Phobos' std.conv.to-conversion from enum to string doesn't scale beyond hundreds of enumerators

[Per Nordlöw]

On Friday, 22 June 2018 at 00:50:05 UTC, Steven Schveighoffer 
wrote:
> The sucky thing is, the compiler is *already* doing a sort on 
> the items in the switch, and *already* doing the duplicate 
> check. It would be cool to be able to leverage this mechanism 
> to avoid the library solution, but I don't know how we can do 
> that, as the semantics for switch are well defined, and there's 
> no other way to hook this builtin functionality.

I would like to see a new trait named, say, `primaryMembers` or 
`nonAliasMembers` that returns exactly what the switch needs. I 
believe this is motivated by the fact that this is a serious 
issue; Without the user notices, the use of enums combined with 
.to!string or io sucks up more and more RAM in the compiler as 
new members are added.

If enough (hundreds) of members are added you can get out of RAM, 
which is what happened to me. What do you think about that idea?

We should plot compilation time and memory usage with enumerator 
count so we can reason about the severity of this issue.