rustc: Stabilize the `proc_macro` feature #52081

alexcrichton · 2018-07-05T17:53:59Z

This commit stabilizes some of the proc_macro language feature as well as a
number of APIs in the proc_macro crate as previously discussed. This
means that on stable Rust you can now define custom procedural macros which
operate as attributes attached to items or macro_rules!-like bang-style
invocations. This extends the suite of currently stable procedural macros,
custom derives, with custom attributes and custom bang macros.

Note though that despite the stabilization in this commit procedural macros are
still not usable on stable Rust. To stabilize that we'll need to stabilize at
least part of the use_extern_macros feature. Currently you can define a
procedural macro attribute but you can't import it to call it!

A summary of the changes made in this PR (as well as the various consequences)
is:

The proc_macro language and library features are now stable.
Other APIs not stabilized in the proc_macro crate are now named under a
different feature, such as proc_macro_diagnostic or proc_macro_span.
A few checks in resolution for proc_macro being enabled have switched over
to use_extern_macros being enabled. This means that code using
#![feature(proc_macro)] today will likely need to move to
#![feature(use_extern_macros)].

It's intended that this PR, once landed, will be followed up with an attempt to
stabilize a small slice of use_extern_macros just for procedural macros to
make this feature 100% usable on stable.

rust-highfive · 2018-07-05T17:54:03Z

r? @aturon

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

rust-highfive · 2018-07-05T17:54:03Z

Warning

These commits modify submodules.

alexcrichton · 2018-07-05T17:55:02Z

r? @nikomatsakis

cc @petrochenkov, @dtolnay, @nrc

petrochenkov · 2018-07-05T19:32:07Z

src/libproc_macro/diagnostic.rs

@@ -13,7 +13,7 @@ use Span;
 use rustc_errors as rustc;

 /// An enum representing a diagnostic level.
-#[unstable(feature = "proc_macro", issue = "38356")]
+#[unstable(feature = "proc_macro_diagnostic", issue = "38356")]


What's the point in renaming unstable library features?
This is only breaking all the code using them.

The proc_macro feature at this point has been used-and-abused I think a bit too much. This PR is, afaik, the main thrust of proc_macro for stabilization. The renamings here aren't intended to purely break everyone else's code, but rather clearly singify different groupings of features instead of leaving them all in a perpetual singular proc_macro bucket

petrochenkov · 2018-07-05T19:34:48Z

src/libproc_macro/lib.rs

@@ -93,13 +93,13 @@ impl !Sync for LexError {}

 impl TokenStream {
    /// Returns an empty `TokenStream` containing no token trees.
-    #[unstable(feature = "proc_macro", issue = "38356")]
+    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]


Are you going to use proc_macro_lib3/4/5/... for the next portions of stabilized APIs? :)
I used proc_macro_12 in my PR (#50473 (comment)), because it's Macros 1.2.
(OK, it doesn't matter anyway.)

As I'm sure you know, the stable feature name doesn't actually matter. I initially changed these while the other unstable features were still proc_macro and then ended up later changing the other proc_macro features to different names. As a result this stuck. It's an arbitrary name.

petrochenkov · 2018-07-05T19:36:46Z

The custom_attribute feature no longer works as unknown attibutes are looked up as macros.

Oh man, this is going to be painful.

petrochenkov · 2018-07-05T19:47:20Z

I don't see much use in landing this PR before stabilizing use_extern_macros and completing #51952, but it's good to have a PR open for some publicity.

I plan to fix tool attributes in the next few weeks, so poor users of #[rustfmt_skip] could migrate to #[rustfmt::skip] if custom attributes are not fixed either.

I think custom attributes could be restored in some form as well, e.g. if some attribute is "definitely unresolved" as a macro, then it can be kept in the source as a custom attribute (still under a feature gate) instead of producing a dummy expansion, like it's done now.

alexcrichton · 2018-07-05T22:25:15Z

While true that this PR isn't too useful landing by itself it does need to land eventually for proc-macro stabilization, and this was larger and more thorny than I thought it would be so I wanted to put it up for review and get it in soon to iron out all the CI issues.

SimonSapin · 2018-07-06T04:09:30Z

The custom_attribute feature no longer works as unknown attibutes are looked up as macros.

Oh man, this is going to be painful.

