Avoid unreachable code error

[UplinkCoder]

An error complaining about m_union not being set cropped up in our codebase.
This change fixes it by putting the case in which it is not set at the end

[s-ludwig]

Thanks! Am I right that this is just some implementation detail (bug) in DMD that makes the difference here? I would suggest to add a small comment, so that this doesn't accidentally get broken in the future (a unit test would be even better, of course).

[andralex]

Looks like a problem with the compiler, the position of the default label shouldn't influence anything.

[UplinkCoder]

@andralex yes this is where the reality of the language implementation and the spec differ.

In this case, the "stage" at which the unreachable assert(0) is introduced it changes the outcome of the control-flow analysis.
@s-ludwig I am thinking about how to word the comment properly.

[andralex]

Submitted https://issues.dlang.org/show_bug.cgi?id=21671 so it doesn't get forgotten.

[UplinkCoder]

@s-ludwig I've applied your suggestion.
Thanks!

[PetarKirov]

Ping @s-ludwig @l-kramer

[s-ludwig]

Okay, thanks! Sorry for the delay, I missed the last update. Will tag a release afterwards.