Add helper function for longest UTF8 sequence

This specialized functionality is used to check the validity of Perl's
extended-length UTF-8, which has some ideosyncratic characteristics from
the shorter sequences.  This means this function doesn't have to
consider those differences.  It will be used in the next commit to avoid
some work, and to eventually enable is_utf8_char_helper() to be
simplified.

1 files changed, 6 insertions, 0 deletions

diff --git a/proto.h b/proto.h
index 7083f13135..26884b042f 100644
--- a/proto.h
+++ b/proto.h
@@ -1708,6 +1708,12 @@ PERL_STATIC_INLINE bool	Perl_is_strict_utf8_string_loclen(const U8 *s, STRLEN le
 #define PERL_ARGS_ASSERT_IS_STRICT_UTF8_STRING_LOCLEN	\
 	assert(s)
 #endif
+PERL_CALLCONV Size_t	Perl_is_utf8_FF_helper_(const U8 * const s0, const U8 * const e, const bool require_partial)
+			__attribute__warn_unused_result__
+			__attribute__pure__;
+#define PERL_ARGS_ASSERT_IS_UTF8_FF_HELPER_	\
+	assert(s0); assert(e)
+
 #ifndef NO_MATHOMS
 PERL_CALLCONV STRLEN	Perl_is_utf8_char(const U8 *s)
 			__attribute__deprecated__;