Use `#![feature(adt_const_params)]` for static query flags by Zalathar · Pull Request #151938 · rust-lang/rust

Zalathar · 2026-02-01T03:51:53Z

As suggested by #151633 (comment), this replaces multiple clunky const booleans with a single const struct, which is a bit nicer.

This should also make it easier to experiment with statically resolving other flags, like eval_always.

There are currently no other compiler crates using feature(adt_const_params), so hopefully it's mature enough for a simple use-case like this one.

rustbot · 2026-02-01T03:51:58Z

r? @nnethercote

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Zalathar · 2026-02-01T06:32:06Z

I suppose we can double-check that this doesn't affect perf.

@bors try @rust-timer queue

Use `#![feature(adt_const_params)]` for static query flags

rust-bors · 2026-02-01T08:43:01Z

☀️ Try build successful (CI)
Build commit: c060cb7 (c060cb7007f9a1a44b132a83850085c1fdf74e80, parent: a1db344c0829cb682df4174e9370b60915751605)

rust-timer · 2026-02-01T09:23:52Z

Finished benchmarking commit (c060cb7): comparison URL.

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

Benchmarking this pull request means it may be perf-sensitive – we'll automatically label it not fit for rolling up. You can override this, but we strongly advise not to, due to possible changes in compiler perf.

@bors rollup=never
@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)	0.1%	[0.0%, 0.4%]	6
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.1%	[-0.1%, -0.1%]	1
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary 1.1%, secondary -4.4%)

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

	mean	range	count
Regressions ❌ (primary)	2.2%	[0.9%, 3.5%]	2
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-1.0%	[-1.0%, -1.0%]	1
Improvements ✅ (secondary)	-4.4%	[-6.2%, -2.6%]	4
All ❌✅ (primary)	1.1%	[-1.0%, 3.5%]	3

Cycles

Results (secondary 0.2%)

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)	5.0%	[2.5%, 7.6%]	3
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-4.6%	[-5.5%, -3.0%]	3
All ❌✅ (primary)	-	-	0

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 476.042s -> 475.156s (-0.19%)
Artifact size: 397.86 MiB -> 400.01 MiB (0.54%)

nnethercote

Seems fine. r=me after considering the suggested name change.

View changes since this review

nnethercote · 2026-02-02T06:06:30Z

compiler/rustc_query_impl/src/lib.rs

+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+struct QueryFlags {
+    is_anon: bool,
+    is_depth_limit: bool,


has_depth_limit?

I went with is_depth_limit on purpose (in the sense of “does this query have the depth_limit modifier) because I didn't want to have to think too hard about whether the more natural has_depth_limit is actually correct or subtly misleading, which would require a deeper investigation of the modifier itself.

So I think it's preferable to land this PR with is_depth_limit, because this PR makes it easier to change the name again later anyway.

nnethercote · 2026-02-02T06:08:58Z

compiler/rustc_query_impl/src/lib.rs

    #[inline(always)]
    fn anon(self) -> bool {
-        ANON
+        FLAGS.is_anon


Hmm, these methods don't have is_ prefixes...

nnethercote · 2026-02-02T06:09:25Z

compiler/rustc_query_impl/src/plumbing.rs

+            const FLAGS: QueryFlags = QueryFlags {
+                is_anon: is_anon!([$($modifiers)*]),
+                is_depth_limit: depth_limit!([$($modifiers)*]),
+                is_feedable: feedable!([$($modifiers)*]),


... but here is_anon! has an is_ prefix but the other two macros don't. More consistency would be nice.

rustbot · 2026-02-02T06:58:22Z

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.

Zalathar · 2026-02-02T07:06:27Z

(Rebased and added some field docs to QueryFlags.)

Zalathar · 2026-02-02T07:25:37Z

I've decided to stick with the existing name is_depth_limit; we can always change it later if we have regrets.

@bors r=nnethercote

rust-bors · 2026-02-02T07:25:40Z

📌 Commit 09de0fd has been approved by nnethercote

It is now in the queue for this repository.

Zalathar · 2026-02-02T07:52:30Z

This theoretically shouldn’t have perf impact, and the perf results look like typical noise to me, so I think this is fine for rollup.

@bors rollup=maybe

…rcote Use `#![feature(adt_const_params)]` for static query flags As suggested by rust-lang#151633 (comment), this replaces multiple clunky const booleans with a single const struct, which is a bit nicer. This should also make it easier to experiment with statically resolving other flags, like `eval_always`. There are currently no other compiler crates using `feature(adt_const_params)`, so hopefully it's mature enough for a simple use-case like this one.

