T-compiler Meeting Agenda 2022-02-03
- 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).
- New MCPs (take a look, see if you like them!)
- No new proposals this time.
- Old MCPs (not seconded, take a look)
pcin place of
unknownin place of
i?86targets” compiler-team#441 (last review activity: 7 months ago)
-Z binary-dep-depinfothe default behavior” compiler-team#464 (last review activity: 4 months ago)
- “Tier 3 target proposal: riscv64gc-linux-android (Android target for
riscv64gc)” compiler-team#472 (last review activity: about 55 days ago)
-Dwarningsto cover all warnings” compiler-team#473 (last review activity: about 55 days ago)
- “Build-time execution sandboxing” compiler-team#475 (last review activity: about 38 days ago)
- “Dealing with type/const ambiguities” compiler-team#480 (last review activity: about 13 days ago)
- Pending FCP requests (check your boxes!)
- No pending FCP requests this time.
- Things in FCP (make sure you’re good with it)
- No FCP requests this time.
- Accepted MCPs
- No new accepted proposals this time.
- Finalized FCPs (disposition merge)
- @_WG-async-foundations by @nikomatsakis and @tmandry (previous checkin)
Niko comments: nothing major to report - there is ongoing polish work as well as refactorings to support RPIT etc.
- @_WG-traits by @nikomatsakis and @Jack Huey (previous checkin)
Still haven’t published the retrospective blog post (Niko was going to write some paragraphs but hasn’t gotten to it yet).
Generic associated types
- A few more bug fix PRs have landed; there a couple PRs waiting for Jack to update
- GAT where clause position question (#90076) has been resolved by lang team: we will accept both positions, but deprecate where clauses before the equals
- Would like to think about and consider the design of std APIs with GATs prior to stabilization
- generic-associated-types-initiative#1 covers
LendingIteratorsplit; would love thoughts on use cases
- Where clause question was the final “blocking” issue for GATs
- A few more issues to triage, a documentation writeup, and library design considerations are precursors to stabilization
- Lazy TAIT PR is open by Oli: #92007
- It’s being coreviewed by Niko and @lcnr
async fn in traits
- @spastorino is working on some ast lowering refactoring that’s a precursor to this
negative impls in coherence
- @spastorino has done some more work here in #93175
- :beta: “Add links to the reference and rust by example for asm! docs and lints” rust#92611
- This PR adds links that where removed in rust#91728
- @Amanieu authored the PR and nominated for beta-backport
- PR approved by @Mara
- :beta: “backport llvm fix for issue 91671.” rust#93426
- PR fixes P-high rust#91671, a crash on compiling on aarch64 + LTO enabled
- PR authored by Felix, also nominated for stable backport
- Approved by @Nikita Popov
- :stable: “backport llvm fix for issue 91671.” rust#93426
- previous PR, also nominated for stable backport
- :stable: “riscv32i:
__atomic_load_4is referenced in libcompiler_builtins” rust#92897
- No backport nominations for
:back: / :shrug: / :hand:
- No PRs waiting on T-compiler
Oldest PRs waiting for review
- “Mir-Opt for copying enums with large discrepancies” rust#85158 (last review activity: 3 months ago)
- Last T-compiler review
- PR turned to
s-waiting-on-team2 days ago
- “Switch to normalized triples for Fuchsia” rust#90510 (last review activity: 2 months ago)
- PR assignee @Esteban Küber, reviewed also by @tmandry
- though last comment seems to indicate it’s a bit stale
unsafediagnostic” rust#91133 (last review activity: 2 months ago)
- Seems PR author is asking a new review from @Esteban Küber (assigned reviewer)
- “Remove eval_always for privacy.” rust#90581 (last review activity: 2 months ago)
- PR author pushed after the last perf report (with mixed results)
- Perhaps this is waiting on someone to trigger
- “Remove eval_always for privacy_access_levels.” rust#91295 (last review activity: 2 months ago)
- rust-highfive assigned to @Aaron Hill
- maybe waiting for a review after last perf run (with regressions)
Issues of Note
- 1 T-compiler P-critical issues
- 69 T-compiler P-high issues
- 0 P-critical, 1 P-high, 0 P-medium, 1 P-low regression-from-stable-to-beta
- 0 P-critical, 1 P-high, 1 P-medium, 0 P-low regression-from-stable-to-nightly
- 0 P-critical, 44 P-high, 80 P-medium, 12 P-low regression-from-stable-to-stable
- “Named format arguments introduce implicit positional arguments” rust#93378
- “rustdoc ICE: ‘no entry found for key’” rust#93476
- Assigned P-critical based on a similar issue (#93428)
- Anyway, it should be fixed by rust#93539
- “Some mixes of Rust with C/C++ are broken for arm64 mac and windows” rust#92885
- No unassigned
P-highnightly regressions this time.
This was a relatively quiet week with regressions and improvements relatively equally each other out. The big exception is with a somewhat large regression in rustdoc which was needed for a large and important architectural change. This could lead to users see somewhat slower doc build times with more memory used especially in projects with large crate dependency graphs.
Triage done by @rylev. Revision range: c54dfee65126a0ac385d55389a316e89095a0713..1ea4851715893ee3f365a8ef09d47165e9a7864f
2 Regressions, 4 Improvements, 2 Mixed; 1 of them in rollups 35 comparisons made in total 29 Untriaged Pull Requests
rustdoc: Pre-calculate traits that are in scope for doc links #88679
- Average relevant regression: 5.4%
- Largest regression in instruction counts: 9.1% on
- All the regressions are localized to rustdoc and are quite substantial but exacerbated by an architectural issue which needs to be solved.
- The regressions are well known and extensively discussed in the PR with the next steps being tracked in an issue.
Store def_id_to_hir_id as variant in hir_owner. #93373
- Average relevant regression: 1.2%
- Average relevant improvement: -0.3%
- Largest regression in instruction counts: 5.5% on
- This is the first commit (originally bundled with #93301) of a larger PR (#89278) which saw larger PR regressions than the two sub PRs combined.
- A more detailed justification for this can be found here, but in general this allows for even more incremental compilation and is thus worth the small immediate compilation performance penalty.
- Fix the unsoundness in the
early_otherwise_branchmir opt pass #91840
- Only traverse attrs once while checking for coherence override attributes #93343
- Rollup of 10 pull requests #93427
- Disable drop range analysis #93284
Store hir_id_to_def_id in OwnerInfo. #93301
- Average relevant regression: 0.6%
- Average relevant improvement: -0.5%
- Largest improvement in instruction counts: -0.6% on
- Largest regression in instruction counts: 2.2% on
- This is the first commit (originally bundled with #93373) of a larger PR (#89278) which saw larger PR regressions than the two sub PRs combined.
core::fmt::ArgumentV1 with generics instead of fn pointer #90891
- Average relevant regression: 1.2%
- Average relevant improvement: -1.2%
- Largest improvement in instruction counts: -6.7% on
- Largest regression in instruction counts: 2.1% on
- The improvements outweigh the regressions considerably and this was considered a fine trade off.
usedstatic is only present in output when in reachable module” rust#47384
- No nominated RFCs for