toke.c: S_is_existing_identifier: Generalize a bit

This commit adds a parameter to this function to allow it to work with a
different sigil than is in the string.  This allows it to see if there
is an identifier with the same name but a different type.  The next
commit will use this generality.

Author: khwilliamson

embed.fnc

@@ -6086,6 +6086,7 @@ S	|int	|intuit_more	|NN char *s				\
 S	|Size_t |is_existing_identifier 				\
 				|NN char *s				\
 				|NN char *e				\
+				|char sigil				\
 				|bool is_utf8
 S	|I32	|lop		|enum yytokentype t			\
 				|I32 f					\

embed.h

@@ -1685,7 +1685,7 @@
 #     define incline(a,b)                       S_incline(aTHX_ a,b)
 #     define intuit_method(a,b,c)               S_intuit_method(aTHX_ a,b,c)
 #     define intuit_more(a,b)                   S_intuit_more(aTHX_ a,b)
-#     define is_existing_identifier(a,b,c)      S_is_existing_identifier(aTHX_ a,b,c)
+#     define is_existing_identifier(a,b,c,d)    S_is_existing_identifier(aTHX_ a,b,c,d)
 #     define lop(a,b,c,d)                       S_lop(aTHX_ a,b,c,d)
 #     define missingterm(a,b)                   S_missingterm(aTHX_ a,b)
 #     define parse_ident(a,b,c,d,e,f)           S_parse_ident(aTHX_ a,b,c,d,e,f)

proto.h

@@ -4468,11 +4468,14 @@ S_scan_const(pTHX_ char *start)
 }
 
 STATIC Size_t
-S_is_existing_identifier(pTHX_ char *s, char *e, bool is_utf8)
+S_is_existing_identifier(pTHX_ char *s, char *e, char sigil, bool is_utf8)
 {
     /* This checks if the string from 's' to (e - 1) with utf8ness 'is_utf8' is
-     * an identifier known to the program.  If so, it returns the length of
-     * the identifier.  If not, it returns 0 */
+     * an identifier known to the program of the type given by 'sigil'.  So for
+     * sigil '$', it checks for a scalar, etc.  If so, it returns the length of
+     * the identifier.  If not, it returns 0
+     *
+     * It overwrites s[0], restoring it before returning */
 
     ptrdiff_t size = e - s;
 
@@ -4493,26 +4496,30 @@ S_is_existing_identifier(pTHX_ char *s, char *e, bool is_utf8)
     char * tmpbuf;
     Newx(tmpbuf, size, char);
 
+    const char save_sigil = s[0];
+    s[0] = sigil;
+
     /* scan_ident doesn't return the sigil, but pad_findmy_pv wants it */
     scan_ident(s, tmpbuf + 1, size - 1, FALSE);
-    tmpbuf[0] = s[0];
+    tmpbuf[0] = sigil;
 
     Size_t len = strlen(tmpbuf) - 1;    /* Doesn't include sigil */
 
     PADOFFSET slot = pad_findmy_pv(tmpbuf, 0);
     if (   slot == NOT_IN_PAD
         && ! gv_fetchpvn_flags(tmpbuf + 1, len,
                                (is_utf8) ? SVf_UTF8 : 0,
-                               (s[0] == '@')
+                               (sigil == '@')
                                 ? SVt_PVAV
-                                : (s[0] == '&')
+                                : (sigil == '&')
                                   ? SVt_PVCV
                                   : SVt_PV))
     {
         len = 0;
     }
 
     Safefree(tmpbuf);
+    s[0] = save_sigil;
 
     return len;
 }
@@ -4695,7 +4702,7 @@ S_intuit_more(pTHX_ char *s, char *e)
              * identifier already found in the program by that name and type.
              * If so, strongly suspect this isn't a character class */
             if (isWORDCHAR_lazy_if_safe(s+1, PL_bufend, UTF)) {
-                Size_t len = is_existing_identifier(s, PL_bufend, UTF);
+                Size_t len = is_existing_identifier(s, PL_bufend, s[0], UTF);
 
                 /* We only mark this as strongly suspect subscript if the
                  * identifier is multi-char; otherwise mildly suspect (even if