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Add MUTABLE_CV(), and eliminate (CV *) casts in *.c.
[perl5.git] / toke.c
diff --git a/toke.c b/toke.c
index b2b6ba1..9f1c886 100644 (file)
--- a/toke.c
+++ b/toke.c
@@ -1,7 +1,7 @@
 /*    toke.c
  *
- *    Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
- *    2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, by Larry Wall and others
+ *    Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
+ *    2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008 by Larry Wall and others
  *
  *    You may distribute under the terms of either the GNU General Public
  *    License or the Artistic License, as specified in the README file.
 #define PERL_IN_TOKE_C
 #include "perl.h"
 
-#define yylval (PL_parser->yylval)
+#define new_constant(a,b,c,d,e,f,g)    \
+       S_new_constant(aTHX_ a,b,STR_WITH_LEN(c),d,e,f, g)
+
+#define pl_yylval      (PL_parser->yylval)
 
 /* YYINITDEPTH -- initial size of the parser's stacks.  */
 #define YYINITDEPTH 200
@@ -224,7 +227,7 @@ static const char* const lex_state_names[] = {
  */
 
 #ifdef DEBUGGING /* Serve -DT. */
-#   define REPORT(retval) tokereport((I32)retval)
+#   define REPORT(retval) tokereport((I32)retval, &pl_yylval)
 #else
 #   define REPORT(retval) (retval)
 #endif
@@ -236,19 +239,19 @@ static const char* const lex_state_names[] = {
 #define PRETERMBLOCK(retval) return (PL_expect = XTERMBLOCK,PL_bufptr = s, REPORT(retval))
 #define PREREF(retval) return (PL_expect = XREF,PL_bufptr = s, REPORT(retval))
 #define TERM(retval) return (CLINE, PL_expect = XOPERATOR, PL_bufptr = s, REPORT(retval))
-#define LOOPX(f) return (yylval.ival=f, PL_expect=XTERM, PL_bufptr=s, REPORT((int)LOOPEX))
-#define FTST(f)  return (yylval.ival=f, PL_expect=XTERMORDORDOR, PL_bufptr=s, REPORT((int)UNIOP))
-#define FUN0(f)  return (yylval.ival=f, PL_expect=XOPERATOR, PL_bufptr=s, REPORT((int)FUNC0))
-#define FUN1(f)  return (yylval.ival=f, PL_expect=XOPERATOR, PL_bufptr=s, REPORT((int)FUNC1))
-#define BOop(f)  return ao((yylval.ival=f, PL_expect=XTERM, PL_bufptr=s, REPORT((int)BITOROP)))
-#define BAop(f)  return ao((yylval.ival=f, PL_expect=XTERM, PL_bufptr=s, REPORT((int)BITANDOP)))
-#define SHop(f)  return ao((yylval.ival=f, PL_expect=XTERM, PL_bufptr=s, REPORT((int)SHIFTOP)))
-#define PWop(f)  return ao((yylval.ival=f, PL_expect=XTERM, PL_bufptr=s, REPORT((int)POWOP)))
-#define PMop(f)  return(yylval.ival=f, PL_expect=XTERM, PL_bufptr=s, REPORT((int)MATCHOP))
-#define Aop(f)   return ao((yylval.ival=f, PL_expect=XTERM, PL_bufptr=s, REPORT((int)ADDOP)))
-#define Mop(f)   return ao((yylval.ival=f, PL_expect=XTERM, PL_bufptr=s, REPORT((int)MULOP)))
-#define Eop(f)   return (yylval.ival=f, PL_expect=XTERM, PL_bufptr=s, REPORT((int)EQOP))
-#define Rop(f)   return (yylval.ival=f, PL_expect=XTERM, PL_bufptr=s, REPORT((int)RELOP))
+#define LOOPX(f) return (pl_yylval.ival=f, PL_expect=XTERM, PL_bufptr=s, REPORT((int)LOOPEX))
+#define FTST(f)  return (pl_yylval.ival=f, PL_expect=XTERMORDORDOR, PL_bufptr=s, REPORT((int)UNIOP))
+#define FUN0(f)  return (pl_yylval.ival=f, PL_expect=XOPERATOR, PL_bufptr=s, REPORT((int)FUNC0))
+#define FUN1(f)  return (pl_yylval.ival=f, PL_expect=XOPERATOR, PL_bufptr=s, REPORT((int)FUNC1))
+#define BOop(f)  return ao((pl_yylval.ival=f, PL_expect=XTERM, PL_bufptr=s, REPORT((int)BITOROP)))
+#define BAop(f)  return ao((pl_yylval.ival=f, PL_expect=XTERM, PL_bufptr=s, REPORT((int)BITANDOP)))
+#define SHop(f)  return ao((pl_yylval.ival=f, PL_expect=XTERM, PL_bufptr=s, REPORT((int)SHIFTOP)))
+#define PWop(f)  return ao((pl_yylval.ival=f, PL_expect=XTERM, PL_bufptr=s, REPORT((int)POWOP)))
+#define PMop(f)  return(pl_yylval.ival=f, PL_expect=XTERM, PL_bufptr=s, REPORT((int)MATCHOP))
+#define Aop(f)   return ao((pl_yylval.ival=f, PL_expect=XTERM, PL_bufptr=s, REPORT((int)ADDOP)))
+#define Mop(f)   return ao((pl_yylval.ival=f, PL_expect=XTERM, PL_bufptr=s, REPORT((int)MULOP)))
+#define Eop(f)   return (pl_yylval.ival=f, PL_expect=XTERM, PL_bufptr=s, REPORT((int)EQOP))
+#define Rop(f)   return (pl_yylval.ival=f, PL_expect=XTERM, PL_bufptr=s, REPORT((int)RELOP))
 
 /* This bit of chicanery makes a unary function followed by
  * a parenthesis into a function with one argument, highest precedence.
@@ -256,7 +259,7 @@ static const char* const lex_state_names[] = {
  * operator (such as C<shift // 0>).
  */
 #define UNI2(f,x) { \
-       yylval.ival = f; \
+       pl_yylval.ival = f; \
        PL_expect = x; \
        PL_bufptr = s; \
        PL_last_uni = PL_oldbufptr; \
@@ -270,7 +273,7 @@ static const char* const lex_state_names[] = {
 #define UNIDOR(f) UNI2(f,XTERMORDORDOR)
 
 #define UNIBRACK(f) { \
-       yylval.ival = f; \
+       pl_yylval.ival = f; \
        PL_bufptr = s; \
        PL_last_uni = PL_oldbufptr; \
        if (*s == '(') \
@@ -280,15 +283,15 @@ static const char* const lex_state_names[] = {
        }
 
 /* grandfather return to old style */
-#define OLDLOP(f) return(yylval.ival=f,PL_expect = XTERM,PL_bufptr = s,(int)LSTOP)
+#define OLDLOP(f) return(pl_yylval.ival=f,PL_expect = XTERM,PL_bufptr = s,(int)LSTOP)
 
 #ifdef DEBUGGING
 
-/* how to interpret the yylval associated with the token */
+/* how to interpret the pl_yylval associated with the token */
 enum token_type {
     TOKENTYPE_NONE,
     TOKENTYPE_IVAL,
-    TOKENTYPE_OPNUM, /* yylval.ival contains an opcode number */
+    TOKENTYPE_OPNUM, /* pl_yylval.ival contains an opcode number */
     TOKENTYPE_PVAL,
     TOKENTYPE_OPVAL,
     TOKENTYPE_GVVAL
@@ -365,15 +368,19 @@ static struct debug_tokens {
     { WHEN,            TOKENTYPE_IVAL,         "WHEN" },
     { WHILE,           TOKENTYPE_IVAL,         "WHILE" },
     { WORD,            TOKENTYPE_OPVAL,        "WORD" },
+    { YADAYADA,                TOKENTYPE_IVAL,         "YADAYADA" },
     { 0,               TOKENTYPE_NONE,         NULL }
 };
 
-/* dump the returned token in rv, plus any optional arg in yylval */
+/* dump the returned token in rv, plus any optional arg in pl_yylval */
 
 STATIC int
-S_tokereport(pTHX_ I32 rv)
+S_tokereport(pTHX_ I32 rv, const YYSTYPE* lvalp)
 {
     dVAR;
+
+    PERL_ARGS_ASSERT_TOKEREPORT;
+
     if (DEBUG_T_TEST) {
        const char *name = NULL;
        enum token_type type = TOKENTYPE_NONE;
@@ -400,22 +407,22 @@ S_tokereport(pTHX_ I32 rv)
        case TOKENTYPE_GVVAL: /* doesn't appear to be used */
            break;
        case TOKENTYPE_IVAL:
-           Perl_sv_catpvf(aTHX_ report, "(ival=%"IVdf")", (IV)yylval.ival);
+           Perl_sv_catpvf(aTHX_ report, "(ival=%"IVdf")", (IV)lvalp->ival);
            break;
        case TOKENTYPE_OPNUM:
            Perl_sv_catpvf(aTHX_ report, "(ival=op_%s)",
-                                   PL_op_name[yylval.ival]);
+                                   PL_op_name[lvalp->ival]);
            break;
        case TOKENTYPE_PVAL:
-           Perl_sv_catpvf(aTHX_ report, "(pval=\"%s\")", yylval.pval);
+           Perl_sv_catpvf(aTHX_ report, "(pval=\"%s\")", lvalp->pval);
            break;
        case TOKENTYPE_OPVAL:
-           if (yylval.opval) {
+           if (lvalp->opval) {
                Perl_sv_catpvf(aTHX_ report, "(opval=op_%s)",
-                                   PL_op_name[yylval.opval->op_type]);
-               if (yylval.opval->op_type == OP_CONST) {
+                                   PL_op_name[lvalp->opval->op_type]);
+               if (lvalp->opval->op_type == OP_CONST) {
                    Perl_sv_catpvf(aTHX_ report, " %s",
-                       SvPEEK(cSVOPx_sv(yylval.opval)));
+                       SvPEEK(cSVOPx_sv(lvalp->opval)));
                }
 
            }
@@ -432,9 +439,12 @@ S_tokereport(pTHX_ I32 rv)
 /* print the buffer with suitable escapes */
 
 STATIC void
-S_printbuf(pTHX_ const char* fmt, const char* s)
+S_printbuf(pTHX_ const char *const fmt, const char *const s)
 {
     SV* const tmp = newSVpvs("");
+
+    PERL_ARGS_ASSERT_PRINTBUF;
+
     PerlIO_printf(Perl_debug_log, fmt, pv_display(tmp, s, strlen(s), 0, 60));
     SvREFCNT_dec(tmp);
 }
@@ -455,11 +465,11 @@ S_ao(pTHX_ int toketype)
     if (*PL_bufptr == '=') {
        PL_bufptr++;
        if (toketype == ANDAND)
-           yylval.ival = OP_ANDASSIGN;
+           pl_yylval.ival = OP_ANDASSIGN;
        else if (toketype == OROR)
-           yylval.ival = OP_ORASSIGN;
+           pl_yylval.ival = OP_ORASSIGN;
        else if (toketype == DORDOR)
-           yylval.ival = OP_DORASSIGN;
+           pl_yylval.ival = OP_DORASSIGN;
        toketype = ASSIGNOP;
     }
     return toketype;
@@ -479,12 +489,14 @@ S_ao(pTHX_ int toketype)
  */
 
 STATIC void
-S_no_op(pTHX_ const char *what, char *s)
+S_no_op(pTHX_ const char *const what, char *s)
 {
     dVAR;
     char * const oldbp = PL_bufptr;
     const bool is_first = (PL_oldbufptr == PL_linestart);
 
