Getting a reference to an immutable string

[ag0aep6g]

On 02/10/2018 11:46 PM, David Zhang wrote:
> This is what I'm talking about:
> 
> void createWindow( ... ) {
> 
>      assert( wndclassName.ptr ); //This fails
> 
>      HWND hwnd = CreateWindowW(
>          wndclassName.ptr, //This too
>          null,
>          0,
>          CW_USEDEFAULT, CW_USEDEFAULT,
>          CW_USEDEFAULT, CW_USEDEFAULT,
>          null,
>          null,
>          null,
>          null
>      );
> }
> 
> wstring wndclassName = "wndclass_name"w;

That's not enough code to reproduce the issue. This works as far as I see:

----
import core.sys.windows.windef: HWND;
import core.sys.windows.winuser: CreateWindowW, CW_USEDEFAULT;

void main()
{
     assert( wndclassName.ptr );

     HWND hwnd = CreateWindowW(
         wndclassName.ptr,
         null,
         0,
         CW_USEDEFAULT, CW_USEDEFAULT,
         CW_USEDEFAULT, CW_USEDEFAULT,
         null,
         null,
         null,
         null
     );
}

wstring wndclassName = "wndclass_name"w;
----

But there is a recent regression on Windows that might be related. Do 
you also have a static constructor (`static this`) that uses 
`wndclassName`? If so, you might be hitting issue 18412.

https://issues.dlang.org/show_bug.cgi?id=18412

If you don't have a static constructor, it might be a different bug. In 
that case, please provide complete code so that we can get to the bottom 
of it.