eclipse-jdt/eclipse.jdt.core

RFE: issue (optional) warning when '==' is used on wrapper types

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#2,176 opened on Mar 18, 2024

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enhancementhelp wanted

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Description

I would like that Eclipse (similar to IDEA) would issue an optional warning when one uses the following construct:

Long x1 = 12345L;
Long x2 = 67890L;
if(x1 == x2)
    System.out.println("Equal");
else
    System.out.println("Not equal");

Because (as apparently we don't all know) Long is a wrapper class and using == only works for Long values between -127 and 127 due to caching (similarly for the other wrapper types).

This would at least uncover one such instance in our code base, of which I suspect to find a greater number alas.

Contributor guide

Research direction
Investigate existing warning infrastructure in Eclipse JDT Core (e.g., for 'null comparison' or 'unnecessary cast'). Identify where to add a new optional warning for '== on wrapper types' and implement it in the compiler/AST visitor. Test with various wrapper types and cached values.
Tech stack
java
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.
1-2 days
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
JavaEclipse JDT Core internals
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60