Stabilize proc macros generating `macro_rules` items #64035

petrochenkov · 2019-08-31T12:26:47Z

Fn-like and attribute proc macros can now generate macro_rules items.

cc #54727

rust-highfive · 2019-08-31T12:26:50Z

r? @eddyb

(rust_highfive has picked a reviewer for you, use r? to override)

JohnCSimon · 2019-09-07T04:38:31Z

Ping from triage - @petrochenkov this has sat idle for 7 days, can you please post the status of this PR?

thank you!

petrochenkov · 2019-09-07T12:14:16Z

Busy week, I'll get to it ~next weekend.

JohnTitor · 2019-09-15T03:22:54Z

Ping from triage: @petrochenkov any updates on this?

JohnCSimon · 2019-09-21T00:04:05Z

Ping from triage.
@petrochenkov Just letting you know, this has sat idle for the last three weeks.
Thank you.

petrochenkov · 2019-09-22T15:20:00Z

Stabilization report

Function-like macros and attribute macros can now generate macro_rules items.

For historical reasons this feature was never gated for derive macros (which were stabilized much earlier than other macro kinds).
So if people need to generate macro_rules, they usually just generate derives expanding to macro_rules instead of generating macro_rules directly.
As a result, the feature is de-facto stable and is actively relied upon by the ecosystem, at least through the proc_macro_hack crate.

Stable proc macros can only use transparent "call-site" hygiene, so in the basic case of a macro_rules item generated by a transparent macro, the item will behave as if it was copy-pasted into the call site.
So, names produced by expanding that macro_rules item will behave as if the item was written directly - local variables and labels will be hygienic, other names will be unhygienic and $crate will refer to the crate containing the macro_rules item, not to the proc macro crate.
This behavior is pretty intuitive and we didn't receive reports of bugs or unexpected behavior in this area, AFAIK.
If you want some specific cases tested, please leave a comment.

If some hygiene rules change in the future, they will most probably affect corner cases with some complex nesting and interactions between various kinds of hygiene mixed.
It will affect people to the same extent whether we stabilize macro_rules-generating fn-like and attribute macros or not, because they will affect derives anyway.

eddyb

This is a pretty straight-forward stabilization, r=me once the decision has been taken.

Centril · 2019-09-26T19:16:41Z

r? @pnkfelix

rfcbot · 2019-10-05T02:46:55Z

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

rfcbot · 2019-10-15T03:03:20Z

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.

petrochenkov · 2019-10-15T07:41:51Z

@bors r=eddyb

bors · 2019-10-15T07:41:52Z

📌 Commit d80be3b has been approved by eddyb

Stabilize proc macros generating `macro_rules` items Fn-like and attribute proc macros can now generate `macro_rules` items. cc rust-lang#54727

@ghost

Rollup of 4 pull requests Successful merges: - #64035 (Stabilize proc macros generating `macro_rules` items) - #65376 (syntax: misc extractions) - #65426 (Remove custom `PartialEq` impls for `LocalInternedString`.) - #65428 (Refactor: Rename `db` locals to `diag`) Failed merges: r? @ghost

