[Issue 19605] invalid forward reference error when getting the `.sizeof` if an opaque enum

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=19605

Basile-z <b2.temp at gmx.com> changed:

           What    |Removed                     |Added
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           Keywords|                            |rejects-valid
                 CC|                            |b2.temp at gmx.com
            Summary|enum X: "Error: enum X is   |invalid forward reference
                   |forward referenced when     |error when getting the
                   |looking for sizeof"         |`.sizeof` if an opaque enum

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