SQLite

The following SQL causes an assertion fault in SQLite 3.19.0 and later:

<blockquote><verbatim>
CREATE TABLE t1(a INTEGER PRIMARY KEY,b UNIQUE);
CREATE INDEX x1 ON t1(-b=b);
INSERT INTO t1 VALUES(1,5),(6,2);
REPLACE INTO t1 SELECT b,0 FROM t1;
</verbatim></blockquote>

The assertion faults begin with check-in [e6e36b288fdf2].  However, further
analysis suggests that that check-in merely exposed the problem and is not
the actual cause of the problem.  The underlying problem appears to be that
the column-cache is attempting to reuse the value of a register that was
never initialized to that column in the first place.

This fault was found by OSSFuzz.