Various steps in moving away from the big reflection enum to reflection functions - #159727

oli-obk · 2026-07-22T16:00:28Z

tracking issue: #146922

Some more of these and we can turn the big TyKind enum into one without any data, but I think these are enough steps for one PR, don't wanna turn it into a mega PR

rustbot · 2026-07-22T16:00:31Z

Some changes occurred to the CTFE machinery

cc @RalfJung, @lcnr

Some changes occurred to the intrinsics. Make sure the CTFE / Miri interpreter
gets adapted for the changes, if necessary.

cc @rust-lang/miri, @RalfJung, @lcnr

rustbot · 2026-07-22T16:00:34Z

r? @JohnTitor

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@fmease

… r=fmease Enforce that we don't generate code for comptime fns ... by ICEing if you try to compute a symbol for them. There are various other ways we can assert it, but they were all a bit icky or already unreachable. r? @fmease (since you asked about it in rust-lang#159727 (comment))

@fmease

Rollup merge of #159777 - oli-obk:really-comptime-this-time, r=fmease Enforce that we don't generate code for comptime fns ... by ICEing if you try to compute a symbol for them. There are various other ways we can assert it, but they were all a bit icky or already unreachable. r? @fmease (since you asked about it in #159727 (comment))

@fmease

Enforce that we don't generate code for comptime fns ... by ICEing if you try to compute a symbol for them. There are various other ways we can assert it, but they were all a bit icky or already unreachable. r? @fmease (since you asked about it in rust-lang/rust#159727 (comment))

oli-obk · 2026-08-03T12:13:43Z

@JohnTitor this is ready for review

JohnTitor

Sorry for the delay!
r=me once my questions and @fmease's comment are resolved.

View changes since this review

rustbot · 2026-08-04T09:19:12Z

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.

oli-obk · 2026-08-04T09:26:22Z

@bors r=JohnTitor

rust-bors · 2026-08-04T09:26:25Z

📌 Commit cecd4a4 has been approved by JohnTitor

It is now in the queue for this repository.

🌲 The tree is currently closed for pull requests below priority 10. This pull request will be tested once the tree is reopened.

Reason for tree closure: manually handling queue due to backlog

Various steps in moving away from the big reflection enum to reflection functions tracking issue: rust-lang#146922 Some more of these and we can turn the big TyKind enum into one without any data, but I think these are enough steps for one PR, don't wanna turn it into a mega PR

…uwer Rollup of 22 pull requests Successful merges: - #160426 (`rust-analyzer` subtree update) - #160372 (Derive the allocator used by tools from rustc's allocator) - #146882 (fully deprecate the legacy integral modules) - #158727 (std: use `readdir` on nearly all UNIX platforms) - #159727 (Various steps in moving away from the big reflection enum to reflection functions) - #160443 (normalize in relations, not generalize, when relating infer with alias) - #160457 (implement -Zllvm-target-feature) - #160480 (Single-pass ASCII lower/upper case conversion) - #160502 (Reduce number of miri tests executed on PR CI) - #157430 (std::random: use little-endian for reproducibility) - #158110 (fix macro attribute feature-gate span) - #159975 (Use real ThinVec in StmtDebugInfos) - #160001 (Suggest mutable method when iterating over binding) - #160024 (Fix mono reachability with no-op landing pads) - #160154 (Add regression test for HRTB associated type projection closure) - #160176 (No more `tests/ui/issues`!) - #160326 (Remove hidden_glob_reexports) - #160407 (Add regression tests for a number of ICEs and diagnostics issues labelled `E-needs-test`) - #160430 (bootstrap: Don't produce mutated/filtered PathSets during command-line matching) - #160472 (Minor fixes to `core::io` & `alloc::io` Documentation) - #160486 (Remove unused `FreeRegionsVisitor`) - #160496 (clarify non-determinism docs for algebraic operations) Failed merges: - #160501 (Add bootstrap CLI snapshot test for testing miri)

Rollup merge of #159727 - oli-obk:reflection_stuff, r=JohnTitor Various steps in moving away from the big reflection enum to reflection functions tracking issue: #146922 Some more of these and we can turn the big TyKind enum into one without any data, but I think these are enough steps for one PR, don't wanna turn it into a mega PR

