Unknown error in LibraryImport with ref parameter

[DrkWzrd]

Here

internal static partial class User32
{

    [LibraryImport("user32.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    public static partial bool DestroyIcon(nint hIcon);

    [LibraryImport("user32.dll", SetLastError = true)]
    public static partial nint CreateIconIndirect(ref ICONINFO iconInfo);

    [LibraryImport("user32.dll", SetLastError = true)]
    public static partial nint GetDC(nint hWnd);

    [LibraryImport("user32.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    public static partial bool ReleaseDC(nint hWnd, nint hDC);

    [StructLayout(LayoutKind.Sequential)]
    internal struct ICONINFO
    {
        [MarshalAs(UnmanagedType.Bool)]
        public bool fIcon;
        public uint xHotspot;
        public uint yHotspot;
        public nint hbmMask;
        public nint hbmColor;
    }
}

CreateIconIndirect yells at me SYSLIB1051, with this message "The generated source will not handle marshalling of parameter"

what's the problem?

[lgztx96]

You may modify it this way

  [StructLayout(LayoutKind.Sequential)]
    internal struct ICONINFO
    {
        public int fIcon;
        public uint xHotspot;
        public uint yHotspot;
        public nint hbmMask;
        public nint hbmColor;
    }

#75376

[DrkWzrd]

Ok, thanks. But I don't understand why a simple blittable struct with the correct attribute can not be handled. It does not make sense that the unsafe code generated to require this trick. It will be nice if someone from the team can explain why this is this way, or if will be fixed in the future.

[huoyaoyuan]

But I don't understand why a simple blittable struct with the correct attribute can not be handled.

It's not a blittable struct. Only [MarshalAs(UnmanagedType.U1)] with bool is blittable, [MarshalAs(UnmanagedType.Bool)] is not.

[DrkWzrd]

Now that makes more sense...