Rename _isQUOTEMETA to isQUOTEMETA

The former is undefined behavior in C in some situations.
The rules are detailed in "Choosing legal symbol names" in perlhacktips

This commit omits the underscore and makes the macro available only to
the core and extensions.  I think I didn't know about PERL_CORE when I
created this macro, so used the leading underscore to discourage its
use from anyone who stumbled upon its existence.  The reason not to make
it public was my uncertainty about if it was the correct thing to do;
my not expecting that it would be useful outside of core; and the
extra work needed to make it a polished interface.  I think now that if
someone requested it be made public, that could safely be done.

Author: khwilliamson

ext/XS-APItest/APItest.xs

@@ -6723,7 +6723,7 @@ test_UTF8_IS_REPLACEMENT(char *s, STRLEN len)
 bool
 test_isQUOTEMETA(UV ord)
     CODE:
-        RETVAL = _isQUOTEMETA(ord);
+        RETVAL = isQUOTEMETA(ord);
     OUTPUT:
         RETVAL
 

handy.h

@@ -1691,7 +1691,9 @@ END_EXTERN_C
       (   (! cBOOL(FITS_IN_8_BITS(c)))                                      \
        || (PL_charclass[(U8) (c)] & CC_mask_(CC_NONLATIN1_FOLD_)))
 
-#   define _isQUOTEMETA(c) generic_isCC_(c, CC_QUOTEMETA_)
+#  if defined(PERL_CORE) || defined(PERL_IN_XS_APITEST)
+#    define isQUOTEMETA(c) generic_isCC_(c, CC_QUOTEMETA_)
+#  endif
 
 /* is c a control character for which we have a mnemonic? */
 #  if defined(PERL_CORE) || defined(PERL_EXT)
@@ -1822,7 +1824,9 @@ END_EXTERN_C
     /* The following are not fully accurate in the above-ASCII range.  I (khw)
      * don't think it's necessary to be so for the purposes where this gets
      * compiled */
-#   define isQUOTEMETA_(c)      (FITS_IN_8_BITS(c) && ! isWORDCHAR_L1(c))
+#   if defined(PERL_CORE) || defined(PERL_IN_XS_APITEST)
+#     define isQUOTEMETA(c)      (FITS_IN_8_BITS(c) && ! isWORDCHAR_L1(c))
+#   endif
 
     /* Many of the macros later in this file are defined in terms of these.  By
      * implementing them with a function, which converts the class number into

pp.c

@@ -5073,7 +5073,7 @@ PP(pp_quotemeta)
                 bool to_quote = FALSE;
 
                 if (UTF8_IS_INVARIANT(*s)) {
-                    if (_isQUOTEMETA(*s)) {
+                    if (isQUOTEMETA(*s)) {
                         to_quote = TRUE;
                     }
                 }
@@ -5086,7 +5086,7 @@ PP(pp_quotemeta)
                     IN_LC_RUNTIME(LC_CTYPE)
                         ||
 #endif
-                        _isQUOTEMETA(EIGHT_BIT_UTF8_TO_NATIVE(*s, *(s + 1))))
+                        isQUOTEMETA(EIGHT_BIT_UTF8_TO_NATIVE(*s, *(s + 1))))
                     {
                         to_quote = TRUE;
                     }
@@ -5108,7 +5108,7 @@ PP(pp_quotemeta)
         }
         else if (IN_UNI_8_BIT) {
             while (len--) {
-                if (_isQUOTEMETA(*s))
+                if (isQUOTEMETA(*s))
                     *d++ = '\\';
                 *d++ = *s++;
             }