[PATCH] D107378: Make enum iteration with seq safe by default

[Aaron Ballman via Phabricator via llvm-commits]

aaron.ballman added a comment.

In D107378#3026392 <https://reviews.llvm.org/D107378#3026392>, @dblaikie wrote:

> @jkuhar - is there some data you could include in the patch description/commit message to help explain/motivate this functionality? Common bugs (links to commits that fixed bugs that would've been found earlier if we had this functionality would be good) introduced by not having this safety/protection over iterating over enums?
>
> @dexonsmith @aaron.ballman - curious what you two think of this for general design. Reckon it's worth the macros and novel traits system (using an inline function rather than/in addition to a template specialization) to allow the trait to be specified closer to the type in nested type situations?

I'm also curious about the motivation behind this. I'm all for preventing misuse where someone tries to form a sequence over enumerations, but I'm not convinced that enumerators form the same notional sequence. As you point out, the enumerators don't have to take on contiguous values. Without some motivating use cases, I think it's better to avoid the extra machinery entirely and prevent this use with enumeration types at all, but I could be convinced if there are some good use cases for it.


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https://reviews.llvm.org/D107378