revert fails with variable
Nobody has claimed this yet.
- Dominant language
- Lean
- Stars
- 9.2k
- Forks
- 990
- Avg merge
- 1d 17h
- Merged PRs (30d)
- 175
Description
Prerequisites
Please put an X between the brackets as you perform the following steps:
- Check that your issue is not already filed:
https://github.com/leanprover/lean4/issues - Reduce the issue to a minimal, self-contained, reproducible test case.
Avoid dependencies to Mathlib or Batteries. - Test your test case against the latest nightly release, for example on
https://live.lean-lang.org/#project=lean-nightly
(You can also use the settings there to switch to “Lean nightly”)
Description
revert fails with metavariables when a variable statement is used, but succeeds if a proper argument is used or nonrec is added.
Context
https://leanprover.zulipchat.com/#narrow/stream/270676-lean4/topic/revert.20and.20variable
affects also extract_goal in mathlib
Steps to Reproduce
variable {P : Prop}
theorem bug --adding nonrec fixes the issue
--{P : Prop} --uncommenting this line fixes the issue
(S : P → Prop) :
∃ (hx : P), S hx := by
apply Exists.intro
· revert P -- tactic 'clear' failed, target depends on 'bug'
sorry
Expected behavior:
revert succeeds, and behaves identically for variables and parameters
Actual behavior:
revert succeeds only without variable
Versions
Lean 4.10.0 (also earlier)
Impact
Add 👍 to issues you consider important. If others are impacted by this issue, please ask them to add 👍 to it.
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
Start by running the minimal reproducer with Lean 4.10.0 and compare the behavior of revert P with a proper parameter or nonrec. Trace the revert tactic and the related clear failure; done means variables and parameters behave identically and the example succeeds without the workaround.
Written by the indexing model from the issue text.
Assessment
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100