Some minor ast validation and visiting cleanups by oli-obk · Pull Request #158998 · rust-lang/rust

oli-obk · 2026-07-09T08:18:10Z

Originally I wanted to mutate the AST during validation, but I will first explore mutating it less and moving more things to arenas. Let's land the parts unrelated to actual mutation.

Original PR description

I think this could be useful for having to handle weird cases less later in the compiler. Either by replacing things with error nodes (e.g. ty/expr), or by editing out the invalid elements (`const fn` -> `fn` in trait methods or trait impls).

petrochenkov · 2026-07-09T10:53:54Z

Either by replacing things with error nodes (e.g. ty/expr), or by editing out the invalid elements (const fn -> fn in trait methods or trait impls).

Can do this in AST lowering, which happens not much later than AST validation?

Historically, the use of mutable AST visitors was minimized to prepare for making AST immutable (or as immutable as possible) and allocating in on arena. Of course nobody ended up having enough resources for this large work.

oli-obk · 2026-07-13T14:15:47Z

Historically, the use of mutable AST visitors was minimized to prepare for making AST immutable (or as immutable as possible) and allocating in on arena. Of course nobody ended up having enough resources for this large work.

I'll explore doing more things in that direction instead

petrochenkov · 2026-07-13T14:31:29Z

@bors r+ rollup

rust-bors · 2026-07-13T14:31:32Z

📌 Commit 03afa49 has been approved by petrochenkov

It is now in the queue for this repository.

Some minor ast validation and visiting cleanups Originally I wanted to mutate the AST during validation, but I will first explore mutating it less and moving more things to arenas. Let's land the parts unrelated to actual mutation. <details> <summary>Original PR description</summary> I think this could be useful for having to handle weird cases less later in the compiler. Either by replacing things with error nodes (e.g. ty/expr), or by editing out the invalid elements (`const fn` -> `fn` in trait methods or trait impls). </details>

…uwer Rollup of 13 pull requests Successful merges: - #159039 (resolve: fix effective visibilities for items in ambiguous glob sets) - #157706 (Deny `todo!()` in tidy) - #156712 (Pointer authentication config and user facing options) - #158535 (Support `#[track_caller]` on EII declarations) - #158632 (First steps of late-bound turbofishing (place FnDef behind a dummy binder)) - #159002 (Small refactorings in `need_type_info` module) - #159202 (Bump rustc-demangle to 0.1.28) - #159216 (Avoid using probe self_ty for delegation arguments) - #159222 (semicolon_in_expressions_from_macros: Lint on non-local macros too) - #156609 (Consider structurally impossible Sized predicates in MIR) - #158854 (Add `#[rustc_test_entrypoint_marker]`) - #158998 (Some minor ast validation and visiting cleanups) - #159123 (doc: clarify attr parser APIs)

Some minor ast validation and visiting cleanups Originally I wanted to mutate the AST during validation, but I will first explore mutating it less and moving more things to arenas. Let's land the parts unrelated to actual mutation. <details> <summary>Original PR description</summary> I think this could be useful for having to handle weird cases less later in the compiler. Either by replacing things with error nodes (e.g. ty/expr), or by editing out the invalid elements (`const fn` -> `fn` in trait methods or trait impls). </details>

…uwer Rollup of 14 pull requests Successful merges: - #159039 (resolve: fix effective visibilities for items in ambiguous glob sets) - #157706 (Deny `todo!()` in tidy) - #158535 (Support `#[track_caller]` on EII declarations) - #158632 (First steps of late-bound turbofishing (place FnDef behind a dummy binder)) - #158846 (Fix unused variable warnings for diverging expressions) - #159002 (Small refactorings in `need_type_info` module) - #159202 (Bump rustc-demangle to 0.1.28) - #159216 (Avoid using probe self_ty for delegation arguments) - #159222 (semicolon_in_expressions_from_macros: Lint on non-local macros too) - #156609 (Consider structurally impossible Sized predicates in MIR) - #157993 (Expose more info about ADTs and functions in rustc_public) - #158854 (Add `#[rustc_test_entrypoint_marker]`) - #158998 (Some minor ast validation and visiting cleanups) - #159123 (doc: clarify attr parser APIs)