…uwer Rollup of 22 pull requests Successful merges: - rust-lang/rust#160426 (`rust-analyzer` subtree update) - rust-lang/rust#160372 (Derive the allocator used by tools from rustc's allocator) - rust-lang/rust#146882 (fully deprecate the legacy integral modules) - rust-lang/rust#158727 (std: use `readdir` on nearly all UNIX platforms) - rust-lang/rust#159727 (Various steps in moving away from the big reflection enum to reflection functions) - rust-lang/rust#160443 (normalize in relations, not generalize, when relating infer with alias) - rust-lang/rust#160457 (implement -Zllvm-target-feature) - rust-lang/rust#160480 (Single-pass ASCII lower/upper case conversion) - rust-lang/rust#160502 (Reduce number of miri tests executed on PR CI) - rust-lang/rust#157430 (std::random: use little-endian for reproducibility) - rust-lang/rust#158110 (fix macro attribute feature-gate span) - rust-lang/rust#159975 (Use real ThinVec in StmtDebugInfos) - rust-lang/rust#160001 (Suggest mutable method when iterating over binding) - rust-lang/rust#160024 (Fix mono reachability with no-op landing pads) - rust-lang/rust#160154 (Add regression test for HRTB associated type projection closure) - rust-lang/rust#160176 (No more `tests/ui/issues`!) - rust-lang/rust#160326 (Remove hidden_glob_reexports) - rust-lang/rust#160407 (Add regression tests for a number of ICEs and diagnostics issues labelled `E-needs-test`) - rust-lang/rust#160430 (bootstrap: Don't produce mutated/filtered PathSets during command-line matching) - rust-lang/rust#160472 (Minor fixes to `core::io` & `alloc::io` Documentation) - rust-lang/rust#160486 (Remove unused `FreeRegionsVisitor`) - rust-lang/rust#160496 (clarify non-determinism docs for algebraic operations) Failed merges: - rust-lang/rust#160501 (Add bootstrap CLI snapshot test for testing miri)

JonathanBrouwer · 2026-08-06T20:18:15Z

@rust-timer build 114cbc0

rust-timer · 2026-08-06T22:52:45Z

Finished benchmarking commit (114cbc0): comparison URL.

Overall result: ❌✅ regressions and improvements - please read:

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.

Next, please: If you can, justify the regressions found in this try perf run in writing along with @rustbot label: +perf-regression-triaged. If not, fix the regressions and do another perf run. Neutral or positive results will clear the label automatically.

@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)	0.2%	[0.2%, 0.3%]	5
Regressions ❌ (secondary)	1.5%	[0.1%, 2.6%]	16
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.1%	[-0.1%, -0.1%]	3
All ❌✅ (primary)	0.2%	[0.2%, 0.3%]	5

Max RSS (memory usage)

Results (primary -0.4%, secondary 16.0%)

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

	mean	range	count
Regressions ❌ (primary)	0.6%	[0.6%, 0.6%]	1
Regressions ❌ (secondary)	20.7%	[0.6%, 29.9%]	16
Improvements ✅ (primary)	-0.9%	[-1.2%, -0.6%]	2
Improvements ✅ (secondary)	-2.7%	[-6.2%, -0.4%]	4
All ❌✅ (primary)	-0.4%	[-1.2%, 0.6%]	3

Cycles

Results (primary 1.0%, secondary 8.6%)

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

	mean	range	count
Regressions ❌ (primary)	1.4%	[0.6%, 3.3%]	4
Regressions ❌ (secondary)	10.6%	[0.4%, 30.7%]	28
Improvements ✅ (primary)	-0.5%	[-0.5%, -0.5%]	1
Improvements ✅ (secondary)	-5.8%	[-14.0%, -0.9%]	4
All ❌✅ (primary)	1.0%	[-0.5%, 3.3%]	5

Binary size

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

Bootstrap: 489.825s -> 489.583s (-0.05%)
Artifact size: 391.14 MiB -> 392.10 MiB (0.24%)

oli-obk · 2026-08-07T06:50:55Z

Huh. None of this should be in any path reachable on stable

oli-obk · 2026-08-07T06:56:53Z

The huge serde regression is in live_symbols_and_ignored_derived_traits, which also shouldn't be affected by this PR

