3851,8 @@ S_intuit_more(pTHX_ register char *s)
            else
                weight -= 100;
        }
+       Zero(seen,256,char);
+       un_char = 255;
        for (; s < send; s++) {
            last_un_char = un_char;
            un_char = (unsigned char)*s;
@@ -3694,7 +3861,7 @@ S_intuit_more(pTHX_ register char *s)
            case '&':
            case '$':
                weight -= seen[un_char] * 10;
-               if (isALNUM_lazy_if(s+1,UTF)) {
+               if (isWORDCHAR_lazy_if(s+1,UTF)) {
                    int len;
                    scan_ident(s, send, tmpbuf, sizeof tmpbuf, FALSE);
                    len = (int)strlen(tmpbuf);
@@ -3741,7 +3908,7 @@ S_intuit_more(pTHX_ register char *s)
                    weight -= 5;        /* cope with negative subscript */
                break;
            default:
-               if (!isALNUM(last_un_char)
+               if (!isWORDCHAR(last_un_char)
                    && !(last_un_char == '$' || last_un_char == '@'
                         || last_un_char == '&')
                    && isALPHA(*s) && s[1] && isALPHA(s[1])) {
@@ -4085,7 +4252,7 @@ Perl_filter_read(pTHX_ int idx, SV *buf_sv, int maxlen)
 }
 
 STATIC char *
-S_filter_gets(pTHX_ register SV *sv, STRLEN append)
+S_filter_gets(pTHX_ SV *sv, STRLEN append)
 {
     dVAR;
 
@@ -4266,7 +4433,6 @@ Perl_madlex(pTHX)
     case FUNC0SUB:
     case UNIOPSUB:
     case LSTOPSUB:
-    case LABEL:
        if (pl_yylval.opval)
            append_madprops(PL_thismad, pl_yylval.opval, 0);
        PL_thismad = 0;
@@ -4281,6 +4447,10 @@ Perl_madlex(pTHX)
        }
        break;
 
+    /* pval */
+    case LABEL:
+       break;
+
     case ']':
     case '}':
        if (PL_faketokens)
@@ -4396,21 +4566,40 @@ S_word_takes_any_delimeter(char *p, STRLEN len)
   stitching them into a tree.
 
   Returns:
-    PRIVATEREF
+    The type of the next token
 
   Structure:
-      if read an identifier
-          if we're in a my declaration
-             croak if they tried to say my($foo::bar)
-             build the ops for a my() declaration
-         if it's an access to a my() variable
-             are we in a sort block?
-                 croak if my($a); $a <=> $b
-             build ops for access to a my() variable
-         if in a dq string, and they've said @foo and we can't find @foo
-             croak
-         build ops for a bareword
-      if we already built the token before, use it.
+      Switch based on the current state:
+         - if we already built the token before, use it
+         - if we have a case modifier in a string, deal with that
+         - handle other cases of interpolation inside a string
+         - scan the next line if we are inside a format
+      In the normal state switch on the next character:
+         - default:
+           if alphabetic, go to key lookup
+           unrecoginized character - croak
+         - 0/4/26: handle end-of-line or EOF
+         - cases for whitespace
+         - \n and #: handle comments and line numbers
+         - various operators, brackets and sigils
+         - numbers
+         - quotes
+         - 'v': vstrings (or go to key lookup)
+         - 'x' repetition operator (or go to key lookup)
+         - other ASCII alphanumerics (key lookup begins here):
+             word before => ?
+             keyword plugin
+             scan built-in keyword (but do nothing with it yet)
+             check for statement label
+             check for lexical subs
+                 goto just_a_word if there is one
+             see whether built-in keyword is overridden
+             switch on keyword number:
+                 - default: just_a_word:
+                     not a built-in keyword; handle bareword lookup
+                     disambiguate between method and sub call
+                     fall back to bareword
+                 - cases for built-in keywords
 */
 
 
@@ -4503,9 +4692,7 @@ Perl_yylex(pTHX)
                    PL_lex_allbrackets--;
                next_type &= 0xffff;
            }
-           if (S_is_opval_token(next_type) && pl_yylval.opval)
-               pl_yylval.opval->op_savefree = 0; /* release */
-           return REPORT(next_type);
+           return REPORT(next_type == 'p' ? pending_ident() : next_type);
        }
 
     /* interpolated case modifiers like \L \U, including \Q and \E.
@@ -4546,9 +4733,11 @@ Perl_yylex(pTHX)
 #ifdef PERL_MAD
            while (PL_bufptr != PL_bufend &&
              PL_bufptr[0] == '\\' && PL_bufptr[1] == 'E') {
-               if (!PL_thiswhite)
+               if (PL_madskills) {
+                 if (!PL_thiswhite)
                    PL_thiswhite = newSVpvs("");
-               sv_catpvn(PL_thiswhite, PL_bufptr, 2);
+                 sv_catpvn(PL_thiswhite, PL_bufptr, 2);
+               }
                PL_bufptr += 2;
            }
 #else
@@ -4564,9 +4753,11 @@ Perl_yylex(pTHX)
            s = PL_bufptr + 1;
            if (s[1] == '\\' && s[2] == 'E') {
 #ifdef PERL_MAD
-               if (!PL_thiswhite)
+               if (PL_madskills) {
+                 if (!PL_thiswhite)
                    PL_thiswhite = newSVpvs("");
-               sv_catpvn(PL_thiswhite, PL_bufptr, 4);
+                 sv_catpvn(PL_thiswhite, PL_bufptr, 4);
+               }
 #endif
                PL_bufptr = s + 3;
                PL_lex_state = LEX_INTERPCONCAT;
@@ -5224,9 +5415,11 @@ Perl_yylex(pTHX)
     case ' ': case '\t': case '\f': case 013:
 #ifdef PERL_MAD
        PL_realtokenstart = -1;
-       if (!PL_thiswhite)
+       if (PL_madskills) {
+         if (!PL_thiswhite)
            PL_thiswhite = newSVpvs("");
-       sv_catpvn(PL_thiswhite, s, 1);
+         sv_catpvn(PL_thiswhite, s, 1);
+       }
 #endif
        s++;
        goto retry;
@@ -5319,7 +5512,7 @@ Perl_yylex(pTHX)
        }
        goto retry;
     case '-':
-       if (s[1] && isALPHA(s[1]) && !isALNUM(s[2])) {
+       if (s[1] && isALPHA(s[1]) && !isWORDCHAR(s[2])) {
            I32 ftst = 0;
            char tmp;
 
