warning: this statement may fall through

[kivadiu]

This program:

#include <iostream>
#include <string>
#include <boost/locale/utf.hpp>
int main() {
  std::string s{"a"};
  auto begin = &s[0];
  auto end = begin + s.size();
  boost::locale::utf::code_point c =
      boost::locale::utf::utf_traits<char>::decode(begin, end);
  std::cout << "codepoint = " << c << '\n';
  return 0;
}

compiled on linux x86_64 with g++ 8.2.0 (same with 7.3.0) and boost 1.68.0 beta 1 with the following command:
g++-8.2.0 -o locale.o -c -Wall -Wextra -std=c++14 -I/softs/lin64-gcc-8.2.0/debug/boost/include locale.cpp
gives the following warnings:

In file included from locale.cpp:3:
/softs/lin64-gcc-8.2.0/debug/boost/include/boost/locale/utf.hpp: In static member function 'static boost::locale::utf::code_point boost::locale::utf::utf_traits<CharType, 1>::decode(Iterator&, Iterator) [with Iterator = char*; CharType = char]':
/softs/lin64-gcc-8.2.0/debug/boost/include/boost/locale/utf.hpp:224:17: warning: this statement may fall through [-Wimplicit-fallthrough=]
                 c = (c << 6) | ( tmp & 0x3F);
                 ^
/softs/lin64-gcc-8.2.0/debug/boost/include/boost/locale/utf.hpp:225:13: note: here
             case 2:
             ^~~~
/softs/lin64-gcc-8.2.0/debug/boost/include/boost/locale/utf.hpp:231:17: warning: this statement may fall through [-Wimplicit-fallthrough=]
                 c = (c << 6) | ( tmp & 0x3F);
                 ^
/softs/lin64-gcc-8.2.0/debug/boost/include/boost/locale/utf.hpp:232:13: note: here
             case 1:
             ^~~~

[Flamefire]

Fixed by #41