---
tags: weekly, rustc
---

# T-compiler Meeting Agenda 2023-04-27

## Announcements

- [Steering: v0 mangling discussion](https://www.google.com/calendar/event?eid=NTFjdWtiaTgyOGFrZGp0dXJiYWxhM3E5YTEgNnU1cnJ0Y2U2bHJ0djA3cGZpM2RhbWdqdXNAZw) at <time:2023-04-28T10:00:00-04:00>
- [Types team meeting](https://www.google.com/calendar/event?eid=MTg3MDhpdTc3YXBqMGMzbnNxanUwdWZnazhfMjAyMzA1MDFUMTQwMDAwWiA2dTVycnRjZTZscnR2MDdwZmkzZGFtZ2p1c0Bn) at <time:2023-05-01T10:00:00-04:00>
- Reminder: if you see a PR/issue that seems like there might be legal implications due to copyright/IP/etc, please let the Core team know (or at least message @_**pnkfelix** or @_**Wesley Wiser** so we can pass it along).

### Other WG meetings ([calendar link](https://calendar.google.com/calendar/embed?src=6u5rrtce6lrtv07pfi3damgjus%40group.calendar.google.com))
- [wg-async weekly](https://www.google.com/calendar/event?eid=N211N3RrYzVqcnVvNnBycGFrcW9mcjNocTNfMjAyMzA0MjdUMTYwMDAwWiA2dTVycnRjZTZscnR2MDdwZmkzZGFtZ2p1c0Bn) at <time:2023-04-27T12:00:00-04:00>
- [wg-rls-2.0 weekly sync-up](https://www.google.com/calendar/event?eid=MXJnbzBscDExNHJjNmVsdGhsaW8xcDljMmdfMjAyMzA1MDFUMTUwMDAwWiA2dTVycnRjZTZscnR2MDdwZmkzZGFtZ2p1c0Bn) at <time:2023-05-01T11:00:00-04:00>