JonathanBrouwer · 2026-08-07T07:53:05Z

Something funky is going on, all PRs in the rollup have this same result

@fmease

Enforce that we don't generate code for comptime fns ... by ICEing if you try to compute a symbol for them. There are various other ways we can assert it, but they were all a bit icky or already unreachable. r? @fmease (since you asked about it in rust-lang/rust#159727 (comment))

…uwer Rollup of 22 pull requests Successful merges: - rust-lang/rust#160426 (`rust-analyzer` subtree update) - rust-lang/rust#160372 (Derive the allocator used by tools from rustc's allocator) - rust-lang/rust#146882 (fully deprecate the legacy integral modules) - rust-lang/rust#158727 (std: use `readdir` on nearly all UNIX platforms) - rust-lang/rust#159727 (Various steps in moving away from the big reflection enum to reflection functions) - rust-lang/rust#160443 (normalize in relations, not generalize, when relating infer with alias) - rust-lang/rust#160457 (implement -Zllvm-target-feature) - rust-lang/rust#160480 (Single-pass ASCII lower/upper case conversion) - rust-lang/rust#160502 (Reduce number of miri tests executed on PR CI) - rust-lang/rust#157430 (std::random: use little-endian for reproducibility) - rust-lang/rust#158110 (fix macro attribute feature-gate span) - rust-lang/rust#159975 (Use real ThinVec in StmtDebugInfos) - rust-lang/rust#160001 (Suggest mutable method when iterating over binding) - rust-lang/rust#160024 (Fix mono reachability with no-op landing pads) - rust-lang/rust#160154 (Add regression test for HRTB associated type projection closure) - rust-lang/rust#160176 (No more `tests/ui/issues`!) - rust-lang/rust#160326 (Remove hidden_glob_reexports) - rust-lang/rust#160407 (Add regression tests for a number of ICEs and diagnostics issues labelled `E-needs-test`) - rust-lang/rust#160430 (bootstrap: Don't produce mutated/filtered PathSets during command-line matching) - rust-lang/rust#160472 (Minor fixes to `core::io` & `alloc::io` Documentation) - rust-lang/rust#160486 (Remove unused `FreeRegionsVisitor`) - rust-lang/rust#160496 (clarify non-determinism docs for algebraic operations) Failed merges: - rust-lang/rust#160501 (Add bootstrap CLI snapshot test for testing miri)

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Jul 22, 2026

rustbot assigned JohnTitor Jul 22, 2026

rustbot added the T-libs Relevant to the library team, which will review and decide on the PR/issue. label Jul 22, 2026

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fmease reviewed Jul 23, 2026

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Comment thread library/core/src/intrinsics/mod.rs Outdated

This was referenced Jul 23, 2026

Enforce that we don't generate code for comptime fns #159777

Merged

reflection and comptime rust-lang/goals#406

Open

oli-obk force-pushed the reflection_stuff branch from f2afff8 to 0214ef6 Compare July 28, 2026 06:50

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JohnTitor approved these changes Aug 3, 2026

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Comment thread compiler/rustc_const_eval/src/const_eval/machine.rs Outdated

Comment thread library/coretests/tests/mem/type_info.rs Outdated

Add reflection method for field names

c7fc5f2

oli-obk force-pushed the reflection_stuff branch from 0214ef6 to a06add3 Compare August 4, 2026 09:19

oli-obk added 4 commits August 4, 2026 11:20

Add reflection method for field offsets

20d5e78

Add reflection method for fetching non-exhaustiveness

538f556

Generalize some arguments to allow more kinds of input

9381472

Add reflection method for getting a type's generic args

cecd4a4

oli-obk force-pushed the reflection_stuff branch from a06add3 to cecd4a4 Compare August 4, 2026 09:25

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 Aug 4, 2026

This was referenced Aug 4, 2026

Rollup of 14 pull requests #160507

Closed

Rollup of 22 pull requests #160517

Merged

rust-bors Bot merged commit ad0ba38 into rust-lang:main Aug 5, 2026
13 checks passed

rustbot added this to the 1.99.0 milestone Aug 5, 2026

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rustbot added the perf-regression Performance regression. label Aug 6, 2026

oli-obk deleted the reflection_stuff branch August 7, 2026 06:50

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rust-timer commented Aug 6, 2026

Overall result: ❌✅ regressions and improvements - please read:

Instruction count

Max RSS (memory usage)

Cycles

Binary size

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