2026-02-23— Last Week in Carbon #6776

josh11b · 2026-02-23T19:49:26Z

josh11b
Feb 23, 2026
Maintainer

Decisions
- (none)
New RFC proposals
- (none)
Active discussions
- #5389 Generic across forms
  - #pattern-matching Should we allow modifiers or enclosing patterns on :? bindings?

Conduct team updates:
- none
Moderation interventions last week:
- We discussed how to help the community remember to stay on-topic,
  job searches and ads being off-topic
Activity in the past week:
- One new contributor 🎉
- 11 authors have pushed 22 commits to trunk.
- 662 files have changed and there have been 28,319 additions and 20,257 deletions
- We merged 22 PRs, opened 10 additional PRs, closed 3 issues, and opened 3 new issues.

02-17 Node category is a bitmask enum
#toolchain #6753 Diagnostics + Eval changes (rough draft) proposed
#toolchain Facet-or-type to type conversion
#toolchain Handling form literals determining a signature's form
- Considering fix by changing parse node types
#toolchain Location spans seem to be confused by r#
#toolchain Interop TODO being addressed by #6761
#toolchain Help with build changes
#toolchain Considered and rejected using CRTP to allow implicitly convert a inst to a category it belongs to directly
PRs:
- forms in #6746 #6745
- dependent expression category in #6744
- non-type template parameters in #6740
- Main.Run in #6751 #6757
- options in #6759 #6750 #6741
- eval fn in #6725
- runtimes in #6701 #6765
- generics in #6667 #6726 #6679
- Convert diagnostics in #6762
- unused pattern bindings in #6518
- mangling in #6764
- others in #6754 #6758
New contributors:
- @TechWizard9999 made their first contribution in #6679

#safety Goals/scope of Carbon memory safety comparison to Rust.
#safety 02-19 Safety for inheritance, expected to be similar to how Rust handles lifetimes with dyn Trait objects
- Continued in Safety Unit No. 36: inheritance.
#safety Spatial safety extension for Clang.
02-18 Terminology around implicitly introduce alias sets
02-19 Talked about Safety Unit No. 33, including ^_erased_external link
02-19 Variant vs. invariant, described very briefly in Safety Unit No. 30: Points-to and aliasing
02-19 associated alias set for interfaces
02-19 Safety story in slides
02-19 var parameters
02-19 globals referenced by returns

#naming Continued discussion of expression category names.
#error-handling Continued discussion of error handling implementation strategies.
#typesystem Should initializing an abstract type from {} work?
- No. You can have values of abstract types, but they can't be initialized that way.
#build-help lldb under VS Code can't see the source files in file_test.
- Make sure to follow all the steps here.
#infra Seeing possible GitHub archive hash instability (again).
#typesystem Can the type system "see into" a non-template :! binding?
- Tentative plan is that it behaves as if it had a constraint making it equal to its initializer.
#typesystem How do we want the implementation of local template bindings to work?
#infra Mac fastbuild seems slow, and is producing warnings.
#build-help Can't find the compiled runtimes.
- find command doesn't follow symlinks, and Bazel output is basically all symlinks.
#infra When stacking PRs, avoid merge commits.
#typesystem When do we require a callsite ref tag, in the presence of form generics?
#language-questions Started getting link error in a toy Carbon program.
- Caused by having multiple entry point functions.
02-19 Considering publishing a NotebookLM instance to answer Carbon questions, around 0.1 launch.
02-19 Scoping next edition of Carbon Copy.