Move target checking for #[lang] to the attribute parser by JonathanBrouwer · Pull Request #158223 · rust-lang/rust

JonathanBrouwer · 2026-06-21T19:10:07Z

Work towards removing the ALL_TARGETS list.

r? @mejrs

rustbot · 2026-06-21T19:33:44Z

Some changes occurred to diagnostic attributes.

cc @mejrs

Some changes occurred in compiler/rustc_attr_parsing

cc @jdonszelmann

rustbot · 2026-06-22T15:09:52Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

mejrs

Aaaaaa that '_ is very infectious.

r=me if not addressing other comment

View changes since this review

mejrs · 2026-06-23T10:10:47Z

+        let allowed_targets: &[_] = if lang_item == LangItem::PanicImpl {
+            &[Allow(Target::Fn), Allow(Target::ForeignFn)]
+        } else {
+            &[Allow(lang_item.target())]
+        };


Thoughts on changing LangItem::target to return &[Target] so that we don't need to special case PanicImpl here? Although I think I can live with this if we aren't getting more multi target lang items.

#[lang = "panic_impl"] may be gone in the near future. I have a branch to replace it with an EII. It is mostly blocked on some diagnostics improvements right now.

I did it this way because the panicimpl lang item will probably soon be replaced with EEIs.
The fact that panic_impl is valid on foreign functions at all is already a complete hack, I hope this won't be used in more places

Yeah, I expect that all future cases will either use EII or #[rustc_std_internal_symbol].

JonathanBrouwer · 2026-06-23T10:33:25Z

@bors r=mejrs rollup

rust-bors · 2026-06-23T10:33:29Z

📌 Commit 9ad6dbf has been approved by mejrs

It is now in the queue for this repository.

@mejrs

Move target checking for #[lang] to the attribute parser Work towards removing the `ALL_TARGETS` list. r? @mejrs

…uwer Rollup of 16 pull requests Successful merges: - #156885 (Fix misattributed type inference error span for index expressions) - #157271 (simplify some `proc_macro` things) - #157883 (Remove strict invariant node_type on hir_type during ty privacy visit) - #157921 (trait solver: Resolve region vars in max universe) - #157960 (delegation: add support for infers in generics) - #158105 (Extract all instance shim variants into new `ShimKind` enum) - #158207 (Resolver: local/external split of `resolve_ident_in_module_non_globs_unadjusted` ) - #158279 (Follow goto and drop when linting unreachable code) - #157807 (don't ice on non-lifetime binders under `-Zassumptions-on-binders`) - #158020 (Update mingw-w64 C toolchain) - #158222 (format: ignore println newline in foreign format hints) - #158223 (Move target checking for #[lang] to the attribute parser) - #158252 (Use `cfg_select` in `std::os`) - #158257 ( fix escaping placeholder check in next solver normalization folder) - #158274 (triagebot: Stop pinging myself) - #158282 (slice_split_once: bounds check optimization note) Failed merges: - #158256 (Avoid parser panics bubbling out to proc macros)

@mejrs

Move target checking for #[lang] to the attribute parser Work towards removing the `ALL_TARGETS` list. r? @mejrs

@mejrs

Move target checking for #[lang] to the attribute parser Work towards removing the `ALL_TARGETS` list. r? @mejrs

…uwer Rollup of 23 pull requests Successful merges: - #158315 (`rust-analyzer` subtree update) - #155739 (Add temporary scope to assert_eq and assert_ne) - #156885 (Fix misattributed type inference error span for index expressions) - #157271 (simplify some `proc_macro` things) - #157883 (Remove strict invariant node_type on hir_type during ty privacy visit) - #157921 (trait solver: Resolve region vars in max universe) - #157960 (delegation: add support for infers in generics) - #157983 (Lift the same-signature restriction for `extern "tail"`) - #158105 (Extract all instance shim variants into new `ShimKind` enum) - #158207 (Resolver: local/external split of `resolve_ident_in_module_non_globs_unadjusted` ) - #158279 (Follow goto and drop when linting unreachable code) - #157527 (Move derive tests into their dedicated folder) - #157807 (don't ice on non-lifetime binders under `-Zassumptions-on-binders`) - #158020 (Update mingw-w64 C toolchain) - #158222 (format: ignore println newline in foreign format hints) - #158223 (Move target checking for #[lang] to the attribute parser) - #158252 (Use `cfg_select` in `std::os`) - #158257 ( fix escaping placeholder check in next solver normalization folder) - #158263 (Only load the feature list once in the entire resolver) - #158274 (triagebot: Stop pinging myself) - #158282 (slice_split_once: bounds check optimization note) - #158300 (Improve unknown crate_type diagnostic suggestions) - #158304 (mailmap: update mu001999) Failed merges: - #158256 (Avoid parser panics bubbling out to proc macros)

