From 5228bb31728eacb790dcbefda07b07a9d2d4b8f7 Mon Sep 17 00:00:00 2001
From: jiangzhx <jiangzhx@gmail.com>
Date: Thu, 8 Jun 2023 12:50:00 +0800
Subject: [PATCH] Make the struct function return the correct data type.

---
 datafusion/expr/src/function.rs | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/datafusion/expr/src/function.rs b/datafusion/expr/src/function.rs
index ed5df5766720..bec672ab6f6c 100644
--- a/datafusion/expr/src/function.rs
+++ b/datafusion/expr/src/function.rs
@@ -352,7 +352,14 @@ pub fn return_type(
             _ => Ok(DataType::Float64),
         },
 
-        BuiltinScalarFunction::Struct => Ok(DataType::Struct(Fields::empty())),
+        BuiltinScalarFunction::Struct => {
+            let return_fields = input_expr_types
+                .iter()
+                .enumerate()
+                .map(|(pos, dt)| Field::new(format!("c{pos}"), dt.clone(), true))
+                .collect::<Vec<Field>>();
+            Ok(DataType::Struct(Fields::from(return_fields)))
+        }
 
         BuiltinScalarFunction::Atan2 => match &input_expr_types[0] {
             DataType::Float32 => Ok(DataType::Float32),