T-compiler Meeting Agenda 2023-03-02

Announcements

T-compiler: P-high Q1 review at time:2023-03-03T10:00:00:00-05
Next week Thursday, 9th next Rust stable (1.68) release
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).
The Governance RFC has been posted

Other WG meetings (calendar link)

MCPs/FCPs

New MCPs (take a look, see if you like them!)
- "Add New Values To MIPS_ALLOWED_FEATURES" compiler-team#595
Old MCPs (stale MCP might be closed as per MCP procedure)
- None at this time
Old MCPs (not seconded, take a look)
- "Lower baseline expectations for i686 unix-like targets" compiler-team#548 (last review activity: about 6 days ago)
- "configurable rustc timeout for compiletest tests" compiler-team#554 (last review activity: about 48 days ago)
- "Rustc Contributor Program Major Change Proposal" compiler-team#557 (last review activity: about 48 days ago)
- "needs_drop as an auto trait" compiler-team#575 (last review activity: about 55 days ago)
- "Add builtin# for compiler-intrinsic syntax" compiler-team#580 (last review activity: about 1 days ago)
- "Synthetic Partial Drop Glue" compiler-team#585 (last review activity: about 25 days ago)
- "Clone "copyables" using copy codegen" compiler-team#588 (last review activity: about 12 days ago)
- "New tier-2 target for wasm32-wasi-preview2" compiler-team#594 (last review activity: about 4 days ago)
Pending FCP requests (check your boxes!)
- "Add deployment-target –print flag for Apple targets" rust#105354
- "Update the version of musl used on *-linux-musl targets to 1.2.3" rust#107129
Things in FCP (make sure you're good with it)
- "Switch PLT default to "yes" for all targets except x86_64." compiler-team#581
- "Implementing "<test_binary> –list –format json" for use by IDE test explorers / runners" compiler-team#592
- "Add internal_features lint for internal unstable features" compiler-team#596
- "Make unused_allocation lint against Box::new too" rust#104363
Accepted MCPs
- " Promote i586-unknown-linux-gnu to Tier 2 with Host Tools " compiler-team#543
- "Store ICE backtraces to disk and point end users at the file location" compiler-team#578
- "Opportunistically show code snippet on panic" compiler-team#591
Finalized FCPs (disposition merge)
- "Stabilize rustdoc --test-run-directory" rust#103682
- "Treat str as containing [u8] for auto trait purposes" rust#107941
- "rustdoc: search by macro when query ends with !" rust#108143

WG checkins

@_WG-diagnostics by @Esteban Küber and @oli (previous checkin):

Translation infrastructure is now per-crate. You can now find the relevant .ftl files within each crate and modifying them only recompiles your current crate.
@_WG-rustc-dev-guide by @Santiago Pastorino and @Yuki Okushi|217081 (previous checkin):
Most notable changes
- new solver: write canonicalization chapter #1595
- update bootstrap guide #1583
- Add section on comparing types #1570
- extend bootstrap related documentations #1563
Most notable WIPs
- new chapter with examples of diagnostic translation PRs #1621
- Add back the canonicalization chapter. #1532
- Improve documentation of MIR queries & passes #1434
- Document inert vs active attributes #1110

Backport nominations

T-compiler stable / T-compiler beta

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

T-rustdoc stable / T-rustdoc beta

No beta nominations for T-rustdoc this time.
No stable nominations for T-rustdoc this time.

