Problem of select count after group

[myyrakle]

The DB used is postgres, and the cargo.toml setting is
diesel = {version= "1", features = ["postgres"] }

The table schema used for testing is as follows:
table! { test (id) { id -> Int8, text -> Nullable<Text>, dead_yn -> Bool, } }

And I tried to count after group by as follows.

    use crate::schema::test;
    use diesel::dsl::count;

    // select sum(id) from test
    let query = test::dsl::test
        .group_by(test::dsl::dead_yn)
        .select((test::dsl::dead_yn, count(test::dsl::id)));
    println!(
        "query {:?}",
        diesel::debug_query::<diesel::pg::Pg, _>(&query)
    );

    let result = query.get_results::<(bool, i64)>(connection).unwrap();
    println!("value {:?}", result);

A compilation error occurs.

error[E0277]: the trait bound diesel::expression::count::count::count<diesel::sql_types::BigInt, schema::test::columns::id>: diesel::Expressionis not satisfied --> src\main.rs:63:17 | 63 | .select(&(test::dsl::dead_yn, count(test::dsl::id))); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the traitNonAggregateis not implemented fordiesel::expression::count::count::count<diesel::sql_types::BigInt, schema::test::columns::id>| = note: required because of the requirements on the impl ofdiesel::Expressionfor(schema::test::columns::dead_yn, diesel::expression::count::count::count<diesel::sql_types::BigInt, schema::test::columns::id>)= note: required because of the requirements on the impl ofdiesel::Expressionfor&(schema::test::columns::dead_yn, diesel::expression::count::count::count<diesel::sql_types::BigInt, schema::test::columns::id>)`

error[E0277]: the trait bound diesel::expression::count::count::count<diesel::sql_types::BigInt, schema::test::columns::id>: NonAggregate is not satisfied
--> src\main.rs:69:24
|
69 | let result = query.get_results::<(bool, i64)>(connection).unwrap();
| ^^^^^^^^^^^ the trait NonAggregate is not implemented for diesel::expression::count::count::count<diesel::sql_types::BigInt, schema::test::columns::id>
|
= note: required because of the requirements on the impl of diesel::Expression for (schema::test::columns::dead_yn, diesel::expression::count::count::count<diesel::sql_types::BigInt, schema::test::columns::id>)
= note: required because of the requirements on the impl of LoadQuery<_, (bool, i64)> for diesel::query_builder::SelectStatement<schema::test::table, query_builder::select_clause::SelectClause<&(schema::test::columns::dead_yn, diesel::expression::count::count::count<diesel::sql_types::BigInt, schema::test::columns::id>)>, query_builder::distinct_clause::NoDistinctClause, query_builder::where_clause::NoWhereClause, query_builder::order_clause::NoOrderClause, query_builder::limit_clause::NoLimitClause, query_builder::offset_clause::NoOffsetClause, query_builder::group_by_clause::GroupByClause<schema::test::columns::dead_yn>>

error: aborting due to 2 previous errors; 2 warnings emitted

For more information about this error, try rustc --explain E0277.
error: could not compile rustywiki

To learn more, run the command again with --verbose.

What am I doing wrong?
Please help.

[weiznich]

.group_by is not part of the public API of any release yet. As consequence we do not support select clauses with mixed aggregate expressions yet. That all means that it is not possible to write such queries using the built-in DSL yet.

Our next feature release will add support for this offically.

[myyrakle]

Thanks for the kind answer.
We are looking forward to the next version.