Project: benchmark
Configuration: Release x64
Visual studio 2019 16.4.3

Compilation of benchmark gives me the following warning. We are using this method with chars, when the signature is
int tolower ( int c );

Could be fixed by preceding IsTruthyFlagValue function with something like
char tolower(char in) { return static_cast<char>(::tolower(in)); }

Microsoft Visual Studio\2019\Enterprise\VC\Tools\MSVC\14.24.28314\include\algorithm(1310,24): warning C4244: '=': conversion from 'int' to 'char', possible loss of data
GoogleBenchmark\benchmark\src\commandlineflags.cc(221): message : see reference to function template instantiation '_OutIt std::transform<std::_String_iterator<std::_String_val<std::_Simple_types<_Elem>>>,std::_String_iterator<std::_String_val<std::_Simple_types<_Elem>>>,int(__cdecl *)(int)>(const _InIt,const _InIt,_OutIt,_Fn)' being compiled
with
[
_OutIt=std::_String_iterator<std::_String_val<std::_Simple_types>>,
_Elem=char,
_InIt=std::_String_iterator<std::_String_val<std::_Simple_types>>,
_Fn=int (__cdecl *)(int)
]