@mejrs

Move target checking for #[lang] to the attribute parser Work towards removing the `ALL_TARGETS` list. r? @mejrs

Rollup of 27 pull requests Successful merges: - #158315 (`rust-analyzer` subtree update) - #155739 (Add temporary scope to assert_eq and assert_ne) - #156885 (Fix misattributed type inference error span for index expressions) - #157271 (simplify some `proc_macro` things) - #157883 (Remove strict invariant node_type on hir_type during ty privacy visit) - #157921 (trait solver: Resolve region vars in max universe) - #157960 (delegation: add support for infers in generics) - #157983 (Lift the same-signature restriction for `extern "tail"`) - #158053 (Optimize network address parser) - #158105 (Extract all instance shim variants into new `ShimKind` enum) - #158207 (Resolver: local/external split of `resolve_ident_in_module_non_globs_unadjusted` ) - #158279 (Follow goto and drop when linting unreachable code) - #157527 (Move derive tests into their dedicated folder) - #157807 (don't ice on non-lifetime binders under `-Zassumptions-on-binders`) - #158020 (Update mingw-w64 C toolchain) - #158039 (c-variadic: test that we use equality up to free lifetimes) - #158222 (format: ignore println newline in foreign format hints) - #158223 (Move target checking for #[lang] to the attribute parser) - #158252 (Use `cfg_select` in `std::os`) - #158257 ( fix escaping placeholder check in next solver normalization folder) - #158263 (Only load the feature list once in the entire resolver) - #158267 (FromUtf8Error::into_utf8_lossy better example and suggest use) - #158274 (triagebot: Stop pinging myself) - #158282 (slice_split_once: bounds check optimization note) - #158300 (Improve unknown crate_type diagnostic suggestions) - #158304 (mailmap: update mu001999) - #158309 (Update `rustc-literal-escaper` version to `0.0.8`) Failed merges: - #158256 (Avoid parser panics bubbling out to proc macros)

@mejrs

Move target checking for #[lang] to the attribute parser Work towards removing the `ALL_TARGETS` list. r? @mejrs

Rollup of 35 pull requests Successful merges: - #158315 (`rust-analyzer` subtree update) - #158336 (Stop excluding `stdarch` test crates from `rust-src`) - #155739 (Add temporary scope to assert_eq and assert_ne) - #156885 (Fix misattributed type inference error span for index expressions) - #157271 (simplify some `proc_macro` things) - #157419 (move rustc_type_ir Term things to term_kind.rs) - #157883 (Remove strict invariant node_type on hir_type during ty privacy visit) - #157921 (trait solver: Resolve region vars in max universe) - #157960 (delegation: add support for infers in generics) - #157983 (Lift the same-signature restriction for `extern "tail"`) - #158053 (Optimize network address parser) - #158105 (Extract all instance shim variants into new `ShimKind` enum) - #158207 (Resolver: local/external split of `resolve_ident_in_module_non_globs_unadjusted` ) - #158279 (Follow goto and drop when linting unreachable code) - #157527 (Move derive tests into their dedicated folder) - #157807 (don't ice on non-lifetime binders under `-Zassumptions-on-binders`) - #157939 (Reorganize `tests/ui/issues` [8/N]) - #157946 (Make `char::is_private_use` and `char::is_assigned` unstably public) - #158003 (Reorganize `tests/ui/issues` [9/N]) - #158020 (Update mingw-w64 C toolchain) - #158039 (c-variadic: test that we use equality up to free lifetimes) - #158060 (Reorganize `tests/ui/issues` [10/N]) - #158222 (format: ignore println newline in foreign format hints) - #158223 (Move target checking for #[lang] to the attribute parser) - #158252 (Use `cfg_select` in `std::os`) - #158263 (Only load the feature list once in the entire resolver) - #158267 (FromUtf8Error::into_utf8_lossy better example and suggest use) - #158272 (Reorganize `tests/ui/issues` [13/N]) - #158274 (triagebot: Stop pinging myself) - #158282 (slice_split_once: bounds check optimization note) - #158300 (Improve unknown crate_type diagnostic suggestions) - #158304 (mailmap: update mu001999) - #158309 (Update `rustc-literal-escaper` version to `0.0.8`) - #158314 (Fix incorrect unsafe debug assertion in unchecked_div_exact) - #158326 (Add `io::ErrorKind::TooManyOpenFiles`)

@mejrs

Move target checking for #[lang] to the attribute parser Work towards removing the `ALL_TARGETS` list. r? @mejrs

