fld := make([]*ast.Field, 0, 2*len(dt.Field)+1) // enough for padding around every field
	sizes := make([]int64, 0, 2*len(dt.Field)+1)
	off := int64(0)

	// Rename struct fields that happen to be named Go keywords into
	// _{keyword}.  Create a map from C ident -> Go ident. The Go ident will
	// be mangled. Any existing identifier that already has the same name on
	// the C-side will cause the Go-mangled version to be prefixed with _.