Fix XRPLF#284

Summary: This work on my compiler, but it turns out some compilers don't implicitly add constness, see: facebook/rocksdb#284. This diff adds constness explicitly.

Test Plan: still compiles

Reviewers: sdong

Reviewed By: sdong

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D23409

table/full_filter_block.cc

@@ -47,7 +47,7 @@ inline void FullFilterBlockBuilder::AddPrefix(const Slice& key) {
 Slice FullFilterBlockBuilder::Finish() {
   if (num_added_ != 0) {
     num_added_ = 0;
-    return filter_bits_builder_->Finish(&filter_data);
+    return filter_bits_builder_->Finish(&filter_data_);
   }
   return Slice();
 }
@@ -64,7 +64,7 @@ FullFilterBlockReader::FullFilterBlockReader(
   filter_bits_reader_.reset(filter_bits_reader);
 
   if (delete_contents_after_use) {
-    filter_data.reset(contents.data());
+    filter_data_.reset(contents.data());
   }
 }
 

table/full_filter_block.h

@@ -56,7 +56,7 @@ class FullFilterBlockBuilder : public FilterBlockBuilder {
 
   uint32_t num_added_;
   std::unique_ptr<FilterBitsBuilder> filter_bits_builder_;
-  std::unique_ptr<const char[]> filter_data;
+  std::unique_ptr<const char[]> filter_data_;
 
   void AddKey(const Slice& key);
   void AddPrefix(const Slice& key);
@@ -95,7 +95,7 @@ class FullFilterBlockReader : public FilterBlockReader {
 
   std::unique_ptr<FilterBitsReader> filter_bits_reader_;
   Slice contents_;
-  std::unique_ptr<const char[]> filter_data;
+  std::unique_ptr<const char[]> filter_data_;
 
   bool MayMatch(const Slice& entry);
 

util/bloom.cc

@@ -54,9 +54,8 @@ class FullFilterBitsBuilder : public FilterBitsBuilder {
   // | ...                | num_probes : 1 byte | num_lines : 4 bytes |
   // +----------------------------------------------------------------+
   virtual Slice Finish(std::unique_ptr<const char[]>* buf) override {
-    char* data = nullptr;
     uint32_t total_bits, num_lines;
-    data = ReserveSpace(hash_entries_.size(), &total_bits, &num_lines);
+    char* data = ReserveSpace(hash_entries_.size(), &total_bits, &num_lines);
     assert(data);
 
     if (total_bits != 0 && num_lines != 0) {
@@ -67,7 +66,8 @@ class FullFilterBitsBuilder : public FilterBitsBuilder {
     data[total_bits/8] = static_cast<char>(num_probes_);
     EncodeFixed32(data + total_bits/8 + 1, static_cast<uint32_t>(num_lines));
 
-    buf->reset(data);
+    const char* const_data = data;
+    buf->reset(const_data);
     hash_entries_.clear();
 
     return Slice(data, total_bits / 8 + 5);