Some minor ast validation and visiting cleanups Originally I wanted to mutate the AST during validation, but I will first explore mutating it less and moving more things to arenas. Let's land the parts unrelated to actual mutation. <details> <summary>Original PR description</summary> I think this could be useful for having to handle weird cases less later in the compiler. Either by replacing things with error nodes (e.g. ty/expr), or by editing out the invalid elements (`const fn` -> `fn` in trait methods or trait impls). </details>

…uwer Rollup of 15 pull requests Successful merges: - #159039 (resolve: fix effective visibilities for items in ambiguous glob sets) - #157706 (Deny `todo!()` in tidy) - #156047 (Fix trait method resolution on an adjusted never type) - #158535 (Support `#[track_caller]` on EII declarations) - #158632 (First steps of late-bound turbofishing (place FnDef behind a dummy binder)) - #158846 (Fix unused variable warnings for diverging expressions) - #159002 (Small refactorings in `need_type_info` module) - #159202 (Bump rustc-demangle to 0.1.28) - #159216 (Avoid using probe self_ty for delegation arguments) - #156609 (Consider structurally impossible Sized predicates in MIR) - #157993 (Expose more info about ADTs and functions in rustc_public) - #158804 (Clarify `as_uninit_mut` may point to uninitialized memory) - #158854 (Add `#[rustc_test_entrypoint_marker]`) - #158998 (Some minor ast validation and visiting cleanups) - #159123 (doc: clarify attr parser APIs)

JonathanBrouwer · 2026-07-13T18:15:52Z

@bors try jobs=x86_64-gnu-llvm-22-3

Some minor ast validation and visiting cleanups try-job: x86_64-gnu-llvm-22-3

…uwer Rollup of 13 pull requests Successful merges: - #157706 (Deny `todo!()` in tidy) - #158535 (Support `#[track_caller]` on EII declarations) - #158632 (First steps of late-bound turbofishing (place FnDef behind a dummy binder)) - #158846 (Fix unused variable warnings for diverging expressions) - #159002 (Small refactorings in `need_type_info` module) - #159202 (Bump rustc-demangle to 0.1.28) - #159216 (Avoid using probe self_ty for delegation arguments) - #156609 (Consider structurally impossible Sized predicates in MIR) - #157993 (Expose more info about ADTs and functions in rustc_public) - #158804 (Clarify `as_uninit_mut` may point to uninitialized memory) - #158854 (Add `#[rustc_test_entrypoint_marker]`) - #158998 (Some minor ast validation and visiting cleanups) - #159123 (doc: clarify attr parser APIs)

rust-bors · 2026-07-13T20:20:08Z

☀️ Try build successful (CI)
Build commit: 49b2692 (49b269221a11079e712097ec30327062c5932345)
Base parent: 225e91c (225e91c03da22cd4b9792b83c1cfc97967101614)

Rollup merge of #158998 - oli-obk:mut_ast_valid, r=petrochenkov Some minor ast validation and visiting cleanups Originally I wanted to mutate the AST during validation, but I will first explore mutating it less and moving more things to arenas. Let's land the parts unrelated to actual mutation. <details> <summary>Original PR description</summary> I think this could be useful for having to handle weird cases less later in the compiler. Either by replacing things with error nodes (e.g. ty/expr), or by editing out the invalid elements (`const fn` -> `fn` in trait methods or trait impls). </details>

…uwer Rollup of 13 pull requests Successful merges: - rust-lang/rust#157706 (Deny `todo!()` in tidy) - rust-lang/rust#158535 (Support `#[track_caller]` on EII declarations) - rust-lang/rust#158632 (First steps of late-bound turbofishing (place FnDef behind a dummy binder)) - rust-lang/rust#158846 (Fix unused variable warnings for diverging expressions) - rust-lang/rust#159002 (Small refactorings in `need_type_info` module) - rust-lang/rust#159202 (Bump rustc-demangle to 0.1.28) - rust-lang/rust#159216 (Avoid using probe self_ty for delegation arguments) - rust-lang/rust#156609 (Consider structurally impossible Sized predicates in MIR) - rust-lang/rust#157993 (Expose more info about ADTs and functions in rustc_public) - rust-lang/rust#158804 (Clarify `as_uninit_mut` may point to uninitialized memory) - rust-lang/rust#158854 (Add `#[rustc_test_entrypoint_marker]`) - rust-lang/rust#158998 (Some minor ast validation and visiting cleanups) - rust-lang/rust#159123 (doc: clarify attr parser APIs)

Kobzol · 2026-07-21T07:48:21Z

@rust-timer build be6cb91

For #159246.

rust-timer · 2026-07-21T14:48:42Z

Finished benchmarking commit (be6cb91): comparison URL.

