[Issue 20719] Self referential struct definition causes stack overflow

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20719

moonlightsentinel at disroot.org changed:

           What    |Removed                     |Added
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                 CC|                            |moonlightsentinel at disroot.o
                   |                            |rg

--- Comment #2 from moonlightsentinel at disroot.org ---
Maybe related reduction from dustmite:

==============================

alias AliasSeq(TList...) = TList;

enum isCopyable(S) = { S foo; };


struct SumType
{
    alias Types = AliasSeq!(typeof(this));

    Types[0] t;

    alias cp = isCopyable!(Types[0]);
}

================================

This also segfaults but prints

test.d(6): Error: struct test.SumType cannot have field t with same struct type

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