@@ -5579,7 +5772,7 @@ Perl_yylex(pTHX)
                }
                sv = newSVpvn_flags(s, len, UTF ? SVf_UTF8 : 0);
                if (*d == '(') {
-                   d = scan_str(d,TRUE,TRUE,FALSE);
+                   d = scan_str(d,TRUE,TRUE,FALSE, FALSE);
                    if (!d) {
                        /* MUST advance bufptr here to avoid bogus
                           "at end of line" context messages from yyerror().
@@ -5824,9 +6017,9 @@ Perl_yylex(pTHX)
                }
                else if (*s == 'q') {
                    if (++t < PL_bufend
-                       && (!isALNUM(*t)
+                       && (!isWORDCHAR(*t)
                            || ((*t == 'q' || *t == 'x') && ++t < PL_bufend
-                               && !isALNUM(*t))))
+                               && !isWORDCHAR(*t))))
                    {
                        /* skip q//-like construct */
                        const char *tmps;
@@ -5865,12 +6058,12 @@ Perl_yylex(pTHX)
                    }
                    else
                        /* skip plain q word */
-                       while (t < PL_bufend && isALNUM_lazy_if(t,UTF))
+                       while (t < PL_bufend && isWORDCHAR_lazy_if(t,UTF))
                             t += UTF8SKIP(t);
                }
-               else if (isALNUM_lazy_if(t,UTF)) {
+               else if (isWORDCHAR_lazy_if(t,UTF)) {
                    t += UTF8SKIP(t);
-                   while (t < PL_bufend && isALNUM_lazy_if(t,UTF))
+                   while (t < PL_bufend && isWORDCHAR_lazy_if(t,UTF))
                         t += UTF8SKIP(t);
                }
                while (t < PL_bufend && isSPACE(*t))
@@ -5940,7 +6133,7 @@ Perl_yylex(pTHX)
        force_next(formbrack ? '.' : '}');
        if (formbrack) LEAVE;
 #ifdef PERL_MAD
-       if (!PL_thistoken)
+       if (PL_madskills && !PL_thistoken)
            PL_thistoken = newSVpvs("");
 #endif
        if (formbrack == 2) { /* means . where arguments were expected */
@@ -6107,8 +6300,8 @@ Perl_yylex(pTHX)
 
                    if (*t == '/' || *t == '?' ||
                        ((*t == 'm' || *t == 's' || *t == 'y')
-                        && !isALNUM(t[1])) ||
-                       (*t == 't' && t[1] == 'r' && !isALNUM(t[2])))
+                        && !isWORDCHAR(t[1])) ||
+                       (*t == 't' && t[1] == 'r' && !isWORDCHAR(t[2])))
                        Perl_warner(aTHX_ packWARN(WARN_SYNTAX),
                                    "!=~ should be !~");
                }
@@ -6245,7 +6438,7 @@ Perl_yylex(pTHX)
                    if (ckWARN(WARN_SYNTAX)) {
                        char *t = s+1;
 
-                       while (isSPACE(*t) || isALNUM_lazy_if(t,UTF) || *t == '$')
+                       while (isSPACE(*t) || isWORDCHAR_lazy_if(t,UTF) || *t == '$')
                            t++;
                        if (*t++ == ',') {
                            PL_bufptr = PEEKSPACE(PL_bufptr); /* XXX can realloc */
@@ -6356,7 +6549,7 @@ Perl_yylex(pTHX)
            if (*s == '[' || *s == '{') {
                if (ckWARN(WARN_SYNTAX)) {
                    const char *t = s + 1;
-                   while (*t && (isALNUM_lazy_if(t,UTF) || strchr(" \t$#+-'\"", *t)))
+                   while (*t && (isWORDCHAR_lazy_if(t,UTF) || strchr(" \t$#+-'\"", *t)))
                        t += UTF ? UTF8SKIP(t) : 1;
                    if (*t == '}' || *t == ']') {
                        t++;
@@ -6424,7 +6617,7 @@ Perl_yylex(pTHX)
             if (PL_oldoldbufptr == PL_last_uni
              && (*PL_last_uni != 's' || s - PL_last_uni < 5
                  || memNE(PL_last_uni, "study", 5)
-                 || isALNUM_lazy_if(PL_last_uni+5,UTF)
+                 || isWORDCHAR_lazy_if(PL_last_uni+5,UTF)
              ))
                 check_uni();
             if (*s == '?')
@@ -6484,7 +6677,7 @@ Perl_yylex(pTHX)
        TERM(THING);
 
     case '\'':
-       s = scan_str(s,!!PL_madskills,FALSE,FALSE);
+       s = scan_str(s,!!PL_madskills,FALSE,FALSE, FALSE);
        DEBUG_T( { printbuf("### Saw string before %s\n", s); } );
        if (PL_expect == XOPERATOR) {
            if (PL_lex_formbrack && PL_lex_brackets == PL_lex_formbrack) {
@@ -6499,7 +6692,7 @@ Perl_yylex(pTHX)
        TERM(sublex_start());
 
     case '"':
-       s = scan_str(s,!!PL_madskills,FALSE,FALSE);
+       s = scan_str(s,!!PL_madskills,FALSE,FALSE, FALSE);
        DEBUG_T( { printbuf("### Saw string before %s\n", s); } );
        if (PL_expect == XOPERATOR) {
            if (PL_lex_formbrack && PL_lex_brackets == PL_lex_formbrack) {
@@ -6522,7 +6715,7 @@ Perl_yylex(pTHX)
        TERM(sublex_start());
 
     case '`':
-       s = scan_str(s,!!PL_madskills,FALSE,FALSE);
+       s = scan_str(s,!!PL_madskills,FALSE,FALSE, FALSE);
        DEBUG_T( { printbuf("### Saw backtick string before %s\n", s); } );
        if (PL_expect == XOPERATOR)
            no_op("Backticks",s);
@@ -6549,8 +6742,16 @@ Perl_yylex(pTHX)
                s = scan_num(s, &pl_yylval);
                TERM(THING);
            }
+           else if ((*start == ':' && start[1] == ':')
+                 || (PL_expect == XSTATE && *start == ':'))
+               goto keylookup;
+           else if (PL_expect == XSTATE) {
+               d = start;
+               while (d < PL_bufend && isSPACE(*d)) d++;
+               if (*d == ':') goto keylookup;
+           }
            /* avoid v123abc() or $h{v1}, allow C<print v10;> */
-           else if (!isALPHA(*start) && (PL_expect == XTERM
+           if (!isALPHA(*start) && (PL_expect == XTERM
                        || PL_expect == XREF || PL_expect == XSTATE
                        || PL_expect == XTERMORDORDOR)) {
                GV *const gv = gv_fetchpvn_flags(s, start - s,
@@ -6673,9 +6874,9 @@ Perl_yylex(pTHX)
        if (!anydelim && PL_expect == XSTATE
              && d < PL_bufend && *d == ':' && *(d + 1) != ':') {
            s = d + 1;
-           pl_yylval.opval = (OP*)newSVOP(OP_CONST, 0,
-                                            newSVpvn_flags(PL_tokenbuf,
-                                                        len, UTF ? SVf_UTF8 : 0));
+           pl_yylval.pval = savepvn(PL_tokenbuf, len+1);
+           pl_yylval.pval[len] = '\0';
+           pl_yylval.pval[len+1] = UTF ? 1 : 0;
            CLINE;
            TOKEN(LABEL);
        }
@@ -6782,6 +6983,10 @@ Perl_yylex(pTHX)
          just_a_word: {
                int pkgname = 0;
                const char lastchar = (PL_bufptr == PL_oldoldbufptr ? 0 : PL_bufptr[-1]);
+               const char penultchar =
+                   lastchar && PL_bufptr - 2 >= PL_linestart
+                        ? PL_bufptr[-2]
+                        : 0;
 #ifdef PERL_MAD
                SV *nextPL_nextwhite = 0;
 #endif
@@ -7010,7 +7215,7 @@ Perl_yylex(pTHX)
                /* Not a method, so call it a subroutine (if defined) */
 
