pub const OPAQUE_SCALARS: &[Scalar];Expand description
The four scalars whose declaration is opaque (DEC-15 decision
2):
nothing in the language constructs or inspects a value of one, so each declares
only its own name and contributes no constructor.
BOOL is deliberately absent. It is a scalar — the compiler knows its
representation — but its declaration is Basics’ genuine type Bool = True | False, and the self-naming rule does not reach it (DEC-15 decision
5).