Question

I use d-ide to develop with D.

With D 2.059 compiler version, the project Windows template compile et run like a charm.

With D 2.060 compiler version, the project Windows template does not compile and rises an error :

main.d(41): Error: cannot implicitly convert expression (& WindowProc) of type extern  
(Windows) int function(void* hWnd, uint message, uint wParam, int lParam) to extern  
(Windows) int function(void*, uint, uint, int) nothrow

Following is the code, thanks for your suggestions.

// Example code taken from winsamp.d (Listed under D examples)

import core.runtime;
import std.c.windows.windows;
import std.string;

enum IDC_BTNCLICK     = 101;
enum IDC_BTNDONTCLICK = 102;

extern(Windows)
int WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int iCmdShow)
{
    int result;
    void exceptionHandler(Throwable e) { throw e; }

    try
    {
        Runtime.initialize(&exceptionHandler);
        result = myWinMain(hInstance, hPrevInstance, lpCmdLine, iCmdShow);
        Runtime.terminate(&exceptionHandler);
    }
    catch (Throwable e)
    {
        MessageBoxA(null, e.toString().toStringz, "Error", MB_OK | MB_ICONEXCLAMATION);
        result = 0;
    }

    return result;
}

int myWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int iCmdShow)
{
    string caption = "The Hello Program";
    string className = "DWndClass";
    HWND hWnd, btnClick, btnDontClick;
    MSG  msg;
    WNDCLASS wndclass;

    wndclass.style         = CS_OWNDC | CS_HREDRAW | CS_VREDRAW;
    wndclass.lpfnWndProc   = &WindowProc;
    wndclass.cbClsExtra    = 0;
    wndclass.cbWndExtra    = 0;
    wndclass.hInstance     = hInstance;
    wndclass.hIcon         = LoadIconA(null, IDI_APPLICATION);
    wndclass.hCursor       = LoadCursorA(null, IDC_CROSS);
    wndclass.hbrBackground = cast(HBRUSH)GetStockObject(WHITE_BRUSH);
    wndclass.lpszMenuName  = null;
    wndclass.lpszClassName = className.toStringz;

    if (!RegisterClassA(&wndclass))
    {
        MessageBoxA(null, "Couldn't register Window Class!", caption.toStringz, MB_ICONERROR);
        return 0;
    }

    hWnd = CreateWindowA(className.toStringz,  // window class name
                         caption.toStringz,    // window caption
                         WS_THICKFRAME   |
                         WS_MAXIMIZEBOX  |
                         WS_MINIMIZEBOX  |
                         WS_SYSMENU      |
                         WS_VISIBLE,           // window style
                         CW_USEDEFAULT,        // initial x position
                         CW_USEDEFAULT,        // initial y position
                         600,                  // initial x size
                         400,                  // initial y size
                         HWND_DESKTOP,         // parent window handle
                         null,                 // window menu handle
                         hInstance,            // program instance handle
                         null);                // creation parameters

    if (hWnd is null)
    {
        MessageBoxA(null, "Couldn't create window.", caption.toStringz, MB_ICONERROR);
        return 0;
    }

    btnClick = CreateWindowA("BUTTON", "Click Me", WS_CHILD | WS_VISIBLE,
                             0, 0, 100, 25, hWnd, cast(HMENU)IDC_BTNCLICK, hInstance, null);

    btnDontClick = CreateWindowA("BUTTON", "DON'T CLICK!", WS_CHILD | WS_VISIBLE,
                                 110, 0, 100, 25, hWnd, cast(HMENU)IDC_BTNDONTCLICK, hInstance, null);

    ShowWindow(hWnd, iCmdShow);
    UpdateWindow(hWnd);

    while (GetMessageA(&msg, null, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessageA(&msg);
    }

    return msg.wParam;
}

int* p;
extern(Windows)
LRESULT WindowProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message)
    {
        case WM_COMMAND:
        {
            switch (LOWORD(wParam))
            {
                case IDC_BTNCLICK:
                    if (HIWORD(wParam) == BN_CLICKED)
                        MessageBoxA(hWnd, "Hello, world!", "Greeting",
                                    MB_OK | MB_ICONINFORMATION);

                    break;

                case IDC_BTNDONTCLICK:
                    if (HIWORD(wParam) == BN_CLICKED)
                    {
                        MessageBoxA(hWnd, "You've been warned...", "Prepare to GP fault",
                                    MB_OK | MB_ICONEXCLAMATION);
                        *p = 1;
                    }

                    break;

                default:
            }

            break;
        }

        case WM_PAINT:
        {
            enum text = "D Does Windows";
            PAINTSTRUCT ps;

            HDC  dc = BeginPaint(hWnd, &ps);
            scope(exit) EndPaint(hWnd, &ps);
            RECT r;
            GetClientRect(hWnd, &r);
            HFONT font = CreateFontA(80, 0, 0, 0, FW_EXTRABOLD, FALSE, FALSE,
                                     FALSE, ANSI_CHARSET, OUT_DEFAULT_PRECIS, CLIP_DEFAULT_PRECIS,
                                     DEFAULT_QUALITY, DEFAULT_PITCH | FF_DONTCARE, "Arial");
            HGDIOBJ old = SelectObject(dc, cast(HGDIOBJ) font);
            SetTextAlign(dc, TA_CENTER | TA_BASELINE);
            TextOutA(dc, r.right / 2, r.bottom / 2, text.toStringz, text.length);
            DeleteObject(SelectObject(dc, old));

            break;
        }

        case WM_DESTROY:
            PostQuitMessage(0);
            break;

        default:
            break;
    }

    return DefWindowProcA(hWnd, message, wParam, lParam);
}

Answer 1

It’s not about D-IDE but more on update for last version of Digital Mars Compiler 2.060 Windows version.

No matter, the solution I’ve found is to put the attribute “nothrow” in front of the window function : nothrow LRESULT WindowProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)

So this question is answered for me.