                if (cv) {
-                   if (lastchar == '-') {
+                   if (lastchar == '-' && penultchar != '-') {
                         const SV *tmpsv = newSVpvn_flags( PL_tokenbuf, len ? len : strlen(PL_tokenbuf), (UTF ? SVf_UTF8 : 0) | SVs_TEMP );
                        Perl_ck_warner_d(aTHX_ packWARN(WARN_AMBIGUOUS),
                                "Ambiguous use of -%"SVf" resolved as -&%"SVf"()",
@@ -7504,6 +7709,7 @@ Perl_yylex(pTHX)
            UNI(OP_DBMCLOSE);
 
        case KEY_dump:
+           PL_expect = XOPERATOR;
            s = force_word(s,WORD,TRUE,FALSE,FALSE);
            LOOPX(OP_DUMP);
 
@@ -7636,6 +7842,7 @@ Perl_yylex(pTHX)
            LOP(OP_GREPSTART, XREF);
 
        case KEY_goto:
+           PL_expect = XOPERATOR;
            s = force_word(s,WORD,TRUE,FALSE,FALSE);
            LOOPX(OP_GOTO);
 
@@ -7758,6 +7965,7 @@ Perl_yylex(pTHX)
            LOP(OP_KILL,XTERM);
 
        case KEY_last:
+           PL_expect = XOPERATOR;
            s = force_word(s,WORD,TRUE,FALSE,FALSE);
            LOOPX(OP_LAST);
        
@@ -7835,7 +8043,17 @@ Perl_yylex(pTHX)
 #endif
                s = scan_word(s, PL_tokenbuf, sizeof PL_tokenbuf, TRUE, &len);
                if (len == 3 && strnEQ(PL_tokenbuf, "sub", 3))
+               {
+                   if (!FEATURE_LEXSUBS_IS_ENABLED)
+                       Perl_croak(aTHX_
+                                 "Experimental \"%s\" subs not enabled",
+                                  tmp == KEY_my    ? "my"    :
+                                  tmp == KEY_state ? "state" : "our");
+                   Perl_ck_warner_d(aTHX_
+                       packWARN(WARN_EXPERIMENTAL__LEXICAL_SUBS),
+                       "The lexical_subs feature is experimental");
                    goto really_sub;
+               }
                PL_in_my_stash = find_in_my_stash(PL_tokenbuf, len);
                if (!PL_in_my_stash) {
                    char tmpbuf[1024];
@@ -7855,6 +8073,7 @@ Perl_yylex(pTHX)
            OPERATOR(MY);
 
        case KEY_next:
+           PL_expect = XOPERATOR;
            s = force_word(s,WORD,TRUE,FALSE,FALSE);
            LOOPX(OP_NEXT);
 
@@ -7881,10 +8100,10 @@ Perl_yylex(pTHX)
            s = SKIPSPACE1(s);
            if (isIDFIRST_lazy_if(s,UTF)) {
                const char *t;
-               for (d = s; isALNUM_lazy_if(d,UTF);) {
+               for (d = s; isWORDCHAR_lazy_if(d,UTF);) {
                    d += UTF ? UTF8SKIP(d) : 1;
                     if (UTF) {
-                        while (UTF8_IS_CONTINUED(*d) && is_utf8_mark((U8*)d)) {
+                        while (UTF8_IS_CONTINUED(*d) && _is_utf8_mark((U8*)d)) {
                             d += UTF ? UTF8SKIP(d) : 1;
                         }
                     }
@@ -7955,7 +8174,7 @@ Perl_yylex(pTHX)
            LOP(OP_PIPE_OP,XTERM);
 
        case KEY_q:
-           s = scan_str(s,!!PL_madskills,FALSE,FALSE);
+           s = scan_str(s,!!PL_madskills,FALSE,FALSE, FALSE);
            if (!s)
                missingterm(NULL);
            pl_yylval.ival = OP_CONST;
@@ -7966,7 +8185,7 @@ Perl_yylex(pTHX)
 
        case KEY_qw: {
            OP *words = NULL;
-           s = scan_str(s,!!PL_madskills,FALSE,FALSE);
+           s = scan_str(s,!!PL_madskills,FALSE,FALSE, FALSE);
            if (!s)
                missingterm(NULL);
            PL_expect = XOPERATOR;
@@ -8016,7 +8235,7 @@ Perl_yylex(pTHX)
        }
 
        case KEY_qq:
-           s = scan_str(s,!!PL_madskills,FALSE,FALSE);
+           s = scan_str(s,!!PL_madskills,FALSE,FALSE, FALSE);
            if (!s)
                missingterm(NULL);
            pl_yylval.ival = OP_STRINGIFY;
@@ -8029,7 +8248,7 @@ Perl_yylex(pTHX)
            TERM(sublex_start());
 
        case KEY_qx:
-           s = scan_str(s,!!PL_madskills,FALSE,FALSE);
+           s = scan_str(s,!!PL_madskills,FALSE,FALSE, FALSE);
            if (!s)
                missingterm(NULL);
            readpipe_override();
@@ -8040,6 +8259,7 @@ Perl_yylex(pTHX)
 
        case KEY_require:
            s = SKIPSPACE1(s);
+           PL_expect = XOPERATOR;
            if (isDIGIT(*s)) {
                s = force_version(s, FALSE);
            }
@@ -8071,6 +8291,7 @@ Perl_yylex(pTHX)
            UNI(OP_RESET);
 
        case KEY_redo:
+           PL_expect = XOPERATOR;
            s = force_word(s,WORD,TRUE,FALSE,FALSE);
            LOOPX(OP_REDO);
 
@@ -8253,7 +8474,9 @@ Perl_yylex(pTHX)
                SV *tmpwhite = 0;
 
                char *tstart = SvPVX(PL_linestr) + PL_realtokenstart;
-               SV *subtoken = newSVpvn_flags(tstart, s - tstart, SvUTF8(PL_linestr));
+               SV *subtoken = PL_madskills
+                  ? newSVpvn_flags(tstart, s - tstart, SvUTF8(PL_linestr))
+                  : NULL;
                PL_thistoken = 0;
 
                d = s;
@@ -8280,7 +8503,11 @@ Perl_yylex(pTHX)
                    if (PL_madskills)
                        nametoke = newSVpvn_flags(s, d - s, SvUTF8(PL_linestr));
 #endif
-                   if (memchr(tmpbuf, ':', len) || key == KEY_our)
+                   *PL_tokenbuf = '&';
+                   if (memchr(tmpbuf, ':', len) || key != KEY_sub
+                    || pad_findmy_pvn(
+                           PL_tokenbuf, len + 1, UTF ? SVf_UTF8 : 0
+                       ) != NOT_IN_PAD)
                        sv_setpvn(PL_subname, tmpbuf, len);
                    else {
                        sv_setsv(PL_subname,PL_curstname);
@@ -8291,7 +8518,6 @@ Perl_yylex(pTHX)
                         SvUTF8_on(PL_subname);
                    have_name = TRUE;
 