+    PERL_ARGS_ASSERT_NO_OP;
+
     if (!s)
        s = oldbp;
     else
@@ -556,17 +568,24 @@ S_missingterm(pTHX_ char *s)
 #define FEATURE_IS_ENABLED(name)                                       \
        ((0 != (PL_hints & HINT_LOCALIZE_HH))                           \
            && S_feature_is_enabled(aTHX_ STR_WITH_LEN(name)))
+/* The longest string we pass in.  */
+#define MAX_FEATURE_LEN (sizeof("switch")-1)
+
 /*
  * S_feature_is_enabled
  * Check whether the named feature is enabled.
  */
 STATIC bool
-S_feature_is_enabled(pTHX_ const char *name, STRLEN namelen)
+S_feature_is_enabled(pTHX_ const char *const name, STRLEN namelen)
 {
     dVAR;
     HV * const hinthv = GvHV(PL_hintgv);
-    char he_name[32] = "feature_";
-    (void) my_strlcpy(&he_name[8], name, 24);
+    char he_name[8 + MAX_FEATURE_LEN] = "feature_";
+
+    PERL_ARGS_ASSERT_FEATURE_IS_ENABLED;
+
+    assert(namelen <= MAX_FEATURE_LEN);
+    memcpy(&he_name[8], name, namelen);
 
     return (hinthv && hv_exists(hinthv, he_name, 8 + namelen));
 }
@@ -576,14 +595,16 @@ S_feature_is_enabled(pTHX_ const char *name, STRLEN namelen)
  */
 
 void
-Perl_deprecate(pTHX_ const char *s)
+Perl_deprecate(pTHX_ const char *const s)
 {
+    PERL_ARGS_ASSERT_DEPRECATE;
+
     if (ckWARN(WARN_DEPRECATED))
        Perl_warner(aTHX_ packWARN(WARN_DEPRECATED), "Use of %s is deprecated", s);
 }
 
 void
-Perl_deprecate_old(pTHX_ const char *s)
+Perl_deprecate_old(pTHX_ const char *const s)
 {
     /* This function should NOT be called for any new deprecated warnings */
     /* Use Perl_deprecate instead                                         */
@@ -593,6 +614,8 @@ Perl_deprecate_old(pTHX_ const char *s)
     /* live under the "syntax" category. It is now a top-level category   */
     /* in its own right.                                                  */
 
+    PERL_ARGS_ASSERT_DEPRECATE_OLD;
+
     if (ckWARN2(WARN_DEPRECATED, WARN_SYNTAX))
        Perl_warner(aTHX_ packWARN2(WARN_DEPRECATED, WARN_SYNTAX),
                        "Use of %s is deprecated", s);
@@ -609,6 +632,9 @@ strip_return(SV *sv)
 {
     register const char *s = SvPVX_const(sv);
     register const char * const e = s + SvCUR(sv);
+
+    PERL_ARGS_ASSERT_STRIP_RETURN;
+
     /* outer loop optimized to do nothing if there are no CR-LFs */
     while (s < e) {
        if (*s++ == '\r' && *s == '\n') {
@@ -685,6 +711,7 @@ Perl_lex_start(pTHX_ SV *line, PerlIO *rsfp, bool new_filter)
 #else
     parser->nexttoke = 0;
 #endif
+    parser->error_count = oparser ? oparser->error_count : 0;
     parser->copline = NOLINE;
     parser->lex_state = LEX_NORMAL;
     parser->expect = XSTATE;
@@ -727,13 +754,15 @@ Perl_lex_start(pTHX_ SV *line, PerlIO *rsfp, bool new_filter)
 void
 Perl_parser_free(pTHX_  const yy_parser *parser)
 {
+    PERL_ARGS_ASSERT_PARSER_FREE;
+
     PL_curcop = parser->saved_curcop;
     SvREFCNT_dec(parser->linestr);
 
     if (parser->rsfp == PerlIO_stdin())
        PerlIO_clearerr(parser->rsfp);
-    else if (parser->rsfp && parser->old_parser
-                         && parser->rsfp != parser->old_parser->rsfp)
+    else if (parser->rsfp && (!parser->old_parser ||
+               (parser->old_parser && parser->rsfp != parser->old_parser->rsfp)))
        PerlIO_close(parser->rsfp);
     SvREFCNT_dec(parser->rsfp_filters);
 
@@ -776,6 +805,8 @@ S_incline(pTHX_ const char *s)
     const char *n;
     const char *e;
 
+    PERL_ARGS_ASSERT_INCLINE;
+
     CopLINE_inc(PL_curcop);
     if (*s++ != '#')
        return;
@@ -817,8 +848,18 @@ S_incline(pTHX_ const char *s)
     if (t - s > 0) {
        const STRLEN len = t - s;
 #ifndef USE_ITHREADS
-       const char * const cf = CopFILE(PL_curcop);
-       STRLEN tmplen = cf ? strlen(cf) : 0;
+       SV *const temp_sv = CopFILESV(PL_curcop);
+       const char *cf;
+       STRLEN tmplen;
+
+       if (temp_sv) {
+           cf = SvPVX(temp_sv);
+           tmplen = SvCUR(temp_sv);
+       } else {
+           cf = NULL;
+           tmplen = 0;
+       }
+
        if (tmplen > 7 && strnEQ(cf, "(eval ", 6)) {
            /* must copy *{"::_<(eval N)[oldfilename:L]"}
             * to *{"::_<newfilename"} */
@@ -861,8 +902,8 @@ S_incline(pTHX_ const char *s)
                    gv_init(gv2, PL_defstash, tmpbuf2, tmplen2, FALSE);
                    /* adjust ${"::_<newfilename"} to store the new file name */
                    GvSV(gv2) = newSVpvn(tmpbuf2 + 2, tmplen2 - 2);
-                   GvHV(gv2) = (HV*)SvREFCNT_inc(GvHV(*gvp));
-                   GvAV(gv2) = (AV*)SvREFCNT_inc(GvAV(*gvp));
+                   GvHV(gv2) = MUTABLE_HV(SvREFCNT_inc(GvHV(*gvp)));
+                   GvAV(gv2) = MUTABLE_AV(SvREFCNT_inc(GvAV(*gvp)));
                }
 
                if (tmpbuf2 != smallbuf) Safefree(tmpbuf2);
@@ -882,6 +923,8 @@ S_incline(pTHX_ const char *s)
 STATIC char *
 S_skipspace0(pTHX_ register char *s)
 {
+    PERL_ARGS_ASSERT_SKIPSPACE0;
+
     s = skipspace(s);
     if (!PL_madskills)
        return s;
@@ -904,6 +947,8 @@ S_skipspace1(pTHX_ register char *s)
     const char *start = s;
     I32 startoff = start - SvPVX(PL_linestr);
 
+    PERL_ARGS_ASSERT_SKIPSPACE1;
+
     s = skipspace(s);
     if (!PL_madskills)
        return s;
@@ -930,6 +975,8 @@ S_skipspace2(pTHX_ register char *s, SV **svp)
     const I32 bufptroff = PL_bufptr - SvPVX(PL_linestr);
     const I32 startoff = s - SvPVX(PL_linestr);
 
+    PERL_ARGS_ASSERT_SKIPSPACE2;
+
     s = skipspace(s);
     PL_bufptr = SvPVX(PL_linestr) + bufptroff;
     if (!PL_madskills || !svp)
@@ -953,7 +1000,7 @@ S_skipspace2(pTHX_ register char *s, SV **svp)
 #endif
 
 STATIC void
-S_update_debugger_info(pTHX_ SV *orig_sv, const char *buf, STRLEN len)
+S_update_debugger_info(pTHX_ SV *orig_sv, const char *const buf, STRLEN len)
 {
     AV *av = CopFILEAVx(PL_curcop);
     if (av) {
@@ -982,11 +1029,14 @@ S_skipspace(pTHX_ register char *s)
     int curoff;
     int startoff = s - SvPVX(PL_linestr);
 
+    PERL_ARGS_ASSERT_SKIPSPACE;
+
     if (PL_skipwhite) {
        sv_free(PL_skipwhite);
        PL_skipwhite = 0;
     }
 #endif
+    PERL_ARGS_ASSERT_SKIPSPACE;
 
     if (PL_lex_formbrack && PL_lex_brackets <= PL_lex_formbrack) {
        while (s < PL_bufend && SPACE_OR_TAB(*s))
@@ -1092,16 +1142,14 @@ S_skipspace(pTHX_ register char *s)
            PL_bufend = SvPVX(PL_linestr) + SvCUR(PL_linestr);
            PL_last_lop = PL_last_uni = NULL;
 
-           /* Close the filehandle.  Could be from -P preprocessor,
+           /* Close the filehandle.  Could be from
             * STDIN, or a regular file.  If we were reading code from
             * STDIN (because the commandline held no -e or filename)
             * then we don't close it, we reset it so the code can
             * read from STDIN too.
             */
 
-           if (PL_preprocess && !PL_in_eval)
-               (void)PerlProc_pclose(PL_rsfp);
-           else if ((PerlIO*)PL_rsfp == PerlIO_stdin())
+           if ((PerlIO*)PL_rsfp == PerlIO_stdin())
                PerlIO_clearerr(PL_rsfp);
            else
                (void)PerlIO_close(PL_rsfp);
@@ -1201,7 +1249,10 @@ STATIC I32
 S_lop(pTHX_ I32 f, int x, char *s)
 {
     dVAR;
-    yylval.ival = f;
+
+    PERL_ARGS_ASSERT_LOP;
+
+    pl_yylval.ival = f;
     CLINE;
     PL_expect = x;
     PL_bufptr = s;
@@ -1306,6 +1357,12 @@ STATIC void
 S_force_next(pTHX_ I32 type)
 {
     dVAR;
+#ifdef DEBUGGING
+    if (DEBUG_T_TEST) {
+        PerlIO_printf(Perl_debug_log, "### forced token:\n");
+       tokereport(type, &NEXTVAL_NEXTTOKE);
+    }
+#endif
 #ifdef PERL_MAD
     if (PL_curforce < 0)
        start_force(PL_lasttoke);
@@ -1327,12 +1384,12 @@ S_force_next(pTHX_ I32 type)
 }
 
 STATIC SV *
-S_newSV_maybe_utf8(pTHX_ const char *start, STRLEN len)
+S_newSV_maybe_utf8(pTHX_ const char *const start, STRLEN len)
 {
     dVAR;
-    SV * const sv = newSVpvn(start,len);
-    if (UTF && !IN_BYTES && is_utf8_string((const U8*)start, len))
-       SvUTF8_on(sv);
+    SV * const sv = newSVpvn_utf8(start, len,
+                                 UTF && !IN_BYTES
+                                 && is_utf8_string((const U8*)start, len));
     return sv;
 }
 
@@ -1360,6 +1417,8 @@ S_force_word(pTHX_ register char *start, int token, int check_keyword, int allow
     register char *s;
     STRLEN len;
 
+    PERL_ARGS_ASSERT_FORCE_WORD;
+
     start = SKIPSPACE1(start);
     s = start;
     if (isIDFIRST_lazy_if(s,UTF) ||
@@ -1404,6 +1463,9 @@ STATIC void
 S_force_ident(pTHX_ register const char *s, int kind)
 {
     dVAR;
+
+    PERL_ARGS_ASSERT_FORCE_IDENT;
+
     if (*s) {
        const STRLEN len = strlen(s);
        OP* const o = (OP*)newSVOP(OP_CONST, 0, newSVpvn(s, len));
@@ -1436,6 +1498,9 @@ Perl_str_to_version(pTHX_ SV *sv)
     const char *start = SvPV_const(sv,len);
     const char * const end = start + len;
     const bool utf = SvUTF8(sv) ? TRUE : FALSE;
+
+    PERL_ARGS_ASSERT_STR_TO_VERSION;
+
     while (start < end) {
        STRLEN skip;
        UV n;
@@ -1470,6 +1535,8 @@ S_force_version(pTHX_ char *s, int guessing)
     I32 startoff = s - SvPVX(PL_linestr);
 #endif
 
+    PERL_ARGS_ASSERT_FORCE_VERSION;
+
     s = SKIPSPACE1(s);
 
     d = s;
@@ -1486,8 +1553,8 @@ S_force_version(pTHX_ char *s, int guessing)
 #endif
         if (*d == ';' || isSPACE(*d) || *d == '}' || !*d) {
            SV *ver;
-            s = scan_num(s, &yylval);
-            version = yylval.opval;
+            s = scan_num(s, &pl_yylval);
+            version = pl_yylval.opval;
            ver = cSVOPx(version)->op_sv;
            if (SvPOK(ver) && !SvNIOK(ver)) {
                SvUPGRADE(ver, SVt_PVNV);
@@ -1540,6 +1607,8 @@ S_tokeq(pTHX_ SV *sv)
     STRLEN len = 0;
     SV *pv = sv;
 
+    PERL_ARGS_ASSERT_TOKEQ;
+
     if (!SvLEN(sv))
        goto finish;
 
@@ -1553,9 +1622,7 @@ S_tokeq(pTHX_ SV *sv)
        goto finish;
     d = s;
     if ( PL_hints & HINT_NEW_STRING ) {
-       pv = sv_2mortal(newSVpvn(SvPVX_const(pv), len));
-       if (SvUTF8(sv))
-           SvUTF8_on(pv);
+       pv = newSVpvn_flags(SvPVX_const(pv), len, SVs_TEMP | SvUTF8(sv));
     }
     while (s < send) {
        if (*s == '\\') {
@@ -1568,7 +1635,7 @@ S_tokeq(pTHX_ SV *sv)
     SvCUR_set(sv, d - SvPVX_const(sv));
   finish:
     if ( PL_hints & HINT_NEW_STRING )
-       return new_constant(NULL, 0, "q", sv, pv, "q");
+       return new_constant(NULL, 0, "q", sv, pv, "q", 1);
     return sv;
 }
 
