LNK2019 error in the C++ interface

[Mike Parker]

On Thursday, 10 June 2021 at 13:19:34 UTC, dokutoku wrote:

> I still haven't solved this problem.

Not sure if this is the issue, but you don't need `extern` on 
these. You already have the `extern(C++)` thing at the top of the 
file.

```d
	extern void str_test(LPCSTR str1);

	nothrow @nogc
	extern void wstr_test(LPCWSTR str1);
```