cases section below.

To access a struct, union, or enum type directly, prefix it with
struct_, union_, or enum_, as in C.struct_stat. The size of any C type
T is available as C.sizeof_T, as in C.sizeof_struct_stat. These
special prefixes means that there is no way to directly reference a C
identifier that starts with "struct_", "union_", "enum_", or
"sizeof_", such as a function named "struct_function".

	if wantFormat := h.Format; wantFormat != FormatUnknown {
		if wantFormat.has(FormatPAX) && !preferPAX {
			wantFormat.mayBe(FormatUSTAR) // PAX implies USTAR allowed too
		}
		format.mayOnlyBe(wantFormat) // Set union of formats allowed and format wanted
	}
	if format == FormatUnknown {
		switch h.Format {
		case FormatUSTAR:
			err = headerError{"Format specifies USTAR", whyNoUSTAR, whyOnlyPAX, whyOnlyGNU}
		case FormatPAX:

	list := make([]string, 0, n)
	for i := 0; i < n; i++ {
		emb := typ.EmbeddedType(i)
		switch emb := emb.(type) {
		case *types.Interface:
			list = append(list, w.sortedEmbeddeds(emb)...)
		case *types.Union:
			var buf bytes.Buffer
			nu := emb.Len()
			for i := 0; i < nu; i++ {
				if i > 0 {
					buf.WriteString(" | ")
				}
				term := emb.Term(i)
				if term.Tilde() {
					buf.WriteByte('~')