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PRs S-waiting-on-team

T-compiler

Other issues in progress or waiting on other teams

Oldest PRs waiting for review

T-compiler

"Parse unnamed struct and union fields" rust#99754 (last review activity: 3 months ago)
- unsure, reroll reviewer?
"Add consts for AssocConst w/ body & ignore regions in is_satisfied_from_param_env" rust#106965 (last review activity: about 27 days ago)
- cc @Boxy [she/her]
"Require type_map::stub callers to supply file information" rust#104342 (last review activity: about 29 days ago)
- are you @Wesley Wiser waiting for the author to reply to your comment on perf. run? Can switch review flag?
"Split implied and super predicate queries, then allow elaborator to filter only supertraits" rust#107614 (last review activity: about 26 days ago)
- unsure about the status. @lcnr / @Jack Huey did your comments imply some more design work?
"Stabilize movbe and cmpxchg16b target features" rust#107711 (last review activity: about 23 days ago)
- autoassigned to @pnkfelix, reroll?

Issues of Note

Short Summary

P-critical

T-compiler

"1.67 regression with ……::{opaque#0}<'_> does not live long enough error" rust#107516
- mentioned last meeting, @Jack Huey offered to help (comment)
- downgrade to P-high? (~1 week to beta branching)
"#[target_feature] is allowed on main" rust#108645
- @nils (Nilstrieb) suggested to high prioritize this unsoundness before it lands into beta
- Related to rust#108646, not unsound but probably P-high and rust#108655 as well
- @Léo Lanteri Thauvin will prepare a revert PR or rust#99767 (RFC #69098) (~1 week to beta branching)
  - Revert in rust#108654
  - Fix in rust#108655

T-types

"1.67 regression with ……::{opaque#0}<'_> does not live long enough error" rust#107516
- (see above)

T-rustdoc

No P-critical issues for T-rustdoc at this time.

P-high regressions

P-high stable regressions

No P-high beta regressions this time.

P-high beta regressions

No P-high beta regressions this time.

Unassigned P-high nightly regressions

No unassigned P-high nightly regressions this time.

Performance logs

triage logs for 2023-03-01

Some noisy benchmarks impeded performance review this week. There was a notable
improvement to a broad range of primary benchmarks, first from PR #108440, which
revised the encodable proc macro to handle the discriminant separately from its
fields, and second from PR #108375, which inlined a number of methods that had
only a single caller. Both of these PR's were authored by the same contributor;
many thanks Zoxc!

Triage done by @pnkfelix.
Revision range: 3fee48c1..31f858d9

Summary:

(instructions:u)	mean	range	count
Regressions (primary)	0.6%	[0.4%, 1.5%]	16
Regressions (secondary)	0.6%	[0.3%, 0.9%]	18
Improvements (primary)	-0.8%	[-17.1%, -0.3%]	112
Improvements (secondary)	-0.7%	[-1.8%, -0.1%]	50
All (primary)	-0.6%	[-17.1%, 1.5%]	128

5 Regressions, 4 Improvements, 6 Mixed; 6 of them in rollups
39 artifact comparisons made in total
30 Untriaged Pull Requests

Regressions

errors: generate typed identifiers in each crate #103042 (Comparison Link)

(instructions:u)	mean	range	count
Regressions (primary)	1.1%	[1.0%, 1.2%]	2
Regressions (secondary)	2.2%	[2.0%, 2.6%]	6
Improvements (primary)	-	-	0
Improvements (secondary)	-	-	0
All (primary)	1.1%	[1.0%, 1.2%]	2

already triaged, believed to be noise.

Rollup of 10 pull requests #108421 (Comparison Link)

(instructions:u)	mean	range	count
Regressions (primary)	0.7%	[0.3%, 1.3%]	4
Regressions (secondary)	2.2%	[2.0%, 2.6%]	6
Improvements (primary)	-	-	0
Improvements (secondary)	-	-	0
All (primary)	0.7%	[0.3%, 1.3%]	4

already triaged, believed to be noise.

Print a backtrace when query forcing fails. #91742 (Comparison Link)

(instructions:u)	mean	range	count
Regressions (primary)	0.3%	[0.2%, 0.7%]	65
Regressions (secondary)	0.5%	[0.2%, 2.3%]	14
Improvements (primary)	-	-	0
Improvements (secondary)	-	-	0
All (primary)	0.3%	[0.2%, 0.7%]	65

The compiler team anticipated fallout here
the actual fallout seems to roughly match.
marked as triaged.

