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detect sub attributes following a signature
[perl5.git] / toke.c
diff --git a/toke.c b/toke.c
index 9972b97..9dbad98 100644 (file)
--- a/toke.c
+++ b/toke.c
@@ -310,6 +310,7 @@ static struct debug_tokens {
     { ANDAND,          TOKENTYPE_NONE,         "ANDAND" },
     { ANDOP,           TOKENTYPE_NONE,         "ANDOP" },
     { ANONSUB,         TOKENTYPE_IVAL,         "ANONSUB" },
+    { ANON_SIGSUB,     TOKENTYPE_IVAL,         "ANON_SIGSUB" },
     { ARROW,           TOKENTYPE_NONE,         "ARROW" },
     { ASSIGNOP,                TOKENTYPE_OPNUM,        "ASSIGNOP" },
     { BITANDOP,                TOKENTYPE_OPNUM,        "BITANDOP" },
@@ -367,6 +368,7 @@ static struct debug_tokens {
     { RELOP,           TOKENTYPE_OPNUM,        "RELOP" },
     { REQUIRE,         TOKENTYPE_NONE,         "REQUIRE" },
     { SHIFTOP,         TOKENTYPE_OPNUM,        "SHIFTOP" },
+    { SIGSUB,          TOKENTYPE_NONE,         "SIGSUB" },
     { SUB,             TOKENTYPE_NONE,         "SUB" },
     { THING,           TOKENTYPE_OPVAL,        "THING" },
     { UMINUS,          TOKENTYPE_NONE,         "UMINUS" },
@@ -456,21 +458,14 @@ S_printbuf(pTHX_ const char *const fmt, const char *const s)
 
     PERL_ARGS_ASSERT_PRINTBUF;
 
-    GCC_DIAG_IGNORE(-Wformat-nonliteral); /* fmt checked by caller */
+    GCC_DIAG_IGNORE_STMT(-Wformat-nonliteral); /* fmt checked by caller */
     PerlIO_printf(Perl_debug_log, fmt, pv_display(tmp, s, strlen(s), 0, 60));
-    GCC_DIAG_RESTORE;
+    GCC_DIAG_RESTORE_STMT;
     SvREFCNT_dec(tmp);
 }
 
 #endif
 
-static int
-S_deprecate_commaless_var_list(pTHX) {
-    PL_expect = XTERM;
-    deprecate_fatal_in("5.28", "Use of comma-less variable list is deprecated");
-    return REPORT(','); /* grandfather non-comma-format format */
-}
-
 /*
  * S_ao
  *
@@ -563,16 +558,18 @@ S_no_op(pTHX_ const char *const what, char *s)
  */
 
 STATIC void
-S_missingterm(pTHX_ char *s)
+S_missingterm(pTHX_ char *s, STRLEN len)
 {
     char tmpbuf[UTF8_MAXBYTES + 1];
     char q;
     bool uni = FALSE;
     SV *sv;
     if (s) {
-       char * const nl = strrchr(s,'\n');
-       if (nl)
-           *nl = '\0';
+       char * const nl = (char *) my_memrchr(s, '\n', len);
+        if (nl) {
+            *nl = '\0';
+            len = nl - s;
+        }
        uni = UTF;
     }
     else if (PL_multi_close < 32) {
@@ -580,24 +577,28 @@ S_missingterm(pTHX_ char *s)
        tmpbuf[1] = (char)toCTRL(PL_multi_close);
        tmpbuf[2] = '\0';
        s = tmpbuf;
+        len = 2;
     }
     else {
        if (LIKELY(PL_multi_close < 256)) {
            *tmpbuf = (char)PL_multi_close;
            tmpbuf[1] = '\0';
+            len = 1;
        }
        else {
+            char *end = (char *)uvchr_to_utf8((U8 *)tmpbuf, PL_multi_close);
+            *end = '\0';
+            len = end - tmpbuf;
            uni = TRUE;
-           *uvchr_to_utf8((U8 *)tmpbuf, PL_multi_close) = 0;
        }
        s = tmpbuf;
     }
-    q = strchr(s,'"') ? '\'' : '"';
-    sv = sv_2mortal(newSVpv(s,0));
+    q = memchr(s, '"', len) ? '\'' : '"';
+    sv = sv_2mortal(newSVpvn(s, len));
     if (uni)
        SvUTF8_on(sv);
-    Perl_croak(aTHX_ "Can't find string terminator %c%" SVf
-                    "%c anywhere before EOF",q,SVfARG(sv),q);
+    Perl_croak(aTHX_ "Can't find string terminator %c%" SVf "%c"
+                     " anywhere before EOF", q, SVfARG(sv), q);
 }
 
 #include "feature.h"
@@ -701,7 +702,6 @@ Perl_lex_start(pTHX_ SV *line, PerlIO *rsfp, U32 flags)
 {
     const char *s = NULL;
     yy_parser *parser, *oparser;
-    const U8* first_bad_char_loc;
 
     if (flags && flags & ~LEX_START_FLAGS)
        Perl_croak(aTHX_ "Lexing code internal error (%s)", "lex_start");
@@ -728,6 +728,7 @@ Perl_lex_start(pTHX_ SV *line, PerlIO *rsfp, U32 flags)
     parser->lex_state = LEX_NORMAL;
     parser->expect = XSTATE;
     parser->rsfp = rsfp;
+    parser->recheck_utf8_validity = FALSE;
     parser->rsfp_filters =
       !(flags & LEX_START_SAME_FILTER) || !oparser
         ? NULL
@@ -744,11 +745,14 @@ Perl_lex_start(pTHX_ SV *line, PerlIO *rsfp, U32 flags)
 
     if (line) {
        STRLEN len;
+        const U8* first_bad_char_loc;
+
        s = SvPV_const(line, len);
 
-        if (SvUTF8(line) && ! is_utf8_string_loc((U8 *) s,
-                                                 SvCUR(line),
-                                                 &first_bad_char_loc))
+        if (   SvUTF8(line)
+            && UNLIKELY(! is_utf8_string_loc((U8 *) s,
+                                             SvCUR(line),
+                                             &first_bad_char_loc)))
         {
             _force_out_malformed_utf8_message(first_bad_char_loc,
                                               (U8 *) s + SvCUR(line),
@@ -765,6 +769,7 @@ Perl_lex_start(pTHX_ SV *line, PerlIO *rsfp, U32 flags)
     } else {
        parser->linestr = newSVpvn("\n;", rsfp ? 1 : 2);
     }
+
     parser->oldoldbufptr =
        parser->oldbufptr =
        parser->bufptr =
@@ -1032,13 +1037,7 @@ Perl_lex_stuff_pvn(pTHX_ const char *pv, STRLEN len, U32 flags)
                SvCUR(PL_parser->linestr) + len+highhalf);
            PL_parser->bufend += len+highhalf;
            for (p = pv; p != e; p++) {
-               U8 c = (U8)*p;
-               if (! UTF8_IS_INVARIANT(c)) {
-                   *bufptr++ = UTF8_TWO_BYTE_HI(c);
-                   *bufptr++ = UTF8_TWO_BYTE_LO(c);
-               } else {
-                   *bufptr++ = (char)c;
-               }
+                append_utf8_from_native_byte(*p, (U8 **) &bufptr);
            }
        }
     } else {
@@ -1053,12 +1052,7 @@ Perl_lex_stuff_pvn(pTHX_ const char *pv, STRLEN len, U32 flags)
                } else if (UTF8_IS_NEXT_CHAR_DOWNGRADEABLE(p, e)) {
                    p++;
                    highhalf++;
-                } else if (! UTF8_IS_INVARIANT(c)) {
-                    _force_out_malformed_utf8_message((U8 *) p, (U8 *) e,
-                                                      0,
-                                                      1 /* 1 means die */ );
-                    NOT_REACHED; /* NOTREACHED */
-               }
+                } else assert(UTF8_IS_INVARIANT(c));
            }
            if (!highhalf)
                goto plain_copy;
@@ -1272,6 +1266,24 @@ Perl_lex_discard_to(pTHX_ char *ptr)
        PL_parser->last_lop -= discard_len;
 }
 
+void
+Perl_notify_parser_that_changed_to_utf8(pTHX)
+{
+    /* Called when $^H is changed to indicate that HINT_UTF8 has changed from
+     * off to on.  At compile time, this has the effect of entering a 'use
+     * utf8' section.  This means that any input was not previously checked for
+     * UTF-8 (because it was off), but now we do need to check it, or our
+     * assumptions about the input being sane could be wrong, and we could
+     * segfault.  This routine just sets a flag so that the next time we look
+     * at the input we do the well-formed UTF-8 check.  If we aren't in the
+     * proper phase, there may not be a parser object, but if there is, setting
+     * the flag is harmless */
+
+    if (PL_parser) {
+        PL_parser->recheck_utf8_validity = TRUE;
+    }
+}
+
 /*
 =for apidoc Amx|bool|lex_next_chunk|U32 flags
 
@@ -1307,7 +1319,6 @@ Perl_lex_next_chunk(pTHX_ U32 flags)
     STRLEN linestart_pos, last_uni_pos, last_lop_pos;
     bool got_some_for_debugger = 0;
     bool got_some;
-    const U8* first_bad_char_loc;
 
     if (flags & ~(LEX_KEEP_PREVIOUS|LEX_FAKE_EOF|LEX_NO_TERM))
        Perl_croak(aTHX_ "Lexing code internal error (%s)", "lex_next_chunk");
@@ -1374,15 +1385,19 @@ Perl_lex_next_chunk(pTHX_ U32 flags)
     PL_parser->bufend = buf + new_bufend_pos;
     PL_parser->bufptr = buf + bufptr_pos;
 
-    if (UTF && ! is_utf8_string_loc((U8 *) PL_parser->bufptr,
-                                    PL_parser->bufend - PL_parser->bufptr,
-                                    &first_bad_char_loc))
-    {
-        _force_out_malformed_utf8_message(first_bad_char_loc,
-                                          (U8 *) PL_parser->bufend,
-                                          0,
-                                          1 /* 1 means die */ );
-        NOT_REACHED; /* NOTREACHED */
+    if (UTF) {
+        const U8* first_bad_char_loc;
+        if (UNLIKELY(! is_utf8_string_loc(
+                            (U8 *) PL_parser->bufptr,
+                                   PL_parser->bufend - PL_parser->bufptr,
+                                   &first_bad_char_loc)))
+        {
+            _force_out_malformed_utf8_message(first_bad_char_loc,
+                                              (U8 *) PL_parser->bufend,
+                                              0,
+                                              1 /* 1 means die */ );
+            NOT_REACHED; /* NOTREACHED */
+        }
     }
 
     PL_parser->oldbufptr = buf + oldbufptr_pos;
@@ -1559,7 +1574,7 @@ Perl_lex_read_space(pTHX_ U32 flags)
                if (s == bufend)
                    need_incline = 1;
                else
-                   incline(s);
+                   incline(s, bufend);
            }
        } else if (isSPACE(c)) {
            s++;
@@ -1578,7 +1593,7 @@ Perl_lex_read_space(pTHX_ U32 flags)
            if (!got_more)
                break;
            if (can_incline && need_incline && PL_parser->rsfp) {
-               incline(s);
+               incline(s, bufend);
                need_incline = 0;
            }
        } else if (!c) {
@@ -1610,7 +1625,7 @@ Note that C<NULL> is a valid C<proto> and will always return C<true>.
  */
 
 bool
-Perl_validate_proto(pTHX_ SV *name, SV *proto, bool warn)
+Perl_validate_proto(pTHX_ SV *name, SV *proto, bool warn, bool curstash)
 {
     STRLEN len, origlen;
     char *p;
@@ -1672,6 +1687,13 @@ Perl_validate_proto(pTHX_ SV *name, SV *proto, bool warn)
                             origlen, UNI_DISPLAY_ISPRINT)
            : pv_pretty(tmpsv, p, origlen, 60, NULL, NULL, PERL_PV_ESCAPE_NONASCII);
 
+       if (curstash && !memchr(SvPVX(name), ':', SvCUR(name))) {
+           SV *name2 = sv_2mortal(newSVsv(PL_curstname));
+           sv_catpvs(name2, "::");
+           sv_catsv(name2, (SV *)name);
+           name = name2;
+       }
+
        if (proto_after_greedy_proto)
            Perl_warner(aTHX_ packWARN(WARN_ILLEGALPROTO),
                        "Prototype after '%c' for %" SVf " : %s",
@@ -1704,7 +1726,7 @@ Perl_validate_proto(pTHX_ SV *name, SV *proto, bool warn)
  */
 
 STATIC void
-S_incline(pTHX_ const char *s)
+S_incline(pTHX_ const char *s, const char *end)
 {
     const char *t;
     const char *n;
@@ -1714,6 +1736,8 @@ S_incline(pTHX_ const char *s)
 
     PERL_ARGS_ASSERT_INCLINE;
 
+    assert(end >= s);
+
     COPLINE_INC_WITH_HERELINES;
     if (!PL_rsfp && !PL_parser->filtered && PL_lex_state == LEX_NORMAL
      && s+1 == PL_bufend && *s == ';') {
@@ -1725,8 +1749,8 @@ S_incline(pTHX_ const char *s)
        return;
     while (SPACE_OR_TAB(*s))
        s++;
-    if (strEQs(s, "line"))
-       s += 4;
+    if (memBEGINs(s, (STRLEN) (end - s), "line"))
+       s += sizeof("line") - 1;
     else
        return;
     if (SPACE_OR_TAB(*s))
@@ -1745,7 +1769,7 @@ S_incline(pTHX_ const char *s)
        return;
     while (SPACE_OR_TAB(*s))
        s++;
-    if (*s == '"' && (t = strchr(s+1, '"'))) {
+    if (*s == '"' && (t = (char *) memchr(s+1, '"', end - s))) {
        s++;
        e = t + 1;
     }
@@ -1899,7 +1923,6 @@ STATIC void
 S_check_uni(pTHX)
 {
     const char *s;
-    const char *t;
 
     if (PL_oldoldbufptr != PL_last_uni)
        return;
@@ -1908,7 +1931,7 @@ S_check_uni(pTHX)
     s = PL_last_uni;
     while (isWORDCHAR_lazy_if_safe(s, PL_bufend, UTF) || *s == '-')
        s += UTF ? UTF8SKIP(s) : 1;
-    if ((t = strchr(s, '(')) && t < PL_bufptr)
+    if (s < PL_bufptr && memchr(s, '(', PL_bufptr - s))
        return;
 
