Panic In `Lean.Environment.replayConsts.replayKernel`
Introduction
Lean is a powerful proof assistant and programming language that is widely used in mathematics and computer science. However, like any complex system, it is not immune to errors and bugs. In this article, we will discuss a specific issue that has been reported in the Lean community, where the server sometimes panics with a message indicating a failure to add a definition to the environment.
Prerequisites
Before we dive into the details of the issue, it is essential to ensure that you have checked the following:
- [X] 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
The Lean server sometimes panics with the following message:
PANIC at Lean.Environment.replayConsts.replayKernel Lean.Environment:1959:15: failed to add <definition>.eq_1 to environment`
(kernel) unknown constant '<definition>'
when you interrupt it (by editing the document) while it is compiling a declaration. Note that although it prints this error message, it doesn't seem to cause any problems later.
Context
This issue has been encountered while editing updateCell
in Std.Data.DTreeMap.Internal.Model
, which is a declaration that takes long to compile. The problem seems to occur when the server is interrupted while compiling a declaration, and it is not clear what triggers this behavior.
Steps to Reproduce
Unfortunately, it is challenging to reproduce this issue with a minimal test case. However, the following steps can be used to reproduce the problem:
- Put the cursor above the definition of
updateCell
- Add a line break
- Wait until the orange bar is no longer next to the entire definition of
updateCell
and only on the line withdef updateCell
(and everything afterupdateCell
) - Add another line break
After a short while, the server should print error messages like:
PANIC at Lean.Environment.replayConsts.replayKernel Lean.Environment:1959:15: failed to add Std.DTreeMap.Internal.Impl.get?ₘ.eq_1 to environment
(kernel) unknown constant 'Std.DTreeMap.Internal.Impl.get?ₘ'
Versions
This issue has been tested on commit 2363d2fa873a6e5f6e48505b3f1387583c5ef14c.
Impact
This issue can cause the Lean server to panic and print error messages, which can be confusing and may lead to frustration. However, it is essential to note that the server seems to recover from this issue without any problems later.
Conclusion
In conclusion, the panic in Lean.Environment.replayConsts.replayKernel
is a complex issue that is challenging to reproduce with a minimal test case. However, by following the steps outlined above, it is possible to reproduce the problem. If you are experiencing this issue, please add :+1: to the relevant issue on the Lean GitHub page to help prioritize the fix.
Recommendations
If you are experiencing this issue, we recommend the following:
- Check the Lean GitHub page for any updates on this issue
- Provide more information about your environment and the steps you took to reproduce the issue
- Consider reducing the issue to a minimal, self-contained, reproducible test case to help the developers debug the problem
Q: What is the panic in Lean.Environment.replayConsts.replayKernel
?
A: The panic in Lean.Environment.replayConsts.replayKernel
is an error that occurs when the Lean server is interrupted while compiling a declaration. It prints an error message indicating a failure to add a definition to the environment, but it does not seem to cause any problems later.
Q: What triggers this panic?
A: The panic seems to occur when the server is interrupted while compiling a declaration, but it is not clear what triggers this behavior. It has been encountered while editing updateCell
in Std.Data.DTreeMap.Internal.Model
, which is a declaration that takes long to compile.
Q: How can I reproduce this panic?
A: Unfortunately, it is challenging to reproduce this panic with a minimal test case. However, the following steps can be used to reproduce the problem:
- Put the cursor above the definition of
updateCell
- Add a line break
- Wait until the orange bar is no longer next to the entire definition of
updateCell
and only on the line withdef updateCell
(and everything afterupdateCell
) - Add another line break
After a short while, the server should print error messages like:
PANIC at Lean.Environment.replayConsts.replayKernel Lean.Environment:1959:15: failed to add Std.DTreeMap.Internal.Impl.get?ₘ.eq_1 to environment
(kernel) unknown constant 'Std.DTreeMap.Internal.Impl.get?ₘ'
Q: What versions of Lean have this panic been tested on?
A: This panic has been tested on commit 2363d2fa873a6e5f6e48505b3f1387583c5ef14c.
Q: Does this panic cause any problems later?
A: No, the server seems to recover from this panic without any problems later.
Q: How can I help resolve this panic?
A: If you are experiencing this panic, please add :+1: to the relevant issue on the Lean GitHub page to help prioritize the fix. Additionally, consider reducing the issue to a minimal, self-contained, reproducible test case to help the developers debug the problem.
Q: What are the recommended steps to take if I am experiencing this panic?
A: If you are experiencing this panic, we recommend the following:
- Check the Lean GitHub page for any updates on this issue
- Provide more information about your environment and the steps you took to reproduce the issue
- Consider reducing the issue to a minimal, self-contained, reproducible test case to help the developers debug the problem
Q: Can I get help from the Lean community if I am experiencing this panic?
A: Yes, the Lean community is active and willing to help. You can ask for help on the Lean GitHub page, the Lean subreddit, or the Lean mailing list. Additionally, you can try reaching out to the Lean developers directly for assistance.
Q: How can I stay up-to-date with the latest developments on this panic?
A: You can stay up-to-date with the latest developments on this panic by checking the Lean GitHub page regularly for updates. Additionally, you can follow the Lean developers on social media to stay informed about the latest news and developments.