google/closure-compiler

Add an @pure annotation

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#2,395 opened on Mar 31, 2017

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feathelp wanted

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Description

I'd like to have an annotation to declare an intent that a function will not have side effects. In the presence of this annotation, I'd like the compiler to warn me if the function has side effects.

In a lot of code, you have simple helper methods that are intended to be side-effect free. It's very easy for a side effect to be accidentally introduced at a later time. I'd like to have a warning issued for this so the developer can correct it.

Contributor guide

Research direction
Investigate how existing annotations like @const and @nosideeffects are implemented in the Closure Compiler. Look for the warning system and how side effects are detected. Then design the @pure annotation and the corresponding warning logic.
Tech stack
java
Domain
tooling
Issue type
Feature
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.
1-2 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
Javacompiler design
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40