     Perl_ck_warner_d(aTHX_ packWARN(WARN_AMBIGUOUS),
@@ -1987,7 +2010,7 @@ S_force_next(pTHX_ I32 type)
  * S_postderef
  *
  * This subroutine handles postfix deref syntax after the arrow has already
- * been emitted.  @* $* etc. are emitted as two separate token right here.
+ * been emitted.  @* $* etc. are emitted as two separate tokens right here.
  * @[ @{ %[ %{ *{ are emitted also as two tokens, but this function emits
  * only the first, leaving yylex to find the next.
  */
@@ -2042,10 +2065,9 @@ STATIC SV *
 S_newSV_maybe_utf8(pTHX_ const char *const start, STRLEN len)
 {
     SV * const sv = newSVpvn_utf8(start, len,
-                          !IN_BYTES
-                          && UTF
-                          && !is_utf8_invariant_string((const U8*)start, len)
-                          && is_utf8_string((const U8*)start, len));
+                    ! IN_BYTES
+                  &&  UTF
+                  &&  is_utf8_non_invariant_string((const U8*)start, len));
     return sv;
 }
 
@@ -2083,8 +2105,10 @@ S_force_word(pTHX_ char *start, int token, int check_keyword, int allow_pack)
        if (check_keyword) {
          char *s2 = PL_tokenbuf;
          STRLEN len2 = len;
-         if (allow_pack && len > 6 && strEQs(s2, "CORE::"))
-           s2 += 6, len2 -= 6;
+         if (allow_pack && memBEGINPs(s2, len, "CORE::")) {
+           s2 += sizeof("CORE::") - 1;
+            len2 -= sizeof("CORE::") - 1;
+          }
          if (keyword(s2, len2, 0))
            return start;
        }
@@ -2263,10 +2287,9 @@ S_force_strict_version(pTHX_ char *s)
 
 /*
  * S_tokeq
- * Tokenize a quoted string passed in as an SV.  It finds the next
- * chunk, up to end of string or a backslash.  It may make a new
- * SV containing that chunk (if HINT_NEW_STRING is on).  It also
- * turns \\ into \.
+ * Turns any \\ into \ in a quoted string passed in in 'sv', returning 'sv',
+ * modified as necessary.  However, if HINT_NEW_STRING is on, 'sv' is
+ * unchanged, and a new SV containing the modified input is returned.
  */
 
 STATIC SV *
@@ -2369,6 +2392,8 @@ S_sublex_start(pTHX)
     PL_parser->lex_super_state = PL_lex_state;
     PL_parser->lex_sub_inwhat = (U16)op_type;
     PL_parser->lex_sub_op = PL_lex_op;
+    PL_parser->sub_no_recover = FALSE;
+    PL_parser->sub_error_count = PL_error_count;
     PL_lex_state = LEX_INTERPPUSH;
 
     PL_expect = XTERM;
@@ -2548,6 +2573,20 @@ S_sublex_done(pTHX)
     else {
        const line_t l = CopLINE(PL_curcop);
        LEAVE;
+        if (PL_parser->sub_error_count != PL_error_count) {
+            const char * const name = OutCopFILE(PL_curcop);
+            if (PL_parser->sub_no_recover) {
+                const char * msg = "";
+                if (PL_in_eval) {
+                    SV *errsv = ERRSV;
+                    if (SvCUR(ERRSV)) {
+                        msg = Perl_form(aTHX_ "%" SVf, SVfARG(errsv));
+                    }
+                }
+                abort_execution(msg, name);
+                NOT_REACHED;
+            }
+        }
        if (PL_multi_close == '<')
            PL_parser->herelines += l - PL_multi_end;
        PL_bufend = SvPVX(PL_linestr);
@@ -2571,29 +2610,15 @@ S_get_and_check_backslash_N_name(pTHX_ const char* s, const char* const e)
     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 (!SvCUR(res)) {
-        deprecate_fatal_in("5.28", "Unknown charname '' is deprecated");
-        return res;
-    }
-
-    if (UTF && ! is_utf8_string_loc((U8 *) backslash_ptr,
-                                     e - backslash_ptr,
-                                     &first_bad_char_loc))
-    {
-        _force_out_malformed_utf8_message(first_bad_char_loc,
-                                          (U8 *) PL_parser->bufend,
-                                          0,
-                                          0 /* 0 means don't die */ );
-        yyerror_pv(Perl_form(aTHX_
-            "Malformed UTF-8 character immediately after '%.*s'",
-            (int) (first_bad_char_loc - (U8 *) backslash_ptr), backslash_ptr),
-                   SVf_UTF8);
-       return NULL;
+        SvREFCNT_dec_NN(res);
+        /* diag_listed_as: Unknown charname '%s' */
+        yyerror("Unknown charname ''");
+        return NULL;
     }
 
     res = new_constant( NULL, 0, "charnames", res, NULL, backslash_ptr,
@@ -2613,8 +2638,7 @@ S_get_and_check_backslash_N_name(pTHX_ const char* s, const char* const e)
         SvTYPE(rv) == SVt_PVCV) && ((stash = CvSTASH(rv)) != NULL))
     {
         const char * const name = HvNAME(stash);
-        if (HvNAMELEN(stash) == sizeof("_charnames")-1
-         && strEQ(name, "_charnames")) {
+         if (memEQs(name, HvNAMELEN(stash), "_charnames")) {
            return res;
        }
     }
@@ -2705,6 +2729,9 @@ S_get_and_check_backslash_N_name(pTHX_ const char* s, const char* const e)
         }
     }
     if (*(s-1) == ' ') {
+        /* diag_listed_as: charnames alias definitions may not contain
+                           trailing white-space; marked by <-- HERE in %s
+         */
         yyerror_pv(
             Perl_form(aTHX_
             "charnames alias definitions may not contain trailing "
@@ -2720,11 +2747,15 @@ S_get_and_check_backslash_N_name(pTHX_ const char* s, const char* const e)
         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 (UNLIKELY(! is_utf8_string_loc((U8 *) str, len,
+                                          &first_bad_char_loc)))
+        {
             _force_out_malformed_utf8_message(first_bad_char_loc,
                                               (U8 *) PL_parser->bufend,
                                               0,
                                               0 /* 0 means don't die */ );
+            /* diag_listed_as: Malformed UTF-8 returned by \N{%s}
+                               immediately after '%s' */
             yyerror_pv(
               Perl_form(aTHX_
                 "Malformed UTF-8 returned by %.*s immediately after '%.*s'",
@@ -2742,6 +2773,8 @@ S_get_and_check_backslash_N_name(pTHX_ const char* s, const char* const e)
 
         /* The final %.*s makes sure that should the trailing NUL be missing
          * that this print won't run off the end of the string */
+        /* diag_listed_as: Invalid character in \N{...}; marked by <-- HERE
+                           in \N{%s} */
         yyerror_pv(
           Perl_form(aTHX_
             "Invalid character in \\N{...}; marked by <-- HERE in %.*s<-- HERE %.*s",
@@ -2753,6 +2786,9 @@ S_get_and_check_backslash_N_name(pTHX_ const char* s, const char* const e)
     }
 
   multi_spaces:
+        /* diag_listed_as: charnames alias definitions may not contain a
+                           sequence of multiple spaces; marked by <-- HERE
+                           in %s */
         yyerror_pv(
           Perl_form(aTHX_
             "charnames alias definitions may not contain a sequence of "
@@ -2877,8 +2913,8 @@ S_scan_const(pTHX_ char *start)
                                            should we have to convert to
                                            UTF-8) */
     SV *res;                           /* result from charnames */
-    STRLEN offset_to_max;   /* The offset in the output to where the range
-                               high-end character is temporarily placed */
+    STRLEN offset_to_max = 0;   /* The offset in the output to where the range
+                                   high-end character is temporarily placed */
 
     /* Does something require special handling in tr/// ?  This avoids extra
      * work in a less likely case.  As such, khw didn't feel it was worth
@@ -2953,9 +2989,9 @@ S_scan_const(pTHX_ char *start)
 
                 /* Here, we don't think we're in a range.  If the new character
                  * is not a hyphen; or if it is a hyphen, but it's too close to
-                 * either edge to indicate a range, then it's a regular
-                 * character. */
-                if (*s != '-' || s >= send - 1 || s == start) {
+                 * either edge to indicate a range, or if we haven't output any
+                 * characters yet then it's a regular character. */
+                if (*s != '-' || s >= send - 1 || s == start || d == SvPVX(sv)) {
 
                     /* A regular character.  Process like any other, but first
                      * clear any flags */
@@ -3024,7 +3060,6 @@ S_scan_const(pTHX_ char *start)
                 bool convert_unicode;
                 IV real_range_max = 0;
 #endif
-
                 /* Get the code point values of the range ends. */
                 if (has_utf8) {
                     /* We know the utf8 is valid, because we just constructed
@@ -3050,7 +3085,11 @@ S_scan_const(pTHX_ char *start)
                  * that code point is already in the output, twice.  We can
                  * just back up over the second instance and avoid all the rest
                  * of the work.  But if it is a variant character, it's been
-                 * counted twice, so decrement */
+                 * counted twice, so decrement.  (This unlikely scenario is
+                 * special cased, like the one for a range of 2 code points
+                 * below, only because the main-line code below needs a range
+                 * of 3 or more to work without special casing.  Might as well
+                 * get it out of the way now.) */
                 if (UNLIKELY(range_max == range_min)) {
                     d = max_ptr;
                     if (! has_utf8 && ! UVCHR_IS_INVARIANT(range_max)) {
@@ -3267,18 +3306,18 @@ S_scan_const(pTHX_ char *start)
 #endif
                 /* Always gets run for ASCII, and sometimes for EBCDIC. */
                 {
-                    SSize_t i;
-
                     /* Here, no conversions are necessary, which means that the
                      * first character in the range is already in 'd' and
                      * valid, so we can skip overwriting it */
                     if (has_utf8) {
+                        SSize_t i;
                         d += UTF8SKIP(d);
                         for (i = range_min + 1; i <= range_max; i++) {
                             append_utf8_from_native_byte((U8) i, (U8 **) &d);
                         }
                     }
                     else {
+                        SSize_t i;
                         d++;
                         assert(range_min + 1 <= range_max);
                         for (i = range_min + 1; i < range_max; i++) {
@@ -3487,7 +3526,8 @@ S_scan_const(pTHX_ char *start)
                {
                    const char* error;
 
-                   bool valid = grok_bslash_o(&s, &uv, &error,
+                   bool valid = grok_bslash_o(&s, PL_bufend,
+                                               &uv, &error,
                                                TRUE, /* Output warning */
                                                FALSE, /* Not strict */
                                                TRUE, /* Output warnings for
@@ -3505,7 +3545,8 @@ S_scan_const(pTHX_ char *start)
                {
                    const char* error;
 
-                   bool valid = grok_bslash_x(&s, &uv, &error,
+                   bool valid = grok_bslash_x(&s, PL_bufend,
+                                               &uv, &error,
                                                TRUE, /* Output warning */
                                                FALSE, /* Not strict */
                                                TRUE,  /* Output warnings for
@@ -3608,11 +3649,12 @@ S_scan_const(pTHX_ char *start)
                  * For non-patterns, the named characters are converted to
                  * their string equivalents.  In patterns, named characters are
                  * not converted to their ultimate forms for the same reasons
-                 * that other escapes aren't.  Instead, they are converted to
-                 * the \N{U+...} form to get the value from the charnames that
-                 * is in effect right now, while preserving the fact that it
-                 * was a named character, so that the regex compiler knows
-                 * this.
+                 * that other escapes aren't (mainly that the ultimate
+                 * character could be considered a meta-symbol by the regex
+                 * compiler).  Instead, they are converted to the \N{U+...}
+                 * form to get the value from the charnames that is in effect
+                 * right now, while preserving the fact that it was a named
+                 * character, so that the regex compiler knows this.
                  *
                 * The structure of this section of code (besides checking for
                 * errors and upgrading to utf8) is:
@@ -3633,18 +3675,19 @@ S_scan_const(pTHX_ char *start)
                s++;
                if (*s != '{') {
                    yyerror("Missing braces on \\N{}");
+                    *d++ = '\0';
                    continue;
                }
                s++;
 
                /* If there is no matching '}', it is an error. */
-               if (! (e = strchr(s, '}'))) {
+               if (! (e = (char *) memchr(s, '}', send - s))) {
                    if (! PL_lex_inpat) {
                        yyerror("Missing right brace on \\N{}");
                    } else {
                        yyerror("Missing right brace on \\N{} or unescaped left brace after \\N");
                    }
-                   continue;
+                    yyquit(); /* Have exhausted the input. */
                }
 
                /* Here it looks like a named character */
@@ -3663,6 +3706,7 @@ S_scan_const(pTHX_ char *start)
                                 "Invalid hexadecimal number in \\N{U+...}"
                             );
                             s = e + 1;
+                            *d++ = '\0';
                             continue;
                         }
                         while (++s < e) {
@@ -3861,6 +3905,7 @@ S_scan_const(pTHX_ char *start)
                                     " in transliteration operator",
                                         /*  +1 to include the "}" */
                                     (int) (e + 1 - start), start));
+                                *d++ = '\0';
                                 goto end_backslash_N;
                             }
 
@@ -3926,15 +3971,16 @@ S_scan_const(pTHX_ char *start)
            case 'c':
                s++;
                if (s < send) {
-                   *d++ = grok_bslash_c(*s++, 1);
+                   *d++ = grok_bslash_c(*s, 1);
                }
                else {
                    yyerror("Missing control char name in \\c");
+                   yyquit();   /* Are at end of input, no sense continuing */
                }
 #ifdef EBCDIC
                 non_portable_endpoint++;
 #endif
-               continue;
+                break;
 
            /* printf-style backslashes, formfeeds, newlines, etc */
            case 'b':
@@ -4114,7 +4160,7 @@ 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_ char *s)
+S_intuit_more(pTHX_ char *s, char *e)
 {
     PERL_ARGS_ASSERT_INTUIT_MORE;
 
@@ -4129,6 +4175,7 @@ S_intuit_more(pTHX_ char *s)
        return TRUE;
     if (*s != '{' && *s != '[')
        return FALSE;
+    PL_parser->sub_no_recover = TRUE;
     if (!PL_lex_inpat)
        return TRUE;
 
@@ -4149,7 +4196,7 @@ S_intuit_more(pTHX_ char *s)
         /* this is terrifying, and it works */
        int weight;
        char seen[256];
-       const char * const send = strchr(s,']');
+       const char * const send = (char *) memchr(s, ']', e - s);
        unsigned char un_char, last_un_char;
        char tmpbuf[sizeof PL_tokenbuf * 4];
 
