Condider migrating to `std::source_location`

[stevenwdv]

Macro's like THROW_IF_WIN32_BOOL_FALSE(b) are painful to use. They have long names, but shorter names could easily clash with other names. I'd much rather do something like using namespace wil::throwing; win32Bool(b). With C++ 20's std::source_location implemented in the latest MSVC version this is now possible.

Additionally, it allows to change the position included in the message. For example:

void throwIfUnexpected(DWORD win32) {
    if (win32 != ERROR_ALREADY_EXISTS) THROW_WIN32(win32);
}

void createFile() {
    if (!CreateFile(... CREATE_ALWAYS ...)) throwIfUnexpected(GetLastError());
}

This will report an error in throwIfUnexpected, but if this function is reused often it would be much more helpful to report the error in the createFile function.

With source_location this would be possible:

void throwIfUnexpected(DWORD win32, std::source_location loc = std::source_location::current()) {
    if (win32 != ERROR_ALREADY_EXISTS) wil::throwWin32(win32, loc); //or something
}

The only downsides are that we cannot get the return address or evaluated expression from source_location. (In C++ 23, the former can be replaced with by using std::stacktrace_entry.)

Very much related: microsoft/cppwinrt#761