-                   *PL_tokenbuf = '&';
 
 #ifdef PERL_MAD
                    start_force(0);
@@ -8343,7 +8569,7 @@ Perl_yylex(pTHX)
                    const bool warnillegalproto = ckWARN(WARN_ILLEGALPROTO);
                     STRLEN tmplen;
 
-                   s = scan_str(s,!!PL_madskills,FALSE,FALSE);
+                   s = scan_str(s,!!PL_madskills,FALSE,FALSE, FALSE);
                    if (!s)
                        Perl_croak(aTHX_ "Prototype not terminated");
                    /* strip spaces and check for bad characters */
@@ -8622,18 +8848,38 @@ Perl_yylex(pTHX)
 #pragma segment Main
 #endif
 
-static void
-S_force_ident_maybe_lex(pTHX_ char pit)
+/*
+  S_pending_ident
+
+  Looks up an identifier in the pad or in a package
+
+  Returns:
+    PRIVATEREF if this is a lexical name.
+    WORD       if this belongs to a package.
+
+  Structure:
+      if we're in a my declaration
+         croak if they tried to say my($foo::bar)
+         build the ops for a my() declaration
+      if it's an access to a my() variable
+         build ops for access to a my() variable
+      if in a dq string, and they've said @foo and we can't find @foo
+         warn
+      build ops for a bareword
+*/
+
+static int
+S_pending_ident(pTHX)
 {
     dVAR;
-    OP *o;
-    int force_type;
     PADOFFSET tmp = 0;
+    const char pit = (char)pl_yylval.ival;
     const STRLEN tokenbuf_len = strlen(PL_tokenbuf);
     /* All routes through this function want to know if there is a colon.  */
     const char *const has_colon = (const char*) memchr (PL_tokenbuf, ':', tokenbuf_len);
 
-    start_force(PL_curforce);
+    DEBUG_T({ PerlIO_printf(Perl_debug_log,
+          "### Pending identifier '%s'\n", PL_tokenbuf); });
 
     /* if we're in a my(), we can't allow dynamics here.
        $foo'bar has already been turned into $foo::bar, so
@@ -8655,11 +8901,10 @@ S_force_ident_maybe_lex(pTHX_ char pit)
                            PL_in_my == KEY_my ? "my" : "state", PL_tokenbuf),
                             UTF ? SVf_UTF8 : 0);
 
-            o = newOP(OP_PADANY, 0);
-            o->op_targ = allocmy(PL_tokenbuf, tokenbuf_len,
+            pl_yylval.opval = newOP(OP_PADANY, 0);
+            pl_yylval.opval->op_targ = allocmy(PL_tokenbuf, tokenbuf_len,
                                                         UTF ? SVf_UTF8 : 0);
-            force_type = PRIVATEREF;
-            goto doforce;
+           return PRIVATEREF;
         }
     }
 
@@ -8680,8 +8925,8 @@ S_force_ident_maybe_lex(pTHX_ char pit)
                SV *  const sym = newSVhek(stashname);
                 sv_catpvs(sym, "::");
                 sv_catpvn_flags(sym, PL_tokenbuf+1, tokenbuf_len - 1, (UTF ? SV_CATUTF8 : SV_CATBYTES ));
-                o = (OP*)newSVOP(OP_CONST, 0, sym);
-                o->op_private = OPpCONST_ENTERED;
+                pl_yylval.opval = (OP*)newSVOP(OP_CONST, 0, sym);
+                pl_yylval.opval->op_private = OPpCONST_ENTERED;
                 if (pit != '&')
                   gv_fetchsv(sym,
                     (PL_in_eval
@@ -8691,14 +8936,12 @@ S_force_ident_maybe_lex(pTHX_ char pit)
                     ((PL_tokenbuf[0] == '$') ? SVt_PV
                      : (PL_tokenbuf[0] == '@') ? SVt_PVAV
                      : SVt_PVHV));
-                force_type = WORD;
-                goto doforce;
+                return WORD;
             }
 
-            o = newOP(OP_PADANY, 0);
-            o->op_targ = tmp;
-            force_type = PRIVATEREF;
-            goto doforce;
+            pl_yylval.opval = newOP(OP_PADANY, 0);
+            pl_yylval.opval->op_targ = tmp;
+            return PRIVATEREF;
         }
     }
 
@@ -8726,10 +8969,11 @@ S_force_ident_maybe_lex(pTHX_ char pit)
     }
 
     /* build ops for a bareword */
-    o = (OP*)newSVOP(OP_CONST, 0, newSVpvn_flags(PL_tokenbuf + 1,
+    pl_yylval.opval = (OP*)newSVOP(OP_CONST, 0,
+                                  newSVpvn_flags(PL_tokenbuf + 1,
                                                      tokenbuf_len - 1,
                                                       UTF ? SVf_UTF8 : 0 ));
-    o->op_private = OPpCONST_ENTERED;
+    pl_yylval.opval->op_private = OPpCONST_ENTERED;
     if (pit != '&')
        gv_fetchpvn_flags(PL_tokenbuf+1, tokenbuf_len - 1,
                     (PL_in_eval ? (GV_ADDMULTI | GV_ADDINEVAL) : GV_ADD)
@@ -8737,11 +8981,7 @@ S_force_ident_maybe_lex(pTHX_ char pit)
                     ((PL_tokenbuf[0] == '$') ? SVt_PV
                      : (PL_tokenbuf[0] == '@') ? SVt_PVAV
                      : SVt_PVHV));
-    force_type = WORD;
-
-   doforce:
-    NEXTVAL_NEXTTOKE.opval = o;
-    force_next(force_type);
+    return WORD;
 }
 
 STATIC void
@@ -8781,7 +9021,7 @@ S_checkcomma(pTHX_ const char *s, const char *name, const char *what)
     if (isIDFIRST_lazy_if(s,UTF)) {
        const char * const w = s;
         s += UTF ? UTF8SKIP(s) : 1;
-       while (isALNUM_lazy_if(s,UTF))
+       while (isWORDCHAR_lazy_if(s,UTF))
            s += UTF ? UTF8SKIP(s) : 1;
        while (s < PL_bufend && isSPACE(*s))
            s++;
@@ -8798,10 +9038,11 @@ S_checkcomma(pTHX_ const char *s, const char *name, const char *what)
     }
 }
 
-/* Either returns sv, or mortalizes sv and returns a new SV*.
+/* Either returns sv, or mortalizes/frees sv and returns a new SV*.
    Best used as sv=new_constant(..., sv, ...).
    If s, pv are NULL, calls subroutine with one argument,
-   and type is used with error messages only. */
+   and <type> is used with error messages only.
+   <type> is assumed to be well formed UTF-8 */
 
 STATIC SV *
 S_new_constant(pTHX_ const char *s, STRLEN len, const char *key, STRLEN keylen,
@@ -8810,26 +9051,34 @@ S_new_constant(pTHX_ const char *s, STRLEN len, const char *key, STRLEN keylen,
     dVAR; dSP;
     HV * table = GvHV(PL_hintgv);               /* ^H */
     SV *res;
+    SV *errsv = NULL;
     SV **cvp;
     SV *cv, *typesv;
     const char *why1 = "", *why2 = "", *why3 = "";
 
