[Issue 4423] [tdpl] enums of struct types

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=4423
Issue 4423 depends on issue 6221, which changed state.

Issue 6221 Summary: Should be possible to pass struct function returns by 'const ref'.
https://issues.dlang.org/show_bug.cgi?id=6221

           What    |Removed                     |Added
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             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

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