@@ -1590,10 +1657,10 @@ S_tokeq(pTHX_ SV *sv)
 
 /*
  * S_sublex_start
- * Assumes that yylval.ival is the op we're creating (e.g. OP_LCFIRST).
+ * Assumes that pl_yylval.ival is the op we're creating (e.g. OP_LCFIRST).
  *
  * Pattern matching will set PL_lex_op to the pattern-matching op to
- * make (we return THING if yylval.ival is OP_NULL, PMFUNC otherwise).
+ * make (we return THING if pl_yylval.ival is OP_NULL, PMFUNC otherwise).
  *
  * OP_CONST and OP_READLINE are easy--just make the new op and return.
  *
@@ -1608,10 +1675,10 @@ STATIC I32
 S_sublex_start(pTHX)
 {
     dVAR;
-    register const I32 op_type = yylval.ival;
+    register const I32 op_type = pl_yylval.ival;
 
     if (op_type == OP_NULL) {
-       yylval.opval = PL_lex_op;
+       pl_yylval.opval = PL_lex_op;
        PL_lex_op = NULL;
        return THING;
     }
@@ -1622,13 +1689,11 @@ S_sublex_start(pTHX)
            /* Overloaded constants, nothing fancy: Convert to SVt_PV: */
            STRLEN len;
            const char * const p = SvPV_const(sv, len);
-           SV * const nsv = newSVpvn(p, len);
-           if (SvUTF8(sv))
-               SvUTF8_on(nsv);
+           SV * const nsv = newSVpvn_flags(p, len, SvUTF8(sv));
            SvREFCNT_dec(sv);
            sv = nsv;
        }
-       yylval.opval = (OP*)newSVOP(op_type, 0, sv);
+       pl_yylval.opval = (OP*)newSVOP(op_type, 0, sv);
        PL_lex_stuff = NULL;
        /* Allow <FH> // "foo" */
        if (op_type == OP_READLINE)
@@ -1638,7 +1703,7 @@ S_sublex_start(pTHX)
     else if (op_type == OP_BACKTICK && PL_lex_op) {
        /* readpipe() vas overriden */
        cSVOPx(cLISTOPx(cUNOPx(PL_lex_op)->op_first)->op_first->op_sibling)->op_sv = tokeq(PL_lex_stuff);
-       yylval.opval = PL_lex_op;
+       pl_yylval.opval = PL_lex_op;
        PL_lex_op = NULL;
        PL_lex_stuff = NULL;
        return THING;
@@ -1651,7 +1716,7 @@ S_sublex_start(pTHX)
 
     PL_expect = XTERM;
     if (PL_lex_op) {
-       yylval.opval = PL_lex_op;
+       pl_yylval.opval = PL_lex_op;
        PL_lex_op = NULL;
        return PMFUNC;
     }
@@ -1735,7 +1800,7 @@ S_sublex_done(pTHX)
        if (SvUTF8(PL_linestr))
            SvUTF8_on(sv);
        PL_expect = XOPERATOR;
-       yylval.opval = (OP*)newSVOP(OP_CONST, 0, sv);
+       pl_yylval.opval = (OP*)newSVOP(OP_CONST, 0, sv);
        return THING;
     }
 
@@ -1808,7 +1873,7 @@ S_sublex_done(pTHX)
   Returns a pointer to the character scanned up to. If this is
   advanced from the start pointer supplied (i.e. if anything was
   successfully parsed), will leave an OP for the substring scanned
-  in yylval. Caller must intuit reason for not parsing further
+  in pl_yylval. Caller must intuit reason for not parsing further
   by looking at the next characters herself.
 
   In patterns:
@@ -1892,6 +1957,8 @@ S_scan_const(pTHX_ char *start)
     bool native_range = TRUE; /* turned to FALSE if the first endpoint is Unicode. */
 #endif
 
+    PERL_ARGS_ASSERT_SCAN_CONST;
+
     if (PL_lex_inwhat == OP_TRANS && PL_sublex_info.sub_op) {
        /* If we are doing a trans and we know we want UTF8 set expectation */
        has_utf8   = PL_sublex_info.sub_op->op_private & (OPpTRANS_FROM_UTF|OPpTRANS_TO_UTF);
@@ -2106,8 +2173,13 @@ S_scan_const(pTHX_ char *start)
        else if (*s == '$') {
            if (!PL_lex_inpat)  /* not a regexp, so $ must be var */
                break;
-           if (s + 1 < send && !strchr("()| \r\n\t", s[1]))
+           if (s + 1 < send && !strchr("()| \r\n\t", s[1])) {
+               if (s[1] == '\\' && ckWARN(WARN_AMBIGUOUS)) {
+                   Perl_warner(aTHX_ packWARN(WARN_AMBIGUOUS),
+                               "Possible unintended interpolation of $\\ in regex");
+               }
                break;          /* in regexp, $ might be tail anchor */
+            }
        }
 
        /* End of else if chain - OP_TRANS rejoin rest */
@@ -2273,7 +2345,6 @@ S_scan_const(pTHX_ char *start)
                    SV *res;
                    STRLEN len;
                    const char *str;
-                   SV *type;
 
                    if (!e) {
                        yyerror("Missing right brace on \\N{}");
@@ -2294,10 +2365,8 @@ S_scan_const(pTHX_ char *start)
                        goto NUM_ESCAPE_INSERT;
                    }
                    res = newSVpvn(s + 1, e - s - 1);
-                   type = newSVpvn(s - 2,e - s + 3);
                    res = new_constant( NULL, 0, "charnames",
-                                       res, NULL, SvPVX(type) );
-                   SvREFCNT_dec(type);         
+                                       res, NULL, s - 2, e - s + 3 );
                    if (has_utf8)
                        sv_utf8_upgrade(res);
                    str = SvPV_const(res,len);
@@ -2450,19 +2519,29 @@ S_scan_const(pTHX_ char *start)
        SvPV_shrink_to_cur(sv);
     }
 
-    /* return the substring (via yylval) only if we parsed anything */
+    /* return the substring (via pl_yylval) only if we parsed anything */
     if (s > PL_bufptr) {
-       if ( PL_hints & ( PL_lex_inpat ? HINT_NEW_RE : HINT_NEW_STRING ) )
-           sv = new_constant(start, s - start,
-                             (const char *)(PL_lex_inpat ? "qr" : "q"),
-                             sv, NULL,
-                             (const char *)
-                             (( PL_lex_inwhat == OP_TRANS
-                                ? "tr"
-                                : ( (PL_lex_inwhat == OP_SUBST && !PL_lex_inpat)
-                                    ? "s"
-                                    : "qq"))));
-       yylval.opval = (OP*)newSVOP(OP_CONST, 0, sv);
+       if ( PL_hints & ( PL_lex_inpat ? HINT_NEW_RE : HINT_NEW_STRING ) ) {
+           const char *const key = PL_lex_inpat ? "qr" : "q";
+           const STRLEN keylen = PL_lex_inpat ? 2 : 1;
+           const char *type;
+           STRLEN typelen;
+
+           if (PL_lex_inwhat == OP_TRANS) {
+               type = "tr";
+               typelen = 2;
+           } else if (PL_lex_inwhat == OP_SUBST && !PL_lex_inpat) {
+               type = "s";
+               typelen = 1;
+           } else  {
+               type = "qq";
+               typelen = 2;
+           }
+
+           sv = S_new_constant(aTHX_ start, s - start, key, keylen, sv, NULL,
+                               type, typelen);
+       }
+       pl_yylval.opval = (OP*)newSVOP(OP_CONST, 0, sv);
     } else
        SvREFCNT_dec(sv);
     return s;
@@ -2493,6 +2572,9 @@ STATIC int
 S_intuit_more(pTHX_ register char *s)
 {
     dVAR;
+
+    PERL_ARGS_ASSERT_INTUIT_MORE;
+
     if (PL_lex_brackets)
        return TRUE;
     if (*s == '-' && s[1] == '>' && (s[2] == '[' || s[2] == '{'))
@@ -2658,6 +2740,8 @@ S_intuit_method(pTHX_ char *start, GV *gv, CV *cv)
     int soff;
 #endif
 
+    PERL_ARGS_ASSERT_INTUIT_METHOD;
+
     if (gv) {
        if (SvTYPE(gv) == SVt_PVGV && GvIO(gv))
            return 0;
@@ -2734,29 +2818,6 @@ S_intuit_method(pTHX_ char *start, GV *gv, CV *cv)
     return 0;
 }
 
-/*
- * S_incl_perldb
- * Return a string of Perl code to load the debugger.  If PERL5DB
- * is set, it will return the contents of that, otherwise a
- * compile-time require of perl5db.pl.
- */
-
-STATIC const char*
-S_incl_perldb(pTHX)
-{
-    dVAR;
-    if (PL_perldb) {
-       const char * const pdb = PerlEnv_getenv("PERL5DB");
-
-       if (pdb)
-           return pdb;
-       SETERRNO(0,SS_NORMAL);
-       return "BEGIN { require 'perl5db.pl' }";
-    }
-    return "";
-}
-
-
 /* Encoded script support. filter_add() effectively inserts a
  * 'pre-processing' function into the current source input stream.
  * Note that the filter function only applies to the current source file
@@ -2807,6 +2868,8 @@ Perl_filter_del(pTHX_ filter_t funcp)
     dVAR;
     SV *datasv;
 
+    PERL_ARGS_ASSERT_FILTER_DEL;
+
 #ifdef DEBUGGING
     DEBUG_P(PerlIO_printf(Perl_debug_log, "filter_del func %p",
                          FPTR2DPTR(void*, funcp)));
@@ -2847,6 +2910,8 @@ Perl_filter_read(pTHX_ int idx, SV *buf_sv, int maxlen)
 #endif
        : maxlen;
 
+    PERL_ARGS_ASSERT_FILTER_READ;
+
     if (!PL_parser || !PL_rsfp_filters)
        return -1;
     if (idx > AvFILLp(PL_rsfp_filters)) {       /* Any more filters?   */
@@ -2902,6 +2967,9 @@ STATIC char *
 S_filter_gets(pTHX_ register SV *sv, register PerlIO *fp, STRLEN append)
 {
     dVAR;
+
+    PERL_ARGS_ASSERT_FILTER_GETS;
+
 #ifdef PERL_CR_FILTER
     if (!PL_rsfp_filters) {
        filter_add(S_cr_textfilter,NULL);
@@ -2920,11 +2988,13 @@ S_filter_gets(pTHX_ register SV *sv, register PerlIO *fp, STRLEN append)
 }
 
 STATIC HV *
-S_find_in_my_stash(pTHX_ const char *pkgname, I32 len)
+S_find_in_my_stash(pTHX_ const char *pkgname, STRLEN len)
 {
     dVAR;
     GV *gv;
 
+    PERL_ARGS_ASSERT_FIND_IN_MY_STASH;
+
     if (len == 11 && *pkgname == '_' && strEQ(pkgname, "__PACKAGE__"))
         return PL_curstash;
 
@@ -2940,10 +3010,10 @@ S_find_in_my_stash(pTHX_ const char *pkgname, I32 len)
     if (gv && GvCV(gv)) {
        SV * const sv = cv_const_sv(GvCV(gv));
        if (sv)
-            pkgname = SvPV_nolen_const(sv);
+            pkgname = SvPV_const(sv, len);
     }
 
-    return gv_stashpv(pkgname, 0);
+    return gv_stashpvn(pkgname, len, 0);
 }
 
 /*
@@ -2956,7 +3026,7 @@ S_readpipe_override(pTHX)
 {
     GV **gvp;
     GV *gv_readpipe = gv_fetchpvs("readpipe", GV_NOTQUAL, SVt_PVCV);
-    yylval.ival = OP_BACKTICK;
+    pl_yylval.ival = OP_BACKTICK;
     if ((gv_readpipe
                && GvCVu(gv_readpipe) && GvIMPORTED_CV(gv_readpipe))
            ||
@@ -2969,9 +3039,6 @@ S_readpipe_override(pTHX)
                newSVOP(OP_CONST, 0, &PL_sv_undef), /* value will be read later */
                newCVREF(0, newGVOP(OP_GV, 0, gv_readpipe))));
     }
-    else {
-       set_csh();
-    }
 }
 
