vimeo/psalm

array_is_list makes the type less specific.

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#8,046 opened on Jun 2, 2022

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 (7 comments) (0 reactions) (1 assignee)PHP (5,369 stars) (668 forks)batch import
Help wantedeasy problemsenhancementgood first issue

Description

https://psalm.dev/r/ffab419792

The test1 function passes the test successfully.

Errors are generated for the test2 function because array_is_list turns the $arr type into a non-empty-list<array<array-key, string>|string>.

Contributor guide

Tech stack
php
Domain
toolingdeveloper experience
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
PHPPsalm internals
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40
Research direction
Examine the handling of array is list in Psalm's type inference, likely in the function stubs or type combining logic. The example in the issue shows that the type becomes less specific after calling array is list. Look for where array is list is defined (e.g., in stubs) and how its return type is constrained. Review the conversation in the issue for any proposed solutions or maintainer input.