@@ -4179,7 +4226,7 @@ S_intuit_more(pTHX_ char *s)
                weight -= seen[un_char] * 10;
                if (isWORDCHAR_lazy_if_safe(s+1, PL_bufend, UTF)) {
                    int len;
-                   scan_ident(s, send, tmpbuf, sizeof tmpbuf, FALSE);
+                   scan_ident(s, tmpbuf, sizeof tmpbuf, FALSE);
                    len = (int)strlen(tmpbuf);
                    if (len > 1 && gv_fetchpvn_flags(tmpbuf, len,
                                                     UTF ? SVf_UTF8 : 0, SVt_PV))
@@ -4420,8 +4467,8 @@ Perl_filter_add(pTHX_ filter_t funcp, SV *datasv)
                    PL_parser->last_uni = buf + last_uni_pos;
                if (PL_parser->last_lop)
                    PL_parser->last_lop = buf + last_lop_pos;
-               SvLEN(linestr) = SvCUR(linestr);
-               SvCUR(linestr) = s-SvPVX(linestr);
+               SvLEN_set(linestr, SvCUR(linestr));
+               SvCUR_set(linestr, s - SvPVX(linestr));
                PL_parser->filtered = 1;
                break;
            }
@@ -4464,6 +4511,7 @@ I32
 Perl_filter_read(pTHX_ int idx, SV *buf_sv, int maxlen)
 {
     filter_t funcp;
+    I32 ret;
     SV *datasv = NULL;
     /* This API is bad. It should have been using unsigned int for maxlen.
        Not sure if we want to change the API, but if not we should sanity
@@ -4546,7 +4594,11 @@ Perl_filter_read(pTHX_ int idx, SV *buf_sv, int maxlen)
     /* Call function. The function is expected to      */
     /* call "FILTER_READ(idx+1, buf_sv)" first.                */
     /* Return: <0:error, =0:eof, >0:not eof            */
-    return (*funcp)(aTHX_ idx, buf_sv, correct_length);
+    ENTER;
+    save_scalar(PL_errgv);
+    ret = (*funcp)(aTHX_ idx, buf_sv, correct_length);
+    LEAVE;
+    return ret;
 }
 
 STATIC char *
@@ -4578,7 +4630,7 @@ S_find_in_my_stash(pTHX_ const char *pkgname, STRLEN len)
 
     PERL_ARGS_ASSERT_FIND_IN_MY_STASH;
 
-    if (len == 11 && *pkgname == '_' && strEQ(pkgname, "__PACKAGE__"))
+    if (memEQs(pkgname, len, "__PACKAGE__"))
         return PL_curstash;
 
     if (len > 2
@@ -4607,6 +4659,7 @@ S_tokenize_use(pTHX_ int is_use, char *s) {
     PERL_ARGS_ASSERT_TOKENIZE_USE;
 
     if (PL_expect != XSTATE)
+       /* diag_listed_as: "use" not allowed in expression */
        yyerror(Perl_form(aTHX_ "\"%s\" not allowed in expression",
                    is_use ? "use" : "no"));
     PL_expect = XTERM;
@@ -4752,6 +4805,20 @@ Perl_yylex(pTHX)
     GV *gv = NULL;
     GV **gvp = NULL;
 
+    if (UNLIKELY(PL_parser->recheck_utf8_validity)) {
+        const U8* first_bad_char_loc;
+        if (UTF && UNLIKELY(! is_utf8_string_loc((U8 *) PL_bufptr,
+                                                        PL_bufend - PL_bufptr,
+                                                        &first_bad_char_loc)))
+        {
+            _force_out_malformed_utf8_message(first_bad_char_loc,
+                                              (U8 *) PL_bufend,
+                                              0,
+                                              1 /* 1 means die */ );
+            NOT_REACHED; /* NOTREACHED */
+        }
+        PL_parser->recheck_utf8_validity = FALSE;
+    }
     DEBUG_T( {
        SV* tmp = newSVpvs("");
        PerlIO_printf(Perl_debug_log, "### %" IVdf ":LEX_%s/X%s %s\n",
@@ -4838,8 +4905,11 @@ Perl_yylex(pTHX)
            }
            else {
                I32 tmp;
-                if (strnEQ(s, "L\\u", 3) || strnEQ(s, "U\\l", 3))
+                if (   memBEGINs(s, (STRLEN) (PL_bufend - s), "L\\u")
+                    || memBEGINs(s, (STRLEN) (PL_bufend - s), "U\\l"))
+                {
                     tmp = *s, *s = s[2], s[2] = (char)tmp;     /* misordered... */
+                }
                if ((*s == 'L' || *s == 'U' || *s == 'F')
                     && (strpbrk(PL_lex_casestack, "LUF")))
                 {
@@ -4930,7 +5000,7 @@ Perl_yylex(pTHX)
        return yylex();
 
     case LEX_INTERPENDMAYBE:
-       if (intuit_more(PL_bufptr)) {
+       if (intuit_more(PL_bufptr, PL_bufend)) {
            PL_lex_state = LEX_INTERPNORMAL;    /* false alarm, more expr */
            break;
        }
@@ -4999,7 +5069,16 @@ Perl_yylex(pTHX)
            s = PL_bufend;
        }
        else {
+            int save_error_count = PL_error_count;
+
            s = scan_const(PL_bufptr);
+
+            /* Set flag if this was a pattern and there were errors.  op.c will
+             * refuse to compile a pattern with this flag set.  Otherwise, we
+             * could get segfaults, etc. */
+            if (PL_lex_inpat && PL_error_count > save_error_count) {
+                ((PMOP*)PL_lex_inpat)->op_pmflags |= PMf_HAS_ERROR;
+            }
            if (*s == '\\')
                PL_lex_state = LEX_INTERPCASEMOD;
            else
@@ -5025,6 +5104,7 @@ Perl_yylex(pTHX)
 
        return yylex();
     case LEX_FORMLINE:
+       assert(PL_lex_formbrack);
        s = scan_formline(PL_bufptr);
        if (!PL_lex_formbrack)
        {
@@ -5075,15 +5155,46 @@ Perl_yylex(pTHX)
                 /* read var name, including sigil, into PL_tokenbuf */
                 PL_tokenbuf[0] = sigil;
                 parse_ident(&s, &dest, dest + sizeof(PL_tokenbuf) - 1,
-                    0, cBOOL(UTF), FALSE);
+                    0, cBOOL(UTF), FALSE, FALSE);
                 *dest = '\0';
                 assert(PL_tokenbuf[1]); /* we have a variable name */
+            }
+            else {
+                *PL_tokenbuf = 0;
+                PL_in_my = 0;
+            }
+
+            s = skipspace(s);
+            /* parse the = for the default ourselves to avoid '+=' etc being accepted here
+             * as the ASSIGNOP, and exclude other tokens that start with =
+             */
+            if (*s == '=' && (!s[1] || strchr("=~>", s[1]) == 0)) {
+                /* save now to report with the same context as we did when
+                 * all ASSIGNOPS were accepted */
+                PL_oldbufptr = s;
+
+                ++s;
+                NEXTVAL_NEXTTOKE.ival = 0;
+                force_next(ASSIGNOP);
+                PL_expect = XTERM;
+            }
+            else if (*s == ',' || *s == ')') {
+                PL_expect = XOPERATOR;
+            }
+            else {
+                /* make sure the context shows the unexpected character and
+                 * hopefully a bit more */
+                if (*s) ++s;
+                while (*s && *s != '$' && *s != '@' && *s != '%' && *s != ')')
+                    s++;
+                PL_bufptr = s; /* for error reporting */
+                yyerror("Illegal operator following parameter in a subroutine signature");
+                PL_in_my = 0;
+            }
+            if (*PL_tokenbuf) {
                 NEXTVAL_NEXTTOKE.ival = sigil;
                 force_next('p'); /* force a signature pending identifier */
             }
-            else
-                PL_in_my = 0;
-            PL_expect = XOPERATOR;
             break;
 
         case ')':
@@ -5108,12 +5219,6 @@ Perl_yylex(pTHX)
     switch (*s) {
     default:
        if (UTF) {
-            if (! isUTF8_CHAR((U8 *) s, (U8 *) PL_bufend)) {
-                _force_out_malformed_utf8_message((U8 *) s, (U8 *) PL_bufend,
-                                                  0,
-                                                  1 /* 1 means die */ );
-                NOT_REACHED; /* NOTREACHED */
-            }
             if (isIDFIRST_utf8_safe(s, PL_bufend)) {
                 goto keylookup;
             }
@@ -5135,12 +5240,23 @@ Perl_yylex(pTHX)
         else {
             c = Perl_form(aTHX_ "\\x%02X", (unsigned char)*s);
         }
-        len = UTF ? Perl_utf8_length(aTHX_ (U8 *) PL_linestart, (U8 *) s) : (STRLEN) (s - PL_linestart);
-        if (len > UNRECOGNIZED_PRECEDE_COUNT) {
-            d = UTF ? (char *) utf8_hop_back((U8 *) s, -UNRECOGNIZED_PRECEDE_COUNT, (U8 *)PL_linestart) : s - UNRECOGNIZED_PRECEDE_COUNT;
-        } else {
+
+        if (s >= PL_linestart) {
             d = PL_linestart;
         }
+        else {
+            /* somehow (probably due to a parse failure), PL_linestart has advanced
+             * pass PL_bufptr, get a reasonable beginning of line
+             */
+            d = s;
+            while (d > SvPVX(PL_linestr) && d[-1] && d[-1] != '\n')
+                --d;
+        }
+        len = UTF ? Perl_utf8_length(aTHX_ (U8 *) d, (U8 *) s) : (STRLEN) (s - d);
+        if (len > UNRECOGNIZED_PRECEDE_COUNT) {
+            d = UTF ? (char *) utf8_hop_back((U8 *) s, -UNRECOGNIZED_PRECEDE_COUNT, (U8 *)d) : s - UNRECOGNIZED_PRECEDE_COUNT;
+        }
+
         Perl_croak(aTHX_  "Unrecognized character %s; marked by <-- HERE after %" UTF8f "<-- HERE near column %d", c,
                           UTF8fARG(UTF, (s - d), d),
                          (int) len + 1);
@@ -5209,10 +5325,15 @@ Perl_yylex(pTHX)
                    sv_catpvs(PL_linestr,"chomp;");
                if (PL_minus_a) {
                    if (PL_minus_F) {
-                       if ((*PL_splitstr == '/' || *PL_splitstr == '\''
-                            || *PL_splitstr == '"')
-                             && strchr(PL_splitstr + 1, *PL_splitstr))
+                        if (   (   *PL_splitstr == '/'
+                                || *PL_splitstr == '\''
+                                || *PL_splitstr == '"')
+                            && strchr(PL_splitstr + 1, *PL_splitstr))
+                        {
+                            /* strchr is ok, because -F pattern can't contain
+                             * embeddded NULs */
                            Perl_sv_catpvf(aTHX_ PL_linestr, "our @F=split(%s);", PL_splitstr);
+                        }
                        else {
                            /* "q\0${splitstr}\0" is legal perl. Yes, even NUL
                               bytes can be used as quoting characters.  :-) */
@@ -5261,10 +5382,10 @@ Perl_yylex(pTHX)
            /* If it looks like the start of a BOM or raw UTF-16,
             * check if it in fact is. */
            if (bof && PL_rsfp
-                && (*s == 0
+                && (   *s == 0
                     || *(U8*)s == BOM_UTF8_FIRST_BYTE
-                        || *(U8*)s >= 0xFE
-                        || s[1] == 0))
+                    || *(U8*)s >= 0xFE
+                    || s[1] == 0))
             {
                Off_t offset = (IV)PerlIO_tell(PL_rsfp);
                bof = (offset == (Off_t)SvCUR(PL_linestr));
@@ -5280,7 +5401,9 @@ Perl_yylex(pTHX)
            }
            if (PL_parser->in_pod) {
                /* Incest with pod. */
-               if (*s == '=' && strEQs(s, "=cut") && !isALPHA(s[4])) {
+                if (    memBEGINPs(s, (STRLEN) (PL_bufend - s), "=cut")
+                    && !isALPHA(s[4]))
+                {
                     SvPVCLEAR(PL_linestr);
                    PL_oldoldbufptr = PL_oldbufptr = s = PL_linestart = SvPVX(PL_linestr);
                    PL_bufend = SvPVX(PL_linestr) + SvCUR(PL_linestr);
@@ -5289,7 +5412,7 @@ Perl_yylex(pTHX)
                }
            }
            if (PL_rsfp || PL_parser->filtered)
-               incline(s);
+               incline(s, PL_bufend);
        } while (PL_parser->in_pod);
        PL_oldoldbufptr = PL_oldbufptr = PL_bufptr = PL_linestart = s;
        PL_bufend = SvPVX(PL_linestr) + SvCUR(PL_linestr);
@@ -5367,8 +5490,6 @@ Perl_yylex(pTHX)
                d = instr(s,"perl -");
                if (!d) {
                    d = instr(s,"perl");
-                    if (d && d[4] == '6')
-                        d = NULL;
 #if defined(DOSISH)
                    /* avoid getting into infinite loops when shebang
                     * line contains "Perl" rather than "perl" */
@@ -5516,24 +5637,20 @@ Perl_yylex(pTHX)
             && !PL_rsfp && !PL_parser->filtered) {
                /* handle eval qq[#line 1 "foo"\n ...] */
                CopLINE_dec(PL_curcop);
-               incline(s);
+               incline(s, PL_bufend);
            }
             d = s;
             while (d < PL_bufend && *d != '\n')
                 d++;
             if (d < PL_bufend)
                 d++;
-            else if (d > PL_bufend)
-                /* Found by Ilya: feed random input to Perl. */
-                Perl_croak(aTHX_ "panic: input overflow, %p > %p",
-                           d, PL_bufend);
             s = d;
             if (in_comment && d == PL_bufend
                 && PL_lex_state == LEX_INTERPNORMAL
                 && PL_lex_inwhat == OP_SUBST && PL_lex_repl == PL_linestr
                 && SvEVALED(PL_lex_repl) && d[-1] == '}') s--;
             else
-                incline(s);
+                incline(s, PL_bufend);
            if (PL_lex_formbrack && PL_lex_brackets <= PL_lex_formbrack) {
                PL_lex_state = LEX_FORMLINE;
                force_next(FORMRBRACK);
@@ -5547,11 +5664,8 @@ Perl_yylex(pTHX)
                 {
                     s++;
                     if (s < PL_bufend)
-                        incline(s);
+                        incline(s, PL_bufend);
                 }
-            else if (s > PL_bufend)
-                /* Found by Ilya: feed random input to Perl. */
-                Perl_croak(aTHX_ "panic: input overflow");
        }
        goto retry;
     case '-':
@@ -5566,7 +5680,7 @@ Perl_yylex(pTHX)
            while (s < PL_bufend && SPACE_OR_TAB(*s))
                s++;
 
