Method subqueryExpr

compiler/semantic/expr.go:1289–1313

(astExpr ast.Expr, array bool, body ast.Seq, inType super.Type)

}

func (t *translator) subqueryExpr(astExpr ast.Expr, array bool, body ast.Seq, inType super.Type) (*sem.SubqueryExpr, super.Type) {
	// We pass inType in whether or not it's correlated since an uncorrelated
	// subquery will just ignore it.
	seq, outType := t.seq(body, inType)
	correlated := isCorrelated(seq)
	e := &sem.SubqueryExpr{
		Node:       astExpr,
		Array:      array,
		Correlated: correlated,
		Body:       seq,
	}
	// Add a nullscan only for uncorrelated queries that don't have a source.
	if !correlated && !HasSource(e.Body) {
		e.Body.Prepend(&sem.NullScan{})
	}
	if !array && t.scope.sql != nil {
		// SQL expects a record with a single column result so unravel this
		// condition with this complex cleanup...
		e.Body, outType = t.scalarSubqueryCheck(astExpr, e.Body, outType)
	}
	if array {
		outType = t.sctx.LookupTypeArray(outType)
	}
	return e, outType
}

func (t *translator) scalarSubqueryCheck(n ast.Node, seq sem.Seq, thisType super.Type) (sem.Seq, super.Type) {
	// In a SQL expression (except for RHS of EXISTS or IN, which both use array result),