`rustc_builtin_macros` cleanup, part 8 by cyrgani · Pull Request #163485 · rust-lang/rust

cyrgani · 2026-09-29T12:47:02Z

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This PR is roughly split into three parts:

The first few commits add helpers to ExtCtxt to both construct some common AST elements in an easier way. They also change some Ident arguments to Symbol to avoid the annoying call-site pattern of repeating the span (cx.some_method(span, Ident::new(name, span), ...)).
The next few commits focus on the derive infrastructure cleanup a bit.
The further following commits make Path construction faster and remove the new_path remnant of the old local path version.

Previous PR: #163389

r? @nnethercote

jieyouxu · 2026-09-29T13:01:32Z

@bors try @rust-timer queue

[PERF] `rustc_builtin_macros` cleanup, part 8

rust-bors · 2026-09-29T14:04:44Z

☀️ Try build successful (CI)
Build commit: 0bcf40d (0bcf40dc0c6b1a2253f428ebaa94e0e54aa98617)
Base parent: b46c90c (b46c90c5619a16a0c7e4d0f4e9e1ad4db4cf106e)

rust-timer · 2026-09-29T16:15:34Z

Finished benchmarking commit (0bcf40d): comparison URL.

Overall result: ✅ improvements - no action needed

Benchmarking means the PR may be perf-sensitive. Consider adding rollup=never if this change is not fit for rolling up.

@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.2%	[-0.3%, -0.2%]	7
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary 0.7%, secondary 2.1%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	2.2%	[2.2%, 2.2%]	1
Regressions ❌ (secondary)	3.6%	[3.4%, 3.8%]	3
Improvements ✅ (primary)	-0.9%	[-0.9%, -0.9%]	1
Improvements ✅ (secondary)	-2.3%	[-2.3%, -2.3%]	1
All ❌✅ (primary)	0.7%	[-0.9%, 2.2%]	2

Cycles

This perf run didn't have relevant results for this metric.

Binary size

This perf run didn't have relevant results for this metric.

Bootstrap: 491.711s -> 491.207s (-0.10%)
Artifact size: 406.38 MiB -> 406.39 MiB (0.00%)

rustbot · 2026-10-09T12:24:02Z

Some changes occurred in compiler/rustc_builtin_macros/src/autodiff.rs

cc @ZuseZ4

nnethercote

I think leaving path_std! and pathvec! seems fine, though perhaps the latter should be renamed path_vec!.

I don't have strong opinions about the substructure change, though the extra error messages are annoying.

View changes since this review

nnethercote · 2026-10-16T14:20:41Z

@petrochenkov: do you have opinions about the first commit ("rename Legacy* macro kinds to Ast*")?

petrochenkov · 2026-10-16T14:36:41Z

@petrochenkov: do you have opinions about the first commit ("rename Legacy* macro kinds to Ast*")?

Yes :D #163485 (comment)

These are especially useful for constructing types and paths referring to primitives.

As I understand it, this would only be needed if the crate defining the derive macros (which is `core`) was using edition 2015. Since `core` uses edition 2024, there is in this case no difference between global and local and we can skip the leading `::`.

Previously, `std_path` converted the given `&[Symbol]` to a `Vec<Ident>` by prepending a `$crate::` and mapping each `Symbol` to an `Ident`. This commit changes the functions that previously took `Vec<Ident>` to directly take `Path` instead, and updates `std_path` to also directly return a `Path`. This allows directly prepending the `$crate::` to the resulting `segments`. It also allows constructing a `Path` from `&[Ident]` instead of `Vec<Ident>`.

`new_path` is just a obsolete trivial wrapper around `cx.std_path_all` now.

Passing around `type_ident` everywhere is what the old code did as well, but it's actually only needed in two places.

And rename other places that were called `ident` but took a `Symbol` to `name` too.

cyrgani · 2026-10-20T21:21:57Z

I added a commit that uses name instead of ident where appropriate and removed the two commits for the path macros and the broader use of Substructure for now.
@rustbot ready

nnethercote · 2026-10-21T08:18:06Z

Thanks!

@bors r+

rust-bors · 2026-10-21T08:18:10Z

📌 Commit a85d97f has been approved by nnethercote

It is now in the queue for this repository.

