Error when executing insert select where table has generated column

[winoros]

Please answer these questions before submitting your issue. Thanks!

1. What did you do?
   If possible, provide a recipe for reproducing the error.

create table t(a int, b int as (a+1), c int);
insert into t (a) select a from t;
insert into t (a, c) select a, c from t;

2. What did you expect to see?

No error.

3. What did you see instead?

Error returned.

4. What version of TiDB are you using (tidb-server -V or run select tidb_version(); on TiDB)?

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