 #ifdef PERL_MAD 
@@ -3082,8 +3149,8 @@ Perl_madlex(pTHX)
     case FUNC0SUB:
     case UNIOPSUB:
     case LSTOPSUB:
-       if (yylval.opval)
-           append_madprops(PL_thismad, yylval.opval, 0);
+       if (pl_yylval.opval)
+           append_madprops(PL_thismad, pl_yylval.opval, 0);
        PL_thismad = 0;
        return optype;
 
@@ -3153,7 +3220,7 @@ Perl_madlex(pTHX)
     }
 
     /* Create new token struct.  Note: opvals return early above. */
-    yylval.tkval = newTOKEN(optype, yylval, PL_thismad);
+    pl_yylval.tkval = newTOKEN(optype, pl_yylval, PL_thismad);
     PL_thismad = 0;
     return optype;
 }
@@ -3162,6 +3229,9 @@ Perl_madlex(pTHX)
 STATIC char *
 S_tokenize_use(pTHX_ int is_use, char *s) {
     dVAR;
+
+    PERL_ARGS_ASSERT_TOKENIZE_USE;
+
     if (PL_expect != XSTATE)
        yyerror(Perl_form(aTHX_ "\"%s\" not allowed in expression",
                    is_use ? "use" : "no"));
@@ -3182,7 +3252,7 @@ S_tokenize_use(pTHX_ int is_use, char *s) {
        s = force_word(s,WORD,FALSE,TRUE,FALSE);
        s = force_version(s, FALSE);
     }
-    yylval.ival = is_use;
+    pl_yylval.ival = is_use;
     return s;
 }
 #ifdef DEBUGGING
@@ -3263,7 +3333,7 @@ Perl_yylex(pTHX)
     case LEX_KNOWNEXT:
 #ifdef PERL_MAD
        PL_lasttoke--;
-       yylval = PL_nexttoke[PL_lasttoke].next_val;
+       pl_yylval = PL_nexttoke[PL_lasttoke].next_val;
        if (PL_madskills) {
            PL_thismad = PL_nexttoke[PL_lasttoke].next_mad;
            PL_nexttoke[PL_lasttoke].next_mad = 0;
@@ -3283,7 +3353,7 @@ Perl_yylex(pTHX)
        }
 #else
        PL_nexttoke--;
-       yylval = PL_nextval[PL_nexttoke];
+       pl_yylval = PL_nextval[PL_nexttoke];
        if (!PL_nexttoke) {
            PL_lex_state = PL_lex_defer;
            PL_expect = PL_lex_expect;
@@ -3384,8 +3454,10 @@ Perl_yylex(pTHX)
                else
                    Perl_croak(aTHX_ "panic: yylex");
                if (PL_madskills) {
-                   SV* const tmpsv = newSVpvs("");
-                   Perl_sv_catpvf(aTHX_ tmpsv, "\\%c", *s);
+                   SV* const tmpsv = newSVpvs("\\ ");
+                   /* replace the space with the character we want to escape
+                    */
+                   SvPVX(tmpsv)[1] = *s;
                    curmad('_', tmpsv);
                }
                PL_bufptr = s + 1;
@@ -3496,8 +3568,8 @@ Perl_yylex(pTHX)
            if (!PL_lex_inpat)
                sv = tokeq(sv);
            else if ( PL_hints & HINT_NEW_RE )
-               sv = new_constant(NULL, 0, "qr", sv, sv, "q");
-           yylval.opval = (OP*)newSVOP(OP_CONST, 0, sv);
+               sv = new_constant(NULL, 0, "qr", sv, sv, "q", 1);
+           pl_yylval.opval = (OP*)newSVOP(OP_CONST, 0, sv);
            s = PL_bufend;
        }
        else {
@@ -3513,7 +3585,7 @@ Perl_yylex(pTHX)
            if (PL_madskills) {
                curmad('X', newSVpvn(PL_bufptr,s-PL_bufptr));
            }
-           NEXTVAL_NEXTTOKE = yylval;
+           NEXTVAL_NEXTTOKE = pl_yylval;
            PL_expect = XTERM;
            force_next(THING);
            if (PL_lex_starts++) {
@@ -3561,7 +3633,8 @@ Perl_yylex(pTHX)
     default:
        if (isIDFIRST_lazy_if(s,UTF))
            goto keylookup;
-       Perl_croak(aTHX_ "Unrecognized character \\x%02X", *s & 255);
+       len = UTF ? Perl_utf8_length(aTHX_ (U8 *) PL_linestart, (U8 *) s) : (STRLEN) (s - PL_linestart);
+       Perl_croak(aTHX_ "Unrecognized character \\x%02X in column %d", *s & 255, (int) len + 1);
     case 4:
     case 26:
        goto fake_eof;                  /* emulate EOF on ^D or ^Z */
@@ -3594,19 +3667,36 @@ Perl_yylex(pTHX)
            if (PL_madskills)
                PL_faketokens = 1;
 #endif
-           sv_setpv(PL_linestr,incl_perldb());
-           if (SvCUR(PL_linestr))
-               sv_catpvs(PL_linestr,";");
-           if (PL_preambleav){
-               while(AvFILLp(PL_preambleav) >= 0) {
-                   SV *tmpsv = av_shift(PL_preambleav);
-                   sv_catsv(PL_linestr, tmpsv);
+           if (PL_perldb) {
+               /* Generate a string of Perl code to load the debugger.
+                * If PERL5DB is set, it will return the contents of that,
+                * otherwise a compile-time require of perl5db.pl.  */
+
+               const char * const pdb = PerlEnv_getenv("PERL5DB");
+
+               if (pdb) {
+                   sv_setpv(PL_linestr, pdb);
+                   sv_catpvs(PL_linestr,";");
+               } else {
+                   SETERRNO(0,SS_NORMAL);
+                   sv_setpvs(PL_linestr, "BEGIN { require 'perl5db.pl' };");
+               }
+           } else
+               sv_setpvs(PL_linestr,"");
+           if (PL_preambleav) {
+               SV **svp = AvARRAY(PL_preambleav);
+               SV **const end = svp + AvFILLp(PL_preambleav);
+               while(svp <= end) {
+                   sv_catsv(PL_linestr, *svp);
+                   ++svp;
                    sv_catpvs(PL_linestr, ";");
-                   sv_free(tmpsv);
                }
                sv_free((SV*)PL_preambleav);
                PL_preambleav = NULL;
            }
+           if (PL_minus_E)
+               sv_catpvs(PL_linestr,
+                         "use feature ':5." STRINGIFY(PERL_VERSION) "';");
            if (PL_minus_n || PL_minus_p) {
                sv_catpvs(PL_linestr, "LINE: while (<>) {");
                if (PL_minus_l)
@@ -3638,8 +3728,6 @@ Perl_yylex(pTHX)
                        sv_catpvs(PL_linestr,"our @F=split(' ');");
                }
            }
-           if (PL_minus_E)
-               sv_catpvs(PL_linestr,"use feature ':5.10';");
            sv_catpvs(PL_linestr, "\n");
            PL_oldoldbufptr = PL_oldbufptr = s = PL_linestart = SvPVX(PL_linestr);
            PL_bufend = SvPVX(PL_linestr) + SvCUR(PL_linestr);
@@ -3656,9 +3744,7 @@ Perl_yylex(pTHX)
                PL_realtokenstart = -1;
 #endif
                if (PL_rsfp) {
-                   if (PL_preprocess && !PL_in_eval)
-                       (void)PerlProc_pclose(PL_rsfp);
-                   else if ((PerlIO *)PL_rsfp == PerlIO_stdin())
+                   if ((PerlIO *)PL_rsfp == PerlIO_stdin())
                        PerlIO_clearerr(PL_rsfp);
                    else
                        (void)PerlIO_close(PL_rsfp);
@@ -3670,10 +3756,10 @@ Perl_yylex(pTHX)
                    if (PL_madskills)
                        PL_faketokens = 1;
 #endif
-                   sv_setpv(PL_linestr,
-                            (const char *)
-                            (PL_minus_p
-                             ? ";}continue{print;}" : ";}"));
+                   if (PL_minus_p)
+                       sv_setpvs(PL_linestr, ";}continue{print;}");
+                   else
+                       sv_setpvs(PL_linestr, ";}");
                    PL_oldoldbufptr = PL_oldbufptr = s = PL_linestart = SvPVX(PL_linestr);
                    PL_bufend = SvPVX(PL_linestr) + SvCUR(PL_linestr);
                    PL_last_lop = PL_last_uni = NULL;
@@ -3705,16 +3791,7 @@ Perl_yylex(pTHX)
 #    endif
 #  endif
 #endif
-#ifdef FTELL_FOR_PIPE_IS_BROKEN
-               /* This loses the possibility to detect the bof
-                * situation on perl -P when the libc5 is being used.
-                * Workaround?  Maybe attach some extra state to PL_rsfp?
-                */
-               if (!PL_preprocess)
-                   bof = PerlIO_tell(PL_rsfp) == SvCUR(PL_linestr);
-#else
                bof = PerlIO_tell(PL_rsfp) == (Off_t)SvCUR(PL_linestr);
-#endif
                if (bof) {
                    PL_bufend = SvPVX(PL_linestr) + SvCUR(PL_linestr);
                    s = swallow_bom((U8*)s);
@@ -3890,17 +3967,18 @@ Perl_yylex(pTHX)
                        const U32 oldpdb = PL_perldb;
                        const bool oldn = PL_minus_n;
                        const bool oldp = PL_minus_p;
+                       const char *d1 = d;
 
                        do {
-                           if (*d == 'M' || *d == 'm' || *d == 'C') {
-                               const char * const m = d;
-                               while (*d && !isSPACE(*d))
-                                   d++;
+                           if (*d1 == 'M' || *d1 == 'm' || *d1 == 'C') {
+                               const char * const m = d1;
+                               while (*d1 && !isSPACE(*d1))
+                                   d1++;
                                Perl_croak(aTHX_ "Too late for \"-%.*s\" option",
-                                     (int)(d - m), m);
+                                     (int)(d1 - m), m);
                            }
-                           d = moreswitches(d);
-                       } while (d);
+                           d1 = moreswitches(d1);
+                       } while (d1);
                        if (PL_doswitches && !switches_done) {
                            int argc = PL_origargc;
                            char **argv = PL_origargv;
@@ -4234,7 +4312,6 @@ Perl_yylex(pTHX)
                    switch (tmp) {
                    case KEY_or:
                    case KEY_and:
-                   case KEY_err:
                    case KEY_for:
                    case KEY_unless:
                    case KEY_if:
@@ -4272,7 +4349,7 @@ Perl_yylex(pTHX)
                        sv_free(sv);
                        if (PL_in_my == KEY_our) {
 #ifdef USE_ITHREADS
-                           GvUNIQUE_on(cGVOPx_gv(yylval.opval));
+                           GvUNIQUE_on(cGVOPx_gv(pl_yylval.opval));
 #else
                            /* skip to avoid loading attributes.pm */
 #endif
@@ -4555,7 +4632,7 @@ Perl_yylex(pTHX)
            }
            break;
        }
-       yylval.ival = CopLINE(PL_curcop);
+       pl_yylval.ival = CopLINE(PL_curcop);
        if (isSPACE(*s) || *s == '#')
            PL_copline = NOLINE;   /* invalidate current command line number */
        TOKEN('{');
@@ -4628,7 +4705,7 @@ Perl_yylex(pTHX)
        }
        else
            PREREF('&');
-       yylval.ival = (OPpENTERSUB_AMPER<<8);
+       pl_yylval.ival = (OPpENTERSUB_AMPER<<8);
        TERM('&');
 
     case '|':
@@ -4700,9 +4777,13 @@ Perl_yylex(pTHX)
                goto leftbracket;
            }
        }
-       yylval.ival = 0;
+       pl_yylval.ival = 0;
        OPERATOR(ASSIGNOP);
     case '!':
+       if (PL_expect == XSTATE && s[1] == '!' && s[2] == '!') {
+           s += 3;
+           LOP(OP_DIE,XTERM);
+       }
        s++;
        {
            const char tmp = *s++;
@@ -4804,9 +4885,9 @@ Perl_yylex(pTHX)
 
        /* This kludge not intended to be bulletproof. */
        if (PL_tokenbuf[1] == '[' && !PL_tokenbuf[2]) {
-           yylval.opval = newSVOP(OP_CONST, 0,
+           pl_yylval.opval = newSVOP(OP_CONST, 0,
                                   newSViv(CopARYBASE_get(&PL_compiling)));
-           yylval.opval->op_private = OPpCONST_ARYBASE;
+           pl_yylval.opval->op_private = OPpCONST_ARYBASE;
            TERM(THING);
        }
 
