GH-44372: [C++] Fix unaligned load/store implementation for clang-18 (#…

…44468) ### Rationale for this change CLang 18 complains about undefined behavior when memcpy is called on a T-unaligned `T*` pointer. This is due to this upstream change: llvm/llvm-project#67766 ### What changes are included in this PR? Workaround by casting to `void*`. ### Are these changes tested? By existing CI tests. ### Are there any user-facing changes? No. * GitHub Issue: #44372 Lead-authored-by: Antoine Pitrou <[email protected]> Co-authored-by: Antoine Pitrou <[email protected]> Signed-off-by: Antoine Pitrou <[email protected]>
apache · Oct 18, 2024 · a5850e1 · a5850e1
1 parent 0c32067
commit a5850e1
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/cpp/src/arrow/util/ubsan.h b/cpp/src/arrow/util/ubsan.h
@@ -63,7 +63,7 @@ inline std::enable_if_t<std::is_trivially_copyable_v<T>, T> SafeLoadAs(
 template <typename T>
 inline std::enable_if_t<std::is_trivially_copyable_v<T>, T> SafeLoad(const T* unaligned) {
   std::remove_const_t<T> ret;
-  std::memcpy(&ret, unaligned, sizeof(T));
+  std::memcpy(&ret, static_cast<const void*>(unaligned), sizeof(T));
   return ret;
 }
 
@@ -73,7 +73,7 @@ inline std::enable_if_t<std::is_trivially_copyable_v<T> &&
                         U>
 SafeCopy(T value) {
   std::remove_const_t<U> ret;
-  std::memcpy(&ret, &value, sizeof(T));
+  std::memcpy(&ret, static_cast<const void*>(&value), sizeof(T));
   return ret;
 }