## MCPs/FCPs

- New MCPs (take a look, see if you like them!)
- No new proposals this time.
- Old MCPs (stale MCP might be closed as per [MCP procedure](https://forge.rust-lang.org/compiler/mcp.html#when-should-major-change-proposals-be-closed))
- None at this time
- Old MCPs (not seconded, take a look)
- "Rustc Contributor Program Major Change Proposal" [compiler-team#557](https://github.com/rust-lang/compiler-team/issues/557) (last review activity: 3 months ago)
- "Add New Values To MIPS_ALLOWED_FEATURES" [compiler-team#595](https://github.com/rust-lang/compiler-team/issues/595) (last review activity: about 34 days ago)
- "Take MIR `Analysis` by `&mut`" [compiler-team#598](https://github.com/rust-lang/compiler-team/issues/598) (last review activity: about 34 days ago)
- "-C linker-flavor=clang" [compiler-team#601](https://github.com/rust-lang/compiler-team/issues/601) (last review activity: about 34 days ago)
- "Increase `TypeId`'s hash from 64 bits to 128 bits." [compiler-team#608](https://github.com/rust-lang/compiler-team/issues/608) (last review activity: about 6 days ago)
- "Disallow incoherent cfgs" [compiler-team#610](https://github.com/rust-lang/compiler-team/issues/610) (last review activity: about 13 days ago)
- "2024: Decrease debuginfo generated by `-Cdebuginfo=1`" [compiler-team#613](https://github.com/rust-lang/compiler-team/issues/613) (last review activity: about 6 days ago)
- "Cell Broadband Engine SPU support" [compiler-team#614](https://github.com/rust-lang/compiler-team/issues/614) (last review activity: about 13 days ago)
- "Revise error code documentation standard" [compiler-team#615](https://github.com/rust-lang/compiler-team/issues/615) (last review activity: about 6 days ago)
- Pending FCP requests (check your boxes!)
- No pending FCP requests this time.
- Things in FCP (make sure you're good with it)
- "Stable -C binary-dep-depinfo flag" [compiler-team#604](https://github.com/rust-lang/compiler-team/issues/604)
- "Enable the LLVM option `NoTrapAfterNoreturn` when `TrapUnreachable` is enabled." [compiler-team#618](https://github.com/rust-lang/compiler-team/issues/618)
- "Redesign bootstrap stages" [compiler-team#619](https://github.com/rust-lang/compiler-team/issues/619)
- "Policy for ICEs on incorrect usage of internal-only features" [compiler-team#620](https://github.com/rust-lang/compiler-team/issues/620)
- "Remove multi-field `repr(simd)`" [compiler-team#621](https://github.com/rust-lang/compiler-team/issues/621)
- "Add a new `--crate-version` flag to rustc" [compiler-team#622](https://github.com/rust-lang/compiler-team/issues/622)
- "Stronger typing for `DefId`s" [compiler-team#623](https://github.com/rust-lang/compiler-team/issues/623)
- "Add deployment-target --print flag for Apple targets" [rust#105354](https://github.com/rust-lang/rust/pull/105354)
- "Stabilize raw-dylib, link_ordinal, import_name_type and -Cdlltool" [rust#109677](https://github.com/rust-lang/rust/pull/109677)
- Accepted MCPs
- "Integrate Enzyme into nightly rustc" [compiler-team#611](https://github.com/rust-lang/compiler-team/issues/611)
- "Add a `--print=unmap-path-prefixes` flag" [compiler-team#612](https://github.com/rust-lang/compiler-team/issues/612)
- "move constructors from `TyCtxt` to the constructed types" [compiler-team#616](https://github.com/rust-lang/compiler-team/issues/616)
- "Rename `NEEDS_SUBST` and `NEEDS_INFER`" [compiler-team#617](https://github.com/rust-lang/compiler-team/issues/617)
- Finalized FCPs (disposition merge)
- "Tracking Issue for `debugger_visualizer`" [rust#95939](https://github.com/rust-lang/rust/issues/95939)
- "Evaluate place expression in `PlaceMention`" [rust#104844](https://github.com/rust-lang/rust/pull/104844)
- "Update the version of musl used on `*-linux-musl` targets to 1.2.3" [rust#107129](https://github.com/rust-lang/rust/pull/107129)

### WG checkins

@_*WG-mir-opt* by @**oli** ([previous checkin](https://hackmd.io/auk0MATiScWFokXL6RlO-w#WG-checkins)):
> Checkin text

@_*WG-polymorphization* by @**davidtwco** ([previous checkin](https://hackmd.io/RN6ovtjCR5m-B5IWrVgkIA#WG-checkins)):
> There's no update for polymorphization this cycle, we're waiting on the trait system refactor work to complete before continuing with it

## Backport nominations

[T-compiler stable](https://github.com/rust-lang/rust/issues?q=is%3Aall+label%3Abeta-nominated+-label%3Abeta-accepted+label%3AT-compiler) / [T-compiler beta](https://github.com/rust-lang/rust/issues?q=is%3Aall+label%3Astable-nominated+-label%3Astable-accepted+label%3AT-compiler)
- :beta: [1.70] "make sysroot finding compatible with multiarch systems" [rust#110281](https://github.com/rust-lang/rust/pull/110281)
- From last [week's meeting](https://rust-lang.zulipchat.com/#narrow/stream/238009-t-compiler.2Fmeetings/topic/.5Bweekly.5D.202023-04-20/near/351337406) (we wanted to wait until merged in nightly)
- Fixes #109994, a packaging issue raised with Debian/Ubuntu distributions
<!--
/poll Approve beta backport of #110281?
approve
decline
don't know
-->
- :beta: [1.70] "Encode lifetime param spans too" [rust#110469](https://github.com/rust-lang/rust/pull/110469)
- From last [week's meeting](https://rust-lang.zulipchat.com/#narrow/stream/238009-t-compiler.2Fmeetings/topic/.5Bweekly.5D.202023-04-20/near/351338956), we wanted to wait for a perf. run triage, [in comment](https://github.com/rust-lang/rust/pull/110469#issuecomment-1518037141)
- Fixes #110464, an ICE. Complements #110425 (beta accepted last week)
<!--
/poll Approve beta backport of #110469?
approve
decline
don't know
-->

- No stable nominations for `T-compiler` this time.

