[Issue 20117] std.typecons.Typedef has opCmp when base type does not

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20117

--- Comment #2 from Simen Kjaeraas <simen.kjaras at gmail.com> ---
Alternatively, Typedef should contain only a single member and use aliases for
the rest. Something like this:

struct Typedef(T, T init = T.init, string cookie=null) {
    // Renaming the current Typedef:
    TypedefImpl!(T, init, cookie) _payload;
    alias _payload this;
    static foreach (e; __traits(allMembers, T))
        mixin("alias "~e~" = _payload."~e~";");
}

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