Fixtype of validation information about ordinary identifiers.
This is a tagged union type, introduced by fty::deftagsum.
Ordinary identifiers [C17:6.2.3/1] denote
objects, functions, enumeration constants, and
This fixtype formalizes the information about ordinary identifiers
tracked by our current validator.
Since our model of types includes both object and function types,
the information for both objects and functions includes (different) types;
that information also includes the linkage [C17:6.2.2],
as well as definition status (see valid-defstatus).
For enumeration constants names,
for now we only track that they are enumeration constants.
For
We will refine this fixtype as we refine our validator.