fix: Transform::Day maps to Date rather than Int for consistency with reference implementation (#479)

Issue: #478

Author: sdd

crates/iceberg/src/spec/partition.rs

@@ -375,7 +375,7 @@ mod tests {
             NestedField::optional(
                 partition_spec.fields[0].field_id,
                 &partition_spec.fields[0].name,
-                Type::Primitive(crate::spec::PrimitiveType::Int)
+                Type::Primitive(crate::spec::PrimitiveType::Date)
             )
         );
         assert_eq!(

crates/iceberg/src/spec/transform.rs

@@ -199,7 +199,7 @@ impl Transform {
                     match p {
                         PrimitiveType::Timestamp
                         | PrimitiveType::Timestamptz
-                        | PrimitiveType::Date => Ok(Type::Primitive(PrimitiveType::Int)),
+                        | PrimitiveType::Date => Ok(Type::Primitive(PrimitiveType::Date)),
                         _ => Err(Error::new(
                             ErrorKind::DataInvalid,
                             format!("{input_type} is not a valid input type of {self} transform",),

crates/iceberg/src/transform/temporal.rs

@@ -328,7 +328,7 @@ mod test {
             ],
             trans_types: vec![
                 (Primitive(Binary), None),
-                (Primitive(Date), Some(Primitive(Int))),
+                (Primitive(Date), Some(Primitive(Date))),
                 (
                     Primitive(Decimal {
                         precision: 8,
@@ -342,8 +342,8 @@ mod test {
                 (Primitive(StringType), None),
                 (Primitive(Uuid), None),
                 (Primitive(Time), None),
-                (Primitive(Timestamp), Some(Primitive(Int))),
-                (Primitive(Timestamptz), Some(Primitive(Int))),
+                (Primitive(Timestamp), Some(Primitive(Date))),
+                (Primitive(Timestamptz), Some(Primitive(Date))),
                 (
                     Struct(StructType::new(vec![NestedField::optional(
                         1,
@@ -378,7 +378,7 @@ mod test {
             ],
             trans_types: vec![
                 (Primitive(Binary), None),
-                (Primitive(Date), Some(Primitive(Int))),
+                (Primitive(Date), Some(Primitive(Date))),
                 (
                     Primitive(Decimal {
                         precision: 8,
@@ -392,8 +392,8 @@ mod test {
                 (Primitive(StringType), None),
                 (Primitive(Uuid), None),
                 (Primitive(Time), None),
-                (Primitive(Timestamp), Some(Primitive(Int))),
-                (Primitive(Timestamptz), Some(Primitive(Int))),
+                (Primitive(Timestamp), Some(Primitive(Date))),
+                (Primitive(Timestamptz), Some(Primitive(Date))),
                 (
                     Struct(StructType::new(vec![NestedField::optional(
                         1,
@@ -428,7 +428,7 @@ mod test {
             ],
             trans_types: vec![
                 (Primitive(Binary), None),
-                (Primitive(Date), Some(Primitive(Int))),
+                (Primitive(Date), Some(Primitive(Date))),
                 (
                     Primitive(Decimal {
                         precision: 8,
@@ -442,8 +442,8 @@ mod test {
                 (Primitive(StringType), None),
                 (Primitive(Uuid), None),
                 (Primitive(Time), None),
-                (Primitive(Timestamp), Some(Primitive(Int))),
-                (Primitive(Timestamptz), Some(Primitive(Int))),
+                (Primitive(Timestamp), Some(Primitive(Date))),
+                (Primitive(Timestamptz), Some(Primitive(Date))),
                 (
                     Struct(StructType::new(vec![NestedField::optional(
                         1,