Does this also break rustc_plugin::Registry::register_attribute in #[plugin_registrar]? Servo still has a lint plugin with (unfortunately) no clear upgrade path.

eddyb · 2018-07-06T08:22:44Z

FWIW, I have mentioned before that if the unrooted_must_root_lint analysis is "close enough" to being sound, it should naturally be replaceable with a trait-based system that's partially implemented inside the compiler itself, with most of the logic being in impls/derives in Servo crates.

SimonSapin · 2018-07-06T09:52:44Z

@eddyb Yes, it might be "just" a matter of someone familiar enough with what the lint does and the soundness of GC rooting to come up with a new design and implementing it. In the meantime, a lint is what we have.

alexcrichton · 2018-07-06T14:31:16Z

@SimonSapin yes it'd break that because those attributes aren't hooked into the normal resolver. You can rename them with a rustc_ prefix, though, and it should continue working. All attributes with a rustc_ prefix are gated and skip the resolver.

alexcrichton · 2018-07-09T22:15:07Z

I think @nikomatsakis is out this week, so...

r? @nrc

alercah · 2018-07-10T13:33:17Z

I have a major reservation about stabilizing that I brought up in the tracking issue.

bors · 2018-07-16T18:09:23Z

⌛ Testing commit 65f3007 with merge 2750fc6...

kennytm · 2018-07-16T20:54:43Z

@bors retry

GitHub outage causing the CIs not seeing the auto branch got updated.

bors · 2018-07-16T20:54:56Z

⌛ Testing commit 65f3007 with merge 1ecf692...

rustc: Stabilize the `proc_macro` feature This commit stabilizes some of the `proc_macro` language feature as well as a number of APIs in the `proc_macro` crate as [previously discussed][1]. This means that on stable Rust you can now define custom procedural macros which operate as attributes attached to items or `macro_rules!`-like bang-style invocations. This extends the suite of currently stable procedural macros, custom derives, with custom attributes and custom bang macros. Note though that despite the stabilization in this commit procedural macros are still not usable on stable Rust. To stabilize that we'll need to stabilize at least part of the `use_extern_macros` feature. Currently you can define a procedural macro attribute but you can't import it to call it! A summary of the changes made in this PR (as well as the various consequences) is: * The `proc_macro` language and library features are now stable. * Other APIs not stabilized in the `proc_macro` crate are now named under a different feature, such as `proc_macro_diagnostic` or `proc_macro_span`. * A few checks in resolution for `proc_macro` being enabled have switched over to `use_extern_macros` being enabled. This means that code using `#![feature(proc_macro)]` today will likely need to move to `#![feature(use_extern_macros)]`. It's intended that this PR, once landed, will be followed up with an attempt to stabilize a small slice of `use_extern_macros` just for procedural macros to make this feature 100% usable on stable. [1]: https://internals.rust-lang.org/t/help-stabilize-a-subset-of-macros-2-0/7252

bors · 2018-07-16T23:10:49Z

☀️ Test successful - status-appveyor, status-travis
Approved by: petrochenkov
Pushing 1ecf692 to master...

rust-highfive · 2018-07-16T23:12:23Z

📣 Toolstate changed by #52081!

Tested on commit 1ecf692.
Direct link to PR: #52081

💔 clippy-driver on windows: test-pass → test-fail (cc @Manishearth @llogiq @mcarton @oli-obk, @rust-lang/infra).
💔 clippy-driver on linux: test-pass → test-fail (cc @Manishearth @llogiq @mcarton @oli-obk, @rust-lang/infra).

@Manishearth

Tested on commit rust-lang/rust@1ecf692. Direct link to PR: <rust-lang/rust#52081> 💔 clippy-driver on windows: test-pass → test-fail (cc @Manishearth @llogiq @mcarton @oli-obk, @rust-lang/infra). 💔 clippy-driver on linux: test-pass → test-fail (cc @Manishearth @llogiq @mcarton @oli-obk, @rust-lang/infra).

rust-lang/rust#52081 stabilized proc macros, but quote is still unstable, so you need to explicitly enable that feature.

Fixes test failures caused by rust-lang#52081

Update clippy Fixes test failures caused by #52081

rust-lang/rust#52081 updated the name of the main feature required for proc-macro-related sub features.

