From 89f1ae998bf6f3539d07970c37297fa8da49c1b8 Mon Sep 17 00:00:00 2001
From: Kevin H Wilson <khwilson@gmail.com>
Date: Wed, 9 Oct 2024 21:58:17 -0400
Subject: [PATCH] add doc and export

---
 cpp/src/arrow/compute/kernels/codegen_internal.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/cpp/src/arrow/compute/kernels/codegen_internal.h b/cpp/src/arrow/compute/kernels/codegen_internal.h
index 6eee2cac40eef..fbd360cda3a10 100644
--- a/cpp/src/arrow/compute/kernels/codegen_internal.h
+++ b/cpp/src/arrow/compute/kernels/codegen_internal.h
@@ -1383,6 +1383,11 @@ Status CastBinaryDecimalArgs(DecimalPromotion promotion, std::vector<TypeHolder>
 ARROW_EXPORT
 Status CastDecimalArgs(TypeHolder* begin, size_t count);
 
+/// Given a DataType, if it is a DecimalType, return a DecimalType with the same scale
+/// and the maximum precision for that DecimalType.
+///
+/// If it is _not_ a DecimalType, return type
+ARROW_EXPORT
 Result<std::shared_ptr<DataType>> WidenDecimalToMaxPrecision(std::shared_ptr<DataType> type);
 
 ARROW_EXPORT