@@ -4954,10 +5035,14 @@ Perl_yylex(pTHX)
            AOPERATOR(DORDOR);
        }
      case '?':                 /* may either be conditional or pattern */
-        if(PL_expect == XOPERATOR) {
+       if (PL_expect == XSTATE && s[1] == '?' && s[2] == '?') {
+           s += 3;
+           LOP(OP_WARN,XTERM);
+       }
+       if (PL_expect == XOPERATOR) {
             char tmp = *s++;
             if(tmp == '?') {
-                 OPERATOR('?');
+               OPERATOR('?');
             }
              else {
                 tmp = *s++;
@@ -4996,16 +5081,20 @@ Perl_yylex(pTHX)
            PL_expect = XSTATE;
            goto rightbracket;
        }
+       if (PL_expect == XSTATE && s[1] == '.' && s[2] == '.') {
+           s += 3;
+           OPERATOR(YADAYADA);
+       }
        if (PL_expect == XOPERATOR || !isDIGIT(s[1])) {
            char tmp = *s++;
            if (*s == tmp) {
                s++;
                if (*s == tmp) {
                    s++;
-                   yylval.ival = OPf_SPECIAL;
+                   pl_yylval.ival = OPf_SPECIAL;
                }
                else
-                   yylval.ival = 0;
+                   pl_yylval.ival = 0;
                OPERATOR(DOTDOT);
            }
            if (PL_expect != XOPERATOR)
@@ -5015,7 +5104,7 @@ Perl_yylex(pTHX)
        /* FALL THROUGH */
     case '0': case '1': case '2': case '3': case '4':
     case '5': case '6': case '7': case '8': case '9':
-       s = scan_num(s, &yylval);
+       s = scan_num(s, &pl_yylval);
        DEBUG_T( { printbuf("### Saw number in %s\n", s); } );
        if (PL_expect == XOPERATOR)
            no_op("Number",s);
@@ -5035,7 +5124,7 @@ Perl_yylex(pTHX)
        }
        if (!s)
            missingterm(NULL);
-       yylval.ival = OP_CONST;
+       pl_yylval.ival = OP_CONST;
        TERM(sublex_start());
 
     case '"':
@@ -5052,12 +5141,12 @@ Perl_yylex(pTHX)
        }
        if (!s)
            missingterm(NULL);
-       yylval.ival = OP_CONST;
+       pl_yylval.ival = OP_CONST;
        /* FIXME. I think that this can be const if char *d is replaced by
           more localised variables.  */
        for (d = SvPV(PL_lex_stuff, len); len; len--, d++) {
            if (*d == '$' || *d == '@' || *d == '\\' || !UTF8_IS_INVARIANT((U8)*d)) {
-               yylval.ival = OP_STRINGIFY;
+               pl_yylval.ival = OP_STRINGIFY;
                break;
            }
        }
@@ -5088,21 +5177,16 @@ Perl_yylex(pTHX)
            while (isDIGIT(*start) || *start == '_')
                start++;
            if (*start == '.' && isDIGIT(start[1])) {
-               s = scan_num(s, &yylval);
+               s = scan_num(s, &pl_yylval);
                TERM(THING);
            }
            /* avoid v123abc() or $h{v1}, allow C<print v10;> */
            else if (!isALPHA(*start) && (PL_expect == XTERM
                        || PL_expect == XREF || PL_expect == XSTATE
                        || PL_expect == XTERMORDORDOR)) {
-               /* XXX Use gv_fetchpvn rather than stomping on a const string */
-               const char c = *start;
-               GV *gv;
-               *start = '\0';
-               gv = gv_fetchpv(s, 0, SVt_PVCV);
-               *start = c;
+               GV *const gv = gv_fetchpvn_flags(s, start - s, 0, SVt_PVCV);
                if (!gv) {
-                   s = scan_num(s, &yylval);
+                   s = scan_num(s, &pl_yylval);
                    TERM(THING);
                }
            }
@@ -5171,7 +5255,7 @@ Perl_yylex(pTHX)
        if (!tmp && PL_expect == XSTATE
              && d < PL_bufend && *d == ':' && *(d + 1) != ':') {
            s = d + 1;
-           yylval.pval = CopLABEL_alloc(PL_tokenbuf);
+           pl_yylval.pval = CopLABEL_alloc(PL_tokenbuf);
            CLINE;
            TOKEN(LABEL);
        }
@@ -5182,10 +5266,10 @@ Perl_yylex(pTHX)
        /* Is this a word before a => operator? */
        if (*d == '=' && d[1] == '>') {
            CLINE;
-           yylval.opval
+           pl_yylval.opval
                = (OP*)newSVOP(OP_CONST, 0,
                               S_newSV_maybe_utf8(aTHX_ PL_tokenbuf, len));
-           yylval.opval->op_private = OPpCONST_BARE;
+           pl_yylval.opval->op_private = OPpCONST_BARE;
            TERM(WORD);
        }
 
@@ -5327,7 +5411,7 @@ Perl_yylex(pTHX)
 #ifdef PERL_MAD
                if (PL_madskills && !PL_thistoken) {
                    char *start = SvPVX(PL_linestr) + PL_realtokenstart;
-                   PL_thistoken = newSVpv(start,s - start);
+                   PL_thistoken = newSVpvn(start,s - start);
                    PL_realtokenstart = s - SvPVX(PL_linestr);
                }
 #endif
@@ -5335,8 +5419,8 @@ Perl_yylex(pTHX)
                /* Presume this is going to be a bareword of some sort. */
 
                CLINE;
-               yylval.opval = (OP*)newSVOP(OP_CONST, 0, sv);
-               yylval.opval->op_private = OPpCONST_BARE;
+               pl_yylval.opval = (OP*)newSVOP(OP_CONST, 0, sv);
+               pl_yylval.opval->op_private = OPpCONST_BARE;
                /* UTF-8 package name? */
                if (UTF && !IN_BYTES &&
                    is_utf8_string((U8*)SvPVX_const(sv), SvCUR(sv)))
@@ -5358,7 +5442,7 @@ Perl_yylex(pTHX)
                    /* Real typeglob, so get the real subroutine: */
                           ? GvCVu(gv)
                    /* A proxy for a subroutine in this package? */
-                          : SvOK(gv) ? (CV *) gv : NULL)
+                          : SvOK(gv) ? MUTABLE_CV(gv) : NULL)
                    : NULL;
 
                /* See if it's the indirect object for a list operator. */
@@ -5415,9 +5499,9 @@ Perl_yylex(pTHX)
                /* Is this a word before a => operator? */
                if (*s == '=' && s[1] == '>' && !pkgname) {
                    CLINE;
-                   sv_setpv(((SVOP*)yylval.opval)->op_sv, PL_tokenbuf);
+                   sv_setpv(((SVOP*)pl_yylval.opval)->op_sv, PL_tokenbuf);
                    if (UTF && !IN_BYTES && is_utf8_string((U8*)PL_tokenbuf, len))
-                     SvUTF8_on(((SVOP*)yylval.opval)->op_sv);
+                     SvUTF8_on(((SVOP*)pl_yylval.opval)->op_sv);
                    TERM(WORD);
                }
 
@@ -5430,18 +5514,7 @@ Perl_yylex(pTHX)
                            d++;
                        if (*d == ')' && (sv = gv_const_sv(gv))) {
                            s = d + 1;
-#ifdef PERL_MAD
-                           if (PL_madskills) {
-                               char *par = SvPVX(PL_linestr) + PL_realtokenstart; 
-                               sv_catpvn(PL_thistoken, par, s - par);
-                               if (PL_nextwhite) {
-                                   sv_free(PL_nextwhite);
-                                   PL_nextwhite = 0;
-                               }
-                           }
-                           else
-#endif
-                               goto its_constant;
+                           goto its_constant;
                        }
                    }
 #ifdef PERL_MAD
@@ -5451,7 +5524,7 @@ Perl_yylex(pTHX)
                    }
                    start_force(PL_curforce);
 #endif
-                   NEXTVAL_NEXTTOKE.opval = yylval.opval;
+                   NEXTVAL_NEXTTOKE.opval = pl_yylval.opval;
                    PL_expect = XOPERATOR;
 #ifdef PERL_MAD
                    if (PL_madskills) {
@@ -5461,7 +5534,7 @@ Perl_yylex(pTHX)
                    }
 #endif
                    force_next(WORD);
-                   yylval.ival = 0;
+                   pl_yylval.ival = 0;
                    TOKEN('&');
                }
 
@@ -5488,11 +5561,11 @@ Perl_yylex(pTHX)
                                "Ambiguous use of -%s resolved as -&%s()",
                                PL_tokenbuf, PL_tokenbuf);
                    /* Check for a constant sub */
-                   if ((sv = gv_const_sv(gv)) && !PL_madskills) {
+                   if ((sv = gv_const_sv(gv))) {
                  its_constant:
-                       SvREFCNT_dec(((SVOP*)yylval.opval)->op_sv);
-                       ((SVOP*)yylval.opval)->op_sv = SvREFCNT_inc_simple(sv);
-                       yylval.opval->op_private = 0;
+                       SvREFCNT_dec(((SVOP*)pl_yylval.opval)->op_sv);
+                       ((SVOP*)pl_yylval.opval)->op_sv = SvREFCNT_inc_simple(sv);
+                       pl_yylval.opval->op_private = 0;
                        TOKEN(WORD);
                    }
 
@@ -5505,9 +5578,9 @@ Perl_yylex(pTHX)
                        cv = GvCV(gv);
                    }
 
-                   op_free(yylval.opval);
-                   yylval.opval = newCVREF(0, newGVOP(OP_GV, 0, gv));
-                   yylval.opval->op_private |= OPpENTERSUB_NOPAREN;
+                   op_free(pl_yylval.opval);
+                   pl_yylval.opval = newCVREF(0, newGVOP(OP_GV, 0, gv));
+                   pl_yylval.opval->op_private |= OPpENTERSUB_NOPAREN;
                    PL_last_lop = PL_oldbufptr;
                    PL_last_lop_op = OP_ENTERSUB;
                    /* Is there a prototype? */
@@ -5526,10 +5599,10 @@ Perl_yylex(pTHX)
                        while (*proto == ';')
                            proto++;
                        if (*proto == '&' && *s == '{') {
-                           sv_setpv(PL_subname,
-                                    (const char *)
-                                    (PL_curstash ?
-                                     "__ANON__" : "__ANON__::__ANON__"));
+                           if (PL_curstash)
+                               sv_setpvs(PL_subname, "__ANON__");
+                           else
+                               sv_setpvs(PL_subname, "__ANON__::__ANON__");
                            PREBLOCK(LSTOPSUB);
                        }
                    }
@@ -5540,7 +5613,7 @@ Perl_yylex(pTHX)
                            PL_thiswhite = 0;
                        }
                        start_force(PL_curforce);
-                       NEXTVAL_NEXTTOKE.opval = yylval.opval;
+                       NEXTVAL_NEXTTOKE.opval = pl_yylval.opval;
                        PL_expect = XTERM;
                        if (PL_madskills) {
                            PL_nextwhite = nextPL_nextwhite;
@@ -5573,15 +5646,15 @@ Perl_yylex(pTHX)
                    }
                    if (probable_sub) {
                        gv = gv_fetchpv(PL_tokenbuf, GV_ADD, SVt_PVCV);
-                       op_free(yylval.opval);
-                       yylval.opval = newCVREF(0, newGVOP(OP_GV, 0, gv));
-                       yylval.opval->op_private |= OPpENTERSUB_NOPAREN;
+                       op_free(pl_yylval.opval);
+                       pl_yylval.opval = newCVREF(0, newGVOP(OP_GV, 0, gv));
+                       pl_yylval.opval->op_private |= OPpENTERSUB_NOPAREN;
                        PL_last_lop = PL_oldbufptr;
                        PL_last_lop_op = OP_ENTERSUB;
                        PL_nextwhite = PL_thiswhite;
                        PL_thiswhite = 0;
                        start_force(PL_curforce);
-                       NEXTVAL_NEXTTOKE.opval = yylval.opval;
+                       NEXTVAL_NEXTTOKE.opval = pl_yylval.opval;
                        PL_expect = XTERM;
                        PL_nextwhite = nextPL_nextwhite;
                        curmad('X', PL_thistoken);
@@ -5590,7 +5663,7 @@ Perl_yylex(pTHX)
                        TOKEN(NOAMP);
                    }
 #else
-                   NEXTVAL_NEXTTOKE.opval = yylval.opval;
+                   NEXTVAL_NEXTTOKE.opval = pl_yylval.opval;
                    PL_expect = XTERM;
                    force_next(WORD);
                    TOKEN(NOAMP);
@@ -5599,10 +5672,10 @@ Perl_yylex(pTHX)
 
