leanprover / leanprover/lean4

Changing `internal.minimalSnapshots` option leads to a panic

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#5,075 1 comment 0 reactions 0 assignees View on GitHub

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bug P-low
Dominant language
Lean
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Merged PRs (30d)
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Description

Steps to Reproduce
  1. Create a Lean file containing
set_option internal.minimalSnapshots true
  1. Delete the final e

Expected behavior: That there be no observable behavior.

Actual behavior: A popup containing "Lean server printed an error: PANIC at outOfBounds Init.GetElem:11:2: index out of bounds" and an error in the VS Code "Output" area reporting "PANIC at Lean.Elab.InfoTree.visitM.go Lean.Server.InfoUtils:56:21: unexpected context-free info tree node".

Versions

Lean 4.12.0 8c96d213f3089ac2352ed95e79645f4cdbd70ebf

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

Reproduce the issue with a Lean file containing set_option internal.minimalSnapshots true, then delete the final e and inspect the VS Code Output area and panic messages. Trace the Lean server handling of this option change; done means the edit produces no observable behavior and no panic or error output.

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
35/100

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