[Issue 23272] [REG2.099] CTFE error of typeid comparison ==

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=23272

--- Comment #3 from Iain Buclaw <ibuclaw at gdcproject.org> ---
Possible reduction of the original.
---
alias AliasSeq(TList...) = TList;

template EnumMembers(E)
{
    alias EnumMembers = AliasSeq;
    static foreach (M; __traits(allMembers, E))
        EnumMembers = AliasSeq!(__traits(getMember, E, M));
}

struct SumType(Ts)
{
    mixin(() {
        auto s = "enum Cases : ubyte {";
        return s ~= "unset}\n";
    }());

    Cases which;
    union {
        Ts cases;
    }
}

auto caseOfTemplated(alias func, T)(T s) {
    final switch (s.which) foreach(CASE; EnumMembers!(T.Cases)) {
        case CASE:
            return func(s.cases);
    }
}


void foo() {
    bool validate() {
        SumType!(int) s;
        caseOfTemplated!(a => typeid(a))(s) == typeid(string);
        return true;
    }
    static assert(validate);
}

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