[T-rustdoc stable](https://github.com/rust-lang/rust/issues?q=is%3Aall+label%3Abeta-nominated+-label%3Abeta-accepted+label%3AT-rustdoc) / [T-rustdoc beta](https://github.com/rust-lang/rust/issues?q=is%3Aall+label%3Astable-nominated+-label%3Astable-accepted+label%3AT-rustdoc)
- No beta nominations for `T-rustdoc` this time.
- No stable nominations for `T-rustdoc` this time.

:back: / :shrug: / :hand:

## PRs S-waiting-on-team

[T-compiler](https://github.com/rust-lang/rust/pulls?q=is%3Aopen+label%3AS-waiting-on-team+label%3AT-compiler)
- "Remove misleading target feature aliases" [rust#107707](https://github.com/rust-lang/rust/pull/107707)
- waiting on `T-lang` (just cc'ing T-compiler)
- "expand: Change how `#![cfg(FALSE)]` behaves on crate root" [rust#110141](https://github.com/rust-lang/rust/pull/110141)
- waiting on `T-lang` (just cc'ing T-compiler)
- Other issues [in progress or waiting on other teams](https://hackmd.io/XYr1BrOWSiqCrl8RCWXRaQ)

### Oldest PRs waiting for review

- "Support linking to rust dylib with --crate-type staticlib" [rust#106560](https://github.com/rust-lang/rust/pull/106560)
- @**pnkfelix** mentioned he could volunteer to review ([comment](https://rust-lang.zulipchat.com/#narrow/stream/238009-t-compiler.2Fmeetings/topic/.5Bweekly.5D.202023-02-02/near/325429461))
- "Add `ConstParamTy` trait" [rust#108161](https://github.com/rust-lang/rust/pull/108161) (last review activity: about 47 days ago)
- cc: @**Boxy [she/her]**
- "Use `ControlFlow` in HIR `Visitor`" [rust#108598](https://github.com/rust-lang/rust/pull/108598) (last review activity: about 47 days ago)
- cc: @**oli** (self-assigned)
- "Move the WorkerLocal type from the rustc-rayon fork into rustc_data_structures" [rust#107782](https://github.com/rust-lang/rust/pull/107782) (last review activity: about 46 days ago)
- cc: @**cjgillot**
- "Remove type ascription from parser and diagnostics" [rust#109128](https://github.com/rust-lang/rust/pull/109128) (last review activity: about 41 days ago)
- PR has been reviewed, I think the author asked explicitly for @**Esteban Küber**
- "On nightly, dump ICE backtraces to disk" [rust#108714](https://github.com/rust-lang/rust/pull/108714) (last review activity: about 33 days ago)
- @**oli** self-assigned so assuming they want to circle back on this

## Issues of Note

### Short Summary

- [0 T-compiler P-critical issues](https://github.com/rust-lang/rust/issues?q=is%3Aopen+label%3AT-compiler+label%3AP-critical)
- [0 of those are unassigned](https://github.com/rust-lang/rust/issues?q=is%3Aopen+label%3AT-compiler+label%3AP-critical+no%3Aassignee)
- [62 T-compiler P-high issues](https://github.com/rust-lang/rust/issues?q=is%3Aopen+label%3AT-compiler+label%3AP-high)
- [30 of those are unassigned](https://github.com/rust-lang/rust/issues?q=is%3Aopen+label%3AT-compiler+label%3AP-high+no%3Aassignee)
- [0 P-critical, 1 P-high, 4 P-medium, 0 P-low regression-from-stable-to-beta](https://github.com/rust-lang/rust/labels/regression-from-stable-to-beta)
- [0 P-critical, 0 P-high, 4 P-medium, 1 P-low regression-from-stable-to-nightly](https://github.com/rust-lang/rust/labels/regression-from-stable-to-nightly)
- [0 P-critical, 36 P-high, 95 P-medium, 15 P-low regression-from-stable-to-stable](https://github.com/rust-lang/rust/labels/regression-from-stable-to-stable)