Rollup of 35 pull requests Successful merges: - #158315 (`rust-analyzer` subtree update) - #158336 (Stop excluding `stdarch` test crates from `rust-src`) - #155739 (Add temporary scope to assert_eq and assert_ne) - #156885 (Fix misattributed type inference error span for index expressions) - #157271 (simplify some `proc_macro` things) - #157419 (move rustc_type_ir Term things to term_kind.rs) - #157883 (Remove strict invariant node_type on hir_type during ty privacy visit) - #157921 (trait solver: Resolve region vars in max universe) - #157960 (delegation: add support for infers in generics) - #157983 (Lift the same-signature restriction for `extern "tail"`) - #158053 (Optimize network address parser) - #158105 (Extract all instance shim variants into new `ShimKind` enum) - #158207 (Resolver: local/external split of `resolve_ident_in_module_non_globs_unadjusted` ) - #158279 (Follow goto and drop when linting unreachable code) - #157527 (Move derive tests into their dedicated folder) - #157807 (don't ice on non-lifetime binders under `-Zassumptions-on-binders`) - #157939 (Reorganize `tests/ui/issues` [8/N]) - #157946 (Make `char::is_private_use` and `char::is_assigned` unstably public) - #158003 (Reorganize `tests/ui/issues` [9/N]) - #158020 (Update mingw-w64 C toolchain) - #158039 (c-variadic: test that we use equality up to free lifetimes) - #158060 (Reorganize `tests/ui/issues` [10/N]) - #158222 (format: ignore println newline in foreign format hints) - #158223 (Move target checking for #[lang] to the attribute parser) - #158252 (Use `cfg_select` in `std::os`) - #158263 (Only load the feature list once in the entire resolver) - #158267 (FromUtf8Error::into_utf8_lossy better example and suggest use) - #158272 (Reorganize `tests/ui/issues` [13/N]) - #158274 (triagebot: Stop pinging myself) - #158282 (slice_split_once: bounds check optimization note) - #158300 (Improve unknown crate_type diagnostic suggestions) - #158304 (mailmap: update mu001999) - #158309 (Update `rustc-literal-escaper` version to `0.0.8`) - #158314 (Fix incorrect unsafe debug assertion in unchecked_div_exact) - #158326 (Add `io::ErrorKind::TooManyOpenFiles`)

@mejrs

Rollup merge of #158223 - JonathanBrouwer:lang-target, r=mejrs Move target checking for #[lang] to the attribute parser Work towards removing the `ALL_TARGETS` list. r? @mejrs

JonathanBrouwer · 2026-06-25T10:56:32Z

@rust-timer build 1555e18
Perf run for #158342

rust-timer · 2026-06-25T18:42:31Z

Finished benchmarking commit (1555e18): comparison URL.

Overall result: ❌✅ regressions and 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)	0.4%	[0.4%, 0.4%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.2%	[-0.2%, -0.2%]	1
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary 4.7%, secondary -2.7%)

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

	mean	range	count
Regressions ❌ (primary)	4.7%	[4.7%, 4.7%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.7%	[-2.7%, -2.7%]	1
All ❌✅ (primary)	4.7%	[4.7%, 4.7%]	1

Cycles

Results (secondary 12.0%)

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)	12.0%	[2.3%, 21.7%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 503.101s -> 504.026s (0.18%)
Artifact size: 353.51 MiB -> 353.59 MiB (0.02%)