-           if (strEQs(s,"=>")) {
+           if (memBEGINs(s, (STRLEN) (PL_bufend - s), "=>")) {
                s = force_word(PL_bufptr,BAREWORD,FALSE,FALSE);
                DEBUG_T( { printbuf("### Saw unary minus before =>, forcing word %s\n", s); } );
                OPERATOR('-');          /* unary minus */
@@ -5703,7 +5817,7 @@ Perl_yylex(pTHX)
     case '*':
        if (PL_expect == XPOSTDEREF) POSTDEREF('*');
        if (PL_expect != XOPERATOR) {
-           s = scan_ident(s, PL_bufend, PL_tokenbuf, sizeof PL_tokenbuf, TRUE);
+           s = scan_ident(s, PL_tokenbuf, sizeof PL_tokenbuf, TRUE);
            PL_expect = XOPERATOR;
            force_ident(PL_tokenbuf, '*');
            if (!*PL_tokenbuf)
@@ -5746,13 +5860,13 @@ Perl_yylex(pTHX)
        }
        else if (PL_expect == XPOSTDEREF) POSTDEREF('%');
        PL_tokenbuf[0] = '%';
-       s = scan_ident(s, PL_bufend, PL_tokenbuf + 1,
-               sizeof PL_tokenbuf - 1, FALSE);
+       s = scan_ident(s, PL_tokenbuf + 1, sizeof PL_tokenbuf - 1, FALSE);
        pl_yylval.ival = 0;
        if (!PL_tokenbuf[1]) {
            PREREF('%');
        }
-       if ((PL_expect != XREF || PL_oldoldbufptr == PL_last_lop) && intuit_more(s)) {
+        if (   (PL_expect != XREF || PL_oldoldbufptr == PL_last_lop)
+            && intuit_more(s, PL_bufend)) {
            if (*s == '[')
                PL_tokenbuf[0] = '@';
        }
@@ -5830,9 +5944,17 @@ Perl_yylex(pTHX)
        case XATTRTERM:
            PL_expect = XTERMBLOCK;
         grabattrs:
+            /* NB: as well as parsing normal attributes, we also end up
+             * here if there is something looking like attributes
+             * following a signature (which is illegal, but used to be
+             * legal in 5.20..5.26). If the latter, we still parse the
+             * attributes so that error messages(s) are less confusing,
+             * but ignore them (parser->sig_seen).
+             */
            s = skipspace(s);
            attrs = NULL;
             while (isIDFIRST_lazy_if_safe(s, PL_bufend, UTF)) {
+                bool sig = PL_parser->sig_seen;
                I32 tmp;
                SV *sv;
                d = scan_word(s, PL_tokenbuf, sizeof PL_tokenbuf, FALSE, &len);
@@ -5871,43 +5993,31 @@ Perl_yylex(pTHX)
                    PL_lex_stuff = NULL;
                }
                else {
-                   if (len == 6 && strnEQ(SvPVX(sv), "unique", len)) {
-                       sv_free(sv);
-                       if (PL_in_my == KEY_our) {
-                            deprecate_disappears_in("5.28",
-                                "Attribute \"unique\" is deprecated");
-                       }
-                       else
-                           Perl_croak(aTHX_ "The 'unique' attribute may only be applied to 'our' variables");
-                   }
-
                    /* NOTE: any CV attrs applied here need to be part of
                       the CVf_BUILTIN_ATTRS define in cv.h! */
-                   else if (!PL_in_my && len == 6 && strnEQ(SvPVX(sv), "lvalue", len)) {
-                       sv_free(sv);
-                       CvLVALUE_on(PL_compcv);
-                   }
-                   else if (!PL_in_my && len == 6 && strnEQ(SvPVX(sv), "locked", len)) {
+                   if (!PL_in_my && memEQs(SvPVX(sv), len, "lvalue")) {
                        sv_free(sv);
-                        deprecate_disappears_in("5.28",
-                            "Attribute \"locked\" is deprecated");
+                       if (!sig)
+                            CvLVALUE_on(PL_compcv);
                    }
-                   else if (!PL_in_my && len == 6 && strnEQ(SvPVX(sv), "method", len)) {
+                   else if (!PL_in_my && memEQs(SvPVX(sv), len, "method")) {
                        sv_free(sv);
-                       CvMETHOD_on(PL_compcv);
+                       if (!sig)
+                            CvMETHOD_on(PL_compcv);
                    }
-                   else if (!PL_in_my && len == 5
-                         && strnEQ(SvPVX(sv), "const", len))
+                   else if (!PL_in_my && memEQs(SvPVX(sv), len, "const"))
                    {
                        sv_free(sv);
-                       Perl_ck_warner_d(aTHX_
-                           packWARN(WARN_EXPERIMENTAL__CONST_ATTR),
-                          ":const is experimental"
-                       );
-                       CvANONCONST_on(PL_compcv);
-                       if (!CvANON(PL_compcv))
-                           yyerror(":const is not permitted on named "
-                                   "subroutines");
+                        if (!sig) {
+                            Perl_ck_warner_d(aTHX_
+                                packWARN(WARN_EXPERIMENTAL__CONST_ATTR),
+                               ":const is experimental"
+                            );
+                            CvANONCONST_on(PL_compcv);
+                            if (!CvANON(PL_compcv))
+                                yyerror(":const is not permitted on named "
+                                        "subroutines");
+                        }
                    }
                    /* After we've set the flags, it could be argued that
                       we don't need to do the attributes.pm-based setting
@@ -5960,6 +6070,14 @@ Perl_yylex(pTHX)
                }
            }
        got_attrs:
+            if (PL_parser->sig_seen) {
+                /* see comment about about sig_seen and parser error
+                 * handling */
+                if (attrs)
+                    op_free(attrs);
+                Perl_croak(aTHX_ "Subroutine attributes must come "
+                                 "before the signature");
+                }
            if (attrs) {
                NEXTVAL_NEXTTOKE.opval = attrs;
                force_next(THING);
@@ -6194,9 +6312,11 @@ Perl_yylex(pTHX)
                        PL_expect = XTERM;
                        break;
                    }
-                   if (strEQs(s, "sub")) {
+                   if (memBEGINs(s, (STRLEN) (PL_bufend - s), "sub")) {
+                        PL_bufptr = s;
                        d = s + 3;
                        d = skipspace(d);
+                        s = PL_bufptr;
                        if (*d == ':') {
                            PL_expect = XTERM;
                            break;
@@ -6218,6 +6338,7 @@ Perl_yylex(pTHX)
        if (PL_lex_brackets && PL_lex_brackstack[PL_lex_brackets-1] == XFAKEEOF)
            TOKEN(0);
       rightbracket:
+       assert(s != PL_bufend);
        s++;
        if (PL_lex_brackets <= 0)
            /* diag_listed_as: Unmatched right %s bracket */
@@ -6248,7 +6369,7 @@ Perl_yylex(pTHX)
            return yylex();             /* ignore fake brackets */
        }
        force_next(formbrack ? '.' : '}');
-       if (formbrack) LEAVE;
+       if (formbrack) LEAVE_with_name("lex_format");
        if (formbrack == 2) { /* means . where arguments were expected */
            force_next(';');
            TOKEN(FORMRBRACK);
@@ -6293,8 +6414,7 @@ Perl_yylex(pTHX)
        }
 
        PL_tokenbuf[0] = '&';
-       s = scan_ident(s - 1, PL_bufend, PL_tokenbuf + 1,
-                      sizeof PL_tokenbuf - 1, TRUE);
+       s = scan_ident(s - 1, PL_tokenbuf + 1, sizeof PL_tokenbuf - 1, TRUE);
        pl_yylval.ival = (OPpENTERSUB_AMPER<<8);
        if (PL_tokenbuf[1]) {
            force_ident_maybe_lex('&');
@@ -6328,7 +6448,9 @@ Perl_yylex(pTHX)
        {
            const char tmp = *s++;
            if (tmp == '=') {
-               if ((s == PL_linestart+2 || s[-3] == '\n') && strEQs(s, "=====")) {
+                if (   (s == PL_linestart+2 || s[-3] == '\n')
+                    && memBEGINs(s, (STRLEN) (PL_bufend - s), "====="))
+                {
                    s = vcs_conflict_marker(s + 5);
                    goto retry;
                }
@@ -6360,19 +6482,21 @@ Perl_yylex(pTHX)
                 && isALPHA(tmp)
                 && (s == PL_linestart+1 || s[-2] == '\n') )
             {
-                if ((PL_in_eval && !PL_rsfp && !PL_parser->filtered)
-                    || PL_lex_state != LEX_NORMAL) {
+                if (   (PL_in_eval && !PL_rsfp && !PL_parser->filtered)
+                    || PL_lex_state != LEX_NORMAL)
+                {
                     d = PL_bufend;
                     while (s < d) {
                         if (*s++ == '\n') {
-                            incline(s);
-                            if (strEQs(s,"=cut")) {
-                                s = strchr(s,'\n');
+                            incline(s, PL_bufend);
+                            if (memBEGINs(s, (STRLEN) (PL_bufend - s), "=cut"))
+                            {
+                                s = (char *) memchr(s,'\n', d - s);
                                 if (s)
                                     s++;
                                 else
                                     s = d;
-                                incline(s);
+                                incline(s, PL_bufend);
                                 goto retry;
                             }
                         }
@@ -6394,7 +6518,7 @@ Perl_yylex(pTHX)
                t++;
            if (*t == '\n' || *t == '#') {
                formbrack = 1;
-               ENTER;
+               ENTER_with_name("lex_format");
                SAVEI8(PL_parser->form_lex_state);
                SAVEI32(PL_lex_formbrack);
                PL_parser->form_lex_state = PL_lex_state;
@@ -6444,10 +6568,12 @@ Perl_yylex(pTHX)
        OPERATOR('!');
     case '<':
        if (PL_expect != XOPERATOR) {
-           if (s[1] != '<' && !strchr(s,'>'))
+           if (s[1] != '<' && !memchr(s,'>', PL_bufend - s))
                check_uni();
            if (s[1] == '<' && s[2] != '>') {
-               if ((s == PL_linestart || s[-1] == '\n') && strEQs(s+2, "<<<<<")) {
+                if (   (s == PL_linestart || s[-1] == '\n')
+                    && memBEGINs(s+2, (STRLEN) (PL_bufend - (s+2)), "<<<<<"))
+                {
                    s = vcs_conflict_marker(s + 7);
                    goto retry;
                }
@@ -6462,7 +6588,9 @@ Perl_yylex(pTHX)
        {
            char tmp = *s++;
            if (tmp == '<') {
-               if ((s == PL_linestart+2 || s[-3] == '\n') && strEQs(s, "<<<<<")) {
+                if (   (s == PL_linestart+2 || s[-3] == '\n')
+                    && memBEGINs(s, (STRLEN) (PL_bufend - s), "<<<<<"))
+                {
                     s = vcs_conflict_marker(s + 5);
                    goto retry;
                }
@@ -6506,7 +6634,9 @@ Perl_yylex(pTHX)
        {
            const char tmp = *s++;
            if (tmp == '>') {
-               if ((s == PL_linestart+2 || s[-3] == '\n') && strEQs(s, ">>>>>")) {
+               if (   (s == PL_linestart+2 || s[-3] == '\n')
+                    && memBEGINs(s, (STRLEN) (PL_bufend - s), ">>>>>"))
+                {
                    s = vcs_conflict_marker(s + 5);
                    goto retry;
                }
@@ -6538,12 +6668,7 @@ Perl_yylex(pTHX)
     case '$':
        CLINE;
 
-       if (PL_expect == XOPERATOR) {
-           if (PL_lex_formbrack && PL_lex_brackets == PL_lex_formbrack) {
-               return deprecate_commaless_var_list();
-           }
-       }
-       else if (PL_expect == XPOSTDEREF) {
+        if (PL_expect == XPOSTDEREF) {
            if (s[1] == '#') {
                s++;
                POSTDEREF(DOLSHARP);
@@ -6556,7 +6681,7 @@ Perl_yylex(pTHX)
                 || strchr("{$:+-@", s[2])))
         {
            PL_tokenbuf[0] = '@';
-           s = scan_ident(s + 1, PL_bufend, PL_tokenbuf + 1,
+           s = scan_ident(s + 1, PL_tokenbuf + 1,
                           sizeof PL_tokenbuf - 1, FALSE);
             if (PL_expect == XOPERATOR) {
                 d = s;
@@ -6574,8 +6699,7 @@ Perl_yylex(pTHX)
        }
 
        PL_tokenbuf[0] = '$';
-       s = scan_ident(s, PL_bufend, PL_tokenbuf + 1,
-                      sizeof PL_tokenbuf - 1, FALSE);
+       s = scan_ident(s, PL_tokenbuf + 1, sizeof PL_tokenbuf - 1, FALSE);
        if (PL_expect == XOPERATOR) {
            d = s;
            if (PL_bufptr > s) {
@@ -6596,8 +6720,8 @@ Perl_yylex(pTHX)
            if (PL_lex_state == LEX_NORMAL || PL_lex_brackets)
                s = skipspace(s);
 
