For layouts such as these:

    struct Foo {
        int x;
        union {
            int y;
            int z;
        };
    };

Jextract will generate:

    static final MemoryLayout Foo$struct$LAYOUT_ = MemoryLayout.ofStruct(
        C_INT.withName("x"),
        C_INT.withName("y"),
        C_INT.withName("z")
    ).withName("Foo");

We should change the layout generation to not flatten layouts of nested anonymous structs into their parents.