### P-critical

[T-compiler](https://github.com/rust-lang/rust/issues?q=is%3Aopen+label%3AP-critical+label%3AT-compiler)
- No `P-critical` issues for `T-compiler` at this time.

[T-types](https://github.com/rust-lang/rust/issues?q=is%3Aopen+label%3AP-critical+label%3AT-types)
- No `P-critical` issues for `T-types` at this time.

[T-rustdoc](https://github.com/rust-lang/rust/issues?q=is%3Aopen+label%3AP-critical+label%3AT-rustdoc)
- No `P-critical` issues for `T-rustdoc` at this time.

### P-high regressions

[P-high beta regressions](https://github.com/rust-lang/rust/issues?q=is%3Aopen+label%3Aregression-from-stable-to-beta+label%3AP-high+-label%3AT-infra+-label%3AT-libs+-label%3AT-libs-api+-label%3AT-release+-label%3AT-rustdoc+-label%3AT-core)
- "const-propagated `arithmetic_overflow` in unreachable code" [rust#109731](https://github.com/rust-lang/rust/issues/109731)
- (nominated for discussion)

[Unassigned P-high nightly regressions](https://github.com/rust-lang/rust/issues?q=is%3Aopen+label%3Aregression-from-stable-to-nightly+label%3AP-high+no%3Aassignee+-label%3AT-infra+-label%3AT-libs+-label%3AT-libs-api+-label%3AT-release+-label%3AT-rustdoc+-label%3AT-core+)
- No unassigned `P-high` nightly regressions this time.

## Performance logs

> [triage logs for 2023-04-25](https://github.com/rust-lang/rustc-perf/blob/f73bbe279ed15b29d4b3abe4219445f42b42cd27/triage/2023-04-25.md)

A week mostly dominated by noise, in particular a persistent bimodality in
keccak and cranelift-codegen. No significant changes outside of that, a
relatively equal mix of regressions and improvements. Most of the bimodality
has been removed below as it's just noise.

Triage done by **@simulacrum**.
Revision range: [74864fa496997a6498e623f0d2019ccb7eb6dad0..fdeef3ed1809aa9bd4ea9ff0fad92010c6de669c](https://perf.rust-lang.org/?start=74864fa496997a6498e623f0d2019ccb7eb6dad0&end=fdeef3ed1809aa9bd4ea9ff0fad92010c6de669c&absolute=false&stat=instructions%3Au)

**Summary**:

| (instructions:u) | mean | range | count |
|:------------------------:|:-----:|:--------------:|:-----:|
| Regressions (primary) | 1.2% | [0.5%, 2.2%] | 11 |
| Regressions (secondary) | 2.0% | [0.6%, 7.7%] | 48 |
| Improvements (primary) | -1.0% | [-3.6%, -0.3%] | 144 |
| Improvements (secondary) | -1.6% | [-6.7%, -0.3%] | 89 |
| All (primary) | -0.9% | [-3.6%, 2.2%] | 155 |

3 Regressions, 6 Improvements, 5 Mixed; 1 of them in rollups
60 artifact comparisons made in total

#### Regressions

Support AIX-style archive type [#106704](https://github.com/rust-lang/rust/pull/106704) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=9c51cf7e7ffd4ca1b7159657a76e1d4fbab18276&end=39c6804b92aa202369e402525cee329556bc1db0&stat=instructions:u)

| (instructions:u) | mean | range | count |
|:------------------------:|:----:|:------------:|:-----:|
| Regressions (primary) | 1.1% | [1.0%, 1.2%] | 6 |
| Regressions (secondary) | 2.5% | [1.1%, 3.9%] | 2 |
| Improvements (primary) | - | - | 0 |
| Improvements (secondary) | - | - | 0 |
| All (primary) | 1.1% | [1.0%, 1.2%] | 6 |

This PR also bumped std dependencies, which likely explains the additional compile time cost in our smallest benchmarks (e.g., helloworld).