-           if ((PL_expect != XREF || PL_oldoldbufptr == PL_last_lop)
-               && intuit_more(s)) {
+           if (   (PL_expect != XREF || PL_oldoldbufptr == PL_last_lop)
+               && intuit_more(s, PL_bufend)) {
                if (*s == '[') {
                    PL_tokenbuf[0] = '@';
                    if (ckWARN(WARN_SYNTAX)) {
@@ -6622,30 +6746,32 @@ Perl_yylex(pTHX)
                else if (*s == '{') {
                    char *t;
                    PL_tokenbuf[0] = '%';
-                   if (strEQ(PL_tokenbuf+1, "SIG")  && ckWARN(WARN_SYNTAX)
-                       && (t = strchr(s, '}')) && (t = strchr(t, '=')))
-                       {
-                           char tmpbuf[sizeof PL_tokenbuf];
-                           do {
-                               t++;
-                           } while (isSPACE(*t));
-                           if (isIDFIRST_lazy_if_safe(t, PL_bufend, UTF)) {
-                               STRLEN len;
-                               t = scan_word(t, tmpbuf, sizeof tmpbuf, TRUE,
-                                             &len);
-                               while (isSPACE(*t))
-                                   t++;
-                                if (  *t == ';'
-                                    && get_cvn_flags(tmpbuf, len, UTF
-                                                                  ? SVf_UTF8
-                                                                  : 0))
-                                {
-                                   Perl_warner(aTHX_ packWARN(WARN_SYNTAX),
-                                       "You need to quote \"%" UTF8f "\"",
-                                        UTF8fARG(UTF, len, tmpbuf));
-                                }
-                           }
-                       }
+                    if (    strEQ(PL_tokenbuf+1, "SIG")
+                        && ckWARN(WARN_SYNTAX)
+                        && (t = (char *) memchr(s, '}', PL_bufend - s))
+                        && (t = (char *) memchr(t, '=', PL_bufend - t)))
+                    {
+                        char tmpbuf[sizeof PL_tokenbuf];
+                        do {
+                            t++;
+                        } while (isSPACE(*t));
+                        if (isIDFIRST_lazy_if_safe(t, PL_bufend, UTF)) {
+                            STRLEN len;
+                            t = scan_word(t, tmpbuf, sizeof tmpbuf, TRUE,
+                                            &len);
+                            while (isSPACE(*t))
+                                t++;
+                            if (  *t == ';'
+                                && get_cvn_flags(tmpbuf, len, UTF
+                                                                ? SVf_UTF8
+                                                                : 0))
+                            {
+                                Perl_warner(aTHX_ packWARN(WARN_SYNTAX),
+                                    "You need to quote \"%" UTF8f "\"",
+                                        UTF8fARG(UTF, len, tmpbuf));
+                            }
+                        }
+                    }
                }
            }
 
@@ -6710,7 +6836,7 @@ Perl_yylex(pTHX)
         if (PL_expect == XPOSTDEREF)
             POSTDEREF('@');
        PL_tokenbuf[0] = '@';
-       s = scan_ident(s, PL_bufend, PL_tokenbuf + 1, sizeof PL_tokenbuf - 1, FALSE);
+       s = scan_ident(s, PL_tokenbuf + 1, sizeof PL_tokenbuf - 1, FALSE);
        if (PL_expect == XOPERATOR) {
             d = s;
             if (PL_bufptr > s) {
@@ -6725,7 +6851,9 @@ Perl_yylex(pTHX)
        }
        if (PL_lex_state == LEX_NORMAL)
            s = skipspace(s);
-       if ((PL_expect != XREF || PL_oldoldbufptr == PL_last_lop) && intuit_more(s)) {
+       if (   (PL_expect != XREF || PL_oldoldbufptr == PL_last_lop)
+            && intuit_more(s, PL_bufend))
+        {
            if (*s == '{')
                PL_tokenbuf[0] = '%';
 
@@ -6834,13 +6962,9 @@ Perl_yylex(pTHX)
        TERM(THING);
 
     case '\'':
-       if (   PL_expect == XOPERATOR
-           && (PL_lex_formbrack && PL_lex_brackets == PL_lex_formbrack))
-               return deprecate_commaless_var_list();
-
        s = scan_str(s,FALSE,FALSE,FALSE,NULL);
        if (!s)
-           missingterm(NULL);
+           missingterm(NULL, 0);
        COPLINE_SET_FROM_MULTI_END;
        DEBUG_T( { printbuf("### Saw string before %s\n", s); } );
        if (PL_expect == XOPERATOR) {
@@ -6850,10 +6974,6 @@ Perl_yylex(pTHX)
        TERM(sublex_start());
 
     case '"':
-       if (   PL_expect == XOPERATOR
-           && (PL_lex_formbrack && PL_lex_brackets == PL_lex_formbrack))
-               return deprecate_commaless_var_list();
-
        s = scan_str(s,FALSE,FALSE,FALSE,NULL);
        DEBUG_T( {
            if (s)
@@ -6866,7 +6986,7 @@ Perl_yylex(pTHX)
                no_op("String",s);
        }
        if (!s)
-           missingterm(NULL);
+           missingterm(NULL, 0);
        pl_yylval.ival = OP_CONST;
        /* FIXME. I think that this can be const if char *d is replaced by
           more localised variables.  */
@@ -6892,7 +7012,7 @@ Perl_yylex(pTHX)
        if (PL_expect == XOPERATOR)
            no_op("Backticks",s);
        if (!s)
-           missingterm(NULL);
+           missingterm(NULL, 0);
        pl_yylval.ival = OP_BACKTICK;
        TERM(sublex_start());
 
@@ -6997,7 +7117,7 @@ Perl_yylex(pTHX)
 
        /* x::* is just a word, unless x is "CORE" */
        if (!anydelim && *s == ':' && s[1] == ':') {
-           if (strEQ(PL_tokenbuf, "CORE")) goto case_KEY_CORE;
+           if (memEQs(PL_tokenbuf, len, "CORE")) goto case_KEY_CORE;
            goto just_a_word;
        }
 
@@ -7179,12 +7299,26 @@ Perl_yylex(pTHX)
                orig_keyword = 0;
                lex = 0;
                off = 0;
+            /* FALLTHROUGH */
        default:                        /* not a keyword */
          just_a_word: {
                int pkgname = 0;
                const char lastchar = (PL_bufptr == PL_oldoldbufptr ? 0 : PL_bufptr[-1]);
                bool safebw;
+               bool no_op_error = FALSE;
 
+               if (PL_expect == XOPERATOR) {
+                   if (PL_bufptr == PL_linestart) {
+                       CopLINE_dec(PL_curcop);
+                       Perl_warner(aTHX_ packWARN(WARN_SEMICOLON), "%s", PL_warn_nosemi);
+                       CopLINE_inc(PL_curcop);
+                   }
+                   else
+                       /* We want to call no_op with s pointing after the
+                          bareword, so defer it.  But we want it to come
+                          before the Bad name croak.  */
+                       no_op_error = TRUE;
+               }
 
                /* Get the rest if it looks like a package qualifier */
 
@@ -7192,6 +7326,10 @@ Perl_yylex(pTHX)
                    STRLEN morelen;
                    s = scan_word(s, PL_tokenbuf + len, sizeof PL_tokenbuf - len,
                                  TRUE, &morelen);
+                   if (no_op_error) {
+                       no_op("Bareword",s);
+                       no_op_error = FALSE;
+                   }
                    if (!morelen)
                        Perl_croak(aTHX_ "Bad name after %" UTF8f "%s",
                                UTF8fARG(UTF, len, PL_tokenbuf),
@@ -7200,15 +7338,8 @@ Perl_yylex(pTHX)
                    pkgname = 1;
                }
 
-               if (PL_expect == XOPERATOR) {
-                   if (PL_bufptr == PL_linestart) {
-                       CopLINE_dec(PL_curcop);
-                       Perl_warner(aTHX_ packWARN(WARN_SEMICOLON), "%s", PL_warn_nosemi);
-                       CopLINE_inc(PL_curcop);
-                   }
-                   else
+               if (no_op_error)
                        no_op("Bareword",s);
-               }
 
                /* See if the name is "Foo::",
                   in which case Foo is a bareword
@@ -7519,10 +7650,10 @@ Perl_yylex(pTHX)
                            if (!*d && !gv_stashpv(PL_tokenbuf, UTF ? SVf_UTF8 : 0))
                             {
                                 /* PL_warn_reserved is constant */
-                                GCC_DIAG_IGNORE(-Wformat-nonliteral);
+                                GCC_DIAG_IGNORE_STMT(-Wformat-nonliteral);
                                Perl_warner(aTHX_ packWARN(WARN_RESERVED), PL_warn_reserved,
                                       PL_tokenbuf);
-                                GCC_DIAG_RESTORE;
+                                GCC_DIAG_RESTORE_STMT;
                             }
                        }
                    }
@@ -7577,14 +7708,6 @@ Perl_yylex(pTHX)
                if (!GvIO(gv))
                    GvIOp(gv) = newIO();
                IoIFP(GvIOp(gv)) = PL_rsfp;
-#if defined(HAS_FCNTL) && defined(F_SETFD) && defined(FD_CLOEXEC)
-               {
-                   const int fd = PerlIO_fileno(PL_rsfp);
-                    if (fd >= 3) {
-                        fcntl(fd,F_SETFD, FD_CLOEXEC);
-                    }
-               }
-#endif
                /* Mark this internal pseudo-handle as clean */
                IoFLAGS(GvIOp(gv)) |= IOf_UNTAINT;
                if ((PerlIO*)PL_rsfp == PerlIO_stdin())
@@ -7769,7 +7892,7 @@ Perl_yylex(pTHX)
                *PL_tokenbuf = '&';
                d = scan_word(s, PL_tokenbuf + 1, sizeof PL_tokenbuf - 1,
                              1, &len);
-               if (len && (len != 4 || strNE(PL_tokenbuf+1, "CORE"))
+               if (len && memNEs(PL_tokenbuf+1, len, "CORE")
                 && !keyword(PL_tokenbuf + 1, len, 0)) {
                     SSize_t off = s-SvPVX(PL_linestr);
                    d = skipspace(d);
@@ -7887,15 +8010,19 @@ Perl_yylex(pTHX)
                 && isIDFIRST_lazy_if_safe(s, PL_bufend, UTF))
             {
                char *p = s;
+                SSize_t s_off = s - SvPVX(PL_linestr);
 
-               if ((PL_bufend - p) >= 3
-                    && strEQs(p, "my") && isSPACE(*(p + 2)))
+                if (   memBEGINPs(p, (STRLEN) (PL_bufend - p), "my")
+                    && isSPACE(*(p + 2)))
                 {
-                   p += 2;
+                    p += 2;
+                }
+                else if (   memBEGINPs(p, (STRLEN) (PL_bufend - p), "our")
+                         && isSPACE(*(p + 3)))
+                {
+                    p += 3;
                 }
-               else if ((PL_bufend - p) >= 4
-                         && strEQs(p, "our") && isSPACE(*(p + 3)))
-                   p += 3;
+
                p = skipspace(p);
                 /* skip optional package name, as in "for my abc $x (..)" */
                if (isIDFIRST_lazy_if_safe(p, PL_bufend, UTF)) {
@@ -7904,6 +8031,9 @@ Perl_yylex(pTHX)
                }
                if (*p != '$' && *p != '\\')
                    Perl_croak(aTHX_ "Missing $ on loop variable");
+
+                /* The buffer may have been reallocated, update s */
+                s = SvPVX(PL_linestr) + s_off;
            }
            OPERATOR(FOR);
 
@@ -8143,7 +8273,7 @@ Perl_yylex(pTHX)
            s = skipspace(s);
             if (isIDFIRST_lazy_if_safe(s, PL_bufend, UTF)) {
                s = scan_word(s, PL_tokenbuf, sizeof PL_tokenbuf, TRUE, &len);
-               if (len == 3 && strEQs(PL_tokenbuf, "sub"))
+               if (memEQs(PL_tokenbuf, len, "sub"))
                    goto really_sub;
                PL_in_my_stash = find_in_my_stash(PL_tokenbuf, len);
                if (!PL_in_my_stash) {
@@ -8260,7 +8390,7 @@ Perl_yylex(pTHX)
        case KEY_q:
            s = scan_str(s,FALSE,FALSE,FALSE,NULL);
            if (!s)
-               missingterm(NULL);
+               missingterm(NULL, 0);
            COPLINE_SET_FROM_MULTI_END;
            pl_yylval.ival = OP_CONST;
            TERM(sublex_start());
@@ -8272,7 +8402,7 @@ Perl_yylex(pTHX)
            OP *words = NULL;
            s = scan_str(s,FALSE,FALSE,FALSE,NULL);
            if (!s)
-               missingterm(NULL);
+               missingterm(NULL, 0);
            COPLINE_SET_FROM_MULTI_END;
            PL_expect = XOPERATOR;
            if (SvCUR(PL_lex_stuff)) {
@@ -8321,7 +8451,7 @@ Perl_yylex(pTHX)
        case KEY_qq:
            s = scan_str(s,FALSE,FALSE,FALSE,NULL);
            if (!s)
-               missingterm(NULL);
+               missingterm(NULL, 0);
            pl_yylval.ival = OP_STRINGIFY;
            if (SvIVX(PL_lex_stuff) == '\'')
                SvIV_set(PL_lex_stuff, 0);      /* qq'$foo' should interpolate */
@@ -8334,7 +8464,7 @@ Perl_yylex(pTHX)
        case KEY_qx:
            s = scan_str(s,FALSE,FALSE,FALSE,NULL);
            if (!s)
-               missingterm(NULL);
+               missingterm(NULL, 0);
            pl_yylval.ival = OP_BACKTICK;
            TERM(sublex_start());
 
@@ -8550,22 +8680,24 @@ Perl_yylex(pTHX)
          really_sub:
            {
                char * const tmpbuf = PL_tokenbuf + 1;
-               expectation attrful;
                bool have_name, have_proto;
                const int key = tmp;
                 SV *format_name = NULL;
+                bool is_sigsub = FEATURE_SIGNATURES_IS_ENABLED;
 
                 SSize_t off = s-SvPVX(PL_linestr);
                s = skipspace(s);
                 d = SvPVX(PL_linestr)+off;
 
+                SAVEBOOL(PL_parser->sig_seen);
+                PL_parser->sig_seen = FALSE;
+
                 if (   isIDFIRST_lazy_if_safe(s, PL_bufend, UTF)
                     || *s == '\''
                     || (*s == ':' && s[1] == ':'))
                {
 
-                   PL_expect = XBLOCK;
-                   attrful = XATTRBLOCK;
+                   PL_expect = XATTRBLOCK;
                    d = scan_word(s, tmpbuf, sizeof PL_tokenbuf - 1, TRUE,
                                  &len);
                     if (key == KEY_format)
@@ -8596,8 +8728,7 @@ Perl_yylex(pTHX)
                        Perl_croak(aTHX_
                                  "Missing name in \"%s\"", PL_bufptr);
                    }
-                   PL_expect = XTERMBLOCK;
-                   attrful = XATTRTERM;
+                   PL_expect = XATTRTERM;
                    sv_setpvs(PL_subname,"?");
                    have_name = FALSE;
                }
@@ -8613,12 +8744,13 @@ Perl_yylex(pTHX)
                }
 
