2025-08-25 — Last Week in Carbon

[josh11b]

Updates on leads issues

• Decisions
  • (none)
• New issues
  • #5969 Core type names and keywords for string types
    • Cases: view, buffer, null-terminated
  • #5979 Should we provide a syntactic shorthand for Core.Optional?
    • Possibilities: postfix or prefix ?, keyword such as opt.
• Active discussions
  • #5903 Built-in character type questions
    • Reopened to ask about the interaction with proposal #1964

Updates on proposals

• Decisions
  • #5914 Updating Carbon's safety strategy
    • Replaces the previous directional safety strategy with a new concrete and updated framework for the safety design. It includes a specific framework for memory safety, simplified build modes, specific "safety modes", and terminology.
    • Provides a directional suggestion for temporal and data-race safety specifically.
• New RFC proposals
  • (none)
• Active discussions
  • #5545 Expression form basics
    • Updated based on feedback
  • #5913 Reworking unformed state
    • Responded to suggestions

Updates on moderation across our community spaces (Discord and GitHub)

• Moderation and conduct teams are still the same size, available in theory from UTC-7 until UTC-5.5: 10 trained members altogether + community lead (hands-off trainer, coach, guide)
  • WIP: Outreach for new interview round of C# community leaders about their community journey
• Activity in the past week:
  • Many habitual contributors were off, so much less activity than usual.
  • … but one new contributor?!
  • Encouraged contributors to check current WIP in PRs before working on something and starting new PRs.
  • Updated AutoMod bots to catch more spam.
  • In the last 7 days in our repo: 6 authors pushed 11 commits to all branches, 10 of which to trunk, we changed 183 files with 4,470 additions and 1,977 deletions, we merged 10 PRs, opened 7 PRs, we did not close any issue and opened 2 new ones

Activity on toolchain

• #toolchain Should we use SmallVectorImpl instead of SmallVector in APIs?
• #toolchain #5975 Consuming elements of an ArrayRef
• PRs:
  • strings in #5963 #5964
  • #toolchain filesystem library in #5968
  • importing nested types from C++ in #5955
  • golden tests in #5965
  • const conversion in #5971
  • fuzzing in #5974
  • Clang runtimes in #5338

Activity on C++ interop

• #interop How do we want bool interop to work, given that we represent it as i1 but Clang represents it as i8 in memory?
  • It looks like we need to widen all loads/stores to a multiple of 8 during lowering.

Other active discussions

These include Discord Chat, GitHub Discussions, or open discussion sessions.

• #getting-started Having trouble opening the project in CLion.
  • scripts/create_copydb.py may help. Most of us use VSCode, but we'd love it if someone contributed instructions for setting up Carbon development in CLion.
• #syntax Detailed answer to a previous question about how modifier/prefix keywords work.
• #syntax Is fn F() -> (X, Y, Z) an initializing expression or a tuple of three initializing expressions
  • It's an initializing expression; this is observable from the fact that let f: array(X, 3) = F(); is invalid.
  • You can get the other semantics with fn F() -> (var X, var Y, var Z).
  • Should the array example be valid anyway?
    • Even if it's valid, it would have slightly different initialization semantics for the two definitions of F.
    • The rules that make it invalid do lead to sub-optimal performance in some cases.
    • Exploring the alternative leads to the side observation that we haven't really delegated this to the library; the core language has to pick a side.
• #typesystem (Follow-up to question last week) we're not prioritizing dyn for 0.1 because it's low-risk.
• #infra The open discussion meetings were unintentionally removed from the calendar.
  • We put them back, but you may need to re-RSVP.
• #language-questions Does Carbon's type system support integer types with user-specified ranges, or units of measurement?
• #getting-started Is there any etiquette for pinging moderators about a problem on Discord?
  • We always appreciate the heads-up. If you DM @ModMail it will ping all the moderators and create a queue for us to resolve.
• #generics-and-templates Specialization is working well enough to support Optional(T*), although we don't have a way to represent the storage type yet.

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