Whether to mangle an external aggregate as a struct or class, as set by extern(C++, struct)
Source file type
Discriminant for which kind of initializer
A linkage attribute as defined by extern(XXX)
Function match levels
Inline setting as defined by pragma(inline, XXX)
Identify Statement types with this enum rather than virtual functions
Variadic argument lists https://dlang.org/spec/function.html#variadic
Determine if it's the ambigous case of where return attaches to.
Defines enums common to dmd and dmd as parse library.