+ else if ( (codepoint & 0x1FF800 ) == 0xD800 ) /* surrogate */
+ /* A UTF-16 surrogate (which should be one of a pair that
+ encode a Unicode codepoint that is outside the Basic
+ Multilingual Plane). Error, not UTF8.
+ RFC2279.2 is slightly unclear on this, but
+ https://unicodebook.readthedocs.io/issues.html#strict-utf8-decoder
+ says "Surrogates characters are also invalid in UTF-8:
+ characters in U+D800—U+DFFF have to be rejected." */
+ complete = -1;