unused variable FP with forall syntax in signature
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bug
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- Dominant language
- Lean
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Description
axiom Foo : ∀ (a : Nat), Prop
-- ^ unused variable `a`
This warning does not happen when using the syntax axiom Foo : (a : Nat) → Prop. (This is supposed to be an exception to the usual unused variable rules because it is a function signature variable, visible in the docstring and also accessible via the Foo (a := 0) syntax.)
Occurs on latest nightly (leanprover/lean4:nightly-2024-11-24).
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Reproduce the warning with the reported axiom Foo : ∀ (a : Nat), Prop example and compare it with the arrow-syntax form on the referenced nightly. Trace the unused-variable warning handling for forall binders, then verify that the function-signature exception is preserved without warnings for this case.
Written by the indexing model from the issue text.
Assessment
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100