vimeo/psalm

Infer class type based upon result of is_a() function call

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#3,629 opened on Jun 22, 2020

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Help wantedenhancement

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Description

https://psalm.dev/r/8a00f9319d

I believe psalm should be able to infer that future calls to \Storage should resolve to \Illuminate\Support\Facades\Storage.

This is laravel's technique for aliasing classes.

If you'd like to provide some notes on how to implement, I'd be happy to take a stab. I'm not sure if the class should just be aliased in the scope of the is_a branch, or across the entire project. I'm thinking it might just need to be within the scope of the conditional

Contributor guide

Research direction
Review Psalm's conditional type narrowing logic in /src/Psalm/Internal/Analyzer/Statements/Expression/Call/FunctionCallAnalyzer.php. Look for handling of is a() and similar functions. Consider adding an alias to the class type in the scope of the conditional branch.
Tech stack
php
Domain
developer experiencetooling
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
PHP
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50