+/*
+ * Handle the non-inline part of the U8_NEXT() macro and its obsolete sibling
+ * UTF8_NEXT_CHAR_SAFE().
+ *
+ * The "strict" parameter controls the error behavior:
+ * <0 "Safe" behavior of U8_NEXT(): All illegal byte sequences yield a negative
+ * code point result.
+ * 0 Obsolete "safe" behavior of UTF8_NEXT_CHAR_SAFE(..., FALSE):
+ * All illegal byte sequences yield a positive code point such that this
+ * result code point would be encoded with the same number of bytes as
+ * the illegal sequence.
+ * >0 Obsolete "strict" behavior of UTF8_NEXT_CHAR_SAFE(..., TRUE):
+ * Same as the obsolete "safe" behavior, but non-characters are also treated
+ * like illegal sequences.
+ *
+ * The special negative (<0) value -2 is used for lenient treatment of surrogate
+ * code points as legal. Some implementations use this for roundtripping of
+ * Unicode 16-bit strings that are not well-formed UTF-16, that is, they
+ * contain unpaired surrogates.
+ *
+ * Note that a UBool is the same as an int8_t.
+ */