Mandatory BitPackedDecoder num_values

Author: AntoinePrv

cpp/src/arrow/util/rle_encoding_internal.h

@@ -599,21 +599,17 @@ class BitPackedDecoder : private BitPackedRunDecoder<T> {
   /// @param value_bit_width is the size in bits of each encoded value.
   /// @param value_count is an optional number of values in the run.
   BitPackedDecoder(const uint8_t* data, rle_size_t data_size, rle_size_t value_bit_width,
-                   rle_size_t value_count = -1) noexcept {
+                   rle_size_t value_count) noexcept {
     Reset(data, data_size, value_bit_width, value_count);
   }
 
   void Reset(const uint8_t* data, rle_size_t data_size, rle_size_t value_bit_width,
-             rle_size_t value_count = -1) noexcept {
+             rle_size_t value_count) noexcept {
+    ARROW_DCHECK_GE(value_count, 0);
     ARROW_DCHECK_GE(value_bit_width, 0);
     ARROW_DCHECK_LE(value_bit_width, 64);
 
     value_bit_width_ = value_bit_width;
-    if (value_count < 0) {
-      ARROW_DCHECK_GT(value_bit_width, 0);
-      const int64_t data_bit_size = static_cast<int64_t>(data_size) * 8;
-      value_count = static_cast<rle_size_t>(data_bit_size / value_bit_width);
-    }
 
     ARROW_DCHECK_LE(value_count, std::numeric_limits<rle_size_t>::max());
     const auto run = BitPackedRun{