Struct Layout

[Silencersn]

I have two structs like:

[StructLayout(LayoutKind.Auto)]
public struct A
{
    public byte Field1;
    public int Field2;
    public short Field3;
}

[StructLayout(LayoutKind.Auto)]
public struct B
{
    public byte Field1;
    public int Field2;
    public short Field3;
}

They have the same data fields and StructLayout.
Whether their physical layout are also the same all the time?

[EgorBo]

@Silencersn Yes, but it's an implementation detail - you should not rely on offsets/sizes or do reinterp-like casts for structs with Auto layout

[huoyaoyuan]

I think it's safe to assume their layout to be the same within a same process? (implying same runtime version and architecture)

[EgorBo]

I think it's safe to assume

Is it written somewhere in the doc/spec?

[huoyaoyuan]

Is it written somewhere in the doc/spec?

I don't think so, but assuming determinism with these factors.

[colejohnson66]

Memory/ReadOnlyMemory depend on layout equivalency so Unsafe.BitCast can be used.

[jkotas]

I don't think so, but assuming determinism with these factors.

The Auto layout can be profile driven (it was prototyped at one point in the past). Two identical types with the same Auto layout can have different physical layout.