Rollup of 9 pull requests #108488 (Comparison Link)

(instructions:u)	mean	range	count
Regressions (primary)	1.4%	[0.8%, 2.0%]	2
Regressions (secondary)	-	-	0
Improvements (primary)	-	-	0
Improvements (secondary)	-	-	0
All (primary)	1.4%	[0.8%, 2.0%]	2

two doc,full regressions: 2% on hyper, 0.76% on serde…
not worth teasing out of rollup; marked as triaged

MIR-Validate StorageLive. #108175 (Comparison Link)

(instructions:u)	mean	range	count
Regressions (primary)	0.6%	[0.6%, 0.7%]	3
Regressions (secondary)	0.3%	[0.3%, 0.5%]	4
Improvements (primary)	-	-	0
Improvements (secondary)	-	-	0
All (primary)	0.6%	[0.6%, 0.7%]	3

regressed helloworld check by 0.6% in three incremental scenarios.
note though that these regressions did not show up in the timer run before the PR landed.
marked as triaged.

Improvements

Rollup of 6 pull requests #108357 (Comparison Link)

(instructions:u)	mean	range	count
Regressions (primary)	-	-	0
Regressions (secondary)	1.8%	[1.8%, 1.8%]	1
Improvements (primary)	-1.0%	[-1.1%, -0.9%]	2
Improvements (secondary)	-2.2%	[-2.5%, -1.9%]	6
All (primary)	-1.0%	[-1.1%, -0.9%]	2

Use tcx.ty_error_with_guaranteed in more places, rename variants #108369 (Comparison Link)

(instructions:u)	mean	range	count
Regressions (primary)	-	-	0
Regressions (secondary)	-	-	0
Improvements (primary)	-1.1%	[-1.2%, -1.0%]	2
Improvements (secondary)	-2.2%	[-2.5%, -2.0%]	6
All (primary)	-1.1%	[-1.2%, -1.0%]	2

Emit the enum discriminant separately for the Encodable macro #108440 (Comparison Link)

(instructions:u)	mean	range	count
Regressions (primary)	-	-	0
Regressions (secondary)	-	-	0
Improvements (primary)	-0.6%	[-1.0%, -0.3%]	91
Improvements (secondary)	-0.6%	[-0.9%, -0.4%]	22
All (primary)	-0.6%	[-1.0%, -0.3%]	91

rustdoc: reduce allocations when generating tooltips #108098 (Comparison Link)

(instructions:u)	mean	range	count
Regressions (primary)	-	-	0
Regressions (secondary)	-	-	0
Improvements (primary)	-5.1%	[-17.0%, -0.6%]	4
Improvements (secondary)	-0.9%	[-0.9%, -0.9%]	1
All (primary)	-5.1%	[-17.0%, -0.6%]	4

Mixed

Rollup of 8 pull requests #108339 (Comparison Link)

(instructions:u)	mean	range	count
Regressions (primary)	0.4%	[0.3%, 0.6%]	4
Regressions (secondary)	0.8%	[0.7%, 0.9%]	6
Improvements (primary)	-0.8%	[-3.0%, -0.2%]	8
Improvements (secondary)	-0.2%	[-0.3%, -0.2%]	2
All (primary)	-0.4%	[-3.0%, 0.6%]	12

seems like a wash, in terms of mix of regressions and improvements. the one outlier was the 3% improvement to opt-full on cranelift-codegen.
the primary regressions were to ripgrep opt-full (0.59%), image opt-full (0.51%), cranelift-codegen check-full (0.42%), and cranelift-codegen check-incr-full (0.27%)
I do not think its worth trying to dissect the rollup at this point though. Marking as triaged.

diagnostics: if AssocFn has self argument, describe as method #108324 (Comparison Link)

(instructions:u)	mean	range	count
Regressions (primary)	1.1%	[1.0%, 1.2%]	2
Regressions (secondary)	2.2%	[2.0%, 2.6%]	6
Improvements (primary)	-	-	0
Improvements (secondary)	-2.3%	[-2.3%, -2.3%]	1
All (primary)	1.1%	[1.0%, 1.2%]	2

already triaged as noise.

