Chandler Carruthandjosh11b
7871237c15
Implements proposal #7016: `self` moves from the deduced implicit list (`fn F[self: Self]()`) to the front of the explicit list. Its type may be written explicitly (`fn F(self: Self)`) or omitted, in which case it defaults to `Self` (`fn F(self)`, `fn F(ref self)`); `self` in the implicit list is rejected. Throughout checking, `self` is modeled as the first explicit parameter. Because a method is just a function whose first parameter is `self`, it can also be called as an ordinary function with the receiver passed explicitly (`Type.M(obj, ...)`), not only as `obj.M(...)`. A new `SemIR::CallArgParamPatterns` helper chooses the parameters matched against the explicit arguments, excluding a leading `self` only when it is supplied as a method-call receiver; arity checking, conversion, and generic deduction use it. The resulting SemIR and lowering are unchanged: `self` is still `call_param0`, and witnesses, thunks, and vtables are unaffected. An omitted `self` type is parsed as a `SelfBindingPattern` node with no type expression; checking synthesizes the `Self` type so it behaves exactly like `self: Self`. However, the exact spelling used must match between a forward declaration and a definition, following #3763's rules around declaration matching. Generated functions, thunks, and C++ interop import/export build `self` as the first explicit parameter, and the `self`-type override (e.g. Derived->Base for a virtual override) applies to the explicit `self`. Placement is validated by new diagnostics: `SelfInImplicitParamList`, `SelfNotFirstParam`, and `SelfOutsideParamList`. The benchmark source generator and the documentation adopt the `(self)` shorthand; the prelude, the examples, and the test data are migrated in the following commits. Assisted-by: Claude Code with Claude Opus 4.7 --------- Co-authored-by: josh11b <15258583+josh11b@users.noreply.github.com>
Docs
This directory contains current, accepted documentation underpinning Carbon. These documents cover all aspects of Carbon ranging from the project down to detailed designs for specific language features.
If you're trying to learn more about Carbon, we recommend starting at
/README.md.
Design
Carbon language's design and rationale are documented in the
design/ directory. This documentation is intended to
support the following audiences:
- People who wish to determine whether Carbon would be the right choice for a project compared to other existing languages.
- People working on the evolution of the Carbon language who wish to understand the rationale and motivation for existing design decisions.
- People working on a specification or implementation of the Carbon language who need a detailed understanding of the intended design.
- People writing Carbon code who wish to understand why the language rules are the way they are.
This is in contrast to proposals, which document the individual decisions that led to this design (along with other changes to the Carbon project), including the rationale and alternatives considered.
Project
The project/ directory contains project-related
documentation for Carbon, including:
- goals, and the principles and roadmap derived from those goals,
- how the project works, and
- how to contribute.
Guides
The guides/ directory contains to-be-written end-user
documentation for developers writing programs in Carbon.
Spec
The spec/ directory contains the to-be-written formal
specification of the Carbon language. This is for implementers of compilers or
other tooling. This is intended to complement the toolchain.