Lean 4 fork for HoTT-compatible kernel extensions (Path types, transport, HITs). Maintained against upstream leanprover/lean4.
f4bbf748df
This PR adds `deriving noncomputable instance Foo for Bar` syntax so
that delta-derived instances can be marked noncomputable. Previously,
when the underlying instance was noncomputable, `deriving instance`
would fail with an opaque async compilation error.
Now:
- `deriving noncomputable instance Foo for Bar` marks the generated
instance as noncomputable (using `addDecl` + `addNoncomputable` instead
of `addAndCompile`)
- `deriving instance Foo for Bar` pre-checks for noncomputable
dependencies and gives an actionable error with a "Try this:" suggestion
pointing to the noncomputable variant
- For handler-based deriving (inductives/structures), `noncomputable`
sets `isNoncomputable` on the scope
The `optDefDeriving` and `optDeriving` trailing parsers are updated with
`notSymbol "noncomputable"` to prevent them from stealing the parse of
`deriving noncomputable instance ...`.
🤖 Prepared with Claude Code
---------
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
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