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mem::Alignment: Naming the -> NonZero<usize> method. #154237
Description
Brought up in #154004 (comment): Should the method on Alignment that gives a NonNull<usize> be spelled as_nonzero, as_nonzero_usize, as_non_zero_usize, get, or what?
Nominating for libs-api thoughts so someone can make a PR for whatever the answer is.
Existing APIs on the type: https://doc.rust-lang.org/1.94.0/std/ptr/struct.Alignment.html
Other things like https://doc.rust-lang.org/1.94.0/std/ptr/struct.NonNull.html#method.as_non_null_ptr use non_null for NonNull, so non_zero would arguably be consistent with that. copy_nonoverlapping was mentioned as well, though there's no NonOverlapping type so the parallel isn't as close. Apparently I'm consistent in what I write, because I made https://doc.rust-lang.org/nightly/std/intrinsics/fn.ctlz_nonzero.html too.
Alternatively, this could be more like NonZero itself and just have new/get, since .get().get() would exist to go Alignment -> NonZero<usize> -> usize. Going safely & infallibly that way is important. Going the other way of course is fallible or unsafe so the types involved are in some sense less important. new_unchecked's precondition is is_power_of_two whether it's on usize or NonZero<usize>, though on the latter that's slightly more efficient of a check (for new), though I suspect the combination optimizes together nicely either way.
Activity
mem::Alignmenttype #102070[-]Naming the `-> NonNull<usize>` method.[/-][+]`mem::Alignment`: Naming the `-> NonNull<usize>` method.[/+]clarfonthey commentedon Mar 23, 2026
Don't feel like deduping/rewarding ATM so here's my analysis of non_zero vs. nonzero I posted: #154004 (comment)
(feel free to incorporate into issue description yourself)
lqd commentedon Mar 23, 2026
(There are a couple mentions of
NonNull<usize>instead ofNonZero<usize>)[-]`mem::Alignment`: Naming the `-> NonNull<usize>` method.[/-][+]`mem::Alignment`: Naming the `-> NonZero<usize>` method.[/+]nia-e commentedon Mar 24, 2026
We discussed this in today's @rust-lang/libs-api meeting and we agreed on naming it
as_nonzero_usize- with the caveat that this isn't necessarily precedent-setting thatas_*methods should specify the return type in the name. Thanks ^^@rustbot label -I-libs-api-nominated
clarfonthey commentedon Mar 24, 2026
So, I guess we can just close this as resolved since that's what the current PR has.
Rollup merge of rust-lang#157226 - theemathas:stab-box-vec-non-null, …
Unrolled build for #157226