Convert wchar* to wstring?

[Thalamus via Digitalmars-d-learn]

I'm sorry for this total newbie question, but for some reason 
this is eluding me. I must be overlooking something obvious, but 
I haven't been able to figure this out and haven't found anything 
helpful.

I am invoking an entry point in a D DLL from C# (via extern (C)), 
and one of the parameters is a string. This works just fine for 
ANSI, but I'm having trouble with the Unicode equivalent.

For ANSI, the message parameter is char*, and string info = 
to!string(message) produces the correct string.

For Unicode, I assumed this would be wchar_t*, as it is in C++. 
(In C++ you can just pass the wchar_t* value to the wstring 
constructor.) So I tried wchar_t*, wchar* and dchar* as well. 
When the message parameter is wchar*, wstring info = 
to!wstring(message) populates the string with the _address_ of 
the wchar*. So when message was in the debugger as 
0x00000000035370e8 L"Writing Exhaustive unit tests is 
exhausting.", the wstring info variable ended up as {length=7 
ptr=0x000000001c174a20 L"35370E8" }. The dstring*/wchar_t* 
version had equivalent results.

Again, I'm sure I'm missing something obvious, but I poked at 
this problem with various types, casts, Phobos library string 
conversions, and I'm just stumped! :)

thanks,
Thalamus