Which code page is used for the implicit conversion of CStringA to CStringW?

Question

I'm asking this more out of curiosity.

Considering this code snippet:

CStringA narrow;
CStringW wide;
...
wide = narrow; // which code page is used for the conversion 
               // of the narrow string to wide string?

Which code page is used for the conversion of the CStringA string to CStringW? It appears to use the CP_ACP code page, but is this guaranteed?

Instead of wide = narrow; I'm actually using wide = CA2W(narrow, CP_ACP);, so I can specify explicitly the desired code page.

Disclaimer: I know that wide strings should be used all over the place, but this is used for a MBCS legacy software.

Answer 1

ATL is open source. ATL StringT uses _AtlGetConversionACP():

inline UINT WINAPI _AtlGetConversionACP() throw()
{
#ifdef _CONVERSION_DONT_USE_THREAD_LOCALE
    return CP_ACP;
#else
    return CP_THREAD_ACP;
#endif
}