     PERL_ARGS_ASSERT_NEW_CONSTANT;
+    /* We assume that this is true: */
+    if (*key == 'c') { assert (strEQ(key, "charnames")); }
+    assert(type || s);
 
     /* charnames doesn't work well if there have been errors found */
-    if (PL_error_count > 0 && strEQ(key,"charnames"))
+    if (PL_error_count > 0 && *key == 'c')
+    {
+       SvREFCNT_dec_NN(sv);
        return &PL_sv_undef;
+    }
 
+    sv_2mortal(sv);                    /* Parent created it permanently */
     if (!table
        || ! (PL_hints & HINT_LOCALIZE_HH)
        || ! (cvp = hv_fetch(table, key, keylen, FALSE))
        || ! SvOK(*cvp))
     {
-       SV *msg;
+       char *msg;
        
        /* Here haven't found what we're looking for.  If it is charnames,
         * perhaps it needs to be loaded.  Try doing that before giving up */
-       if (strEQ(key,"charnames")) {
+       if (*key == 'c') {
            Perl_load_module(aTHX_
                            0,
                            newSVpvs("_charnames"),
@@ -8851,23 +9100,32 @@ S_new_constant(pTHX_ const char *s, STRLEN len, const char *key, STRLEN keylen,
            }
        }
        if (!table || !(PL_hints & HINT_LOCALIZE_HH)) {
-           msg = Perl_newSVpvf(aTHX_
-                           "Constant(%s) unknown", (type ? type: "undef"));
+           msg = Perl_form(aTHX_
+                              "Constant(%.*s) unknown",
+                               (int)(type ? typelen : len),
+                               (type ? type: s));
        }
        else {
-       why1 = "$^H{";
-       why2 = key;
-       why3 = "} is not defined";
-    report:
-       msg = Perl_newSVpvf(aTHX_ "Constant(%s): %s%s%s",
-                           (type ? type: "undef"), why1, why2, why3);
-       }
-       yyerror(SvPVX_const(msg));
-       SvREFCNT_dec(msg);
-       return sv;
+            why1 = "$^H{";
+            why2 = key;
+            why3 = "} is not defined";
+        report:
+            if (*key == 'c') {
+                msg = Perl_form(aTHX_
+                            /* The +3 is for '\N{'; -4 for that, plus '}' */
+                            "Unknown charname '%.*s'", (int)typelen - 4, type + 3
+                      );
+            }
+            else {
+                msg = Perl_form(aTHX_ "Constant(%.*s): %s%s%s",
+                                    (int)(type ? typelen : len),
+                                    (type ? type: s), why1, why2, why3);
+            }
+        }
+       yyerror_pv(msg, UTF ? SVf_UTF8 : 0);
+       return SvREFCNT_inc_simple_NN(sv);
     }
 now_ok:
-    sv_2mortal(sv);                    /* Parent created it permanently */
     cv = *cvp;
     if (!pv && s)
        pv = newSVpvn_flags(s, len, SVs_TEMP);
@@ -8893,15 +9151,18 @@ now_ok:
     SPAGAIN ;
 
     /* Check the eval first */
-    if (!PL_in_eval && SvTRUE(ERRSV)) {
-       sv_catpvs(ERRSV, "Propagated");
-       yyerror(SvPV_nolen_const(ERRSV)); /* Duplicates the message inside eval */
+    if (!PL_in_eval && ((errsv = ERRSV), SvTRUE_NN(errsv))) {
+       STRLEN errlen;
+       const char * errstr;
+       sv_catpvs(errsv, "Propagated");
+       errstr = SvPV_const(errsv, errlen);
+       yyerror_pvn(errstr, errlen, 0); /* Duplicates the message inside eval */
        (void)POPs;
-       res = SvREFCNT_inc_simple(sv);
+       res = SvREFCNT_inc_simple_NN(sv);
     }
     else {
        res = POPs;
-       SvREFCNT_inc_simple_void(res);
+       SvREFCNT_inc_simple_void_NN(res);
     }
 
     PUTBACK ;
@@ -8914,6 +9175,7 @@ now_ok:
        why2 = key;
        why3 = "}} did not return a defined value";
        sv = res;
+       (void)sv_2mortal(sv);
        goto report;
     }
 
@@ -8924,7 +9186,7 @@ now_ok:
    *slp
    */
 STATIC char *
-S_scan_word(pTHX_ register char *s, char *dest, STRLEN destlen, int allow_package, STRLEN *slp)
+S_scan_word(pTHX_ char *s, char *dest, STRLEN destlen, int allow_package, STRLEN *slp)
 {
     dVAR;
     char *d = dest;
@@ -8934,9 +9196,12 @@ S_scan_word(pTHX_ register char *s, char *dest, STRLEN destlen, int allow_packag
 
     for (;;) {
        if (d >= e)
-           Perl_croak(aTHX_ ident_too_long);
-       if (isALNUM(*s) || (!UTF && isALNUMC_L1(*s)))   /* UTF handled below */
+           Perl_croak(aTHX_ "%s", ident_too_long);
+       if (isWORDCHAR(*s)
+            || (!UTF && isALPHANUMERIC_L1(*s))) /* UTF handled below */
+        {
            *d++ = *s++;
+        }
        else if (allow_package && (*s == '\'') && isIDFIRST_lazy_if(s+1,UTF)) {
            *d++ = ':';
            *d++ = ':';
@@ -8946,14 +9211,14 @@ S_scan_word(pTHX_ register char *s, char *dest, STRLEN destlen, int allow_packag
            *d++ = *s++;
            *d++ = *s++;
        }
-       else if (UTF && UTF8_IS_START(*s) && isALNUM_utf8((U8*)s)) {
+       else if (UTF && UTF8_IS_START(*s) && isWORDCHAR_utf8((U8*)s)) {
            char *t = s + UTF8SKIP(s);
            size_t len;
-           while (UTF8_IS_CONTINUED(*t) && is_utf8_mark((U8*)t))
+           while (UTF8_IS_CONTINUED(*t) && _is_utf8_mark((U8*)t))
                t += UTF8SKIP(t);
            len = t - s;
            if (d + len > e)
-               Perl_croak(aTHX_ ident_too_long);
+               Perl_croak(aTHX_ "%s", ident_too_long);
            Copy(s, d, len, char);
            d += len;
            s = t;
@@ -8967,7 +9232,7 @@ S_scan_word(pTHX_ register char *s, char *dest, STRLEN destlen, int allow_packag
 }
 