Rollup of 5 pull requests Successful merges: - #151938 (Use `#![feature(adt_const_params)]` for static query flags) - #151825 (more float constants) - #151974 (Update documentation for `Result::ok()`) - #151978 (Query cleanups) - #151979 (Fix uninitialized UEFI globals in tests)

…rcote Use `#![feature(adt_const_params)]` for static query flags As suggested by rust-lang#151633 (comment), this replaces multiple clunky const booleans with a single const struct, which is a bit nicer. This should also make it easier to experiment with statically resolving other flags, like `eval_always`. There are currently no other compiler crates using `feature(adt_const_params)`, so hopefully it's mature enough for a simple use-case like this one.

…uwer Rollup of 11 pull requests Successful merges: - #150992 (link modifier `export-symbols`: export all global symbols from selected uptream c static libraries) - #151695 (compiletest: Support `--extern` modifiers with `proc-macro` directive) - #151938 (Use `#![feature(adt_const_params)]` for static query flags) - #151172 (Use default field values in a few more cases) - #151825 (more float constants) - #151870 (regression test for alias-relate changes in lub) - #151902 (explain why we dont skip some of this work when there are field projections) - #151974 (Update documentation for `Result::ok()`) - #151978 (Query cleanups) - #151979 (Fix uninitialized UEFI globals in tests) - #151992 (Port `#[rustc_hidden_type_of_opaque]` to attribute parser)

…rcote Use `#![feature(adt_const_params)]` for static query flags As suggested by rust-lang#151633 (comment), this replaces multiple clunky const booleans with a single const struct, which is a bit nicer. This should also make it easier to experiment with statically resolving other flags, like `eval_always`. There are currently no other compiler crates using `feature(adt_const_params)`, so hopefully it's mature enough for a simple use-case like this one.

…uwer Rollup of 12 pull requests Successful merges: - #149596 (resolve: Report more visibility-related early resolution ambiguities for imports) - #151695 (compiletest: Support `--extern` modifiers with `proc-macro` directive) - #151938 (Use `#![feature(adt_const_params)]` for static query flags) - #151172 (Use default field values in a few more cases) - #151825 (more float constants) - #151870 (regression test for alias-relate changes in lub) - #151872 (Add inline syntax for diagnostic messages) - #151902 (explain why we dont skip some of this work when there are field projections) - #151909 (Skip overlapping spans in argument error suggestions) - #151978 (Query cleanups) - #151979 (Fix uninitialized UEFI globals in tests) - #151992 (Port `#[rustc_hidden_type_of_opaque]` to attribute parser)

Rollup merge of #151938 - Zalathar:adt-query-flags, r=nnethercote Use `#![feature(adt_const_params)]` for static query flags As suggested by #151633 (comment), this replaces multiple clunky const booleans with a single const struct, which is a bit nicer. This should also make it easier to experiment with statically resolving other flags, like `eval_always`. There are currently no other compiler crates using `feature(adt_const_params)`, so hopefully it's mature enough for a simple use-case like this one.

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rust-bors bot pushed a commit that referenced this pull request Feb 1, 2026

Auto merge of #151938 - Zalathar:adt-query-flags, r=<try>

c060cb7

Use `#![feature(adt_const_params)]` for static query flags

rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Feb 1, 2026

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rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Feb 1, 2026

nnethercote approved these changes Feb 2, 2026

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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 Feb 2, 2026

Zalathar force-pushed the adt-query-flags branch from cfdddc2 to d91d5dd Compare February 2, 2026 06:58

Use #![feature(adt_const_params)] for static query flags

09de0fd

Zalathar force-pushed the adt-query-flags branch from d91d5dd to 09de0fd Compare February 2, 2026 07:05

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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Feb 2, 2026

jhpratt mentioned this pull request Feb 2, 2026

Rollup of 5 pull requests #151987

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JonathanBrouwer mentioned this pull request Feb 2, 2026

Rollup of 11 pull requests #151997

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This was referenced Feb 2, 2026

Rollup of 11 pull requests #152005

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Rollup of 12 pull requests #152006

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rust-bors bot merged commit 1c42fd4 into rust-lang:main Feb 3, 2026
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Zalathar deleted the adt-query-flags branch February 3, 2026 04:46

github-actions bot mentioned this pull request Feb 10, 2026

Toolchain upgrade to nightly-2026-02-09 flux-rs/flux#1345

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cuviper added this to the 1.95.0 milestone Feb 19, 2026

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rust-timer commented Feb 1, 2026

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

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