                /* Call it a bare word */
 
+               bareword:
                if (PL_hints & HINT_STRICT_SUBS)
-                   yylval.opval->op_private |= OPpCONST_STRICT;
+                   pl_yylval.opval->op_private |= OPpCONST_STRICT;
                else {
-               bareword:
                    if (lastchar != '-') {
                        if (ckWARN(WARN_RESERVED)) {
                            d = PL_tokenbuf;
@@ -5629,17 +5702,17 @@ Perl_yylex(pTHX)
            }
 
        case KEY___FILE__:
-           yylval.opval = (OP*)newSVOP(OP_CONST, 0,
+           pl_yylval.opval = (OP*)newSVOP(OP_CONST, 0,
                                        newSVpv(CopFILE(PL_curcop),0));
            TERM(THING);
 
        case KEY___LINE__:
-            yylval.opval = (OP*)newSVOP(OP_CONST, 0,
+            pl_yylval.opval = (OP*)newSVOP(OP_CONST, 0,
                                     Perl_newSVpvf(aTHX_ "%"IVdf, (IV)CopLINE(PL_curcop)));
            TERM(THING);
 
        case KEY___PACKAGE__:
-           yylval.opval = (OP*)newSVOP(OP_CONST, 0,
+           pl_yylval.opval = (OP*)newSVOP(OP_CONST, 0,
                                        (PL_curstash
                                         ? newSVhek(HvNAME_HEK(PL_curstash))
                                         : &PL_sv_undef));
@@ -5666,9 +5739,7 @@ Perl_yylex(pTHX)
 #endif
                /* Mark this internal pseudo-handle as clean */
                IoFLAGS(GvIOp(gv)) |= IOf_UNTAINT;
-               if (PL_preprocess)
-                   IoTYPE(GvIOp(gv)) = IoTYPE_PIPE;
-               else if ((PerlIO*)PL_rsfp == PerlIO_stdin())
+               if ((PerlIO*)PL_rsfp == PerlIO_stdin())
                    IoTYPE(GvIOp(gv)) = IoTYPE_STD;
                else
                    IoTYPE(GvIOp(gv)) = IoTYPE_RDONLY;
@@ -5737,7 +5808,7 @@ Perl_yylex(pTHX)
                        PL_realtokenstart = -1;
                    }
                    while ((s = filter_gets(PL_endwhite, PL_rsfp,
-                                SvCUR(PL_endwhite))) != Nullch) ;
+                                SvCUR(PL_endwhite))) != NULL) ;
                }
 #endif
                PL_rsfp = NULL;
@@ -5879,10 +5950,10 @@ Perl_yylex(pTHX)
                s = force_word(s,WORD,TRUE,TRUE,FALSE);
            if (orig_keyword == KEY_do) {
                orig_keyword = 0;
-               yylval.ival = 1;
+               pl_yylval.ival = 1;
            }
            else
-               yylval.ival = 0;
+               pl_yylval.ival = 0;
            OPERATOR(DO);
 
        case KEY_die:
@@ -5910,7 +5981,7 @@ Perl_yylex(pTHX)
            PREBLOCK(ELSE);
 
        case KEY_elsif:
-           yylval.ival = CopLINE(PL_curcop);
+           pl_yylval.ival = CopLINE(PL_curcop);
            OPERATOR(ELSIF);
 
        case KEY_eq:
@@ -5932,9 +6003,6 @@ Perl_yylex(pTHX)
        case KEY_eof:
            UNI(OP_EOF);
 
-       case KEY_err:
-           OPERATOR(DOROP);
-
        case KEY_exp:
            UNI(OP_EXP);
 
@@ -5942,7 +6010,6 @@ Perl_yylex(pTHX)
            UNI(OP_EACH);
 
        case KEY_exec:
-           set_csh();
            LOP(OP_EXEC,XREF);
 
        case KEY_endhostent:
@@ -5965,7 +6032,7 @@ Perl_yylex(pTHX)
 
        case KEY_for:
        case KEY_foreach:
-           yylval.ival = CopLINE(PL_curcop);
+           pl_yylval.ival = CopLINE(PL_curcop);
            s = SKIPSPACE1(s);
            if (PL_expect == XSTATE && isIDFIRST_lazy_if(s,UTF)) {
                char *p = s;
@@ -6103,18 +6170,17 @@ Perl_yylex(pTHX)
            FUN0(OP_GETLOGIN);
 
        case KEY_given:
-           yylval.ival = CopLINE(PL_curcop);
+           pl_yylval.ival = CopLINE(PL_curcop);
            OPERATOR(GIVEN);
 
        case KEY_glob:
-           set_csh();
            LOP(OP_GLOB,XTERM);
 
        case KEY_hex:
            UNI(OP_HEX);
 
        case KEY_if:
-           yylval.ival = CopLINE(PL_curcop);
+           pl_yylval.ival = CopLINE(PL_curcop);
            OPERATOR(IF);
 
        case KEY_index:
@@ -6146,7 +6212,7 @@ Perl_yylex(pTHX)
            UNI(OP_LCFIRST);
 
        case KEY_local:
-           yylval.ival = 0;
+           pl_yylval.ival = 0;
            OPERATOR(LOCAL);
 
        case KEY_length:
@@ -6225,7 +6291,7 @@ Perl_yylex(pTHX)
                }
 #endif
            }
-           yylval.ival = 1;
+           pl_yylval.ival = 1;
            OPERATOR(MY);
 
        case KEY_next:
@@ -6266,7 +6332,7 @@ Perl_yylex(pTHX)
            LOP(OP_OPEN,XTERM);
 
        case KEY_or:
-           yylval.ival = OP_OR;
+           pl_yylval.ival = OP_OR;
            OPERATOR(OROP);
 
        case KEY_ord:
@@ -6312,7 +6378,7 @@ Perl_yylex(pTHX)
            s = scan_str(s,!!PL_madskills,FALSE);
            if (!s)
                missingterm(NULL);
-           yylval.ival = OP_CONST;
+           pl_yylval.ival = OP_CONST;
            TERM(sublex_start());
 
        case KEY_quotemeta:
@@ -6352,9 +6418,7 @@ Perl_yylex(pTHX)
                            for (; !isSPACE(*d) && len; --len, ++d)
                                /**/;
                        }
-                       sv = newSVpvn(b, d-b);
-                       if (DO_UTF8(PL_lex_stuff))
-                           SvUTF8_on(sv);
+                       sv = newSVpvn_utf8(b, d-b, DO_UTF8(PL_lex_stuff));
                        words = append_elem(OP_LIST, words,
                                            newSVOP(OP_CONST, 0, tokeq(sv)));
                    }
@@ -6376,7 +6440,7 @@ Perl_yylex(pTHX)
            s = scan_str(s,!!PL_madskills,FALSE);
            if (!s)
                missingterm(NULL);
-           yylval.ival = OP_STRINGIFY;
+           pl_yylval.ival = OP_STRINGIFY;
            if (SvIVX(PL_lex_stuff) == '\'')
                SvIV_set(PL_lex_stuff, 0);      /* qq'$foo' should intepolate */
            TERM(sublex_start());
@@ -6412,10 +6476,10 @@ Perl_yylex(pTHX)
            }
            if (orig_keyword == KEY_require) {
                orig_keyword = 0;
-               yylval.ival = 1;
+               pl_yylval.ival = 1;
            }
            else 
-               yylval.ival = 0;
+               pl_yylval.ival = 0;
            PL_expect = XTERM;
            PL_bufptr = s;
            PL_last_uni = PL_oldbufptr;
@@ -6449,11 +6513,9 @@ Perl_yylex(pTHX)
            UNI(OP_READDIR);
 
        case KEY_readline:
-           set_csh();
            UNIDOR(OP_READLINE);
 
        case KEY_readpipe:
-           set_csh();
            UNIDOR(OP_BACKTICK);
 
        case KEY_rewinddir:
@@ -6473,7 +6535,7 @@ Perl_yylex(pTHX)
 
        case KEY_s:
            s = scan_subst(s);
-           if (yylval.opval)
+           if (pl_yylval.opval)
                TERM(sublex_start());
            else
                TOKEN(1);       /* force error */
@@ -6626,7 +6688,7 @@ Perl_yylex(pTHX)
                    (*s == ':' && s[1] == ':'))
                {
 #ifdef PERL_MAD
-                   SV *nametoke;
+                   SV *nametoke = NULL;
 #endif
 
                    PL_expect = XBLOCK;
@@ -6687,6 +6749,12 @@ Perl_yylex(pTHX)
                if (*s == '(') {
                    char *p;
                    bool bad_proto = FALSE;
+                   bool in_brackets = FALSE;
+                   char greedy_proto = ' ';
+                   bool proto_after_greedy_proto = FALSE;
+                   bool must_be_last = FALSE;
+                   bool underscore = FALSE;
+                   bool seen_underscore = FALSE;
                    const bool warnsyntax = ckWARN(WARN_SYNTAX);
 
                    s = scan_str(s,!!PL_madskills,FALSE);
@@ -6698,14 +6766,47 @@ Perl_yylex(pTHX)
                    for (p = d; *p; ++p) {
                        if (!isSPACE(*p)) {
                            d[tmp++] = *p;
-                           if (warnsyntax && !strchr("$@%*;[]&\\_", *p))
-                               bad_proto = TRUE;
+
+                           if (warnsyntax) {
+                               if (must_be_last)
+                                   proto_after_greedy_proto = TRUE;
+                               if (!strchr("$@%*;[]&\\_", *p)) {
+                                   bad_proto = TRUE;
+                               }
+                               else {
+                                   if ( underscore ) {
+                                       if ( *p != ';' )
+                                           bad_proto = TRUE;
+                                       underscore = FALSE;
+                                   }
+                                   if ( *p == '[' ) {
+                                       in_brackets = TRUE;
+                                   }
+                                   else if ( *p == ']' ) {
+                                       in_brackets = FALSE;
+                                   }
+                                   else if ( (*p == '@' || *p == '%') &&
+                                        ( tmp < 2 || d[tmp-2] != '\\' ) &&
+                                        !in_brackets ) {
+                                       must_be_last = TRUE;
+                                       greedy_proto = *p;
+                                   }
+                                   else if ( *p == '_' ) {
+                                       underscore = seen_underscore = TRUE;
+                                   }
+                               }
+                           }
                        }
                    }
                    d[tmp] = '\0';
+                   if (proto_after_greedy_proto)
+                       Perl_warner(aTHX_ packWARN(WARN_SYNTAX),
+                                   "Prototype after '%c' for %"SVf" : %s",
+                                   greedy_proto, SVfARG(PL_subname), d);
                    if (bad_proto)
                        Perl_warner(aTHX_ packWARN(WARN_SYNTAX),
-                                   "Illegal character in prototype for %"SVf" : %s",
+                                   "Illegal character %sin prototype for %"SVf" : %s",
+                                   seen_underscore ? "after '_' " : "",
                                    SVfARG(PL_subname), d);
                    SvCUR_set(PL_lex_stuff, tmp);
                    have_proto = TRUE;
@@ -6718,7 +6819,7 @@ Perl_yylex(pTHX)
                    CURMAD('Q', PL_thisclose);
                    NEXTVAL_NEXTTOKE.opval =
                        (OP*)newSVOP(OP_CONST, 0, PL_lex_stuff);
-                   PL_lex_stuff = Nullsv;
+                   PL_lex_stuff = NULL;
                    force_next(THING);
 
                    s = SKIPSPACE2(s,tmpwhite);
@@ -6757,9 +6858,10 @@ Perl_yylex(pTHX)
                }
 #endif
                if (!have_name) {
-                   sv_setpv(PL_subname,
-                            (const char *)
-                            (PL_curstash ? "__ANON__" : "__ANON__::__ANON__"));
+                   if (PL_curstash)
+                       sv_setpvs(PL_subname, "__ANON__");
+                   else
+                       sv_setpvs(PL_subname, "__ANON__::__ANON__");
                    TOKEN(ANONSUB);
                }
 #ifndef PERL_MAD
@@ -6772,7 +6874,6 @@ Perl_yylex(pTHX)
            }
 
        case KEY_system:
-           set_csh();
            LOP(OP_SYSTEM,XREF);
 
        case KEY_symlink:
@@ -6828,11 +6929,11 @@ Perl_yylex(pTHX)
            UNI(OP_UNTIE);
 
        case KEY_until:
-           yylval.ival = CopLINE(PL_curcop);
+           pl_yylval.ival = CopLINE(PL_curcop);
            OPERATOR(UNTIL);
 
        case KEY_unless:
-           yylval.ival = CopLINE(PL_curcop);
+           pl_yylval.ival = CopLINE(PL_curcop);
            OPERATOR(UNLESS);
 
        case KEY_unlink:
@@ -6864,11 +6965,11 @@ Perl_yylex(pTHX)
            LOP(OP_VEC,XTERM);
 
        case KEY_when:
-           yylval.ival = CopLINE(PL_curcop);
+           pl_yylval.ival = CopLINE(PL_curcop);
            OPERATOR(WHEN);
 
        case KEY_while:
-           yylval.ival = CopLINE(PL_curcop);
+           pl_yylval.ival = CopLINE(PL_curcop);
            OPERATOR(WHILE);
 
        case KEY_warn:
@@ -6905,7 +7006,7 @@ Perl_yylex(pTHX)
            goto just_a_word;
 
        case KEY_xor:
-           yylval.ival = OP_XOR;
+           pl_yylval.ival = OP_XOR;
            OPERATOR(OROP);
 
        case KEY_y:
@@ -6926,6 +7027,9 @@ S_pending_ident(pTHX)
     PADOFFSET tmp = 0;
     /* pit holds the identifier we read and pending_ident is reset */
     char pit = PL_pending_ident;
+    const STRLEN tokenbuf_len = strlen(PL_tokenbuf);
+    /* All routes through this function want to know if there is a colon.  */
+    const char *const has_colon = (const char*) memchr (PL_tokenbuf, ':', tokenbuf_len);
     PL_pending_ident = 0;
 
