g++ L"string~" + operator like Visual C++

in Visual C++,

CString a = L"Hello " + L"World!";

or

CString a = L"" + 123;

can be done, right?

L"~" is wchar* type, but how it can be done?

Is it valid only for Visual C++? I mean, is it supported at Visual C++'s complier level? And g++ cannot do?

Or can I overload primitive(global) operator something like

wchar_t* operator+(wchar_t* L, wchar_t* R){...}