                /* Look for a prototype */
-               if (*s == '(' && !FEATURE_SIGNATURES_IS_ENABLED) {
+               if (*s == '(' && !is_sigsub) {
                    s = scan_str(s,FALSE,FALSE,FALSE,NULL);
                    COPLINE_SET_FROM_MULTI_END;
                    if (!s)
                        Perl_croak(aTHX_ "Prototype not terminated");
-                   (void)validate_proto(PL_subname, PL_lex_stuff, ckWARN(WARN_ILLEGALPROTO));
+                   (void)validate_proto(PL_subname, PL_lex_stuff,
+                                        ckWARN(WARN_ILLEGALPROTO), 0);
                    have_proto = TRUE;
 
                    s = skipspace(s);
@@ -8626,9 +8758,9 @@ Perl_yylex(pTHX)
                else
                    have_proto = FALSE;
 
-               if (*s == ':' && s[1] != ':')
-                   PL_expect = attrful;
-               else if ((*s != '{' && *s != '(') && key != KEY_format) {
+               if (  !(*s == ':' && s[1] != ':')
+                    && (*s != '{' && *s != '(') && key != KEY_format)
+                {
                     assert(key == KEY_sub || key == KEY_AUTOLOAD ||
                            key == KEY_DESTROY || key == KEY_BEGIN ||
                            key == KEY_UNITCHECK || key == KEY_CHECK ||
@@ -8652,10 +8784,16 @@ Perl_yylex(pTHX)
                        sv_setpvs(PL_subname, "__ANON__");
                    else
                        sv_setpvs(PL_subname, "__ANON__::__ANON__");
-                   TOKEN(ANONSUB);
+                    if (is_sigsub)
+                        TOKEN(ANON_SIGSUB);
+                    else
+                        TOKEN(ANONSUB);
                }
                force_ident_maybe_lex('&');
-               TOKEN(SUB);
+                if (is_sigsub)
+                    TOKEN(SIGSUB);
+                else
+                    TOKEN(SUB);
            }
 
        case KEY_system:
@@ -8843,6 +8981,7 @@ S_pending_ident(pTHX)
 
     DEBUG_T({ PerlIO_printf(Perl_debug_log,
           "### Pending identifier '%s'\n", PL_tokenbuf); });
+    assert(tokenbuf_len >= 2);
 
     /* if we're in a my(), we can't allow dynamics here.
        $foo'bar has already been turned into $foo::bar, so
@@ -8853,8 +8992,11 @@ S_pending_ident(pTHX)
     if (PL_in_my) {
         if (PL_in_my == KEY_our) {     /* "our" is merely analogous to "my" */
             if (has_colon)
+                /* diag_listed_as: No package name allowed for variable %s
+                                   in "our" */
                 yyerror_pv(Perl_form(aTHX_ "No package name allowed for "
-                                  "variable %s in \"our\"",
+                                  "%se %s in \"our\"",
+                                  *PL_tokenbuf=='&' ?"subroutin":"variabl",
                                   PL_tokenbuf), UTF ? SVf_UTF8 : 0);
             tmp = allocmy(PL_tokenbuf, tokenbuf_len, UTF ? SVf_UTF8 : 0);
         }
@@ -8863,13 +9005,13 @@ S_pending_ident(pTHX)
             if (has_colon) {
                 /* "my" variable %s can't be in a package */
                 /* PL_no_myglob is constant */
-                GCC_DIAG_IGNORE(-Wformat-nonliteral);
+                GCC_DIAG_IGNORE_STMT(-Wformat-nonliteral);
                 yyerror_pv(Perl_form(aTHX_ PL_no_myglob,
                             PL_in_my == KEY_my ? "my" : "state",
                             *PL_tokenbuf == '&' ? "subroutin" : "variabl",
                             PL_tokenbuf),
                             UTF ? SVf_UTF8 : 0);
-                GCC_DIAG_RESTORE;
+                GCC_DIAG_RESTORE_STMT;
             }
 
             if (PL_in_my == KEY_sigvar) {
@@ -9014,7 +9156,6 @@ S_checkcomma(pTHX_ const char *s, const char *name, const char *what)
            s++;
        if (*s == ',') {
            GV* gv;
-           PADOFFSET off;
            if (keyword(w, s - w, 0))
                return;
 
@@ -9022,6 +9163,7 @@ S_checkcomma(pTHX_ const char *s, const char *name, const char *what)
            if (gv && GvCVu(gv))
                return;
            if (s - w <= 254) {
+                PADOFFSET off;
                char tmpbuf[256];
                Copy(w, tmpbuf+1, s - w, char);
                *tmpbuf = '&';
@@ -9181,8 +9323,10 @@ S_new_constant(pTHX_ const char *s, STRLEN len, const char *key, STRLEN keylen,
 
 PERL_STATIC_INLINE void
 S_parse_ident(pTHX_ char **s, char **d, char * const e, int allow_package,
-                    bool is_utf8, bool check_dollar)
+                    bool is_utf8, bool check_dollar, bool tick_warn)
 {
+    int saw_tick = 0;
+    const char *olds = *s;
     PERL_ARGS_ASSERT_PARSE_IDENT;
 
     while (*s < PL_bufend) {
@@ -9216,6 +9360,7 @@ S_parse_ident(pTHX_ char **s, char **d, char * const e, int allow_package,
             *(*d)++ = ':';
             *(*d)++ = ':';
             (*s)++;
+            saw_tick++;
         }
         else if (allow_package && **s == ':' && (*s)[1] == ':'
            /* Disallow things like Foo::$bar. For the curious, this is
@@ -9229,6 +9374,30 @@ S_parse_ident(pTHX_ char **s, char **d, char * const e, int allow_package,
         else
             break;
     }
+    if (UNLIKELY(tick_warn && saw_tick && PL_lex_state == LEX_INTERPNORMAL
+              && !PL_lex_brackets && ckWARN(WARN_SYNTAX))) {
+        char *d;
+       char *d2;
+        Newx(d, *s - olds + saw_tick + 2, char); /* +2 for $# */
+        d2 = d;
+        SAVEFREEPV(d);
+        Perl_warner(aTHX_ packWARN(WARN_SYNTAX),
+                         "Old package separator used in string");
+        if (olds[-1] == '#')
+            *d2++ = olds[-2];
+        *d2++ = olds[-1];
+        while (olds < *s) {
+            if (*olds == '\'') {
+                *d2++ = '\\';
+                *d2++ = *olds++;
+            }
+           else
+                *d2++ = *olds++;
+        }
+        Perl_warner(aTHX_ packWARN(WARN_SYNTAX),
+                         "\t(Did you mean \"%" UTF8f "\" instead?)\n",
+                          UTF8fARG(is_utf8, d2-d, d));
+    }
     return;
 }
 
@@ -9244,7 +9413,7 @@ S_scan_word(pTHX_ char *s, char *dest, STRLEN destlen, int allow_package, STRLEN
 
     PERL_ARGS_ASSERT_SCAN_WORD;
 
-    parse_ident(&s, &d, e, allow_package, is_utf8, TRUE);
+    parse_ident(&s, &d, e, allow_package, is_utf8, TRUE, FALSE);
     *d = '\0';
     *slp = d - dest;
     return s;
@@ -9270,7 +9439,7 @@ S_scan_word(pTHX_ char *s, char *dest, STRLEN destlen, int allow_package, STRLEN
                             && LIKELY((U8) *(s) != LATIN1_TO_NATIVE(0xAD)))))
 
 STATIC char *
-S_scan_ident(pTHX_ char *s, const char *send, char *dest, STRLEN destlen, I32 ck_uni)
+S_scan_ident(pTHX_ char *s, char *dest, STRLEN destlen, I32 ck_uni)
 {
     I32 herelines = PL_parser->herelines;
     SSize_t bracket = -1;
@@ -9292,7 +9461,7 @@ S_scan_ident(pTHX_ char *s, const char *send, char *dest, STRLEN destlen, I32 ck
        }
     }
     else {  /* See if it is a "normal" identifier */
-        parse_ident(&s, &d, e, 1, is_utf8, FALSE);
+        parse_ident(&s, &d, e, 1, is_utf8, FALSE, TRUE);
     }
     *d = '\0';
     d = dest;
@@ -9311,7 +9480,7 @@ S_scan_ident(pTHX_ char *s, const char *send, char *dest, STRLEN destlen, I32 ck
             || isDIGIT_A((U8)s[1])
             || s[1] == '$'
             || s[1] == '{'
-            || strEQs(s+1,"::")) )
+            || memBEGINs(s+1, (STRLEN) (PL_bufend - (s+1)), "::")) )
     {
         /* Dereferencing a value in a scalar variable.
            The alternatives are different syntaxes for a scalar variable.
@@ -9358,19 +9527,36 @@ S_scan_ident(pTHX_ char *s, const char *send, char *dest, STRLEN destlen, I32 ck
         bool skip;
         char *s2;
         /* If we were processing {...} notation then...  */
-        if (isIDFIRST_lazy_if_safe(d, e, is_utf8)) {
-            /* if it starts as a valid identifier, assume that it is one.
-               (the later check for } being at the expected point will trap
-               cases where this doesn't pan out.)  */
-            d += is_utf8 ? UTF8SKIP(d) : 1;
-            parse_ident(&s, &d, e, 1, is_utf8, TRUE);
-           *d = '\0';
+        if (isIDFIRST_lazy_if_safe(d, e, is_utf8)
+            || (!isPRINT(*d) /* isCNTRL(d), plus all non-ASCII */
+                 && isWORDCHAR(*s))
+        ) {
+            /* note we have to check for a normal identifier first,
+             * as it handles utf8 symbols, and only after that has
+             * been ruled out can we look at the caret words */
+            if (isIDFIRST_lazy_if_safe(d, e, is_utf8) ) {
+                /* if it starts as a valid identifier, assume that it is one.
+                   (the later check for } being at the expected point will trap
+                   cases where this doesn't pan out.)  */
+                d += is_utf8 ? UTF8SKIP(d) : 1;
+                parse_ident(&s, &d, e, 1, is_utf8, TRUE, TRUE);
+                *d = '\0';
+            }
+            else { /* caret word: ${^Foo} ${^CAPTURE[0]} */
+                d++;
+                while (isWORDCHAR(*s) && d < e) {
+                    *d++ = *s++;
+                }
+                if (d >= e)
+                    Perl_croak(aTHX_ "%s", ident_too_long);
+                *d = '\0';
+            }
             tmp_copline = CopLINE(PL_curcop);
             if (s < PL_bufend && isSPACE(*s)) {
                 s = skipspace(s);
             }
            if ((*s == '[' || (*s == '{' && strNE(dest, "sub")))) {
-                /* ${foo[0]} and ${foo{bar}} notation.  */
+                /* ${foo[0]} and ${foo{bar}} and ${^CAPTURE[0]} notation.  */
                if (ckWARN(WARN_AMBIGUOUS) && keyword(dest, d - dest, 0)) {
                    const char * const brack =
                        (const char *)
@@ -9389,26 +9575,16 @@ S_scan_ident(pTHX_ char *s, const char *send, char *dest, STRLEN destlen, I32 ck
                return s;
            }
        }
-       /* Handle extended ${^Foo} variables
-        * 1999-02-27 mjd-perl-patch@plover.com */
-       else if (! isPRINT(*d) /* isCNTRL(d), plus all non-ASCII */
-                && isWORDCHAR(*s))
-       {
-           d++;
-           while (isWORDCHAR(*s) && d < e) {
-               *d++ = *s++;
-           }
-           if (d >= e)
-               Perl_croak(aTHX_ "%s", ident_too_long);
-           *d = '\0';
-       }
 
         if ( !tmp_copline )
             tmp_copline = CopLINE(PL_curcop);
-        if ((skip = s < PL_bufend && isSPACE(*s)))
+        if ((skip = s < PL_bufend && isSPACE(*s))) {
             /* Avoid incrementing line numbers or resetting PL_linestart,
                in case we have to back up.  */
+            STRLEN s_off = s - SvPVX(PL_linestr);
             s2 = peekspace(s);
+            s = SvPVX(PL_linestr) + s_off;
+        }
         else
             s2 = s;
 
@@ -9450,9 +9626,12 @@ S_scan_ident(pTHX_ char *s, const char *send, char *dest, STRLEN destlen, I32 ck
             CopLINE_set(PL_curcop, orig_copline);
             PL_parser->herelines = herelines;
            *dest = '\0';
+            PL_parser->sub_no_recover = TRUE;
        }
     }
-    else if (PL_lex_state == LEX_INTERPNORMAL && !PL_lex_brackets && !intuit_more(s))
+    else if (   PL_lex_state == LEX_INTERPNORMAL
+             && !PL_lex_brackets
+             && !intuit_more(s, PL_bufend))
        PL_lex_state = LEX_INTERPEND;
     return s;
 }
@@ -9685,18 +9864,14 @@ S_scan_subst(pTHX_ char *start)
 
        PL_multi_end = 0;
        pm->op_pmflags |= PMf_EVAL;
-       while (es-- > 0) {
-           if (es)
-               sv_catpvs(repl, "eval ");
-           else
-               sv_catpvs(repl, "do ");
-       }
-       sv_catpvs(repl, "{");
+        for (; es > 1; es--) {
+            sv_catpvs(repl, "eval ");
+        }
+        sv_catpvs(repl, "do {");
        sv_catsv(repl, PL_parser->lex_sub_repl);
        sv_catpvs(repl, "}");
        SvREFCNT_dec(PL_parser->lex_sub_repl);
        PL_parser->lex_sub_repl = repl;
-        es = 1;
     }
 
 
@@ -9852,11 +10027,9 @@ S_scan_heredoc(pTHX_ char *s)
        else
            term = '"';
        if (! isWORDCHAR_lazy_if_safe(s, PL_bufend, UTF))
-           deprecate_fatal_in("5.28", "Use of bare << to mean <<\"\" is deprecated");
+           Perl_croak(aTHX_ "Use of bare << to mean <<\"\" is forbidden");
        peek = s;
-        while (
-               isWORDCHAR_lazy_if_safe(peek, PL_bufend, UTF))
-        {
+        while (isWORDCHAR_lazy_if_safe(peek, PL_bufend, UTF)) {
            peek += UTF ? UTF8SKIP(peek) : 1;
        }
        len = (peek - s >= e - d) ? (e - d) : (peek - s);
@@ -9871,7 +10044,7 @@ S_scan_heredoc(pTHX_ char *s)
     len = d - PL_tokenbuf;
 