Ensure mir_drops_elaborated_and_const_checked when requiring codegen. [#110107](https://github.com/rust-lang/rust/pull/110107) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=4a03f14b099bf19f0124872b3f6d99ef00db7902&end=fa4cc63a6bd6f32903269e52b8f59b284d0e76c4&stat=instructions:u)

| (instructions:u) | mean | range | count |
|:------------------------:|:----:|:------------:|:-----:|
| Regressions (primary) | - | - | 0 |
| Regressions (secondary) | 2.0% | [1.7%, 2.4%] | 10 |
| Improvements (primary) | - | - | 0 |
| Improvements (secondary) | - | - | 0 |
| All (primary) | - | - | 0 |

Per [comment on the PR](https://github.com/rust-lang/rust/pull/110107#issuecomment-1501563158) this is enabling lints to run on dead code, expected regression.

Encode lifetime param spans too [#110469](https://github.com/rust-lang/rust/pull/110469) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=80a2ec49a4ffb7a351c41c8db14711297324b587&end=37b22cf2d5d787106077d4f9ef3092ca80e92a1b&stat=instructions:u)

| (instructions:u) | mean | range | count |
|:------------------------:|:----:|:------------:|:-----:|
| Regressions (primary) | 0.5% | [0.2%, 0.7%] | 21 |
| Regressions (secondary) | 0.7% | [0.3%, 0.9%] | 4 |
| Improvements (primary) | - | - | 0 |
| Improvements (secondary) | - | - | 0 |
| All (primary) | 0.5% | [0.2%, 0.7%] | 21 |

[This comment](https://github.com/rust-lang/rust/pull/110469#issuecomment-1518037141) justifies the regressions.

#### Improvements

Don't allocate on SimplifyCfg/Locals/Const on every MIR pass [#110477](https://github.com/rust-lang/rust/pull/110477) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=da481403e7e3c91878ef8fe3099c04dbb862a145&end=9e7f72c57d83a6e64f54b436dc3373871c3c4bb0&stat=instructions:u)

| (instructions:u) | mean | range | count |
|:------------------------:|:-----:|:--------------:|:-----:|
| Regressions (primary) | - | - | 0 |
| Regressions (secondary) | - | - | 0 |
| Improvements (primary) | -0.5% | [-0.7%, -0.3%] | 10 |
| Improvements (secondary) | -0.6% | [-0.7%, -0.4%] | 9 |
| All (primary) | -0.5% | [-0.7%, -0.3%] | 10 |

Rm const traits in libcore [#110393](https://github.com/rust-lang/rust/pull/110393) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=d7f9e81650dcee3e2d5ad1973a71da644a2eff93&end=3a5c8e91f094bb1cb1346651fe3512f0b603d826&stat=instructions:u)

| (instructions:u) | mean | range | count |
|:------------------------:|:-----:|:--------------:|:-----:|
| Regressions (primary) | - | - | 0 |
| Regressions (secondary) | - | - | 0 |
| Improvements (primary) | -0.9% | [-2.6%, -0.4%] | 15 |
| Improvements (secondary) | -1.7% | [-2.8%, -0.5%] | 24 |
| All (primary) | -0.9% | [-2.6%, -0.4%] | 15 |

