LuaLS / LuaLS/lua-language-server

Array type matches any table

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Dominant language
Lua
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Description

How are you using the lua-language-server?

Other

Which OS are you using?

Linux

What is the issue affecting?

Type Checking

Expected Behaviour

When assigning a class/key-value table to a type defined as an array, a diagnostics error should be raised.

Actual Behaviour

No diagnostics error is raised.

Reproduction steps
local dict = {a = 'a'}

---@type number[]
local array = dict

Observe that no diagnostics error is raised when assigning dict to array, which is defined as an array.

Additional Notes

lua-langauge-server should check for the presence of non-integer indices in a table. If there are any, the table should not match the array type.

I believe the present issue is the underlying issue in #1721.

Version

3.13.6-1

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

The issue names no source file or test. Start by running the provided Lua reproduction with lua-language-server 3.13.6-1 and trace the type-checking path for table-to-array assignment. Done means a diagnostic is reported for a table containing a non-integer key while valid arrays remain accepted.

Written by the indexing model from the issue text.

Assessment

Tech stack
lua
Domain
devtools
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
42/100

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