last_insert_rowid() returns 1 after INSERT with RETURNING #5490
Description
Description
last_insert_rowid() is not updated when INSERT uses RETURNING. The value is clobbered by the ephemeral table's NewRowid instruction, which always assigns rowid 1. Inside RETURNING expressions last_insert_rowid() returns the correct value, but after the statement completes it reverts to the ephemeral table's rowid.
Reproducer
CREATE TABLE t1(a INTEGER PRIMARY KEY, b TEXT);
INSERT INTO t1 VALUES(10, 'a');
SELECT last_insert_rowid();
-- Turso: 10
-- SQLite: 10
-- Inside RETURNING: correct
INSERT INTO t1 VALUES(20, 'b') RETURNING last_insert_rowid();
-- Turso: 20
-- SQLite: 20
-- After RETURNING: wrong
SELECT last_insert_rowid();
-- Turso: 1
-- SQLite: 20
INSERT INTO t1 VALUES(50, 'c') RETURNING *;
SELECT last_insert_rowid();
-- Turso: 1
-- SQLite: 50Per SQLite documentation: "An INSERT that fails due to a constraint violation is not a successful INSERT and does not change the value returned by this routine." Since INSERT with RETURNING succeeds, last_insert_rowid() should reflect the real table's rowid, not the ephemeral table's.
The ephemeral table used to buffer RETURNING rows uses NewRowid which sets last_insert_rowid to 1, clobbering the real value.
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