In `LexicalResolver`, don't construct graph unless necessary. [#110527](https://github.com/rust-lang/rust/pull/110527) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=7fde08365c4c3cfc9a9f8a6a02693b789adbe6da&end=23a76a8ab5f7b29a1eb7aca5f3e4c4a9b866d5b7&stat=instructions:u)

| (instructions:u) | mean | range | count |
|:------------------------:|:-----:|:--------------:|:-----:|
| Regressions (primary) | - | - | 0 |
| Regressions (secondary) | - | - | 0 |
| Improvements (primary) | -0.3% | [-0.4%, -0.2%] | 4 |
| Improvements (secondary) | -0.4% | [-0.8%, -0.2%] | 11 |
| All (primary) | -0.3% | [-0.4%, -0.2%] | 4 |

Enable flatten-format-args by default. [#109999](https://github.com/rust-lang/rust/pull/109999) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=8bdcc62cb0362869f0e7b43a6ae4f96b953d3cbc&end=d19b64fb54391b64ce99981577c67c93ac2a9ffa&stat=instructions:u)

| (instructions:u) | mean | range | count |
|:------------------------:|:-----:|:--------------:|:-----:|
| Regressions (primary) | - | - | 0 |
| Regressions (secondary) | - | - | 0 |
| Improvements (primary) | -1.5% | [-2.3%, -0.6%] | 10 |
| Improvements (secondary) | - | - | 0 |
| All (primary) | -1.5% | [-2.3%, -0.6%] | 10 |

Allow to feed a value in another query's cache and remove `WithOptConstParam` [#96840](https://github.com/rust-lang/rust/pull/96840) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=b92a41c6760801a7128ca0ec69ba4ba9c9194054&end=1f5768bc67ecb025342770e14e03699699965706&stat=instructions:u)

| (instructions:u) | mean | range | count |
|:------------------------:|:-----:|:--------------:|:-----:|
| Regressions (primary) | - | - | 0 |
| Regressions (secondary) | 0.6% | [0.6%, 0.6%] | 1 |
| Improvements (primary) | -0.8% | [-2.1%, -0.3%] | 57 |
| Improvements (secondary) | -0.9% | [-1.7%, -0.3%] | 26 |
| All (primary) | -0.8% | [-2.1%, -0.3%] | 57 |

Report allocation errors as panics [#109507](https://github.com/rust-lang/rust/pull/109507) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=21fab435da99d6ef14c1c870650ee976499564f3&end=39cf520299794e6c1b6b471db5d9935e0c6271ab&stat=instructions:u)

| (instructions:u) | mean | range | count |
|:------------------------:|:-----:|:--------------:|:-----:|
| Regressions (primary) | - | - | 0 |
| Regressions (secondary) | - | - | 0 |
| Improvements (primary) | -0.2% | [-0.2%, -0.2%] | 3 |
| Improvements (secondary) | - | - | 0 |
| All (primary) | -0.2% | [-0.2%, -0.2%] | 3 |

#### Mixed

rustc_metadata: Remove `Span` from `ModChild` [#109772](https://github.com/rust-lang/rust/pull/109772) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=4e463012580415a932ae4fc255aff45982c70369&end=c609da59d9fc05b1c7dc879d79700ccd8140b5fc&stat=instructions:u)

| (instructions:u) | mean | range | count |
|:------------------------:|:-----:|:--------------:|:-----:|
| Regressions (primary) | 0.4% | [0.3%, 0.5%] | 5 |
| Regressions (secondary) | 0.2% | [0.2%, 0.2%] | 1 |
| Improvements (primary) | -0.4% | [-0.7%, -0.2%] | 15 |
| Improvements (secondary) | -1.4% | [-4.2%, -0.4%] | 13 |
| All (primary) | -0.2% | [-0.7%, 0.5%] | 20 |

