I've identified the cause of bug #4253:
/* Trim trailing space */ while (*pbuf && !t_isspace(pbuf)) pbuf++; *pbuf
='\0';
At least on Macs, t_isspace is capable of returning "true" when pointed
at the second byte of a 2-byte UTF8 character. This explains the report
that the letter "�" has a problem when some other ones don't. Of
course pbuf needs to be incremented using pg_mblen not just ++.
I looked around for other occurrences of the same problem and found
a couple. I also found occurrences of the same pattern for skipping
whitespace:
while (*s && t_isspace(s)) s++;
This is safe if and only if t_isspace is never true for multibyte
characters ... can anyone think of a counterexample?
regards, tom lane