Rollup of 35 pull requests Successful merges: - rust-lang/rust#158315 (`rust-analyzer` subtree update) - rust-lang/rust#158336 (Stop excluding `stdarch` test crates from `rust-src`) - rust-lang/rust#155739 (Add temporary scope to assert_eq and assert_ne) - rust-lang/rust#156885 (Fix misattributed type inference error span for index expressions) - rust-lang/rust#157271 (simplify some `proc_macro` things) - rust-lang/rust#157419 (move rustc_type_ir Term things to term_kind.rs) - rust-lang/rust#157883 (Remove strict invariant node_type on hir_type during ty privacy visit) - rust-lang/rust#157921 (trait solver: Resolve region vars in max universe) - rust-lang/rust#157960 (delegation: add support for infers in generics) - rust-lang/rust#157983 (Lift the same-signature restriction for `extern "tail"`) - rust-lang/rust#158053 (Optimize network address parser) - rust-lang/rust#158105 (Extract all instance shim variants into new `ShimKind` enum) - rust-lang/rust#158207 (Resolver: local/external split of `resolve_ident_in_module_non_globs_unadjusted` ) - rust-lang/rust#158279 (Follow goto and drop when linting unreachable code) - rust-lang/rust#157527 (Move derive tests into their dedicated folder) - rust-lang/rust#157807 (don't ice on non-lifetime binders under `-Zassumptions-on-binders`) - rust-lang/rust#157939 (Reorganize `tests/ui/issues` [8/N]) - rust-lang/rust#157946 (Make `char::is_private_use` and `char::is_assigned` unstably public) - rust-lang/rust#158003 (Reorganize `tests/ui/issues` [9/N]) - rust-lang/rust#158020 (Update mingw-w64 C toolchain) - rust-lang/rust#158039 (c-variadic: test that we use equality up to free lifetimes) - rust-lang/rust#158060 (Reorganize `tests/ui/issues` [10/N]) - rust-lang/rust#158222 (format: ignore println newline in foreign format hints) - rust-lang/rust#158223 (Move target checking for #[lang] to the attribute parser) - rust-lang/rust#158252 (Use `cfg_select` in `std::os`) - rust-lang/rust#158263 (Only load the feature list once in the entire resolver) - rust-lang/rust#158267 (FromUtf8Error::into_utf8_lossy better example and suggest use) - rust-lang/rust#158272 (Reorganize `tests/ui/issues` [13/N]) - rust-lang/rust#158274 (triagebot: Stop pinging myself) - rust-lang/rust#158282 (slice_split_once: bounds check optimization note) - rust-lang/rust#158300 (Improve unknown crate_type diagnostic suggestions) - rust-lang/rust#158304 (mailmap: update mu001999) - rust-lang/rust#158309 (Update `rustc-literal-escaper` version to `0.0.8`) - rust-lang/rust#158314 (Fix incorrect unsafe debug assertion in unchecked_div_exact) - rust-lang/rust#158326 (Add `io::ErrorKind::TooManyOpenFiles`)

rustbot added A-attributes Area: Attributes (`#[…]`, `#![…]`) 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 Jun 21, 2026

JonathanBrouwer force-pushed the lang-target branch from d920642 to 6f84b3b Compare June 21, 2026 19:32

rustbot assigned mejrs Jun 21, 2026

JonathanBrouwer marked this pull request as ready for review June 21, 2026 19:33

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 Jun 21, 2026

JonathanBrouwer force-pushed the lang-target branch from 6f84b3b to dfb0455 Compare June 21, 2026 19:41

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JonathanBrouwer added 3 commits June 22, 2026 17:09

Move target checking for #[lang] to the attribute parser

f99e894

Add lifetime parameter to AllowedTargets

b8758a3

Use AllowedTargets::ManuallyChecked for LangParser

9ad6dbf

JonathanBrouwer force-pushed the lang-target branch from dfb0455 to 9ad6dbf Compare June 22, 2026 15:09

mejrs approved these changes Jun 23, 2026

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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 Jun 23, 2026

JonathanBrouwer mentioned this pull request Jun 23, 2026

Rollup of 16 pull requests #158301

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JonathanBrouwer mentioned this pull request Jun 23, 2026

Rollup of 23 pull requests #158316

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JonathanBrouwer mentioned this pull request Jun 23, 2026

Rollup of 23 pull requests #158324

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jhpratt added a commit to jhpratt/rust that referenced this pull request Jun 24, 2026

Rollup merge of rust-lang#158223 - JonathanBrouwer:lang-target, r=mejrs

399855f

Move target checking for #[lang] to the attribute parser Work towards removing the `ALL_TARGETS` list. r? @mejrs

jhpratt mentioned this pull request Jun 24, 2026

Rollup of 27 pull requests #158335

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jhpratt added a commit to jhpratt/rust that referenced this pull request Jun 24, 2026

Rollup merge of rust-lang#158223 - JonathanBrouwer:lang-target, r=mejrs

fe2bfaf

Move target checking for #[lang] to the attribute parser Work towards removing the `ALL_TARGETS` list. r? @mejrs

This was referenced Jun 24, 2026

Rollup of 34 pull requests #158337

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Rollup of 35 pull requests #158342

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JonathanBrouwer mentioned this pull request Jun 24, 2026

[CI] Rollup of 35 pull requests #158354

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rust-bors Bot merged commit df53430 into rust-lang:main Jun 25, 2026
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rustbot added this to the 1.98.0 milestone Jun 25, 2026

rust-timer added a commit that referenced this pull request Jun 25, 2026

Unrolled build for #158223

1555e18

Rollup merge of #158223 - JonathanBrouwer:lang-target, r=mejrs Move target checking for #[lang] to the attribute parser Work towards removing the `ALL_TARGETS` list. r? @mejrs

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Overall result: ❌✅ regressions and improvements - no action needed

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