Rollup of 10 pull requests [#110546](https://github.com/rust-lang/rust/pull/110546) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=df0d9b492da81a647eedf17210cf55b86a44888c&end=9c51cf7e7ffd4ca1b7159657a76e1d4fbab18276&stat=instructions:u)

| (instructions:u) | mean | range | count |
|:------------------------:|:-----:|:--------------:|:-----:|
| Regressions (primary) | 1.6% | [1.1%, 2.1%] | 3 |
| Regressions (secondary) | - | - | 0 |
| Improvements (primary) | - | - | 0 |
| Improvements (secondary) | -3.1% | [-3.1%, -3.1%] | 1 |
| All (primary) | 1.6% | [1.1%, 2.1%] | 3 |

resolve: Remove `module_children_untracked` [#110542](https://github.com/rust-lang/rust/pull/110542) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=1151ea6006020e227c74285b24ab53b7964524e6&end=409661936f929b254ffc8adb644cf35d1f9765c4&stat=instructions:u)

| (instructions:u) | mean | range | count |
|:------------------------:|:-----:|:--------------:|:-----:|
| Regressions (primary) | 0.6% | [0.2%, 0.9%] | 11 |
| Regressions (secondary) | - | - | 0 |
| Improvements (primary) | -0.3% | [-0.3%, -0.3%] | 1 |
| Improvements (secondary) | -1.5% | [-1.9%, -1.0%] | 3 |
| All (primary) | 0.6% | [-0.3%, 0.9%] | 12 |

Turn on ConstDebugInfo pass. [#107404](https://github.com/rust-lang/rust/pull/107404) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=f12a7fa00fb7a99a92661bb9ae2b768dac0c5d40&end=9e540df7931a32ca286eb2e907afde78b718fd17&stat=instructions:u)

| (instructions:u) | mean | range | count |
|:------------------------:|:-----:|:--------------:|:-----:|
| Regressions (primary) | 0.4% | [0.2%, 0.7%] | 12 |
| Regressions (secondary) | 0.4% | [0.4%, 0.4%] | 1 |
| Improvements (primary) | - | - | 0 |
| Improvements (secondary) | -0.3% | [-0.3%, -0.3%] | 2 |
| All (primary) | 0.4% | [0.2%, 0.7%] | 12 |

Remove the size of locals heuristic in MIR inlining [#110705](https://github.com/rust-lang/rust/pull/110705) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=3462f79e94f466a56ddaccfcdd3a3d44dd1dda9f&end=915aa06700af4a2363639bae70201cd7387470ad&stat=instructions:u)

| (instructions:u) | mean | range | count |
|:------------------------:|:-----:|:--------------:|:-----:|
| Regressions (primary) | 0.9% | [0.3%, 2.7%] | 9 |
| Regressions (secondary) | 1.9% | [0.3%, 7.9%] | 34 |
| Improvements (primary) | -0.6% | [-1.8%, -0.2%] | 59 |
| Improvements (secondary) | -0.8% | [-2.5%, -0.2%] | 46 |
| All (primary) | -0.4% | [-1.8%, 2.7%] | 68 |

## Nominated Issues

[T-compiler](https://github.com/rust-lang/rust/issues?q=is%3Aopen+label%3AI-compiler-nominated)
- "const-propagated `arithmetic_overflow` in unreachable code" [rust#109731](https://github.com/rust-lang/rust/issues/109731)
- briefly touched in [previous meeting](https://rust-lang.zulipchat.com/#narrow/stream/238009-t-compiler.2Fmeetings/topic/.5Bweekly.5D.202023-04-13/near/349134541)
- nominated by Wesley ([comment](https://github.com/rust-lang/rust/issues/109731#issuecomment-1516469403)) to keep the discussion focus whether this could be considered a regression or not, possibly documenting it. Taking a decision Before it reaches stable (now in beta)
- @**jyn** comments:
> I don't think we should try to warn on unreachable code, it seems ok to silence the lint there. I just don't think we should treat it as a regression and breaking change. This is a lint and not a hard error for a reason.

[RFC](https://github.com/rust-lang/rfcs/issues?q=is%3Aopen+label%3AI-compiler-nominated)
- No I-compiler-nominated RFCs this time.

## Next week's WG checkins

- @_*WG-rls2.0* by @**Lukas Wirth**
- @_*WG-self-profile* by @**mw** and @**Wesley Wiser**

Agenda draft: draft: https://hackmd.io/KZoEURJsQPaQtTg0gyHnIg