A new prelude for the 2021 edition (trait-only edition) #3114

djc · 2021-04-26T20:39:49Z

As requested by the Libs team (via @m-ou-se), here's a smaller, trait-only 2021 prelude RFC. This also addresses some of the feedback from RFC 3090 and includes a more detailed migration lint design.

Rendered

m-ou-se

Thanks!

A few comments:

text/0000-prelude-2021-traits.md

m-ou-se · 2021-04-28T10:28:50Z

There's a few comments and small details that need to be addressed before we can merge this. But I'm starting the libs FCP process now to not delay this any further. We already discussed these additions in a meeting earlier this year, but we still need formal approval for these prelude additions.

Specifically, this RFC proposes to make the prelude dependent on the edition, and to add to add three traits to the Rust 2021 prelude:

TryInto
TryFrom
FromIterator

@rfcbot merge

rfcbot · 2021-04-28T10:28:50Z

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

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!

See this document for info about what commands tagged team members can give me.

yaahc · 2021-04-29T17:42:37Z

Looks good to me.

Conditional based on the existing comments all being resolved:

@rfcbot reviewed

Co-authored-by: Kornel <[email protected]>

Co-authored-by: Mara Bos <[email protected]>

Lokathor · 2021-04-30T20:21:11Z

Nit Pick: The inherent impl not method on bool was already rejected from being added to core on the grounds that people would get an unused import warning, and so we'll have to wait for some inherent traits proposal to be accepted and stabilized (which could take far longer than the 2021 edition)

djc · 2021-04-30T20:23:36Z

Oh, that's good to know. Do you have a reference for that?

Lokathor · 2021-04-30T20:24:54Z

rust-lang/rust#82786

So, yeah, we should just put Not in the darn prelude in 2021 and get all this nonsense over with.

CryZe · 2021-04-30T20:51:04Z

Putting just Not in and not the various other unary operators or even all operators would be pretty inconsistent. Since it's also potentially a pretty strong idiomatic shift even (with many people adopting it and many not), it seems too controversial to just slip into an RFC of common not so controversial imports, especially if this would only be a workaround to the path ahead of adding inherent trait impls.

Lokathor · 2021-04-30T21:05:09Z

pretty strong idiomatic shift

this feels like an overstatement of the situation. It's a single method.

m-ou-se · 2021-05-03T13:30:50Z

@nikomatsakis Can you sign off on the migration plan?

@BurntSushi @dtolnay @sfackler If any of you have time to review this; would be nice to start the FCP soon. (Sorry for the rush, but it'd be nice if we can finish the list of 2021 edition changes before publishing the blog post. This is the last one that still needs fcp. :) )

rfcbot · 2021-05-03T13:53:11Z

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

BurntSushi · 2021-05-03T13:53:47Z

LGTM. Thanks for putting this together!

With respect to Not, I agree with @CryZe's perspective here.

With respect to naming, I personally would prefer rust2021 instead of rust_2021. I find the former far more aesthetically pleasing, to the point that it outweighs any rigorous consistency argument with naming elsewhere. With that said, I don't believe that these are names that folks will be uttering or even reading frequently, so this is a pretty minor point.

nikomatsakis

I approve the migration lint description =)

m-ou-se · 2021-05-03T20:36:49Z

With respect to naming, I personally would prefer rust2021 instead of rust_2021. I find the former far more aesthetically pleasing, to the point that it outweighs any rigorous consistency argument with naming elsewhere. With that said, I don't believe that these are names that folks will be uttering or even reading frequently, so this is a pretty minor point.

Some data: There are zero matches for rust20\d\d in compiler/, but 53 matches for rust_20\d\d. We already have user-facing names like #![warn(rust_2018_idioms)] with underscores. Internally in rustc it's written like that too for functions like span.rust_2018().

BurntSushi · 2021-05-03T21:11:35Z

@m-ou-se Ah okay. That's enough to change my preference then. Thanks for that data!

rfcbot · 2021-05-13T13:54:32Z

The final comment period, with a disposition to merge, as per the review above, is now complete.

As the automated representative of the governance process, I would like to thank the author for their work and everyone else who contributed.

The RFC will be merged soon.

m-ou-se · 2021-05-25T17:56:41Z

Huzzah! The @rust-lang/libs team has decided to accept this RFC.

To track further discussion, subscribe to the tracking issue here: rust-lang/rust#85684

New prelude RFC: rust-lang/rfcs#3114 Tracking issue: rust-lang#85684

…joshtriplett Stabilize {std, core}::prelude::rust_*. This stabilizes the `{core, std}::prelude::{rust_2015, rust_2018, rust_2021}` modules. The usage of these modules as the prelude in those editions was already stabilized. This just stabilizes the modules themselves, making it possible for a user to explicitly refer to them. Tracking issue: rust-lang#85684 FCP on the RFC that included this finished here: rust-lang/rfcs#3114 (comment)

camsteffen · 2021-06-14T18:36:32Z

Maybe I'm too late, but I want to suggest adding Deref/DerefMut. It seems odd that I need to import in order to write something like x.deref().to_owned().

