Lean 4 fork for HoTT-compatible kernel extensions (Path types, transport, HITs). Maintained against upstream leanprover/lean4.
51e87865c5
This PR adds a `@[deprecated_arg]` attribute that marks individual function parameters as deprecated. When a caller uses the old parameter name, the elaborator emits a deprecation warning with a code action hint to rename or delete the argument, and silently forwards the value to the correct binder. Supported forms: - `@[deprecated_arg old new (since := "...")]` — renamed parameter, warns and forwards - `@[deprecated_arg old new "reason" (since := "...")]` — with custom message - `@[deprecated_arg removed (since := "...")]` — removed parameter, errors with delete hint - `@[deprecated_arg removed "reason" (since := "...")]` — removed with custom message A warning is emitted if `(since := "...")` is omitted. When a parameter is deprecated without a replacement, the elaborator treats it as no longer present: using it as a named argument produces an error. Note that positional uses of deprecated arguments are not checked — if a function's arity changed, the caller will simply get a "function expected" error. The `linter.deprecated.arg` option (default `true`) controls behavior: when enabled, renamed args produce warnings and removed args produce specific deprecation errors with code action hints; when disabled, both fall through to the standard "invalid argument name" error. This lets library authors phase out old parameter names without breaking downstream code immediately. Example (renamed parameter): ```lean @[deprecated_arg old new (since := "2026-03-18")] def f (new : Nat) : Nat := new /-- warning: parameter `old` of `f` has been deprecated, use `new` instead Hint: Rename this argument: o̵l̵d̵n̲e̲w̲ --- info: f 42 : Nat -/ #guard_msgs in #check f (old := 42) ``` Example (removed parameter): ```lean @[deprecated_arg removed (since := "2026-03-18")] def g (x : Nat) : Nat := x /-- error: parameter `removed` of `g` has been deprecated Hint: Delete this argument: (̵r̵e̵m̵o̵v̵e̵d̵ ̵:̵=̵ ̵4̵2̵)̵ -/ #guard_msgs in #check g (removed := 42) ``` |
||
|---|---|---|
| .claude | ||
| .github | ||
| .vscode | ||
| doc | ||
| images | ||
| releases_drafts | ||
| script | ||
| src | ||
| stage0 | ||
| tests | ||
| .gitattributes | ||
| .gitignore | ||
| .gitpod.Dockerfile | ||
| .gitpod.yml | ||
| .ignore | ||
| CMakeLists.txt | ||
| CMakePresets.json | ||
| CODEOWNERS | ||
| CONTRIBUTING.md | ||
| flake.lock | ||
| flake.nix | ||
| lean-toolchain | ||
| LICENSE | ||
| LICENSES | ||
| README.md | ||
| RELEASES.md | ||
This is the repository for Lean 4.
About
- Quickstart
- Homepage
- Theorem Proving Tutorial
- Functional Programming in Lean
- Documentation Overview
- Language Reference
- Release notes starting at v4.0.0-m3
- Examples
- External Contribution Guidelines
Installation
See Install Lean.
Contributing
Please read our Contribution Guidelines first.
Building from Source
See Building Lean.