Fixtype of information about a structure, union, or enumeration type.
This is a tagged union type, introduced by fty::deftagsum.
For now we only capture information about structure types; we use placeholders for union and enumeration types.
The information about a structure type consists of
a list of member types (see member-type).
This mirrors (the
The members must have unique names [C:6.2.3]. There must be at least one member [C:6.2.5/20], or two if the last one is a flexible array member [C:6.7.2.1/18]. Currently we do not capture these requirements in this fixtype.