Version 1.40.0 (2019-12-19) =========================== Language -------- - [You can now use tuple `struct`s and tuple `enum` variant's constructors in `const` contexts.][65188] e.g. ```rust pub struct Point(i32, i32); const ORIGIN: Point = { let constructor = Point; constructor(0, 0) }; ``` - [You can now mark `struct`s, `enum`s, and `enum` variants with the `#[non_exhaustive]` attribute to indicate that there may be variants or fields added in the future.][64639] For example this requires adding a wild-card branch (`_ => {}`) to any match statements on a non-exhaustive `enum`. [(RFC 2008)] - [You can now use function-like procedural macros in `extern` blocks and in type positions.][63931] e.g. `type Generated = macro!();` - [Function-like and attribute procedural macros can now emit `macro_rules!` items, so you can now have your macros generate macros.][64035] - [The `meta` pattern matcher in `macro_rules!` now correctly matches the modern attribute syntax.][63674] For example `(#[$m:meta])` now matches `#[attr]`, `#[attr{tokens}]`, `#[attr[tokens]]`, and `#[attr(tokens)]`. Compiler -------- - [Added tier 3 support\* for the `thumbv7neon-unknown-linux-musleabihf` target.][66103] - [Added tier 3 support for the `aarch64-unknown-none-softfloat` target.][64589] - [Added tier 3 support for the `mips64-unknown-linux-muslabi64`, and `mips64el-unknown-linux-muslabi64` targets.][65843] \* Refer to Rust's [platform support page][forge-platform-support] for more information on Rust's tiered platform support. Libraries --------- - [The `is_power_of_two` method on unsigned numeric types is now a `const` function.][65092] Stabilized APIs --------------- - [`BTreeMap::get_key_value`] - [`HashMap::get_key_value`] - [`Option::as_deref_mut`] - [`Option::as_deref`] - [`Option::flatten`] - [`UdpSocket::peer_addr`] - [`f32::to_be_bytes`] - [`f32::to_le_bytes`] - [`f32::to_ne_bytes`] - [`f64::to_be_bytes`] - [`f64::to_le_bytes`] - [`f64::to_ne_bytes`] - [`f32::from_be_bytes`] - [`f32::from_le_bytes`] - [`f32::from_ne_bytes`] - [`f64::from_be_bytes`] - [`f64::from_le_bytes`] - [`f64::from_ne_bytes`] - [`mem::take`] - [`slice::repeat`] - [`todo!`] Cargo ----- - [Cargo will now always display warnings, rather than only on fresh builds.][cargo/7450] - [Feature flags (except `--all-features`) passed to a virtual workspace will now produce an error.][cargo/7507] Previously these flags were ignored. - [You can now publish `dev-dependencies` without including a `version`.][cargo/7333] Misc ---- - [You can now specify the `#[cfg(doctest)]` attribute to include an item only when running documentation tests with `rustdoc`.][63803] Compatibility Notes ------------------- - [As previously announced, any previous NLL warnings in the 2015 edition are now hard errors.][64221] - [The `include!` macro will now warn if it failed to include the entire file.][64284] The `include!` macro unintentionally only includes the first _expression_ in a file, and this can be unintuitive. This will become either a hard error in a future release, or the behavior may be fixed to include all expressions as expected. - [Using `#[inline]` on function prototypes and consts now emits a warning under `unused_attribute` lint.][65294] Using `#[inline]` anywhere else inside traits or `extern` blocks now correctly emits a hard error. [65294]: rust-lang/rust#65294 [66103]: rust-lang/rust#66103 [65843]: rust-lang/rust#65843 [65188]: rust-lang/rust#65188 [65092]: rust-lang/rust#65092 [64589]: rust-lang/rust#64589 [64639]: rust-lang/rust#64639 [64221]: rust-lang/rust#64221 [64284]: rust-lang/rust#64284 [63931]: rust-lang/rust#63931 [64035]: rust-lang/rust#64035 [63674]: rust-lang/rust#63674 [63803]: rust-lang/rust#63803 [cargo/7450]: rust-lang/cargo#7450 [cargo/7507]: rust-lang/cargo#7507 [cargo/7525]: rust-lang/cargo#7525 [cargo/7333]: rust-lang/cargo#7333 [(rfc 2008)]: https://rust-lang.github.io/rfcs/2008-non-exhaustive.html [`f32::to_be_bytes`]: https://doc.rust-lang.org/std/primitive.f32.html#method.to_be_bytes [`f32::to_le_bytes`]: https://doc.rust-lang.org/std/primitive.f32.html#method.to_le_bytes [`f32::to_ne_bytes`]: https://doc.rust-lang.org/std/primitive.f32.html#method.to_ne_bytes [`f64::to_be_bytes`]: https://doc.rust-lang.org/std/primitive.f64.html#method.to_be_bytes [`f64::to_le_bytes`]: https://doc.rust-lang.org/std/primitive.f64.html#method.to_le_bytes [`f64::to_ne_bytes`]: https://doc.rust-lang.org/std/primitive.f64.html#method.to_ne_bytes [`f32::from_be_bytes`]: https://doc.rust-lang.org/std/primitive.f32.html#method.from_be_bytes [`f32::from_le_bytes`]: https://doc.rust-lang.org/std/primitive.f32.html#method.from_le_bytes [`f32::from_ne_bytes`]: https://doc.rust-lang.org/std/primitive.f32.html#method.from_ne_bytes [`f64::from_be_bytes`]: https://doc.rust-lang.org/std/primitive.f64.html#method.from_be_bytes [`f64::from_le_bytes`]: https://doc.rust-lang.org/std/primitive.f64.html#method.from_le_bytes [`f64::from_ne_bytes`]: https://doc.rust-lang.org/std/primitive.f64.html#method.from_ne_bytes [`option::flatten`]: https://doc.rust-lang.org/std/option/enum.Option.html#method.flatten [`option::as_deref`]: https://doc.rust-lang.org/std/option/enum.Option.html#method.as_deref [`option::as_deref_mut`]: https://doc.rust-lang.org/std/option/enum.Option.html#method.as_deref_mut [`hashmap::get_key_value`]: https://doc.rust-lang.org/std/collections/struct.HashMap.html#method.get_key_value [`btreemap::get_key_value`]: https://doc.rust-lang.org/std/collections/struct.BTreeMap.html#method.get_key_value [`slice::repeat`]: https://doc.rust-lang.org/std/primitive.slice.html#method.repeat [`mem::take`]: https://doc.rust-lang.org/std/mem/fn.take.html [`udpsocket::peer_addr`]: https://doc.rust-lang.org/std/net/struct.UdpSocket.html#method.peer_addr [`todo!`]: https://doc.rust-lang.org/std/macro.todo.html

