Error: WndProc - nothrow

[deed]

I get this error from a minimal windows example:

import core.runtime;
import std.c.windows.windows;
import std.string;
pragma(lib, "gdi32.lib");

extern (Windows)
{
int WinMain( ... ) { ... }
HRESULT appMain( ... ) {
    ...
    WNDCLASS wc;
    ...
    wc.lpfnWndProc = &wndProc;
    ...
}
HRESULT wndProc( ... ) { ... }
}

Error: cannot implicitly convert expression (& wndProc) of type
extern (Windows) int function(void* hwnd, uint message, uint 
wParam, int lParam)
to
extern (Windows) int function(void*, uint, uint, int) nothrow
shell returned 1

What does the nothrow stems from? Is this something new?