2026-05-04 — Last Week in Carbon #7165

josh11b · 2026-05-04T18:07:37Z

josh11b
May 4, 2026
Maintainer

Decisions
- (none)
New RFC proposals
- #7140 Orphan rule for scopes
  - #generics-and-templates Prior discussion.
Active discussions
- #5990 Principle: The signature is the contract
  - Closed by author

Conduct team updates:
- None
Moderation interventions last week:
- None
Activity in the past week:
- 7 authors have pushed 29 commits to trunk and 29 commits to all branches.
- On trunk 290 files have changed and there have been 17,208 additions and 11,113 deletions
- We merged 29 PRs, opened 10 additional PRs, closed 0 issues, and opened 9 new issues.

#toolchain Why do we avoid C++20 ranges?
#toolchain We allow binding a ref to a temporary. Is that a mistake?
- Yes, it looks like there are several problems here.
#toolchain Should AddInst "magically" put the inst on the right stack?
#toolchain How to deal with action that news 3 operands?
#toolchain Do we still need to disallow multiple associated functions?
- Still has the quadratic behavior that we imposed this limit to avoid.
#toolchain 04-30 How to depict BundleStore in raw SemIR dumps?
#toolchain Should zygoloid keep sending semi-automated cleanup PRs? Do we prefer smaller or larger?
#toolchain Should we disable warnings for C++26 extensions, e.g. to allow multiple _ placeholders?
#toolchain How to support Inst::ArgAndKind use cases with bundles?
Toolchain release notes
PRs:
- C++ arithmetic operators in #7123
- indirect import in #7121 #7122
- var parameters in #7023 #7125
- forms in #7100
- thunks in #7115
- Carbon class fields from C++ in #7119
- Carbon methods called from C++ in #7130
- ambiguous .Self in #7132
- C++ dynamic class in #7141
- dependent PR infra in #7124 #7117 #7127 #7136 #7137 #7145
- debugging in #7148 #7149
- others in #7114 #7128 #7131 #6961 #7153 #7155 #7150 #7156 #7154 #7158

04-28 Discussing the possibility of giving a talk on Carbon’s memory safety model at NDC TechTown.

#infra Continued discussion of cmake support and other build system issues.
04-27 Potential future conference talks.
#infra Continuing to refine stacked-PR script
#generics-and-templates SymbolicBindingType has been removed; FacetAccessType now covers those use cases.
#interop How will we migrate X-Macros to Carbon?
#generics-and-templates appendix-rewrite-constraints.md looks very out of date.
04-28 When and how should we disambiguate a .Self in a nested where clause. Not decided, and turned into leads issue #7138.
#generics-and-templates Are member access designators in a nested where clause enough to satisfy the requirement that it “applies a restriction to the current type”? Concerns added to leads issue #7138.
#infra Should Carbon keep backups of GitHub?
#generics-and-templates What scopes can an impl be declared or redeclared in?
04-30 Alternate name for "form"?
#interop Are types that don't implement Destroy non-destructible, or trivially destructible?
#packages-and-libraries What are the rules for transitive imports?
#style What type should size() return?
#getting-started Having trouble with the getting-started Bazel instructions.