 #ifndef PERL_STRICT_CR
-    d = strchr(s, '\r');
+    d = (char *) memchr(s, '\r', PL_bufend - s);
     if (d) {
        char * const olds = s;
        s = d;
@@ -9980,8 +10153,9 @@ S_scan_heredoc(pTHX_ char *s)
 
                    /* No whitespace or all! */
                    if (backup == s || *backup == '\n') {
-                       Newxz(indent, indent_len + 1, char);
+                       Newx(indent, indent_len + 1, char);
                        memcpy(indent, backup + 1, indent_len);
+                       indent[indent_len] = 0;
                        s--; /* before our delimiter */
                        PL_parser->herelines--; /* this line doesn't count */
                        break;
@@ -10115,8 +10289,9 @@ S_scan_heredoc(pTHX_ char *s)
 
                /* All whitespace or none! */
                if (backup == found || SPACE_OR_TAB(*backup)) {
-                   Newxz(indent, indent_len + 1, char);
+                   Newx(indent, indent_len + 1, char);
                    memcpy(indent, backup, indent_len);
+                   indent[indent_len] = 0;
                    SvREFCNT_dec(PL_linestr);
                    PL_linestr = linestr_save;
                    PL_linestart = SvPVX(linestr_save);
@@ -10207,7 +10382,7 @@ S_scan_heredoc(pTHX_ char *s)
   interminable:
     SvREFCNT_dec(tmpstr);
     CopLINE_set(PL_curcop, origline);
-    missingterm(PL_tokenbuf + 1);
+    missingterm(PL_tokenbuf + 1, sizeof(PL_tokenbuf) - 1);
 }
 
 /* scan_inputsymbol
@@ -10240,7 +10415,7 @@ S_scan_inputsymbol(pTHX_ char *start)
 
     PERL_ARGS_ASSERT_SCAN_INPUTSYMBOL;
 
-    end = strchr(s, '\n');
+    end = (char *) memchr(s, '\n', PL_bufend - s);
     if (!end)
        end = PL_bufend;
     if (s[1] == '<' && s[2] == '>' && s[3] == '>') {
@@ -10435,7 +10610,7 @@ S_scan_str(pTHX_ char *start, int keep_bracketed_quoted, int keep_delims, int re
     I32 brackets = 1;          /* bracket nesting level */
     bool has_utf8 = FALSE;     /* is there any utf8 content? */
     IV termcode;               /* terminating char. code */
-    U8 termstr[UTF8_MAXBYTES]; /* terminating string */
+    U8 termstr[UTF8_MAXBYTES+1]; /* terminating string */
     STRLEN termlen;            /* length of terminating string */
     line_t herelines;
 
@@ -10545,10 +10720,15 @@ S_scan_str(pTHX_ char *start, int keep_bracketed_quoted, int keep_delims, int re
                }
                /* terminate when run out of buffer (the for() condition), or
                   have found the terminator */
-               else if (*s == term) {
-                   if (termlen == 1)
+               else if (*s == term) {  /* First byte of terminator matches */
+                   if (termlen == 1)   /* If is the only byte, are done */
                        break;
-                   if (s+termlen <= PL_bufend && memEQ(s, (char*)termstr, termlen))
+
+                    /* If the remainder of the terminator matches, also are
+                     * done, after checking that is a separate grapheme */
+                    if (   s + termlen <= PL_bufend
+                        && memEQ(s + 1, (char*)termstr + 1, termlen - 1))
+                    {
                         if (   check_grapheme
                             && UNLIKELY(! _is_grapheme((U8 *) start,
                                                               (U8 *) s,
@@ -10559,9 +10739,12 @@ S_scan_str(pTHX_ char *start, int keep_bracketed_quoted, int keep_delims, int re
                                         "%s", non_grapheme_msg);
                         }
                        break;
+                    }
                }
-               else if (!has_utf8 && !UTF8_IS_INVARIANT((U8)*s) && UTF)
+               else if (!has_utf8 && !UTF8_IS_INVARIANT((U8)*s) && UTF) {
                    has_utf8 = TRUE;
+                }
+
                *to = *s;
            }
        }
@@ -10854,6 +11037,7 @@ Perl_scan_num(pTHX_ const char *start, YYSTYPE* lvalp)
                  digit:
                    just_zero = FALSE;
                    if (!overflowed) {
+                       assert(shift >= 0);
                        x = u << shift; /* make room for the digit */
 
                         total_bits += shift;
@@ -10934,19 +11118,22 @@ Perl_scan_num(pTHX_ const char *start, YYSTYPE* lvalp)
                     NV nv_mult = 1.0;
 #endif
                     bool accumulate = TRUE;
-                    for (h++; (isXDIGIT(*h) || *h == '_'); h++) {
+                    U8 b;
+                    int lim = 1 << shift;
+                    for (h++; ((isXDIGIT(*h) && (b = XDIGIT_VALUE(*h)) < lim) ||
+                               *h == '_'); h++) {
                         if (isXDIGIT(*h)) {
-                            U8 b = XDIGIT_VALUE(*h);
                             significant_bits += shift;
 #ifdef HEXFP_UQUAD
                             if (accumulate) {
                                 if (significant_bits < NV_MANT_DIG) {
                                     /* We are in the long "run" of xdigits,
                                      * accumulate the full four bits. */
+                                   assert(shift >= 0);
                                     hexfp_uquad <<= shift;
                                     hexfp_uquad |= b;
                                     hexfp_frac_bits += shift;
-                                } else {
+                                } else if (significant_bits - shift < NV_MANT_DIG) {
                                     /* We are at a hexdigit either at,
                                      * or straddling, the edge of mantissa.
                                      * We will try grabbing as many as
@@ -10955,7 +11142,9 @@ Perl_scan_num(pTHX_ const char *start, YYSTYPE* lvalp)
                                       significant_bits - NV_MANT_DIG;
                                     if (tail <= 0)
                                        tail += shift;
+                                   assert(tail >= 0);
                                     hexfp_uquad <<= tail;
+                                   assert((shift - tail) >= 0);
                                     hexfp_uquad |= b >> (shift - tail);
                                     hexfp_frac_bits += tail;
 
@@ -10994,7 +11183,7 @@ Perl_scan_num(pTHX_ const char *start, YYSTYPE* lvalp)
                             }
 #else /* HEXFP_NV */
                             if (accumulate) {
-                                nv_mult /= 16.0;
+                                nv_mult /= nvshift[shift];
                                 if (nv_mult > 0.0)
                                     hexfp_nv += b * nv_mult;
                                 else
@@ -11175,9 +11364,11 @@ Perl_scan_num(pTHX_ const char *start, YYSTYPE* lvalp)
               || UNLIKELY(hexfp && isALPHA_FOLD_EQ(*s, 'p')))
             && strchr("+-0123456789_", s[1]))
         {
-            floatit = TRUE;
+            int exp_digits = 0;
+            const char *save_s = s;
+            char * save_d = d;
 
-           /* regardless of whether user said 3E5 or 3e5, use lower 'e',
+            /* regardless of whether user said 3E5 or 3e5, use lower 'e',
                ditto for p (hexfloats) */
             if ((isALPHA_FOLD_EQ(*s, 'e'))) {
                /* At least some Mach atof()s don't grok 'E' */
@@ -11209,6 +11400,7 @@ Perl_scan_num(pTHX_ const char *start, YYSTYPE* lvalp)
            /* read digits of exponent */
            while (isDIGIT(*s) || *s == '_') {
                if (isDIGIT(*s)) {
+                    ++exp_digits;
                    if (d >= e)
                        Perl_croak(aTHX_ "%s", number_too_long);
                    *d++ = *s++;
@@ -11220,6 +11412,20 @@ Perl_scan_num(pTHX_ const char *start, YYSTYPE* lvalp)
                   lastub = s++;
                }
            }
+
+            if (!exp_digits) {
+                /* no exponent digits, the [eEpP] could be for something else,
+                 * though in practice we don't get here for p since that's preparsed
+                 * earlier, and results in only the 0xX being consumed, so behave similarly
+                 * for decimal floats and consume only the D.DD, leaving the [eE] to the
+                 * next token.
+                 */
+                s = save_s;
+                d = save_d;
+            }
+            else {
+                floatit = TRUE;
+            }
        }
 
 
@@ -11246,7 +11452,6 @@ Perl_scan_num(pTHX_ const char *start, YYSTYPE* lvalp)
               floatit = TRUE;
         }
        if (floatit) {
-            STORE_LC_NUMERIC_UNDERLYING_SET_STANDARD();
            /* terminate the string */
            *d = '\0';
             if (UNLIKELY(hexfp)) {
@@ -11263,7 +11468,6 @@ Perl_scan_num(pTHX_ const char *start, YYSTYPE* lvalp)
             } else {
                 nv = Atof(PL_tokenbuf);
             }
-            RESTORE_LC_NUMERIC_UNDERLYING();
             sv = newSVnv(nv);
        }
 
@@ -11301,8 +11505,6 @@ Perl_scan_num(pTHX_ const char *start, YYSTYPE* lvalp)
 STATIC char *
 S_scan_formline(pTHX_ char *s)
 {
-    char *eol;
-    char *t;
     SV * const stuff = newSVpvs("");
     bool needargs = FALSE;
     bool eofmt = FALSE;
@@ -11310,8 +11512,9 @@ S_scan_formline(pTHX_ char *s)
     PERL_ARGS_ASSERT_SCAN_FORMLINE;
 
     while (!needargs) {
+        char *eol;
        if (*s == '.') {
-           t = s+1;
+            char *t = s+1;
 #ifdef PERL_STRICT_CR
            while (SPACE_OR_TAB(*t))
                t++;
@@ -11328,6 +11531,7 @@ S_scan_formline(pTHX_ char *s)
        if (!eol++)
                eol = PL_bufend;
        if (*s != '#') {
+            char *t;
            for (t = s; t < eol; t++) {
                if (*t == '~' && t[1] == '~' && SvCUR(stuff)) {
                    needargs = FALSE;
@@ -11362,7 +11566,7 @@ S_scan_formline(pTHX_ char *s)
            if (!got_some)
                break;
        }
-       incline(s);
+       incline(s, PL_bufend);
     }
   enough:
     if (!SvCUR(stuff) || needargs)
@@ -11419,6 +11623,39 @@ Perl_start_subparse(pTHX_ I32 is_format, U32 flags)
     return oldsavestack_ix;
 }
 
+
+/* Do extra initialisation of a CV (typically one just created by
+ * start_subparse()) if that CV is for a named sub
+ */
+
+void
+Perl_init_named_cv(pTHX_ CV *cv, OP *nameop)
+{
+    PERL_ARGS_ASSERT_INIT_NAMED_CV;
+
+    if (nameop->op_type == OP_CONST) {
+        const char *const name = SvPV_nolen_const(((SVOP*)nameop)->op_sv);
+        if (   strEQ(name, "BEGIN")
+            || strEQ(name, "END")
+            || strEQ(name, "INIT")
+            || strEQ(name, "CHECK")
+            || strEQ(name, "UNITCHECK")
+        )
+          CvSPECIAL_on(cv);
+    }
+    else
+    /* State subs inside anonymous subs need to be
+     clonable themselves. */
+    if (   CvANON(CvOUTSIDE(cv))
+        || CvCLONE(CvOUTSIDE(cv))
+        || !PadnameIsSTATE(PadlistNAMESARRAY(CvPADLIST(
+                        CvOUTSIDE(cv)
+                     ))[nameop->op_targ])
+    )
+      CvCLONE_on(cv);
+}
+
+
 static int
 S_yywarn(pTHX_ const char *const s, U32 flags)
 {
@@ -11429,6 +11666,29 @@ S_yywarn(pTHX_ const char *const s, U32 flags)
     return 0;
 }
 
+void
+Perl_abort_execution(pTHX_ const char * const msg, const char * const name)
+{
+    PERL_ARGS_ASSERT_ABORT_EXECUTION;
+
+    if (PL_minus_c)
+        Perl_croak(aTHX_ "%s%s had compilation errors.\n", msg, name);
+    else {
+        Perl_croak(aTHX_
+                "%sExecution of %s aborted due to compilation errors.\n", msg, name);
+    }
+    NOT_REACHED; /* NOTREACHED */
+}
+
+void
+Perl_yyquit(pTHX)
+{
+    /* Called, after at least one error has been found, to abort the parse now,
+     * instead of trying to forge ahead */
+
+    yyerror_pvn(NULL, 0, 0);
+}
+
 int
 Perl_yyerror(pTHX_ const char *const s)
 {
@@ -11452,100 +11712,120 @@ Perl_yyerror_pvn(pTHX_ const char *const s, STRLEN len, U32 flags)
     SV * const where_sv = newSVpvs_flags("", SVs_TEMP);
     int yychar  = PL_parser->yychar;
 
