Question

Is it possible to declare struct array field in another struct?

[StructLayout(LayoutKind.Sequential, Pack = 1)]
public unsafe struct A
{
}

[StructLayout(LayoutKind.Sequential, Pack = 1)]
public unsafe struct B
{
    public fixed A FieldA[123];
}

Visual Studio tells that FieldA can only be an array of any simple type not a struct. Is there any solution/workaround here?

Answer 1

Is it possible to declare struct array field in another struct?

Yes, but there are restrictions if you want to make it a fixed-size buffer. From section 18.7.1 of the C# 4 spec:

The buffer element type of a fixed size buffer declaration specifies the element type of the buffer(s) introduced by the declaration. The buffer element type must be one of the predefined types sbyte, byte, short, ushort, int, uint, long, ulong, char, float, double, or bool.

I don’t know of any alternatives to emulate fixed sized buffers of arbitrary structs.