Check BuiltIn Decoration rules.

Check BuiltIn Decoration rules.

When applied to a structure-type member, all members of that structure
type must also be decorated with BuiltIn. (No allowed mixing of built-in
variables and non-built-in variables within a single structure.)

When applied to a structure-type member, that structure type cannot be
contained as a member of another structure type.

There is at most one object per Storage Class that can contain a
structure type containing members decorated with BuiltIn, consumed per
entry-point.