bug(binder): wrong type inference for struct with multiple fields in CASE expression

[kwannoel]

Describe the bug

Single field struct

dev=> select CASE WHEN false THEN ROW(1.1) ELSE ROW(0) END;
 case
------
 (0)
(1 row)

dev=> EXPLAIN select CASE WHEN false THEN ROW(1.1) ELSE ROW(0) END;
                                       QUERY PLAN
----------------------------------------------------------------------------------------
 BatchProject { exprs: [Case(false:Boolean, Row(1.1:Decimal), Row(0:Int32::Decimal))] }
 └─BatchValues { rows: [[]] }
(2 rows)

Multiple field

dev=> select CASE WHEN false THEN ROW(1.1, INTERVAL '1') ELSE ROW(0, INTERVAL '1') END;
ERROR:  QueryError: Bind error: types Struct(StructType { fields: [Decimal, Interval], field_names: [] }) and Struct(StructType { fields: [Int32, Interval], field_names: [] }) cannot be matched
dev=>

To Reproduce

select CASE WHEN false THEN ROW(1.1, INTERVAL '1') ELSE ROW(0, INTERVAL '1') END;

Expected behavior

postgres=# select CASE WHEN false THEN ROW(1.1, INTERVAL '1') ELSE ROW(0, INTERVAL '1') END;
     row
--------------
 (0,00:00:01)
(1 row)

Additional context

No response

[xiangjinwu]

It is due to the fact that we do not allow casting between the same type, so the 2nd field fails to match interval to interval 😂

risingwave/src/frontend/src/expr/type_inference/cast.rs

Line 157 in c479c29

.all(|(src, dst)| cast_ok(src, dst, allows))

Maybe changing this to src == dst || cast_ok(src, dst, allows) would help.

[kwannoel]

Hmm... Seems like the following case is still not fixed.

select CASE WHEN true THEN ROW(1::int, interval '1') ELSE ROW(1.1::decimal, interval '1') END;
ERROR:  QueryError: Bind error: types Struct(StructType { fields: [Int32, Interval], field_names: [] }) and Struct(StructType { fields: [Decimal, Interval], field_names: [] }) cannot be matched

pg

postgres=# select CASE WHEN true THEN ROW(1::int, interval '1') ELSE ROW(1.1::decimal, interval '1') END;
     row
--------------
 (1,00:00:01)
(1 row)

Reopen to track.

Ignore this, it works as expected I was testing on the old branch 😶‍🌫️