Aggregate plan schema build error if aggr exprs contain cast and column

[lewiszlw]

Describe the bug

Execute below sqls in datafusion-cli

create table t (a int);
select max(a) as a1, max(cast(a, bigint)) as a2 from t;

will get error: Schema error: Schema contains duplicate unqualified field name "max(t.a)". I tried in postgres and it won't fail.

I've found root cause. it's due to aggregate plan output schema building.

datafusion/datafusion/expr/src/logical_plan/plan.rs

Lines 3492 to 3497 in 5258352

	qualified_fields.extend(exprlist_to_fields(aggr_expr.as_slice(), &input)?);
	let schema = DFSchema::new_with_metadata(
	qualified_fields,
	input.schema().metadata().clone(),
	)?;

It will call SchemaDisplay code.

datafusion/datafusion/expr/src/expr.rs

Lines 2799 to 2802 in 5258352

	// Cast expr is not shown to be consistent with Postgres and Spark <https://github.com/apache/datafusion/pull/3222>
	Expr::Cast(Cast { expr, .. }) | Expr::TryCast(TryCast { expr, .. }) => {
	write!(f, "{}", SchemaDisplay(expr))
	}

The schema name of cast expr is same with column expr.
But the comment says Cast expr is not shown to be consistent with Postgres and Spark. So I don't know what is the right fix.

To Reproduce

No response

Expected behavior

No response

Additional context

No response

[Jefffrey]

Seems similar to #3353

I looked into #3353 a bit before, haven't gotten around to typing up my investigation/thoughts yet (hopefully soon)