Thread

Re: BUG #19341: REPLACE() fails to match final character when using nondeterministic ICU collation

Laurenz Albe <laurenz.albe@cybertec.at> — 2025-12-02T17:51:14Z

On Tue, 2025-12-02 at 12:25 -0500, Tom Lane wrote:
> Laurenz Albe <laurenz.albe@cybertec.at> writes:
> > > > for (const char *test_end = hptr; test_end <= haystack_end; test_end += pg_mblen(test_end))
> 
> > During the last iteration of the loop, "test_end" will be equal to "haystack_end",
> > and the loop increment will call "pg_mblen(test_end)".
> 
> Right, clearly unsafe (and I bet valgrind would complain about it).
> You need to rearrange the loop logic so that we won't attempt to
> increment test_end that last time through.  Perhaps a for-loop
> isn't the best way to write it.

Right.  The attached patch v3 turns it into a while loop to avoid
the problem.

Yours,
Laurenz Albe