[BUG] Fix CSV roundtrip for decimals (actually an f64->decimal castin…

…g bug) (#1626)

Co-authored-by: Jay Chia <[email protected]@users.noreply.github.com>

src/daft-core/src/array/ops/cast.rs

@@ -186,21 +186,13 @@ where
         )?
     } else if can_cast_types(&self_arrow_type, &target_arrow_type) {
         // Cast from logical Arrow2 type to logical Arrow2 type.
-        let arrow_logical = cast(
+        cast(
             to_cast.data(),
             &target_arrow_type,
             CastOptions {
                 wrapped: true,
                 partial: false,
             },
-        )?;
-        cast(
-            arrow_logical.as_ref(),
-            &target_arrow_physical_type,
-            CastOptions {
-                wrapped: true,
-                partial: false,
-            },
         )?
     } else if can_cast_types(&self_physical_arrow_type, &target_arrow_physical_type) {
         // Cast from physical Arrow2 type to physical Arrow2 type.

tests/io/test_csv_roundtrip.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import datetime
+import decimal
 
 import pyarrow as pa
 import pytest
@@ -23,8 +24,12 @@
         ([b"a", b"b", b""], pa.large_binary(), DataType.binary(), DataType.string()),
         ([True, False, None], pa.bool_(), DataType.bool(), DataType.bool()),
         ([None, None, None], pa.null(), DataType.null(), DataType.null()),
-        # TODO: This is broken, needs more investigation into why
-        # ([decimal.Decimal("1.23"), decimal.Decimal("1.24"), None], pa.decimal128(16, 8), DataType.decimal128(16, 8), DataType.float64()),
+        (
+            [decimal.Decimal("1.23"), decimal.Decimal("1.24"), None],
+            pa.decimal128(16, 8),
+            DataType.decimal128(16, 8),
+            DataType.float64(),
+        ),
         ([datetime.date(1994, 1, 1), datetime.date(1995, 1, 1), None], pa.date32(), DataType.date(), DataType.date()),
         (
             [datetime.datetime(1994, 1, 1), datetime.datetime(1995, 1, 1), None],