🌲 The tree is currently closed for pull requests below priority 5. This pull request will be tested once the tree is reopened.

Reason for tree closure: spurious failures

@nnethercote

…rcote `rustc_builtin_macros` cleanup, part 8 This PR is roughly split into three parts: - The first few commits add helpers to `ExtCtxt` to both construct some common AST elements in an easier way. They also change some `Ident` arguments to `Symbol` to avoid the annoying call-site pattern of repeating the span (`cx.some_method(span, Ident::new(name, span), ...)`). - The next few commits focus on the derive infrastructure cleanup a bit. - The further following commits make `Path` construction faster and remove the `new_path` remnant of the old local path version. Previous PR: rust-lang#163389 r? @nnethercote

…uwer Rollup of 8 pull requests Successful merges: - #162460 (Feat - `#[inline(always)] + #[target_feature(enable = "....")]` #2) - #163485 (`rustc_builtin_macros` cleanup, part 8) - #164578 (Don't ignore unknown LLVM diagnostics) - #162369 (Document the `recursion_limit` built-in attribute) - #162840 (tier 3 target policy: target CPU and features must be supported by upstream backend) - #164330 (Skip redundant monomorphization checks) - #164656 (stabilize ExitCodeExt for Windows) - #164660 (Touch up attribute docs)

@nnethercote

…rcote `rustc_builtin_macros` cleanup, part 8 This PR is roughly split into three parts: - The first few commits add helpers to `ExtCtxt` to both construct some common AST elements in an easier way. They also change some `Ident` arguments to `Symbol` to avoid the annoying call-site pattern of repeating the span (`cx.some_method(span, Ident::new(name, span), ...)`). - The next few commits focus on the derive infrastructure cleanup a bit. - The further following commits make `Path` construction faster and remove the `new_path` remnant of the old local path version. Previous PR: rust-lang#163389 r? @nnethercote

rust-bors · 2026-10-21T16:22:41Z

⌛ Testing commit a85d97f with merge ae9d6d5...

Workflow: https://github.com/rust-lang/rust/actions/runs/39634220880

@nnethercote

`rustc_builtin_macros` cleanup, part 8 This PR is roughly split into three parts: - The first few commits add helpers to `ExtCtxt` to both construct some common AST elements in an easier way. They also change some `Ident` arguments to `Symbol` to avoid the annoying call-site pattern of repeating the span (`cx.some_method(span, Ident::new(name, span), ...)`). - The next few commits focus on the derive infrastructure cleanup a bit. - The further following commits make `Path` construction faster and remove the `new_path` remnant of the old local path version. Previous PR: #163389 r? @nnethercote

JonathanBrouwer · 2026-10-21T16:35:16Z

@bors yield

rust-bors · 2026-10-21T16:36:20Z

Auto build was cancelled. Cancelled workflows:

https://github.com/rust-lang/rust/actions/runs/39634220880

The next pull request likely to be tested is #164699.

…uwer Rollup of 13 pull requests Successful merges: - #162460 (Feat - `#[inline(always)] + #[target_feature(enable = "....")]` #2) - #163485 (`rustc_builtin_macros` cleanup, part 8) - #164457 (Add `vec_visualizer` lldb test) - #161253 (Implement `AsMut<T>` and `AsRef<T>` for `!`.) - #162369 (Document the `recursion_limit` built-in attribute) - #162840 (tier 3 target policy: target CPU and features must be supported by upstream backend) - #164329 (use default_field_values in declare_lint) - #164330 (Skip redundant monomorphization checks) - #164527 (doc: added addtional docs for Write) - #164656 (stabilize ExitCodeExt for Windows) - #164660 (Touch up attribute docs) - #164681 (tidy: use repository-relative path for style checks) - #164688 (re-enable test_dir_remove_dir test on QNX)

@nnethercote

Rollup merge of #163485 - cyrgani:builtin-macros-8, r=nnethercote `rustc_builtin_macros` cleanup, part 8 This PR is roughly split into three parts: - The first few commits add helpers to `ExtCtxt` to both construct some common AST elements in an easier way. They also change some `Ident` arguments to `Symbol` to avoid the annoying call-site pattern of repeating the span (`cx.some_method(span, Ident::new(name, span), ...)`). - The next few commits focus on the derive infrastructure cleanup a bit. - The further following commits make `Path` construction faster and remove the `new_path` remnant of the old local path version. Previous PR: #163389 r? @nnethercote

rust-timer · 2026-10-22T04:01:50Z

Note

This PR was benchmarked as part of triage of its containing rollup: triage URL.

