Compiler warnings

[vitaut]

GCC:

format.cc: In member function ‘void fmt::internal::BasicArgFormatter<Impl, Char>::visit_char(int) [with Impl = fmt::internal::ArgFormatter<char>, Char = char]’:
format.h:1186:14:   instantiated from ‘Result fmt::internal::ArgVisitor<Impl, Result>::visit(const fmt::internal::Arg&) [with Impl = fmt::internal::ArgFormatter<char>, Result = void]’
format.cc:1213:3:   instantiated from ‘const Char* fmt::BasicFormatter<Char>::format(const Char*&, const fmt::internal::Arg&) [with Char = char]’
format.cc:1290:59:   instantiated from here
format.cc:448:5: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]

MSVC:

c:\projects\cppformat\format.h(295): warning C4267: 'return': conversion from 'size_t' to 'int', possible loss of data [C:\projects\cppformat\test\no-windows-h-test.vcxproj]
         c:\projects\cppformat\format.h(292): note: while compiling class template member function 'int fmt::BasicStringRef<wchar_t>::compare(fmt::BasicStringRef<wchar_t>) const'
         c:\projects\cppformat\format.h(305): note: see reference to function template instantiation 'int fmt::BasicStringRef<wchar_t>::compare(fmt::BasicStringRef<wchar_t>) const' being compiled
         C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\include\xtree(1449): note: see reference to class template instantiation 'fmt::BasicStringRef<wchar_t>' being compiled