pitrou commented on code in PR #36018:
URL: https://github.com/apache/arrow/pull/36018#discussion_r1254455956


##########
cpp/src/arrow/array/data.cc:
##########
@@ -384,26 +382,31 @@ void ArraySpan::FillFromScalar(const Scalar& value) {
       this->child_data[i].FillFromScalar(*scalar.value[i]);
     }
   } else if (is_union(type_id)) {
+    // Dense union needs scratch space to store both offsets and a type code
+    struct UnionScratchSpace {
+      alignas(int64_t) uint8_t type_code;
+      alignas(int64_t) uint8_t offsets[sizeof(int32_t) * 2];
+    };
+    static_assert(sizeof(UnionScratchSpace) <= 
sizeof(UnionScalar::scratch_space_));
+    auto* union_scratch_space =
+        new (checked_cast<const UnionScalar&>(value).scratch_space_) 
UnionScratchSpace{};

Review Comment:
   Well, we already do this with things such as `struct MonthDayNanos`, don't 
we? So, yes, I think we should keep things simple here.



-- 
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

To unsubscribe, e-mail: [email protected]

For queries about this service, please contact Infrastructure at:
[email protected]

Reply via email to