# define isUPPER_A(c) cBOOL(FITS_IN_8_BITS(c) && (PL_charclass[(U8) NATIVE_TO_UNI(c)] & _CC_UPPER_A))
# define isWORDCHAR_A(c) cBOOL(FITS_IN_8_BITS(c) && (PL_charclass[(U8) NATIVE_TO_UNI(c)] & _CC_WORDCHAR_A))
# define isXDIGIT_A(c) cBOOL(FITS_IN_8_BITS(c) && (PL_charclass[(U8) NATIVE_TO_UNI(c)] & _CC_XDIGIT_A))
+ /* Either participates in a fold with a character above 255, or is a
+ * multi-char fold */
# define _HAS_NONLATIN1_FOLD_CLOSURE_ONLY_FOR_USE_BY_REGCOMP_DOT_C_AND_REGEXEC_DOT_C(c) ((! cBOOL(FITS_IN_8_BITS(c))) || (PL_charclass[(U8) NATIVE_TO_UNI(c)] & _CC_NONLATIN1_FOLD))
#else /* No perl.h. */
# define isOCTAL_A(c) ((c) >= '0' && (c) <= '9')
#define isBLANK_LC_uni(c) isBLANK(c) /* could be wrong */
#define isALNUM_utf8(p) is_utf8_alnum(p)
-/* The ID_Start of Unicode was originally quite limiting: it assumed an
- * L-class character (meaning that you could not have, say, a CJK charac-
- * ter). So, instead, perl has for a long time allowed ID_Continue but
- * not digits.
- * We still preserve that for backward compatibility. But we also make sure
- * that it is alphanumeric, so S_scan_word in toke.c will not hang. See
- * http://rt.perl.org/rt3/Ticket/Display.html?id=74022
- * for more detail than you ever wanted to know about. */
-#define isIDFIRST_utf8(p) \
- (is_utf8_idcont(p) && !is_utf8_digit(p) && is_utf8_alnum(p))
+/* To prevent S_scan_word in toke.c from hanging, we have to make sure that
+ * IDFIRST is an alnum. See
+ * http://rt.perl.org/rt3/Ticket/Display.html?id=74022
+ * for more detail than you ever wanted to know about. This used to be not the
+ * XID version, but we decided to go with the more modern Unicode definition */
+#define isIDFIRST_utf8(p) (is_utf8_xidfirst(p) && is_utf8_alnum(p))
+#define isIDCONT_utf8(p) is_utf8_xidcont(p)
#define isALPHA_utf8(p) is_utf8_alpha(p)
#define isSPACE_utf8(p) is_utf8_space(p)
#define isDIGIT_utf8(p) is_utf8_digit(p)