leanprover / leanprover/lean4

`exact?` suggests an extra `id`

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bug P-low
Dominant language
Lean
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Description

Prerequisites

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Description

exact? suggests term with id

Context
Steps to Reproduce
  1. In this proof, hover over exact? to see what it suggests: example (a : Nat) (ha : a ≠ 0) : (0 < a ∨ a < 0) := by exact?

Expected behavior:

It suggests exact Nat.lt_or_gt_of_ne (Ne.symm ha)

Actual behavior:

It suggests exact Nat.lt_or_gt_of_ne (id (Ne.symm ha)) (note the extra id)

Versions
Lean 4.16.0-nightly-2025-01-19
Target: x86_64-unknown-linux-gnu
Impact

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Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reproducing the minimal exact? example from the issue against the listed Lean nightly version, then trace the exact? suggestion path to find where the redundant id is introduced. Done means the same proof suggests exact Nat.lt_or_gt_of_ne (Ne.symm ha) without the extra id.

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
Clearly specified
Newbie friendliness
38/100

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