     /* PL_realtokenstart = realtokenend = PL_bufptr - SvPVX(PL_linestr); */
@@ -6940,19 +7044,19 @@ S_pending_ident(pTHX)
     */
     if (PL_in_my) {
         if (PL_in_my == KEY_our) {     /* "our" is merely analogous to "my" */
-            if (strchr(PL_tokenbuf,':'))
+            if (has_colon)
                 yyerror(Perl_form(aTHX_ "No package name allowed for "
                                   "variable %s in \"our\"",
                                   PL_tokenbuf));
             tmp = allocmy(PL_tokenbuf);
         }
         else {
-            if (strchr(PL_tokenbuf,':'))
+            if (has_colon)
                 yyerror(Perl_form(aTHX_ PL_no_myglob,
                            PL_in_my == KEY_my ? "my" : "state", PL_tokenbuf));
 
-            yylval.opval = newOP(OP_PADANY, 0);
-            yylval.opval->op_targ = allocmy(PL_tokenbuf);
+            pl_yylval.opval = newOP(OP_PADANY, 0);
+            pl_yylval.opval->op_targ = allocmy(PL_tokenbuf);
             return PRIVATEREF;
         }
     }
@@ -6969,7 +7073,7 @@ S_pending_ident(pTHX)
        (although why you'd do that is anyone's guess).
     */
 
-    if (!strchr(PL_tokenbuf,':')) {
+    if (!has_colon) {
        if (!PL_in_my)
            tmp = pad_findmy(PL_tokenbuf);
         if (tmp != NOT_IN_PAD) {
@@ -6980,9 +7084,9 @@ S_pending_ident(pTHX)
                HEK * const stashname = HvNAME_HEK(stash);
                SV *  const sym = newSVhek(stashname);
                 sv_catpvs(sym, "::");
-                sv_catpv(sym, PL_tokenbuf+1);
-                yylval.opval = (OP*)newSVOP(OP_CONST, 0, sym);
-                yylval.opval->op_private = OPpCONST_ENTERED;
+                sv_catpvn(sym, PL_tokenbuf+1, tokenbuf_len - 1);
+                pl_yylval.opval = (OP*)newSVOP(OP_CONST, 0, sym);
+                pl_yylval.opval->op_private = OPpCONST_ENTERED;
                 gv_fetchsv(sym,
                     (PL_in_eval
                         ? (GV_ADDMULTI | GV_ADDINEVAL)
@@ -7011,8 +7115,8 @@ S_pending_ident(pTHX)
                 }
             }
 
-            yylval.opval = newOP(OP_PADANY, 0);
-            yylval.opval->op_targ = tmp;
+            pl_yylval.opval = newOP(OP_PADANY, 0);
+            pl_yylval.opval->op_targ = tmp;
             return PRIVATEREF;
         }
     }
@@ -7023,7 +7127,8 @@ S_pending_ident(pTHX)
        table.
     */
     if (pit == '@' && PL_lex_state != LEX_NORMAL && !PL_lex_brackets) {
-        GV *gv = gv_fetchpv(PL_tokenbuf+1, 0, SVt_PVAV);
+        GV *const gv = gv_fetchpvn_flags(PL_tokenbuf + 1, tokenbuf_len - 1, 0,
+                                        SVt_PVAV);
         if ((!gv || ((PL_tokenbuf[0] == '@') ? !GvAV(gv) : !GvHV(gv)))
                && ckWARN(WARN_AMBIGUOUS)
                /* DO NOT warn for @- and @+ */
@@ -7039,10 +7144,11 @@ S_pending_ident(pTHX)
     }
 
     /* build ops for a bareword */
-    yylval.opval = (OP*)newSVOP(OP_CONST, 0, newSVpv(PL_tokenbuf+1, 0));
-    yylval.opval->op_private = OPpCONST_ENTERED;
-    gv_fetchpv(
-           PL_tokenbuf+1,
+    pl_yylval.opval = (OP*)newSVOP(OP_CONST, 0, newSVpvn(PL_tokenbuf + 1,
+                                                     tokenbuf_len - 1));
+    pl_yylval.opval->op_private = OPpCONST_ENTERED;
+    gv_fetchpvn_flags(
+           PL_tokenbuf + 1, tokenbuf_len - 1,
            /* If the identifier refers to a stash, don't autovivify it.
             * Change 24660 had the side effect of causing symbol table
             * hashes to always be defined, even if they were freshly
@@ -7055,7 +7161,9 @@ S_pending_ident(pTHX)
             * tests still give the expected answers, even though what
             * they're actually testing has now changed subtly.
             */
-           (*PL_tokenbuf == '%' && *(d = PL_tokenbuf + strlen(PL_tokenbuf) - 1) == ':' && d[-1] == ':'
+           (*PL_tokenbuf == '%'
+            && *(d = PL_tokenbuf + tokenbuf_len - 1) == ':'
+            && d[-1] == ':'
             ? 0
             : PL_in_eval ? (GV_ADDMULTI | GV_ADDINEVAL) : GV_ADD),
            ((PL_tokenbuf[0] == '$') ? SVt_PV
@@ -7072,6 +7180,9 @@ I32
 Perl_keyword (pTHX_ const char *name, I32 len, bool all_keywords)
 {
     dVAR;
+
+    PERL_ARGS_ASSERT_KEYWORD;
+
   switch (len)
   {
     case 1: /* 5 tokens of length 1 */
@@ -7338,14 +7449,6 @@ Perl_keyword (pTHX_ const char *name, I32 len, bool all_keywords)
 
               goto unknown;
 
-            case 'r':
-              if (name[2] == 'r')
-              {                                   /* err        */
-                return (all_keywords || FEATURE_IS_ENABLED("err") ? -KEY_err : 0);
-              }
-
-              goto unknown;
-
             case 'x':
               if (name[2] == 'p')
               {                                   /* exp        */
@@ -10468,6 +10571,8 @@ S_checkcomma(pTHX_ const char *s, const char *name, const char *what)
 {
     dVAR;
 
+    PERL_ARGS_ASSERT_CHECKCOMMA;
+
     if (*s == ' ' && s[1] == '(') {    /* XXX gotta be a better way */
        if (ckWARN(WARN_SYNTAX)) {
            int level = 1;
@@ -10520,8 +10625,8 @@ S_checkcomma(pTHX_ const char *s, const char *name, const char *what)
    and type is used with error messages only. */
 
 STATIC SV *
-S_new_constant(pTHX_ const char *s, STRLEN len, const char *key, SV *sv, SV *pv,
-              const char *type)
+S_new_constant(pTHX_ const char *s, STRLEN len, const char *key, STRLEN keylen,
+              SV *sv, SV *pv, const char *type, STRLEN typelen)
 {
     dVAR; dSP;
     HV * const table = GvHV(PL_hintgv);                 /* ^H */
@@ -10530,6 +10635,8 @@ S_new_constant(pTHX_ const char *s, STRLEN len, const char *key, SV *sv, SV *pv,
     SV *cv, *typesv;
     const char *why1 = "", *why2 = "", *why3 = "";
 
+    PERL_ARGS_ASSERT_NEW_CONSTANT;
+
     if (!table || !(PL_hints & HINT_LOCALIZE_HH)) {
        SV *msg;
        
@@ -10555,7 +10662,7 @@ S_new_constant(pTHX_ const char *s, STRLEN len, const char *key, SV *sv, SV *pv,
        SvREFCNT_dec(msg);
        return sv;
     }
-    cvp = hv_fetch(table, key, strlen(key), FALSE);
+    cvp = hv_fetch(table, key, keylen, FALSE);
     if (!cvp || !SvOK(*cvp)) {
        why1 = "$^H{";
        why2 = key;
@@ -10565,9 +10672,9 @@ S_new_constant(pTHX_ const char *s, STRLEN len, const char *key, SV *sv, SV *pv,
     sv_2mortal(sv);                    /* Parent created it permanently */
     cv = *cvp;
     if (!pv && s)
-       pv = sv_2mortal(newSVpvn(s, len));
+       pv = newSVpvn_flags(s, len, SVs_TEMP);
     if (type && pv)
-       typesv = sv_2mortal(newSVpv(type, 0));
+       typesv = newSVpvn_flags(type, typelen, SVs_TEMP);
     else
        typesv = &PL_sv_undef;
 
@@ -10624,6 +10731,9 @@ S_scan_word(pTHX_ register char *s, char *dest, STRLEN destlen, int allow_packag
     dVAR;
     register char *d = dest;
     register char * const e = d + destlen - 3;  /* two-character token, ending NUL */
+
+    PERL_ARGS_ASSERT_SCAN_WORD;
+
     for (;;) {
        if (d >= e)
            Perl_croak(aTHX_ ident_too_long);
@@ -10667,6 +10777,8 @@ S_scan_ident(pTHX_ register char *s, register const char *send, char *dest, STRL
     register char *d = dest;
     register char * const e = d + destlen + 3;    /* two-character token, ending NUL */
 
+    PERL_ARGS_ASSERT_SCAN_IDENT;
+
     if (isSPACE(*s))
        s = PEEKSPACE(s);
     if (isDIGIT(*s)) {
@@ -10821,9 +10933,11 @@ S_scan_ident(pTHX_ register char *s, register const char *send, char *dest, STRL
 void
 Perl_pmflag(pTHX_ U32* pmfl, int ch)
 {
+    PERL_ARGS_ASSERT_PMFLAG;
+
     PERL_UNUSED_CONTEXT;
     if (ch<256) {
-        char c = (char)ch;
+        const char c = (char)ch;
         switch (c) {
             CASE_STD_PMMOD_FLAGS_PARSE_SET(pmfl);
             case GLOBAL_PAT_MOD:    *pmfl |= PMf_GLOBAL; break;
@@ -10846,6 +10960,7 @@ S_scan_pat(pTHX_ char *start, I32 type)
     char *modstart;
 #endif
 
+    PERL_ARGS_ASSERT_SCAN_PAT;
 
     if (!s) {
        const char * const delimiter = skipspace(start);
@@ -10899,7 +11014,7 @@ S_scan_pat(pTHX_ char *start, I32 type)
     }
 
     PL_lex_op = (OP*)pm;
-    yylval.ival = OP_MATCH;
+    pl_yylval.ival = OP_MATCH;
     return s;
 }
 
@@ -10915,7 +11030,9 @@ S_scan_subst(pTHX_ char *start)
     char *modstart;
 #endif
 
-    yylval.ival = OP_NULL;
+    PERL_ARGS_ASSERT_SCAN_SUBST;
+
+    pl_yylval.ival = OP_NULL;
 
     s = scan_str(start,!!PL_madskills,FALSE);
 
