ALTER TABLE results in an assertion failure "Assertion `expr.return_type == vector.type' failed"

[mrigger]

Consider the following statements:

CREATE TABLE t0(c0 INT, c1 VARCHAR);
INSERT INTO t0(c1) VALUES(NULL);
ALTER TABLE t0 ALTER c1 TYPE TIMESTAMP;

Unexpectedly, the ALTER TABLE results in an assertion failure:

/duckdb/src/execution/expression_executor.cpp:87: void duckdb::ExpressionExecutor::Verify(duckdb::Expression&, duckdb::Vector&, duckdb::idx_t): Assertion `expr.return_type == vector.type' failed.

I found this based on commit 289b2ea.

[Mytherin]

Thanks, fixed! This was a silly mistake: the vector that was scanned got the type of the first column of the table (INTEGER) rather than the type of the actual column that was changed (VARCHAR), which resulted in a type mismatch.