leanprover / leanprover/lean4

`#check` does not issue deprecation warning or handle overloaded definitions

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bug P-medium
Dominant language
Lean
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Description

Prerequisites

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Description

#check ident does not issue a warning if ident is deprecated. It also does not print all definitions of overloaded constants, and does not issue an error in this case.

Context

Zulip discussion

Steps to Reproduce
@[deprecated] def A := 0
@[deprecated] def B.A := 0
open B

#check A

Expected behavior: Warns that A is deprecated. Either raises an error that says A is overloaded or print types of both A and B.A. Both of these are done if the user does #check (A) instead.

Actual behavior: #check prints the type of B.A without warning

Versions

Lean version 4.13.0-rc3

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 running the minimal reproducer from the issue against the Lean nightly release and compare #check A with #check (A). Use the linked Zulip discussion for context. Done means deprecated identifiers produce a warning and overloaded definitions are either reported as ambiguous or both types are printed.

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
Clearly specified
Newbie friendliness
35/100

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