Explicit little endian name

Author: AntoinePrv

cpp/src/arrow/util/rle_bitmap_internal.h

@@ -168,7 +168,7 @@ class RleRunToBitmapDecoder
 
   void Reset(const RunType& run) noexcept {
     values_left_ = run.values_count();
-    if (run.value() == 0) {
+    if (run.value_little_endian() == 0) {
       value_pattern_ = uint8_t{0};
     } else {
       value_pattern_ = uint8_t{0xFF};

cpp/src/arrow/util/rle_encoding_internal.h

@@ -114,8 +114,11 @@ class RleRun {
     std::copy(data, data + raw_data_size(value_bit_width), data_.begin());
   }
 
-  /// The repeated value in the run
-  uint64_t value() const noexcept { return SafeLoadAs<uint64_t>(data_.data()); }
+  /// The repeated value in the run in little endian form (as stored in the buffer).
+  uint64_t value_little_endian() const noexcept {
+    // Underlying memcpy is required to avoid undefined behavior.
+    return SafeLoadAs<uint64_t>(data_.data());
+  }
 
   /// The number of repeated values in this run.
   constexpr rle_size_t values_count() const noexcept { return values_count_; }
@@ -278,10 +281,8 @@ class RleRunDecoder {
       // if the bool value isn't 0 or 1.
       value_ = *run.raw_data_ptr() & 1;
     } else {
-      // Memcopy is required to avoid undefined behavior.
-      value_ = {};
-      std::memcpy(&value_, run.raw_data_ptr(), run.raw_data_size(value_bit_width));
-      value_ = ::arrow::bit_util::FromLittleEndian(value_);
+      value_ = static_cast<value_type>(
+          ::arrow::bit_util::FromLittleEndian(run.value_little_endian()));
     }
   }