@@ -10986,8 +11103,12 @@ S_scan_subst(pTHX_ char *start)
        PL_sublex_info.super_bufend = PL_bufend;
        PL_multi_end = 0;
        pm->op_pmflags |= PMf_EVAL;
-       while (es-- > 0)
-           sv_catpv(repl, (const char *)(es ? "eval " : "do "));
+       while (es-- > 0) {
+           if (es)
+               sv_catpvs(repl, "eval ");
+           else
+               sv_catpvs(repl, "do ");
+       }
        sv_catpvs(repl, "{");
        sv_catsv(repl, PL_lex_repl);
        if (strchr(SvPVX(PL_lex_repl), '#'))
@@ -10999,7 +11120,7 @@ S_scan_subst(pTHX_ char *start)
     }
 
     PL_lex_op = (OP*)pm;
-    yylval.ival = OP_SUBST;
+    pl_yylval.ival = OP_SUBST;
     return s;
 }
 
@@ -11010,14 +11131,16 @@ S_scan_trans(pTHX_ char *start)
     register char* s;
     OP *o;
     short *tbl;
-    I32 squash;
-    I32 del;
-    I32 complement;
+    U8 squash;
+    U8 del;
+    U8 complement;
 #ifdef PERL_MAD
     char *modstart;
 #endif
 
-    yylval.ival = OP_NULL;
+    PERL_ARGS_ASSERT_SCAN_TRANS;
+
+    pl_yylval.ival = OP_NULL;
 
     s = scan_str(start,!!PL_madskills,FALSE);
     if (!s)
@@ -11079,7 +11202,7 @@ S_scan_trans(pTHX_ char *start)
       (DO_UTF8(PL_lex_repl) ? OPpTRANS_TO_UTF   : 0);
 
     PL_lex_op = o;
-    yylval.ival = OP_TRANS;
+    pl_yylval.ival = OP_TRANS;
 
 #ifdef PERL_MAD
     if (PL_madskills) {
@@ -11114,6 +11237,8 @@ S_scan_heredoc(pTHX_ register char *s)
     PL_realtokenstart = -1;
 #endif
 
+    PERL_ARGS_ASSERT_SCAN_HEREDOC;
+
     s += 2;
     d = PL_tokenbuf;
     e = PL_tokenbuf + sizeof PL_tokenbuf - 1;
@@ -11350,14 +11475,14 @@ retval:
            sv_recode_to_utf8(tmpstr, PL_encoding);
     }
     PL_lex_stuff = tmpstr;
-    yylval.ival = op_type;
+    pl_yylval.ival = op_type;
     return s;
 }
 
 /* scan_inputsymbol
    takes: current position in input buffer
    returns: new position in input buffer
-   side-effects: yylval and lex_op are set.
+   side-effects: pl_yylval and lex_op are set.
 
    This code handles:
 
@@ -11377,10 +11502,11 @@ S_scan_inputsymbol(pTHX_ char *start)
     register char *s = start;          /* current position in buffer */
     char *end;
     I32 len;
-
     char *d = PL_tokenbuf;                                     /* start of temp holding space */
     const char * const e = PL_tokenbuf + sizeof PL_tokenbuf;   /* end of temp holding space */
 
+    PERL_ARGS_ASSERT_SCAN_INPUTSYMBOL;
+
     end = strchr(s, '\n');
     if (!end)
        end = PL_bufend;
@@ -11417,8 +11543,7 @@ S_scan_inputsymbol(pTHX_ char *start)
     */
 
     if (d - PL_tokenbuf != len) {
-       yylval.ival = OP_GLOB;
-       set_csh();
+       pl_yylval.ival = OP_GLOB;
        s = scan_str(start,!!PL_madskills,FALSE);
        if (!s)
           Perl_croak(aTHX_ "Glob not terminated");
@@ -11493,8 +11618,8 @@ intro_sym:
            }
            if (!readline_overriden)
                PL_lex_op->op_flags |= OPf_SPECIAL;
-           /* we created the ops in PL_lex_op, so make yylval.ival a null op */
-           yylval.ival = OP_NULL;
+           /* we created the ops in PL_lex_op, so make pl_yylval.ival a null op */
+           pl_yylval.ival = OP_NULL;
        }
 
        /* If it's none of the above, it must be a literal filehandle
@@ -11507,7 +11632,7 @@ intro_sym:
                            newGVOP(OP_GV, 0, gv),
                            newCVREF(0, newGVOP(OP_GV, 0, gv_readline))))
                : (OP*)newUNOP(OP_READLINE, 0, newGVOP(OP_GV, 0, gv));
-           yylval.ival = OP_NULL;
+           pl_yylval.ival = OP_NULL;
        }
     }
 
@@ -11578,6 +11703,8 @@ S_scan_str(pTHX_ char *start, int keep_quoted, int keep_delims)
     char *tstart;
 #endif
 
+    PERL_ARGS_ASSERT_SCAN_STR;
+
     /* skip space before the delimiter */
     if (isSPACE(*s)) {
        s = PEEKSPACE(s);
@@ -11887,7 +12014,7 @@ S_scan_str(pTHX_ char *start, int keep_quoted, int keep_delims)
   scan_num
   takes: pointer to position in buffer
   returns: pointer to new position in buffer
-  side-effects: builds ops for the constant in yylval.op
+  side-effects: builds ops for the constant in pl_yylval.op
 
   Read a number in any of the formats that Perl accepts:
 
@@ -11918,6 +12045,8 @@ Perl_scan_num(pTHX_ const char *start, YYSTYPE* lvalp)
     const char *lastub = NULL;         /* position of last underbar */
     static char const number_too_long[] = "Number too long";
 
+    PERL_ARGS_ASSERT_SCAN_NUM;
+
     /* We use the first character to decide what type of number this is */
 
     switch (*s) {
@@ -12097,9 +12226,9 @@ Perl_scan_num(pTHX_ const char *start, YYSTYPE* lvalp)
            }
            if (just_zero && (PL_hints & HINT_NEW_INTEGER))
                sv = new_constant(start, s - start, "integer",
-                                 sv, NULL, NULL);
+                                 sv, NULL, NULL, 0);
            else if (PL_hints & HINT_NEW_BINARY)
-               sv = new_constant(start, s - start, "binary", sv, NULL, NULL);
+               sv = new_constant(start, s - start, "binary", sv, NULL, NULL, 0);
        }
        break;
 
@@ -12262,13 +12391,13 @@ Perl_scan_num(pTHX_ const char *start, YYSTYPE* lvalp)
            sv_setnv(sv, nv);
        }
 
-       if ( floatit ? (PL_hints & HINT_NEW_FLOAT) :
-                      (PL_hints & HINT_NEW_INTEGER) )
-           sv = new_constant(PL_tokenbuf,
-                             d - PL_tokenbuf,
-                             (const char *)
-                             (floatit ? "float" : "integer"),
-                             sv, NULL, NULL);
+       if ( floatit
+            ? (PL_hints & HINT_NEW_FLOAT) : (PL_hints & HINT_NEW_INTEGER) ) {
+           const char *const key = floatit ? "float" : "integer";
+           const STRLEN keylen = floatit ? 5 : 7;
+           sv = S_new_constant(aTHX_ PL_tokenbuf, d - PL_tokenbuf,
+                               key, keylen, sv, NULL, NULL, 0);
+       }
        break;
 
     /* if it starts with a v, it could be a v-string */
@@ -12300,14 +12429,16 @@ S_scan_formline(pTHX_ register char *s)
     bool eofmt = FALSE;
 #ifdef PERL_MAD
     char *tokenstart = s;
-    SV* savewhite;
-    
+    SV* savewhite = NULL;
+
     if (PL_madskills) {
        savewhite = PL_thiswhite;
        PL_thiswhite = 0;
     }
 #endif
 
+    PERL_ARGS_ASSERT_SCAN_FORMLINE;
+
     while (!needargs) {
        if (*s == '.') {
            t = s+1;
@@ -12420,20 +12551,6 @@ S_scan_formline(pTHX_ register char *s)
     return s;
 }
 
-STATIC void
-S_set_csh(pTHX)
-{
-#ifdef CSH
-    dVAR;
-    if (!PL_cshlen)
-       PL_cshlen = strlen(PL_cshname);
-#else
-#if defined(USE_ITHREADS)
-    PERL_UNUSED_CONTEXT;
-#endif
-#endif
-}
-
 I32
 Perl_start_subparse(pTHX_ I32 is_format, U32 flags)
 {
@@ -12448,12 +12565,12 @@ Perl_start_subparse(pTHX_ I32 is_format, U32 flags)
     save_item(PL_subname);
     SAVESPTR(PL_compcv);
 
-    PL_compcv = (CV*)newSV_type(is_format ? SVt_PVFM : SVt_PVCV);
+    PL_compcv = MUTABLE_CV(newSV_type(is_format ? SVt_PVFM : SVt_PVCV));
     CvFLAGS(PL_compcv) |= flags;
 
     PL_subline = CopLINE(PL_curcop);
     CvPADLIST(PL_compcv) = pad_new(padnew_SAVE|padnew_SAVESUB);
-    CvOUTSIDE(PL_compcv) = (CV*)SvREFCNT_inc_simple(outsidecv);
+    CvOUTSIDE(PL_compcv) = MUTABLE_CV(SvREFCNT_inc_simple(outsidecv));
     CvOUTSIDE_SEQ(PL_compcv) = PL_cop_seqmax;
 
     return oldsavestack_ix;
@@ -12463,9 +12580,12 @@ Perl_start_subparse(pTHX_ I32 is_format, U32 flags)
 #pragma segment Perl_yylex
 #endif
 int
-Perl_yywarn(pTHX_ const char *s)
+Perl_yywarn(pTHX_ const char *const s)
 {
     dVAR;
+
+    PERL_ARGS_ASSERT_YYWARN;
+
     PL_in_eval |= EVAL_WARNONLY;
     yyerror(s);
     PL_in_eval &= ~EVAL_WARNONLY;
@@ -12473,7 +12593,7 @@ Perl_yywarn(pTHX_ const char *s)
 }
 
 int
-Perl_yyerror(pTHX_ const char *s)
+Perl_yyerror(pTHX_ const char *const s)
 {
     dVAR;
     const char *where = NULL;
@@ -12482,6 +12602,8 @@ Perl_yyerror(pTHX_ const char *s)
     SV *msg;
     int yychar  = PL_parser->yychar;
 
+    PERL_ARGS_ASSERT_YYERROR;
+
     if (!yychar || (yychar == ';' && !PL_rsfp))
        where = "at EOF";
     else if (PL_oldoldbufptr && PL_bufptr > PL_oldoldbufptr &&
@@ -12529,11 +12651,13 @@ Perl_yyerror(pTHX_ const char *s)
            where = "within string";
     }
     else {
-       SV * const where_sv = sv_2mortal(newSVpvs("next char "));
+       SV * const where_sv = newSVpvs_flags("next char ", SVs_TEMP);
        if (yychar < 32)
            Perl_sv_catpvf(aTHX_ where_sv, "^%c", toCTRL(yychar));
-       else if (isPRINT_LC(yychar))
-           Perl_sv_catpvf(aTHX_ where_sv, "%c", 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);
        where = SvPVX_const(where_sv);
@@ -12551,8 +12675,10 @@ Perl_yyerror(pTHX_ const char *s)
                 (int)PL_multi_open,(int)PL_multi_close,(IV)PL_multi_start);
         PL_multi_end = 0;
     }
-    if (PL_in_eval & EVAL_WARNONLY && ckWARN_d(WARN_SYNTAX))
-       Perl_warner(aTHX_ packWARN(WARN_SYNTAX), "%"SVf, SVfARG(msg));
+    if (PL_in_eval & EVAL_WARNONLY) {
+       if (ckWARN_d(WARN_SYNTAX))
+           Perl_warner(aTHX_ packWARN(WARN_SYNTAX), "%"SVf, SVfARG(msg));
+    }
     else
        qerror(msg);
     if (PL_error_count >= 10) {
@@ -12576,6 +12702,9 @@ S_swallow_bom(pTHX_ U8 *s)
 {
     dVAR;
     const STRLEN slen = SvCUR(PL_linestr);
+
+    PERL_ARGS_ASSERT_SWALLOW_BOM;
+
     switch (s[0]) {
     case 0xFF:
        if (s[1] == 0xFE) {
@@ -12749,11 +12878,14 @@ passed in, for performance reasons.
 */
 
 char *
-Perl_scan_vstring(pTHX_ const char *s, const char *e, SV *sv)
+Perl_scan_vstring(pTHX_ const char *s, const char *const e, SV *sv)
 {
     dVAR;
     const char *pos = s;
     const char *start = s;
+
+    PERL_ARGS_ASSERT_SCAN_VSTRING;
+
     if (*pos == 'v') pos++;  /* get past 'v' */
     while (pos < e && (isDIGIT(*pos) || *pos == '_'))
        pos++;