-    PERL_ARGS_ASSERT_YYERROR_PVN;
-
-    if (!yychar || (yychar == ';' && !PL_rsfp))
-       sv_catpvs(where_sv, "at EOF");
-    else if (   PL_oldoldbufptr
-             && PL_bufptr > PL_oldoldbufptr
-             && PL_bufptr - PL_oldoldbufptr < 200
-             && PL_oldoldbufptr != PL_oldbufptr
-             && PL_oldbufptr != PL_bufptr)
-    {
-       /*
-               Only for NetWare:
-               The code below is removed for NetWare because it abends/crashes on NetWare
-               when the script has error such as not having the closing quotes like:
-                   if ($var eq "value)
-               Checking of white spaces is anyway done in NetWare code.
-       */
+    /* Output error message 's' with length 'len'.  'flags' are SV flags that
+     * apply.  If the number of errors found is large enough, it abandons
+     * parsing.  If 's' is NULL, there is no message, and it abandons
+     * processing unconditionally */
+
+    if (s != NULL) {
+        if (!yychar || (yychar == ';' && !PL_rsfp))
+            sv_catpvs(where_sv, "at EOF");
+        else if (   PL_oldoldbufptr
+                 && PL_bufptr > PL_oldoldbufptr
+                 && PL_bufptr - PL_oldoldbufptr < 200
+                 && PL_oldoldbufptr != PL_oldbufptr
+                 && PL_oldbufptr != PL_bufptr)
+        {
+            /*
+                    Only for NetWare:
+                    The code below is removed for NetWare because it
+                    abends/crashes on NetWare when the script has error such as
+                    not having the closing quotes like:
+                        if ($var eq "value)
+                    Checking of white spaces is anyway done in NetWare code.
+            */
 #ifndef NETWARE
-       while (isSPACE(*PL_oldoldbufptr))
-           PL_oldoldbufptr++;
+            while (isSPACE(*PL_oldoldbufptr))
+                PL_oldoldbufptr++;
 #endif
-       context = PL_oldoldbufptr;
-       contlen = PL_bufptr - PL_oldoldbufptr;
-    }
-    else if (  PL_oldbufptr
-            && PL_bufptr > PL_oldbufptr
-            && PL_bufptr - PL_oldbufptr < 200
-            && PL_oldbufptr != PL_bufptr) {
-       /*
-               Only for NetWare:
-               The code below is removed for NetWare because it abends/crashes on NetWare
-               when the script has error such as not having the closing quotes like:
-                   if ($var eq "value)
-               Checking of white spaces is anyway done in NetWare code.
-       */
+            context = PL_oldoldbufptr;
+            contlen = PL_bufptr - PL_oldoldbufptr;
+        }
+        else if (  PL_oldbufptr
+                && PL_bufptr > PL_oldbufptr
+                && PL_bufptr - PL_oldbufptr < 200
+                && PL_oldbufptr != PL_bufptr) {
+            /*
+                    Only for NetWare:
+                    The code below is removed for NetWare because it
+                    abends/crashes on NetWare when the script has error such as
+                    not having the closing quotes like:
+                        if ($var eq "value)
+                    Checking of white spaces is anyway done in NetWare code.
+            */
 #ifndef NETWARE
-       while (isSPACE(*PL_oldbufptr))
-           PL_oldbufptr++;
+            while (isSPACE(*PL_oldbufptr))
+                PL_oldbufptr++;
 #endif
-       context = PL_oldbufptr;
-       contlen = PL_bufptr - PL_oldbufptr;
-    }
-    else if (yychar > 255)
-       sv_catpvs(where_sv, "next token ???");
-    else if (yychar == YYEMPTY) {
-       if (PL_lex_state == LEX_NORMAL)
-           sv_catpvs(where_sv, "at end of line");
-       else if (PL_lex_inpat)
-           sv_catpvs(where_sv, "within pattern");
-       else
-           sv_catpvs(where_sv, "within string");
-    }
-    else {
-       sv_catpvs(where_sv, "next char ");
-       if (yychar < 32)
-           Perl_sv_catpvf(aTHX_ where_sv, "^%c", toCTRL(yychar));
-       else if (isPRINT_LC(yychar)) {
-           const char string = yychar;
-           sv_catpvn(where_sv, &string, 1);
-       }
-       else
-           Perl_sv_catpvf(aTHX_ where_sv, "\\%03o", yychar & 255);
-    }
-    msg = newSVpvn_flags(s, len, (flags & SVf_UTF8) | SVs_TEMP);
-    Perl_sv_catpvf(aTHX_ msg, " at %s line %" IVdf ", ",
-        OutCopFILE(PL_curcop),
-        (IV)(PL_parser->preambling == NOLINE
-               ? CopLINE(PL_curcop)
-               : PL_parser->preambling));
-    if (context)
-       Perl_sv_catpvf(aTHX_ msg, "near \"%" UTF8f "\"\n",
-                            UTF8fARG(UTF, contlen, context));
-    else
-       Perl_sv_catpvf(aTHX_ msg, "%" SVf "\n", SVfARG(where_sv));
-    if (PL_multi_start < PL_multi_end && (U32)(CopLINE(PL_curcop) - PL_multi_end) <= 1) {
-        Perl_sv_catpvf(aTHX_ msg,
-        "  (Might be a runaway multi-line %c%c string starting on line %" IVdf ")\n",
-                (int)PL_multi_open,(int)PL_multi_close,(IV)PL_multi_start);
-        PL_multi_end = 0;
-    }
-    if (PL_in_eval & EVAL_WARNONLY) {
-       PL_in_eval &= ~EVAL_WARNONLY;
-       Perl_ck_warner_d(aTHX_ packWARN(WARN_SYNTAX), "%" SVf, SVfARG(msg));
+            context = PL_oldbufptr;
+            contlen = PL_bufptr - PL_oldbufptr;
+        }
+        else if (yychar > 255)
+            sv_catpvs(where_sv, "next token ???");
+        else if (yychar == YYEMPTY) {
+            if (PL_lex_state == LEX_NORMAL)
+                sv_catpvs(where_sv, "at end of line");
+            else if (PL_lex_inpat)
+                sv_catpvs(where_sv, "within pattern");
+            else
+                sv_catpvs(where_sv, "within string");
+        }
+        else {
+            sv_catpvs(where_sv, "next char ");
+            if (yychar < 32)
+                Perl_sv_catpvf(aTHX_ where_sv, "^%c", toCTRL(yychar));
+            else if (isPRINT_LC(yychar)) {
+                const char string = yychar;
+                sv_catpvn(where_sv, &string, 1);
+            }
+            else
+                Perl_sv_catpvf(aTHX_ where_sv, "\\%03o", yychar & 255);
+        }
+        msg = newSVpvn_flags(s, len, (flags & SVf_UTF8) | SVs_TEMP);
+        Perl_sv_catpvf(aTHX_ msg, " at %s line %" IVdf ", ",
+            OutCopFILE(PL_curcop),
+            (IV)(PL_parser->preambling == NOLINE
+                   ? CopLINE(PL_curcop)
+                   : PL_parser->preambling));
+        if (context)
+            Perl_sv_catpvf(aTHX_ msg, "near \"%" UTF8f "\"\n",
+                                 UTF8fARG(UTF, contlen, context));
+        else
+            Perl_sv_catpvf(aTHX_ msg, "%" SVf "\n", SVfARG(where_sv));
+        if (   PL_multi_start < PL_multi_end
+            && (U32)(CopLINE(PL_curcop) - PL_multi_end) <= 1)
+        {
+            Perl_sv_catpvf(aTHX_ msg,
+            "  (Might be a runaway multi-line %c%c string starting on"
+            " line %" IVdf ")\n",
+                    (int)PL_multi_open,(int)PL_multi_close,(IV)PL_multi_start);
+            PL_multi_end = 0;
+        }
+        if (PL_in_eval & EVAL_WARNONLY) {
+            PL_in_eval &= ~EVAL_WARNONLY;
+            Perl_ck_warner_d(aTHX_ packWARN(WARN_SYNTAX), "%" SVf, SVfARG(msg));
+        }
+        else {
+            qerror(msg);
+        }
     }
-    else
-       qerror(msg);
-    if (PL_error_count >= 10) {
-       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));
-       else
-           Perl_croak(aTHX_ "%s has too many errors.\n",
-            OutCopFILE(PL_curcop));
+    if (s == NULL || PL_error_count >= 10) {
+        const char * msg = "";
+        const char * const name = OutCopFILE(PL_curcop);
+
+       if (PL_in_eval) {
+            SV * errsv = ERRSV;
+            if (SvCUR(errsv)) {
+                msg = Perl_form(aTHX_ "%" SVf, SVfARG(errsv));
+            }
+        }
+
+        if (s == NULL) {
+            abort_execution(msg, name);
+        }
+        else {
+            Perl_croak(aTHX_ "%s%s has too many errors.\n", msg, name);
+        }
     }
     PL_in_my = 0;
     PL_in_my_stash = NULL;
@@ -11567,7 +11847,9 @@ S_swallow_bom(pTHX_ U8 *s)
                /* diag_listed_as: Unsupported script encoding %s */
                Perl_croak(aTHX_ "Unsupported script encoding UTF-32LE");
 #ifndef PERL_NO_UTF16_FILTER
+#ifdef DEBUGGING
            if (DEBUG_p_TEST || DEBUG_T_TEST) PerlIO_printf(Perl_debug_log, "UTF-16LE script encoding (BOM)\n");
+#endif
            s += 2;
            if (PL_bufend > (char*)s) {
                s = add_utf16_textfilter(s, TRUE);
@@ -11581,7 +11863,9 @@ S_swallow_bom(pTHX_ U8 *s)
     case 0xFE:
        if (s[1] == 0xFF) {   /* UTF-16 big-endian? */
 #ifndef PERL_NO_UTF16_FILTER
+#ifdef DEBUGGING
            if (DEBUG_p_TEST || DEBUG_T_TEST) PerlIO_printf(Perl_debug_log, "UTF-16BE script encoding (BOM)\n");
+#endif
            s += 2;
            if (PL_bufend > (char *)s) {
                s = add_utf16_textfilter(s, FALSE);
@@ -11593,10 +11877,11 @@ S_swallow_bom(pTHX_ U8 *s)
        }
        break;
     case BOM_UTF8_FIRST_BYTE: {
-        const STRLEN len = sizeof(BOM_UTF8_TAIL) - 1; /* Exclude trailing NUL */
-        if (slen > len && memEQ(s+1, BOM_UTF8_TAIL, len)) {
+        if (memBEGINs(s+1, slen - 1, BOM_UTF8_TAIL)) {
+#ifdef DEBUGGING
             if (DEBUG_p_TEST || DEBUG_T_TEST) PerlIO_printf(Perl_debug_log, "UTF-8 script encoding (BOM)\n");
-            s += len + 1;                      /* UTF-8 */
+#endif
+            s += sizeof(BOM_UTF8) - 1;                     /* UTF-8 */
         }
         break;
     }
@@ -11614,7 +11899,9 @@ S_swallow_bom(pTHX_ U8 *s)
                   * 00 xx 00 xx
                   * are a good indicator of UTF-16BE. */
 #ifndef PERL_NO_UTF16_FILTER
+#ifdef DEBUGGING
                  if (DEBUG_p_TEST || DEBUG_T_TEST) PerlIO_printf(Perl_debug_log, "UTF-16BE script encoding (no BOM)\n");
+#endif
                  s = add_utf16_textfilter(s, FALSE);
 #else
                  /* diag_listed_as: Unsupported script encoding %s */
@@ -11630,7 +11917,9 @@ S_swallow_bom(pTHX_ U8 *s)
                   * xx 00 xx 00
                   * are a good indicator of UTF-16LE. */
 #ifndef PERL_NO_UTF16_FILTER
+#ifdef DEBUGGING
              if (DEBUG_p_TEST || DEBUG_T_TEST) PerlIO_printf(Perl_debug_log, "UTF-16LE script encoding (no BOM)\n");
+#endif
              s = add_utf16_textfilter(s, TRUE);
 #else
              /* diag_listed_as: Unsupported script encoding %s */
@@ -11731,9 +12020,14 @@ S_utf16_textfilter(pTHX_ int idx, SV *sv, int maxlen)
            }
        }
 
+        /* 'chars' isn't quite the right name, as code points above 0xFFFF
+         * require 4 bytes per char */
        chars = SvCUR(utf16_buffer) >> 1;
        have = SvCUR(utf8_buffer);
-       SvGROW(utf8_buffer, have + chars * 3 + 1);
+
+        /* Assume the worst case size as noted by the functions: twice the
+         * number of input bytes */
+       SvGROW(utf8_buffer, have + chars * 4 + 1);
 
        if (reverse) {
            end = utf16_to_utf8_reversed((U8*)SvPVX(utf16_buffer),
@@ -11892,6 +12186,79 @@ Perl_keyword_plugin_standard(pTHX_
     return KEYWORD_PLUGIN_DECLINE;
 }
 
+/*
+=for apidoc Amx|void|wrap_keyword_plugin|Perl_keyword_plugin_t new_plugin|Perl_keyword_plugin_t *old_plugin_p
+
+Puts a C function into the chain of keyword plugins.  This is the
+preferred way to manipulate the L</PL_keyword_plugin> variable.
+C<new_plugin> is a pointer to the C function that is to be added to the
+keyword plugin chain, and C<old_plugin_p> points to the storage location
+where a pointer to the next function in the chain will be stored.  The
+value of C<new_plugin> is written into the L</PL_keyword_plugin> variable,
+while the value previously stored there is written to C<*old_plugin_p>.
+
+L</PL_keyword_plugin> is global to an entire process, and a module wishing
+to hook keyword parsing may find itself invoked more than once per
+process, typically in different threads.  To handle that situation, this
+function is idempotent.  The location C<*old_plugin_p> must initially
+(once per process) contain a null pointer.  A C variable of static
+duration (declared at file scope, typically also marked C<static> to give
+it internal linkage) will be implicitly initialised appropriately, if it
+does not have an explicit initialiser.  This function will only actually
+modify the plugin chain if it finds C<*old_plugin_p> to be null.  This
+function is also thread safe on the small scale.  It uses appropriate
+locking to avoid race conditions in accessing L</PL_keyword_plugin>.
+
+When this function is called, the function referenced by C<new_plugin>
+must be ready to be called, except for C<*old_plugin_p> being unfilled.
+In a threading situation, C<new_plugin> may be called immediately, even
+before this function has returned.  C<*old_plugin_p> will always be
+appropriately set before C<new_plugin> is called.  If C<new_plugin>
+decides not to do anything special with the identifier that it is given
+(which is the usual case for most calls to a keyword plugin), it must
+chain the plugin function referenced by C<*old_plugin_p>.
+
+Taken all together, XS code to install a keyword plugin should typically
+look something like this:
+
+    static Perl_keyword_plugin_t next_keyword_plugin;
+    static OP *my_keyword_plugin(pTHX_
+        char *keyword_plugin, STRLEN keyword_len, OP **op_ptr)
+    {
+        if (memEQs(keyword_ptr, keyword_len,
+                   "my_new_keyword")) {
+            ...
+        } else {
+            return next_keyword_plugin(aTHX_
+                keyword_ptr, keyword_len, op_ptr);
+        }
+    }
+    BOOT:
+        wrap_keyword_plugin(my_keyword_plugin,
+                            &next_keyword_plugin);
+
+Direct access to L</PL_keyword_plugin> should be avoided.
+
+=cut
+*/
+
+void
+Perl_wrap_keyword_plugin(pTHX_
+    Perl_keyword_plugin_t new_plugin, Perl_keyword_plugin_t *old_plugin_p)
+{
+    dVAR;
+
+    PERL_UNUSED_CONTEXT;
+    PERL_ARGS_ASSERT_WRAP_KEYWORD_PLUGIN;
+    if (*old_plugin_p) return;
+    KEYWORD_PLUGIN_MUTEX_LOCK;
+    if (!*old_plugin_p) {
+        *old_plugin_p = PL_keyword_plugin;
+        PL_keyword_plugin = new_plugin;
+    }
+    KEYWORD_PLUGIN_MUTEX_UNLOCK;
+}
+
 #define parse_recdescent(g,p) S_parse_recdescent(aTHX_ g,p)
 static void
 S_parse_recdescent(pTHX_ int gramtype, I32 fakeeof)