2025-04-14 — Last Week in Carbon #5309

josh11b · 2025-04-14T22:05:56Z

josh11b
Apr 14, 2025
Maintainer

Decisions
- #5270 Move explorer out of toolchain git repo
  - Approved: Explorer has been removed from the main git repo. Now available in a separate repo, and a tag in the main repo.
  - See also discussion on #explorer (continued from last week) and 04-08
New RFC proposals
- #5270 Move explorer out of toolchain git repo
Active discussions
- #5164 Updates to pattern matching for objects
  - Updated to reflect decision on #5250.

10 trained moderation & conduct team members + community lead, in theory available from UTC-7 to UTC+5.5.
- DONE: Transparency report for Q1 of 2025
- WIP: reaching out to other communities we’d like to learn from in terms of journey and interview some of their leaders, and started summarizing first input (currently: Swift folks in OSS projects)
Last week’s stats across our spaces:
- In the last 7 days in our repo: 8 authors pushed 41 commits to trunk, we changed 1,593 files with 18,276 additions and 63,923 deletions, with 41 merged PRs, 8 open PRs, 1 closed issue and 3 new ones
- One user account posting duplicate comments on GitHub was banned, and their comments were hidden.

04-07 #5255 #5283 #5272 impl witnesses with symbolic values
04-07 destructors for structural types
04-08 importing
04-08 #5256 fyi, renamings in the parse subdirectory have given new meaning to State
04-10 Keeping state across functions in lower
04-10 Only folding specifics for the same generic for now, not arbitrary functions that produce the same LLVM IR.
04-10 Example using an associated type in a function body.
04-11 #5202 #5258 #5260 #5281 #5280 Incrementally building generics
#5278 #toolchain Crash looking for someone to fix
#toolchain #5288 #5294 introducing TypeInstId that holds an InstId that is known to represent a type.
#toolchain Restructuring var parameters to better support importing
PRs:
- ...where .Self impls... in #5238
- clang-tidy in #5267 #5268 #5265 #5282
- test updates in #5254 #5289
- type structure comparison in #5247
- Carbon/C++ interop in #5197 #5156
- global constants in #5273 #5275
- SemIRLoc merged into LocId in #5274 #5284
- final impl in #5269
- renames in #5286 #5285
- explorer removal in #5287 #5291 #5290 #5292 #5293
- other in #5257 #5277 #5298

#strategy: Discussion of implementing #5233.
- Created the #last-week-in-carbon channel, as proposed.
- Is it for coordinating the last-week-in-carbon posts, or is it a "news feed" of things that might go into those posts?
#pattern-matching: When does type conversion happen during pattern matching?
- Current design is "as late as possible", meaning at a var pattern and at binding patterns.
- Conversion at var patterns will make it harder to support user-defined destructuring.
- Consequently, it also makes it harder to model tuples as ordinary library types.
#infra: Deleting some obsolete repos under carbon-language
- Some have small amounts of history not preserved elsewhere
#naming: What should we call a constant that's not associated with a particular eval block?
- Had been using "abstract" or "orphan", but those both mean something else.
- "Indefinite"? "Unassociated"? "Disconnected"? "Unattached"?
#initialization: Major revisions to draft proposal on reworking unformed state.
- Feedback would be appreciated. Some discussion on 04-10.
#general-design: Is there a way to drop fields from a struct? e.g.

{.a = 1, .b = 2, .c = 3} as {.a: i32, .b: i32}

Currently no, but it seems like we should have something.
04-09 Changes expected to impl lookup to support function overloading and representing categories and phases in interfaces such as Call.
04-11 Compile-time functions