…joshtriplett Stabilize {std, core}::prelude::rust_*. This stabilizes the `{core, std}::prelude::{rust_2015, rust_2018, rust_2021}` modules. The usage of these modules as the prelude in those editions was already stabilized. This just stabilizes the modules themselves, making it possible for a user to explicitly refer to them. Tracking issue: rust-lang#85684 FCP on the RFC that included this finished here: rust-lang/rfcs#3114 (comment)

…_lint, r=nikomatsakis Add `future_prelude_collision` lint Implements rust-lang#84594. (RFC rust-lang/rfcs#3114 ([rendered](https://github.com/rust-lang/rfcs/blob/master/text/3114-prelude-2021.md))) Not entirely complete but wanted to have my progress decently available while I finish off the last little bits. Things left to implement: * [x] UI tests for lints * [x] Only emit lint for 2015 and 2018 editions * [ ] Lint name/message bikeshedding * [x] Implement for `FromIterator` (from best I can tell, the current approach as mentioned from [this comment](rust-lang#84594 (comment)) won't work due to `FromIterator` instances not using dot-call syntax, but if I'm correct about this then that would also need to be fixed for `TryFrom`/`TryInto`)* * [x] Add to `rust-2021-migration` group? (See rust-lang#85512) (added to `rust-2021-compatibility` group) * [ ] Link to edition guide in lint docs *edit: looked into it, `lookup_method` will also not be hit for `TryFrom`/`TryInto` for non-dotcall syntax. If anyone who is more familiar with typecheck knows the equivalent for looking up associated functions, feel free to chime in.

…int, r=nikomatsakis Add `future_prelude_collision` lint Implements rust-lang#84594. (RFC rust-lang/rfcs#3114 ([rendered](https://github.com/rust-lang/rfcs/blob/master/text/3114-prelude-2021.md))) Not entirely complete but wanted to have my progress decently available while I finish off the last little bits. Things left to implement: * [x] UI tests for lints * [x] Only emit lint for 2015 and 2018 editions * [ ] Lint name/message bikeshedding * [x] Implement for `FromIterator` (from best I can tell, the current approach as mentioned from [this comment](rust-lang#84594 (comment)) won't work due to `FromIterator` instances not using dot-call syntax, but if I'm correct about this then that would also need to be fixed for `TryFrom`/`TryInto`)* * [x] Add to `rust-2021-migration` group? (See rust-lang#85512) (added to `rust-2021-compatibility` group) * [ ] Link to edition guide in lint docs *edit: looked into it, `lookup_method` will also not be hit for `TryFrom`/`TryInto` for non-dotcall syntax. If anyone who is more familiar with typecheck knows the equivalent for looking up associated functions, feel free to chime in.

Initial version of prelude-2021 RFC (traits only)

b88bcf0

djc force-pushed the prelude-2021-traits branch from 981eb6d to b88bcf0 Compare April 26, 2021 20:42

djc mentioned this pull request Apr 26, 2021

Prelude additions #3090

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m-ou-se reviewed Apr 26, 2021

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m-ou-se added the T-libs-api Relevant to the library API team, which will review and decide on the RFC. label Apr 28, 2021

rfcbot added proposed-final-comment-period Currently awaiting signoff of all team members in order to enter the final comment period. disposition-merge This RFC is in PFCP or FCP with a disposition to merge it. labels Apr 28, 2021

djc and others added 3 commits April 30, 2021 22:12

Update text/0000-prelude-2021-traits.md

ca92f70

Co-authored-by: Kornel <[email protected]>

Update text/0000-prelude-2021-traits.md

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Co-authored-by: Mara Bos <[email protected]>

Address review feedback

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m-ou-se mentioned this pull request May 3, 2021

Migration lints for 2021 prelude rust-lang/rust#84594

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Nemo157 mentioned this pull request May 12, 2021

from_iter_instead_of_collect feels like a blanket ban of the FromIterator trait rust-lang/rust-clippy#7213

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rfcbot added the finished-final-comment-period The final comment period is finished for this RFC. label May 13, 2021

rfcbot added to-announce and removed final-comment-period Will be merged/postponed/closed in ~10 calendar days unless new substational objections are raised. labels May 13, 2021

m-ou-se mentioned this pull request May 25, 2021

Tracking issue for edition-specific preludes rust-lang/rust#85684

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m-ou-se merged commit 8f1618a into rust-lang:master May 25, 2021

m-ou-se mentioned this pull request May 25, 2021

New prelude rust-lang/rust#85687

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Add future_prelude_collision lint rust-lang/rust#85707

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bors added a commit to rust-lang-ci/rust that referenced this pull request Jun 2, 2021

Auto merge of rust-lang#85687 - m-ou-se:new-prelude, r=yaahc

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New prelude RFC: rust-lang/rfcs#3114 Tracking issue: rust-lang#85684

m-ou-se mentioned this pull request Jun 14, 2021

Stabilize {std, core}::prelude::rust_*. rust-lang/rust#86294

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🎉 Rust 2021 celebration and thanks rust-lang/rust#88623

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A new prelude for the 2021 edition (trait-only edition) #3114

A new prelude for the 2021 edition (trait-only edition) #3114

djc commented Apr 26, 2021 •

edited by m-ou-se

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m-ou-se commented May 25, 2021

camsteffen commented Jun 14, 2021

A new prelude for the 2021 edition (trait-only edition) #3114

A new prelude for the 2021 edition (trait-only edition) #3114

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