Fixes test failures caused by rust-lang/rust#52081

rust-highfive assigned aturon Jul 5, 2018

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jul 5, 2018

alexcrichton mentioned this pull request Jul 5, 2018

Stabilize use_extern_macros #50911

Merged

rust-highfive assigned nikomatsakis and unassigned aturon Jul 5, 2018

alexcrichton mentioned this pull request Jul 5, 2018

Tracking issue for RFC 1566: Procedural macros #38356

Closed

31 tasks

petrochenkov self-assigned this Jul 5, 2018

petrochenkov reviewed Jul 5, 2018

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jebrosen mentioned this pull request Jul 6, 2018

Merge proc_macro_ expansion feature gates as proc_macro_hygiene #52121

Merged

LukasKalbertodt mentioned this pull request Jul 7, 2018

Rewrite most of the crate with updated dependencies auto-impl-rs/auto_impl#9

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ubnt-intrepid mentioned this pull request Jul 8, 2018

Tracking issue for code generation tsukuyomi-rs/tsukuyomi#80

Closed

4 tasks

est31 mentioned this pull request Jul 8, 2018

Compile with stable Rust rwf2/Rocket#19

Closed

11 tasks

jebrosen mentioned this pull request Jul 9, 2018

Tracking issue for proc_macro conversion rwf2/Rocket#693

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11 tasks

rust-highfive assigned nrc and unassigned nikomatsakis and petrochenkov Jul 9, 2018

petrochenkov mentioned this pull request Jul 10, 2018

Tracking issue for "macro naming and modularisation" (RFC #1561) #35896

Closed

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 Jul 16, 2018

bors mentioned this pull request Jul 16, 2018

Rollup of 9 pull requests #52433

Merged

bors merged commit 65f3007 into rust-lang:master Jul 16, 2018

Manishearth added a commit to rust-lang/rust-clippy that referenced this pull request Jul 16, 2018

Update mini-macro post proc macro stabilization

3246a1f

rust-lang/rust#52081 stabilized proc macros, but quote is still unstable, so you need to explicitly enable that feature.

Manishearth added a commit to Manishearth/rust that referenced this pull request Jul 16, 2018

Update clippy

536005a

Fixes test failures caused by rust-lang#52081

Manishearth mentioned this pull request Jul 16, 2018

Update clippy #52448

Merged

bors added a commit that referenced this pull request Jul 17, 2018

Auto merge of #52448 - Manishearth:clippyup, r=Mark-Simulacrum

55c04ba

Update clippy Fixes test failures caused by #52081

dtolnay mentioned this pull request Jul 17, 2018

Update to fine-grained proc_macro feature gates dtolnay/proc-macro2#107

Merged

bjorn3 mentioned this pull request Jul 17, 2018

Added initial Rust codegen-meta implementation. bytecodealliance/cranelift#403

Merged

koute mentioned this pull request Jul 17, 2018

Fails to build on recent nightly (2018-07-17) koute/stdweb#252

Closed

alexcrichton added this to the Rust 2018 Preview 2 milestone Jul 17, 2018

Arnavion pushed a commit to Arnavion/fac-rs that referenced this pull request Jul 17, 2018

Fixed build on latest nightly.

c4515c0

rust-lang/rust#52081 updated the name of the main feature required for proc-macro-related sub features.

SimonSapin mentioned this pull request Jul 17, 2018

Bad error message when using attributes proc_macro #52469

Closed

lambda-fairy mentioned this pull request Jul 18, 2018

Build fails on rustc 1.29.0-nightly (1ecf6929d 2018-07-16) lambda-fairy/maud#139

Closed

alexcrichton deleted the proc-macro-stable branch July 18, 2018 14:50

pitdicker mentioned this pull request Jul 18, 2018

Fix wasm-bindgen feature rust-random/rand#559

Merged

ef4 mentioned this pull request Jul 20, 2018

Unable to init project because of compiler errors with proc-macro2 rustwasm/wasm-pack#219

Closed

lachlansneff mentioned this pull request Jul 27, 2018

Port the DSL to Rust bytecodealliance/cranelift#342

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petrochenkov mentioned this pull request Sep 17, 2018

Updated RELEASES.md for 1.30.0 #54300

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azriel91 mentioned this pull request Oct 24, 2018

[Proof of concept] derive specs system amethyst/specs#499

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juaby mentioned this pull request Oct 28, 2018

error[E0554]: #![feature] may not be used on the stable release channel google/tarpc#201

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flip1995 pushed a commit to flip1995/rust-clippy that referenced this pull request May 5, 2020

Update clippy

dc8e75d

Fixes test failures caused by rust-lang/rust#52081

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rustc: Stabilize the proc_macro feature #52081

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rustc: Stabilize the `proc_macro` feature #52081

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