 STATIC char *
-S_scan_ident(pTHX_ register char *s, register const char *send, char *dest, STRLEN destlen, I32 ck_uni)
+S_scan_ident(pTHX_ char *s, const char *send, char *dest, STRLEN destlen, I32 ck_uni)
 {
     dVAR;
     char *bracket = NULL;
@@ -8982,15 +9247,15 @@ S_scan_ident(pTHX_ register char *s, register const char *send, char *dest, STRL
     if (isDIGIT(*s)) {
        while (isDIGIT(*s)) {
            if (d >= e)
-               Perl_croak(aTHX_ ident_too_long);
+               Perl_croak(aTHX_ "%s", ident_too_long);
            *d++ = *s++;
        }
     }
     else {
        for (;;) {
            if (d >= e)
-               Perl_croak(aTHX_ ident_too_long);
-           if (isALNUM(*s))    /* UTF handled below */
+               Perl_croak(aTHX_ "%s", ident_too_long);
+           if (isWORDCHAR(*s)) /* UTF handled below */
                *d++ = *s++;
            else if (*s == '\'' && isIDFIRST_lazy_if(s+1,UTF)) {
                *d++ = ':';
@@ -9001,12 +9266,12 @@ S_scan_ident(pTHX_ register char *s, register const char *send, char *dest, STRL
                *d++ = *s++;
                *d++ = *s++;
            }
-           else if (UTF && UTF8_IS_START(*s) && isALNUM_utf8((U8*)s)) {
+           else if (UTF && UTF8_IS_START(*s) && isWORDCHAR_utf8((U8*)s)) {
                char *t = s + UTF8SKIP(s);
-               while (UTF8_IS_CONTINUED(*t) && is_utf8_mark((U8*)t))
+               while (UTF8_IS_CONTINUED(*t) && _is_utf8_mark((U8*)t))
                    t += UTF8SKIP(t);
                if (d + (t - s) > e)
-                   Perl_croak(aTHX_ ident_too_long);
+                   Perl_croak(aTHX_ "%s", ident_too_long);
                Copy(s, d, t - s, char);
                d += t - s;
                s = t;
@@ -9023,7 +9288,7 @@ S_scan_ident(pTHX_ register char *s, register const char *send, char *dest, STRL
        return s;
     }
     if (*s == '$' && s[1] &&
-       (isALNUM_lazy_if(s+1,UTF) || s[1] == '$' || s[1] == '{' || strnEQ(s+1,"::",2)) )
+       (isWORDCHAR_lazy_if(s+1,UTF) || s[1] == '$' || s[1] == '{' || strnEQ(s+1,"::",2)) )
     {
        return s;
     }
@@ -9064,9 +9329,9 @@ S_scan_ident(pTHX_ register char *s, register const char *send, char *dest, STRL
            d += UTF8SKIP(d);
            if (UTF) {
                char *end = s;
-               while ((end < send && isALNUM_lazy_if(end,UTF)) || *end == ':') {
+               while ((end < send && isWORDCHAR_lazy_if(end,UTF)) || *end == ':') {
                    end += UTF8SKIP(end);
-                   while (end < send && UTF8_IS_CONTINUED(*end) && is_utf8_mark((U8*)end))
+                   while (end < send && UTF8_IS_CONTINUED(*end) && _is_utf8_mark((U8*)end))
                        end += UTF8SKIP(end);
                }
                Copy(s, d, end - s, char);
@@ -9074,10 +9339,10 @@ S_scan_ident(pTHX_ register char *s, register const char *send, char *dest, STRL
                s = end;
            }
            else {
-               while ((isALNUM(*s) || *s == ':') && d < e)
+               while ((isWORDCHAR(*s) || *s == ':') && d < e)
                    *d++ = *s++;
                if (d >= e)
-                   Perl_croak(aTHX_ ident_too_long);
+                   Perl_croak(aTHX_ "%s", ident_too_long);
            }
            *d = '\0';
            while (s < send && SPACE_OR_TAB(*s))
@@ -9100,15 +9365,15 @@ S_scan_ident(pTHX_ register char *s, register const char *send, char *dest, STRL
        }
        /* Handle extended ${^Foo} variables
         * 1999-02-27 mjd-perl-patch@plover.com */
-       else if (!isALNUM(*d) && !isPRINT(*d) /* isCTRL(d) */
-                && isALNUM(*s))
+       else if (!isWORDCHAR(*d) && !isPRINT(*d) /* isCTRL(d) */
+                && isWORDCHAR(*s))
        {
            d++;
-           while (isALNUM(*s) && d < e) {
+           while (isWORDCHAR(*s) && d < e) {
                *d++ = *s++;
            }
            if (d >= e)
-               Perl_croak(aTHX_ ident_too_long);
+               Perl_croak(aTHX_ "%s", ident_too_long);
            *d = '\0';
        }
        if (*s == '}') {
@@ -9159,7 +9424,7 @@ S_pmflag(pTHX_ const char* const valid_flags, U32 * pmfl, char** s, char* charse
     STRLEN charlen = UTF ? UTF8SKIP(*s) : 1;
 
     if ( charlen != 1 || ! strchr(valid_flags, c) ) {
-        if (isALNUM_lazy_if(*s, UTF)) {
+        if (isWORDCHAR_lazy_if(*s, UTF)) {
             yyerror_pv(Perl_form(aTHX_ "Unknown regexp modifier \"/%.*s\"", (int)charlen, *s),
                        UTF ? SVf_UTF8 : 0);
             (*s) += charlen;
@@ -9243,7 +9508,8 @@ S_scan_pat(pTHX_ char *start, I32 type)
 {
     dVAR;
     PMOP *pm;
-    char *s = scan_str(start,!!PL_madskills,FALSE, PL_reg_state.re_reparsing);
+    char *s = scan_str(start,!!PL_madskills,FALSE, PL_reg_state.re_reparsing,
+                       TRUE /* look for escaped bracketed metas */ );
     const char * const valid_flags =
        (const char *)((type == OP_QR) ? QR_PAT_MODS : M_PAT_MODS);
     char charset = '\0';    /* character set modifier */
@@ -9346,7 +9612,8 @@ S_scan_subst(pTHX_ char *start)
 
     pl_yylval.ival = OP_NULL;
 
-    s = scan_str(start,!!PL_madskills,FALSE,FALSE);
+    s = scan_str(start,!!PL_madskills,FALSE,FALSE,
+                 TRUE /* look for escaped bracketed metas */ );
 
     if (!s)
        Perl_croak(aTHX_ "Substitution pattern not terminated");
@@ -9364,7 +9631,7 @@ S_scan_subst(pTHX_ char *start)
 #endif
 
     first_start = PL_multi_start;
-    s = scan_str(s,!!PL_madskills,FALSE,FALSE);
+    s = scan_str(s,!!PL_madskills,FALSE,FALSE, FALSE);
     if (!s) {
        if (PL_lex_stuff) {
            SvREFCNT_dec(PL_lex_stuff);
@@ -9450,7 +9717,7 @@ S_scan_trans(pTHX_ char *start)
 
     pl_yylval.ival = OP_NULL;
 
-    s = scan_str(start,!!PL_madskills,FALSE,FALSE);
+    s = scan_str(start,!!PL_madskills,FALSE,FALSE, FALSE);
     if (!s)
        Perl_croak(aTHX_ "Transliteration pattern not terminated");
 
