import-js/eslint-plugin-import

false positive no-unused-modules with Flow

Open

#1,539 opened on Nov 13, 2019

View on GitHub
 (2 comments) (2 reactions) (0 assignees)JavaScript (4,946 stars) (1,540 forks)batch import
bugflowhelp wanted

Description

When type import goes before default import from the same file, the default export is marked as unused:

// foo.js

// @flow strict
export type Foo = string
export default ''

// index.js

// @flow strict
import type {Foo} from './foo'
import foo from './foo'

3:1 error exported declaration 'default' not used within other modules import/no-unused-modules

It works OK if I change the imports order:

// index.js

// @flow strict
import foo from './foo'
import type {Foo} from './foo'

Repro: https://github.com/Hypnosphi/no-unused-modules-repro

Contributor guide

Tech stack
javascript
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
ESLint plugin architectureFlow type import syntaxUnderstanding of no unused modules rule
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
45
Research direction
The bug is in the no unused modules rule, likely in how it handles type imports before default imports. Start by examining src/rules/no unused modules.js to understand the export detection logic. Clone the repro repository at https://github.com/Hypnosphi/no unused modules repro to reproduce the issue and test fixes. Check if existing tests cover Flow type imports and consider adding a test case for the specific import order.