message: Do not expose protected API
diff: @@ -86,9 +86,7 @@ public:
  return *this;
  }
  - /// Replaces the internal character sequence with a new one.
  - /// @param s A pointer to the first character.
  - /// @param n The length of the character sequence.
  +protected:
  std::basic_streambuf<CharT, Traits>*
  setbuf(CharT* s, std::streamsize n) override {
  this->setg(s, s, s + n);
  @@ -96,7 +94,6 @@ public:
  return this;
  }
  -protected:
  std::streamsize xsputn(const char_type* s, std::streamsize n) override {
  auto available = this->epptr() - this->pptr();
  auto actual = std::min(n, static_cast<std::streamsize>(available));
  