Finished benchmarking commit (6351b4b): comparison URL.

Overall result: ✅ improvements - no action needed

@rustbot label: -perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.1%	[-0.1%, -0.1%]	2
Improvements ✅ (secondary)	-0.2%	[-0.3%, -0.1%]	11
All ❌✅ (primary)	-0.1%	[-0.1%, -0.1%]	2

Max RSS (memory usage)

Results (secondary -2.3%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.3%	[-2.4%, -2.2%]	2
All ❌✅ (primary)	-	-	0

Cycles

This perf run didn't have relevant results for this metric.

Binary size

This perf run didn't have relevant results for this metric.

Artifact size: 406.57 MiB -> 406.49 MiB (-0.02%)

rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Sep 29, 2026

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rust-bors Bot pushed a commit that referenced this pull request Sep 29, 2026

Auto merge of #163485 - cyrgani:builtin-macros-8, r=<try>

0bcf40d

[PERF] `rustc_builtin_macros` cleanup, part 8

petrochenkov reviewed Sep 29, 2026

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rust-cloud-vms Bot force-pushed the builtin-macros-8 branch from 7eace55 to c96f45e Compare October 9, 2026 12:08

rustbot assigned nnethercote Oct 9, 2026

cyrgani changed the title ~~[PERF] rustc_builtin_macros cleanup, part 8~~ rustc_builtin_macros cleanup, part 8 Oct 9, 2026

cyrgani marked this pull request as ready for review October 9, 2026 12:23

rustbot 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 Oct 9, 2026

cyrgani commented Oct 9, 2026

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Comment thread compiler/rustc_builtin_macros/src/deriving/generic/mod.rs Outdated

nnethercote reviewed Oct 16, 2026

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Comment thread compiler/rustc_expand/src/build.rs Outdated

Comment thread compiler/rustc_builtin_macros/src/alloc_error_handler.rs Outdated

Comment thread compiler/rustc_expand/src/build.rs Outdated

nnethercote 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 Oct 16, 2026

cyrgani added 4 commits October 20, 2026 21:04

rename Legacy* macro kinds to Ast*

d262a58

add cx.ty_sym and cx.path_sym

889a646

These are especially useful for constructing types and paths referring to primitives.

cx.param only needs a Symbol

0469c46

cx.pat_ident only needs a Symbol

2f0211e

cyrgani added 5 commits October 20, 2026 21:04

remove new_path

1341e1d

`new_path` is just a obsolete trivial wrapper around `cx.std_path_all` now.

do the Self constructor fix properly

98fb06a

Passing around `type_ident` everywhere is what the old code did as well, but it's actually only needed in two places.

rename _sym prefix to _name

a85d97f

And rename other places that were called `ident` but took a `Symbol` to `name` too.

rust-cloud-vms Bot force-pushed the builtin-macros-8 branch from c96f45e to a85d97f Compare October 20, 2026 21:17

rustbot 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 Oct 20, 2026

rust-bors Bot 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-review Status: Awaiting review from the assignee but also interested parties. labels Oct 21, 2026

JonathanBrouwer mentioned this pull request Oct 21, 2026

Rollup of 8 pull requests #164687

Closed

This was referenced Oct 21, 2026

Rollup of 14 pull requests #164697

Closed

Rollup of 13 pull requests #164699

Merged

rust-bors Bot merged commit 2ede6da into rust-lang:main Oct 21, 2026
14 of 15 checks passed

rustbot added this to the 1.101.0 milestone Oct 21, 2026

cyrgani deleted the builtin-macros-8 branch October 21, 2026 20:15

github-actions Bot mentioned this pull request Oct 22, 2026

Toolchain upgrade to nightly-2026-10-22 flux-rs/flux#1847

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Overall result: ✅ improvements - no action needed

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