Incorrect syntax construction in `,*` antiquotation
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bug
P-low
- Dominant language
- Lean
- Stars
- 9.2k
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- Avg merge
- 1d 17h
- Merged PRs (30d)
- 175
Description
This constructs a list syntax node containing three , separators (and no elements). If you match on the result, Lean believes it's a list literal with two elements.
import Lean open Lean
#eval Unhygienic.run do
let x : Array Term := #[]
`([$x,*, $x,*, $x,*, $x,*])
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 reproducer in the issue and inspecting the syntax produced by the ,* antiquotation. Trace the antiquotation expansion and verify that the resulting list syntax contains the intended elements and separators, then confirm matching no longer reports the wrong element count.
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
- 35/100