Invalid return type not detected for union types

Description

Contributor guide

Tech stack

None

Domain

tooling

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

Basic knowledge of PHPUnderstanding of Psalm static analysisFamiliarity with union types

Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.

30

Research direction

Investigate how Psalm currently handles return type checking for union types. Look at the comments on the issue for any hints about the expected behavior. The fix likely involves modifying the type checker to detect invalid return types in union scenarios. Refer to the Psalm source code, particularly files related to return type analysis and union type handling.