@@ -9466,7 +9733,7 @@ S_scan_trans(pTHX_ char *start)
     }
 #endif
 
-    s = scan_str(s,!!PL_madskills,FALSE,FALSE);
+    s = scan_str(s,!!PL_madskills,FALSE,FALSE, FALSE);
     if (!s) {
        if (PL_lex_stuff) {
            SvREFCNT_dec(PL_lex_stuff);
@@ -9551,7 +9818,7 @@ S_scan_trans(pTHX_ char *start)
 */
 
 STATIC char *
-S_scan_heredoc(pTHX_ register char *s)
+S_scan_heredoc(pTHX_ char *s)
 {
     dVAR;
     I32 op_type = OP_SCALAR;
@@ -9594,9 +9861,9 @@ S_scan_heredoc(pTHX_ register char *s)
            s++, term = '\'';
        else
            term = '"';
-       if (!isALNUM_lazy_if(s,UTF))
+       if (!isWORDCHAR_lazy_if(s,UTF))
            deprecate("bare << to mean <<\"\"");
-       for (; isALNUM_lazy_if(s,UTF); s++) {
+       for (; isWORDCHAR_lazy_if(s,UTF); s++) {
            if (d < e)
                *d++ = *s;
        }
@@ -9746,8 +10013,10 @@ S_scan_heredoc(pTHX_ register char *s)
                                bufend - shared->re_eval_start);
            shared->re_eval_start -= s-d;
        }
-       if (CxTYPE(cx) == CXt_EVAL && CxOLD_OP_TYPE(cx) == OP_ENTEREVAL
-        && cx->blk_eval.cur_text == linestr) {
+       if (cxstack_ix >= 0 && CxTYPE(cx) == CXt_EVAL &&
+            CxOLD_OP_TYPE(cx) == OP_ENTEREVAL &&
+            cx->blk_eval.cur_text == linestr)
+        {
            cx->blk_eval.cur_text = newSVsv(linestr);
            SvSCREAM_on(cx->blk_eval.cur_text);
        }
@@ -9902,7 +10171,7 @@ S_scan_inputsymbol(pTHX_ char *start)
     if (*d == '$' && d[1]) d++;
 
     /* allow <Pkg'VALUE> or <Pkg::VALUE> */
-    while (*d && (isALNUM_lazy_if(d,UTF) || *d == '\'' || *d == ':'))
+    while (*d && (isWORDCHAR_lazy_if(d,UTF) || *d == '\'' || *d == ':'))
        d += UTF ? UTF8SKIP(d) : 1;
 
     /* If we've tried to read what we allow filehandles to look like, and
@@ -9913,7 +10182,7 @@ S_scan_inputsymbol(pTHX_ char *start)
 
     if (d - PL_tokenbuf != len) {
        pl_yylval.ival = OP_GLOB;
-       s = scan_str(start,!!PL_madskills,FALSE,FALSE);
+       s = scan_str(start,!!PL_madskills,FALSE,FALSE, FALSE);
        if (!s)
           Perl_croak(aTHX_ "Glob not terminated");
        return s;
@@ -10055,20 +10324,25 @@ intro_sym:
 */
 
 STATIC char *
-S_scan_str(pTHX_ char *start, int keep_quoted, int keep_delims, int re_reparse)
+S_scan_str(pTHX_ char *start, int keep_quoted, int keep_delims, int re_reparse,
+        bool deprecate_escaped_meta /* Should we issue a deprecation warning
+                                       for certain paired metacharacters that
+                                       appear escaped within it */
+    )
 {
     dVAR;
-    SV *sv;                            /* scalar value: string */
-    const char *tmps;                  /* temp string, used for delimiter matching */
+    SV *sv;                    /* scalar value: string */
+    const char *tmps;          /* temp string, used for delimiter matching */
     char *s = start;           /* current position in the buffer */
     char term;                 /* terminating character */
     char *to;                  /* current position in the sv's data */
-    I32 brackets = 1;                  /* bracket nesting level */
-    bool has_utf8 = FALSE;             /* is there any utf8 content? */
-    I32 termcode;                      /* terminating char. code */
-    U8 termstr[UTF8_MAXBYTES];         /* terminating string */
-    STRLEN termlen;                    /* length of terminating string */
-    int last_off = 0;                  /* last position for nesting bracket */
+    I32 brackets = 1;          /* bracket nesting level */
+    bool has_utf8 = FALSE;     /* is there any utf8 content? */
+    I32 termcode;              /* terminating char. code */
+    U8 termstr[UTF8_MAXBYTES]; /* terminating string */
+    STRLEN termlen;            /* length of terminating string */
+    int last_off = 0;          /* last position for nesting bracket */
+    char *escaped_open = NULL;
 #ifdef PERL_MAD
     int stuffstart;
     char *tstart;
@@ -10115,6 +10389,18 @@ S_scan_str(pTHX_ char *start, int keep_quoted, int keep_delims, int re_reparse)
 
     PL_multi_close = term;
 
+    /* A warning is raised if the input parameter requires it for escaped (by a
+     * backslash) paired metacharacters {} [] and () when the delimiters are
+     * those same characters, and the backslash is ineffective.  This doesn't
+     * happen for <>, as they aren't metas. */
+    if (deprecate_escaped_meta
+        && (PL_multi_open == PL_multi_close
+            || ! ckWARN_d(WARN_DEPRECATED)
+            || PL_multi_open == '<'))
+    {
+        deprecate_escaped_meta = FALSE;
+    }
+
     /* create a new SV to hold the contents.  79 is the SV's initial length.
        What a random number. */
     sv = newSV_type(SVt_PVIV);
@@ -10128,7 +10414,7 @@ S_scan_str(pTHX_ char *start, int keep_quoted, int keep_delims, int re_reparse)
     s += termlen;
 #ifdef PERL_MAD
     tstart = SvPVX(PL_linestr) + stuffstart;
-    if (!PL_thisopen && !keep_delims) {
+    if (PL_madskills && !PL_thisopen && !keep_delims) {
        PL_thisopen = newSVpvn(tstart, s - tstart);
        stuffstart = s - SvPVX(PL_linestr);
     }
@@ -10253,7 +10539,44 @@ S_scan_str(pTHX_ char *start, int keep_quoted, int keep_delims, int re_reparse)
                if (*s == '\\' && s+1 < PL_bufend) {
                    if (!keep_quoted &&
                        ((s[1] == PL_multi_open) || (s[1] == PL_multi_close)))
+                    {
                        s++;
+
+                        /* Here, 'deprecate_escaped_meta' is true iff the
+                         * delimiters are paired metacharacters, and 's' points
+                         * to an occurrence of one of them within the string,
+                         * which was preceded by a backslash.  If this is a
+                         * context where the delimiter is also a metacharacter,
+                         * the backslash is useless, and deprecated.  () and []
+                         * are meta in any context. {} are meta only when
+                         * appearing in a quantifier or in things like '\p{'.
+                         * They also aren't meta unless there is a matching
+                         * closed, escaped char later on within the string.
+                         * If 's' points to an open, set a flag; if to a close,
+                         * test that flag, and raise a warning if it was set */
+
+                       if (deprecate_escaped_meta) {
+                            if (*s == PL_multi_open) {
+                                if (*s != '{') {
+                                    escaped_open = s;
+                                }
+                                else if (regcurly(s,
+                                                  TRUE /* Look for a closing
+                                                          '\}' */)
+                                         || (s - start > 2  /* Look for e.g.
+                                                               '\x{' */
+                                             && _generic_isCC(*(s-2), _CC_BACKSLASH_FOO_LBRACE_IS_META)))
+                                {
+                                    escaped_open = s;
+                                }
+                            }
+                            else if (escaped_open) {
+                                Perl_warner(aTHX_ packWARN(WARN_DEPRECATED),
+                                    "Useless use of '\\'; doesn't escape metacharacter '%c'", PL_multi_open);
+                                escaped_open = NULL;
+                            }
+                        }
+                    }
                    else
                        *to++ = *s++;
                }
@@ -10409,7 +10732,7 @@ Perl_scan_num(pTHX_ const char *start, YYSTYPE* lvalp)
     SV *sv = NULL;                     /* place to put the converted number */
     bool floatit;                      /* boolean: int or float? */
     const char *lastub = NULL;         /* position of last underbar */
-    static char const number_too_long[] = "Number too long";
+    static const char* const number_too_long = "Number too long";
 