rust-highfive assigned eddyb Aug 31, 2019

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Aug 31, 2019

petrochenkov mentioned this pull request Aug 31, 2019

Tracking issue for procedural macros and "hygiene 2.0" #54727

Open

Centril added needs-fcp This change is insta-stable, so needs a completed FCP to proceed. relnotes Marks issues that should be documented in the release notes of the next release. T-lang Relevant to the language team, which will review and decide on the PR/issue. labels Aug 31, 2019

Centril added this to the 1.39 milestone Aug 31, 2019

Centril added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Aug 31, 2019

petrochenkov force-pushed the stabmacgen branch 2 times, most recently from 92aa55c to 2cb35b0 Compare September 22, 2019 14:56

petrochenkov changed the title ~~[WIP] Stabilize proc macros generating macro_rules items~~ Stabilize proc macros generating macro_rules items Sep 22, 2019

petrochenkov added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Sep 22, 2019

petrochenkov mentioned this pull request Sep 22, 2019

proc_macro API: Expose macro_rules hygiene #64690

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eddyb approved these changes Sep 25, 2019

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oli-obk added S-waiting-on-team Status: Awaiting decision from the relevant subteam (see the T-<team> label). I-nominated and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Sep 25, 2019

Centril modified the milestones: 1.39, 1.40 Sep 26, 2019

rust-highfive assigned pnkfelix and unassigned eddyb Sep 26, 2019

rfcbot added the final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. label Oct 5, 2019

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petrochenkov added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-team Status: Awaiting decision from the relevant subteam (see the T-<team> label). labels Oct 15, 2019

petrochenkov added 2 commits October 15, 2019 10:03

Stabilize proc macros generating macro_rules items

b39e188

Test basic hygiene for macro_rules produced by transparent macros

d80be3b

petrochenkov force-pushed the stabmacgen branch from 2cb35b0 to d80be3b Compare October 15, 2019 07:41

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Oct 15, 2019

Centril mentioned this pull request Oct 15, 2019

Rollup of 4 pull requests #65430

Closed

Centril mentioned this pull request Oct 15, 2019

Rollup of 4 pull requests #65433

Merged

bors merged commit d80be3b into rust-lang:master Oct 15, 2019

ehuss mentioned this pull request Oct 16, 2019

Update now that proc macros can expand to macro_rules. rust-lang/reference#694

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TethysSvensson mentioned this pull request Oct 22, 2019

Add support for nested multiversioned functions calebzulawski/multiversion#8

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hobofan mentioned this pull request Nov 19, 2019

RFC: Delegation rust-lang/rfcs#2393

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nrxus mentioned this pull request Dec 27, 2019

Is proc-macro-hack needed? nrxus/faux#5

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la10736 mentioned this pull request Dec 28, 2019

Reusable set of tests la10736/rstest#80

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coolreader18 mentioned this pull request Jan 10, 2020

Don't use proc-macro-hack; use our own slightly-less-hacky hack RustPython/RustPython#1669

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Stabilize proc macros generating `macro_rules` items #64035

Stabilize proc macros generating `macro_rules` items #64035

petrochenkov commented Aug 31, 2019 •

edited

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bors commented Oct 15, 2019

Stabilize proc macros generating macro_rules items #64035

Stabilize proc macros generating macro_rules items #64035

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petrochenkov commented Aug 31, 2019 • edited

rust-highfive commented Aug 31, 2019

JohnCSimon commented Sep 7, 2019

petrochenkov commented Sep 7, 2019

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JohnCSimon commented Sep 21, 2019

petrochenkov commented Sep 22, 2019

Stabilization report

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bors commented Oct 15, 2019

Stabilize proc macros generating `macro_rules` items #64035

Stabilize proc macros generating `macro_rules` items #64035

petrochenkov commented Aug 31, 2019 •

edited