2026-01-12— Last Week in Carbon #6585

josh11b · 2026-01-13T00:11:07Z

josh11b
Jan 13, 2026
Maintainer

Decisions
- #6254 C++ Interop: Toolchain Implementation for Function Calls
  - Approved.
- #6333 CLI and separate compilation
  - Approved.
New RFC proposals
- (none)
Active discussions
- #5990: Principle: The signature is the contract
  - Concerns about the name of the principle, and need better delineation of uses that do/don't reference members of the entity.
  - #general-design Could this be tied to something like the C++ notion of value-dependence?
  - Is an expression like A.B.C(X, Y) always the name path of an entity, or does it depend on C?

Moderation interventions last week:
- (none)
Activity in the past week:
- 1 new contributor! 🎉
- 9 authors have pushed 27 commits to trunk and 27 commits to all branches.
- On trunk, 422 files have changed and there have been 10,035 additions and 4,924 deletions
- We merged 27 PRs, opened 11 PRs, and closed 1 issue.

#safety Continued discussion of xr0
01-05 01-05 01-06 #safety const in type of object or alias set
- Question comes down to whether ordinary type interfaces can overload on const or only form interfaces
- Conclusion: only form interfaces can overload on const, and so const is part of the type of alias sets (and therefore pointers & references), not objects.
01-05 Need to clarify the argument/parameter/deduced terminology in Safety Unit No. 30: Points-to and aliasing
01-07 01-08 Safety syntax questions, like where to write alias set arguments and const, how to write the sum of alias sets

#error-handling Link to Stop Forwarding Errors, Start Designing Them
#strategy Someone tried to do Advent of Code in Carbon using C++ interop.
#infra Are the current best practices for stacked PRs recorded anywhere?
- No. Key points are to identify in the PR where the review starts, and to not add more commits after that. Details of how to do that vary.
#strategy New programming language Temper claims to translate to "all the other languages" (for a loose definition of "all")
#functions How to represent function calls with compound forms in textual SemIR (spun off from #6532)
#infra Is there a way that Compiler Explorer users can share the runtimes cache?
#style Should we disable the readability-function-size clang-tidy?
- Looks like we can reconfigure it instead.