     PERL_ARGS_ASSERT_SCAN_NUM;
 
@@ -10619,7 +10942,7 @@ Perl_scan_num(pTHX_ const char *start, YYSTYPE* lvalp)
            else {
                /* check for end of fixed-length buffer */
                if (d >= e)
-                   Perl_croak(aTHX_ number_too_long);
+                   Perl_croak(aTHX_ "%s", number_too_long);
                /* if we're ok, copy the character */
                *d++ = *s++;
            }
@@ -10649,7 +10972,7 @@ Perl_scan_num(pTHX_ const char *start, YYSTYPE* lvalp)
            for (; isDIGIT(*s) || *s == '_'; s++) {
                /* fixed length buffer check */
                if (d >= e)
-                   Perl_croak(aTHX_ number_too_long);
+                   Perl_croak(aTHX_ "%s", number_too_long);
                if (*s == '_') {
                   if (lastub && s == lastub + 1)
                       Perl_ck_warner(aTHX_ packWARN(WARN_SYNTAX),
@@ -10701,7 +11024,7 @@ Perl_scan_num(pTHX_ const char *start, YYSTYPE* lvalp)
            while (isDIGIT(*s) || *s == '_') {
                if (isDIGIT(*s)) {
                    if (d >= e)
-                       Perl_croak(aTHX_ number_too_long);
+                       Perl_croak(aTHX_ "%s", number_too_long);
                    *d++ = *s++;
                }
                else {
@@ -10757,7 +11080,11 @@ Perl_scan_num(pTHX_ const char *start, YYSTYPE* lvalp)
     case 'v':
 vstring:
                sv = newSV(5); /* preallocate storage space */
+               ENTER_with_name("scan_vstring");
+               SAVEFREESV(sv);
                s = scan_vstring(s, PL_bufend, sv);
+               SvREFCNT_inc_simple_void_NN(sv);
+               LEAVE_with_name("scan_vstring");
        break;
     }
 
@@ -10772,7 +11099,7 @@ vstring:
 }
 
 STATIC char *
-S_scan_formline(pTHX_ register char *s)
+S_scan_formline(pTHX_ char *s)
 {
     dVAR;
     char *eol;
@@ -10914,7 +11241,8 @@ Perl_start_subparse(pTHX_ I32 is_format, U32 flags)
     CvOUTSIDE(PL_compcv) = MUTABLE_CV(SvREFCNT_inc_simple(outsidecv));
     CvOUTSIDE_SEQ(PL_compcv) = PL_cop_seqmax;
     if (outsidecv && CvPADLIST(outsidecv))
-       CvPADLIST(PL_compcv)->xpadl_outid = CvPADLIST(outsidecv)->xpadl_id;
+       CvPADLIST(PL_compcv)->xpadl_outid =
+           PadlistNAMES(CvPADLIST(outsidecv));
 
     return oldsavestack_ix;
 }
@@ -10958,7 +11286,6 @@ Perl_yyerror_pvn(pTHX_ const char *const s, STRLEN len, U32 flags)
     SV *msg;
     SV * const where_sv = newSVpvs_flags("", SVs_TEMP);
     int yychar  = PL_parser->yychar;
-    U32 is_utf8 = flags & SVf_UTF8;
 
     PERL_ARGS_ASSERT_YYERROR_PVN;
 
@@ -11019,7 +11346,7 @@ Perl_yyerror_pvn(pTHX_ const char *const s, STRLEN len, U32 flags)
        else
            Perl_sv_catpvf(aTHX_ where_sv, "\\%03o", yychar & 255);
     }
-    msg = sv_2mortal(newSVpvn_flags(s, len, is_utf8));
+    msg = newSVpvn_flags(s, len, (flags & SVf_UTF8) | SVs_TEMP);
     Perl_sv_catpvf(aTHX_ msg, " at %s line %"IVdf", ",
         OutCopFILE(PL_curcop), (IV)CopLINE(PL_curcop));
     if (context)
@@ -11040,9 +11367,10 @@ Perl_yyerror_pvn(pTHX_ const char *const s, STRLEN len, U32 flags)
     else
        qerror(msg);
     if (PL_error_count >= 10) {
-       if (PL_in_eval && SvCUR(ERRSV))
+       SV * errsv;
+       if (PL_in_eval && ((errsv = ERRSV), SvCUR(errsv)))
            Perl_croak(aTHX_ "%"SVf"%s has too many errors.\n",
-                      SVfARG(ERRSV), OutCopFILE(PL_curcop));
+                      SVfARG(errsv), OutCopFILE(PL_curcop));
        else
            Perl_croak(aTHX_ "%s has too many errors.\n",
             OutCopFILE(PL_curcop));
@@ -11306,13 +11634,18 @@ vstring, as well as updating the passed in sv.
 
 Function must be called like
 
-       sv = newSV(5);
+       sv = sv_2mortal(newSV(5));
        s = scan_vstring(s,e,sv);
 
 where s and e are the start and end of the string.
 The sv should already be large enough to store the vstring
 passed in, for performance reasons.
 
+This function may croak if fatal warnings are enabled in the
+calling scope, hence the sv_2mortal in the example (to prevent
+a leak).  Make sure to do SvREFCNT_inc afterwards if you use
+sv_2mortal.
+
 */
 
 char *
@@ -11678,11 +12011,10 @@ Perl_parse_label(pTHX_ U32 flags)
     if (PL_lex_state == LEX_KNOWNEXT) {
        PL_parser->yychar = yylex();
        if (PL_parser->yychar == LABEL) {
-           SV *lsv;
+           char * const lpv = pl_yylval.pval;
+           STRLEN llen = strlen(lpv);
            PL_parser->yychar = YYEMPTY;
-           lsv = newSV_type(SVt_PV);
-           sv_copypv(lsv, cSVOPx(pl_yylval.opval)->op_sv);
-           return lsv;
+           return newSVpvn_flags(lpv, llen, lpv[llen+1] ? SVf_UTF8 : 0);
        } else {
            yyunlex();
            goto no_label;