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☔ The latest upstream changes (presumably #155175) made this pull request unmergeable. Please resolve the merge conflicts.

In the meeting today, we talked a bit about the name. Framing it as "target has {property}" seems right, especially in light of the existing target_has_atomic. But the word "equal" here is a bit unfortunate — one wonders, "equal to what?"

This cfg is testing that align_of::<Atomic<T>>() == align_of::<T>(). I.e., that the alignment of the atomic for some type T is the inner alignment — the alignment of the inner type.

What about target_has_atomic_inner_alignment?

One potential naming concern with cfg(target_has_atomic_equal_alignment="N") is that reading aloud something like target_has_atomic="32" can already read out aloud as something like “target has atomic equal[s] thirty-two”, so there’s potential confusion in adding the word “equal” in that same position where an ”equals“ sign appears for a different (related) cfg flag.

When looking for possible other names, it also makes sense to keep in mind that this flag is going to be used with a ="N"-kind of suffix (or ="8"/="16"/="32"/="64"/="ptr") indicating which atomic size we’re talking about.

Types like u8, u16… etc make up a majority of “primitive” types. See also std::primitive. So I’ve been thinking reference to primitive could help answer the question of “what is it supposed to be equal to?”

In the space of “names starting with target_has_atomic_”, I’m able to come up with things like the following.

• #[cfg(target_has_atomic_alignment_matching_primitive="32")]
• #[cfg(target_has_atomic_aligned_like_primitive="32")]
• #[cfg(target_has_atomic_primitive_align="32")]

Out of the proposals above I like #[cfg(target_has_atomic_primitive_align="32")] the most (with close second being #[cfg(target_has_atomic_aligned_like_primitive="32")]). What would be the next step, should I re-nominate this to check if T-lang would be okay with that (or other) name(s), or?..

It's still nominated. We'll pick it back up to discuss.

We talked about this in the lang call today. Let's propose to do it with the name cfg(target_has_atomic_primitive_alignment).

@rfcbot fcp merge lang

Team member @traviscross has proposed to merge this. The next step is review by the rest of the tagged team members:

• @joshtriplett
• @nikomatsakis
• @scottmcm
• @tmandry
• @traviscross

No concerns currently listed.

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

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🔔 This is now entering its final comment period, as per the review above. 🔔