Overall result: ✅ improvements - no action needed

Benchmarking means the PR may be perf-sensitive. It's automatically marked not fit for rolling up. Overriding is possible but disadvised: it risks changing compiler perf.

@bors rollup=never rustc-perf
@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)	-1.8%	[-2.5%, -0.5%]	14
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary 2.2%, secondary -20.0%)

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)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-20.0%	[-23.2%, -11.6%]	13
All ❌✅ (primary)	2.2%	[2.2%, 2.2%]	1

Cycles

Results (secondary -14.4%)

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)	-14.4%	[-19.6%, -6.4%]	13
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 488.117s -> 487.409s (-0.15%)
Artifact size: 389.87 MiB -> 389.87 MiB (-0.00%)

…uwer Rollup of 13 pull requests Successful merges: - rust-lang/rust#157706 (Deny `todo!()` in tidy) - rust-lang/rust#158535 (Support `#[track_caller]` on EII declarations) - rust-lang/rust#158632 (First steps of late-bound turbofishing (place FnDef behind a dummy binder)) - rust-lang/rust#158846 (Fix unused variable warnings for diverging expressions) - rust-lang/rust#159002 (Small refactorings in `need_type_info` module) - rust-lang/rust#159202 (Bump rustc-demangle to 0.1.28) - rust-lang/rust#159216 (Avoid using probe self_ty for delegation arguments) - rust-lang/rust#156609 (Consider structurally impossible Sized predicates in MIR) - rust-lang/rust#157993 (Expose more info about ADTs and functions in rustc_public) - rust-lang/rust#158804 (Clarify `as_uninit_mut` may point to uninitialized memory) - rust-lang/rust#158854 (Add `#[rustc_test_entrypoint_marker]`) - rust-lang/rust#158998 (Some minor ast validation and visiting cleanups) - rust-lang/rust#159123 (doc: clarify attr parser APIs)

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 Jul 9, 2026

petrochenkov self-assigned this Jul 9, 2026

oli-obk added 2 commits July 13, 2026 12:21

simplify ast validation struct visiting
bd4d8f6

Use shorter borrows for FnKind
03afa49

oli-obk force-pushed the mut_ast_valid branch from 3bc0a82 to 03afa49Compare July 13, 2026 14:11

oli-obk changed the title ~~Make ast validation able to mutate the ast~~Some minor ast validation and visiting cleanupsJul 13, 2026

oli-obk marked this pull request as ready for review July 13, 2026 14:15

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 Jul 13, 2026

rust-borsBot 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 Jul 13, 2026

JonathanBrouwer mentioned this pull request Jul 13, 2026
Rollup of 13 pull requests #159231
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JonathanBrouwer mentioned this pull request Jul 13, 2026
Rollup of 14 pull requests #159236
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JonathanBrouwer mentioned this pull request Jul 13, 2026
Rollup of 15 pull requests #159240
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rust-borsBot pushed a commit that referenced this pull request Jul 13, 2026
Auto merge of#158998- oli-obk:mut_ast_valid, r=<try>
49b2692
Some minor ast validation and visiting cleanups try-job: x86_64-gnu-llvm-22-3

JonathanBrouwer mentioned this pull request Jul 13, 2026
Rollup of 13 pull requests #159246
Merged

rust-borsBot merged commit 34d04a5 into rust-lang:mainJul 13, 2026
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rustbot added this to the 1.99.0 milestone Jul 13, 2026

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Some minor ast validation and visiting cleanups - #158998

Some minor ast validation and visiting cleanups#158998
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Overall result: ✅ improvements - no action needed

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