Update cargo #108330 (Comparison Link)

(instructions:u)	mean	range	count
Regressions (primary)	-	-	0
Regressions (secondary)	2.5%	[2.5%, 2.5%]	1
Improvements (primary)	-1.0%	[-1.1%, -0.9%]	2
Improvements (secondary)	-2.2%	[-2.5%, -1.9%]	6
All (primary)	-1.0%	[-1.1%, -0.9%]	2

already triaged as noise

Rollup of 7 pull requests #108386 (Comparison Link)

(instructions:u)	mean	range	count
Regressions (primary)	1.0%	[0.9%, 1.1%]	2
Regressions (secondary)	2.0%	[0.4%, 2.6%]	7
Improvements (primary)	-	-	0
Improvements (secondary)	-2.5%	[-2.5%, -2.5%]	1
All (primary)	1.0%	[0.9%, 1.1%]	2

primary cranelift-codegen; secondary keccak, coercions, unused-warnings
seems like the same cases that were already categorized as noise by nnethercote in several other cases
marking as triaged.

Rollup of 7 pull requests #108464 (Comparison Link)

(instructions:u)	mean	range	count
Regressions (primary)	-	-	0
Regressions (secondary)	0.4%	[0.4%, 0.4%]	1
Improvements (primary)	-0.7%	[-0.9%, -0.6%]	6
Improvements (secondary)	-	-	0
All (primary)	-0.7%	[-0.9%, -0.6%]	6

already triaged

Add inlining attributes for query system functions #108375 (Comparison Link)

(instructions:u)	mean	range	count
Regressions (primary)	-	-	0
Regressions (secondary)	0.4%	[0.2%, 0.7%]	5
Improvements (primary)	-0.4%	[-1.1%, -0.2%]	38
Improvements (secondary)	-0.4%	[-0.7%, -0.2%]	12
All (primary)	-0.4%	[-1.1%, -0.2%]	38

wins clearly outweigh losses here.
marking as triaged.

Nominated Issues

T-compiler

No I-compiler-nominated issues this time.

RFC

No I-compiler-nominated RFCs this time.

Next week meeting

Checkins:

Impl Trait initiative by @oli
@_WG-llvm by @nagisa and @Nikita Popov

Agenda draft: https://hackmd.io/Y3MpcGIXRuKpDGmYZV-TJg

Syntax	Example	Reference
# Header	Header	基本排版
- Unordered List	Unordered List
1. Ordered List	Ordered List
- [ ] Todo List	Todo List
> Blockquote	Blockquote
Bold font	Bold font
Italics font	Italics font
~~Strikethrough~~	~~Strikethrough~~
19^th^	19^th
H~2~O	H₂O
++Inserted text++	Inserted text
==Marked text==	Marked text
[link text](https:// "title")	Link
![image alt](https:// "title")	Image
`Code`	`Code`	在筆記中貼入程式碼
```javascript var i = 0; ```	`var i = 0;`	在筆記中貼入程式碼
:smile:		Emoji list
{%youtube youtube_id %}	Externals
$L^aT_eX$	L^aT_eX
:::info This is a alert area. :::	This is a alert area.

T-compiler Meeting Agenda 2023-03-02

Announcements

Other WG meetings (calendar link)

MCPs/FCPs

WG checkins

Most notable changes

Most notable WIPs

Backport nominations

PRs S-waiting-on-team

Oldest PRs waiting for review

Issues of Note

Short Summary

P-critical

P-high regressions

Performance logs

Regressions

Improvements

Mixed

Nominated Issues

Next week meeting