import-js/eslint-plugin-import

Re-exporting all flow types can cause trouble with export rule

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#1,937 opened on Nov 5, 2020

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Description

file-a.js

// @flow
const Bar = 'Bar';

export {Bar};

file-b.js

// @flow

export {Bar} from './file-a';

export type * from './file-a';

export type * is read by export rule as exporting everything inside file-a.js (not just the types), so it causes:

file-b.js
  3:9  error  Multiple exports of name 'Bar'  import/export
  5:1  error  Multiple exports of name 'Bar'  import/export

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.
2
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.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Basic JavaScriptUnderstanding of ESLint pluginsFamiliarity with Flow types
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70
Research direction
Investigate the 'export' rule in the eslint plugin import package to understand how it processes re exports via `export type *`. The issue is that the rule treats `export type *` as re exporting all named exports, including non type exports, causing a false positive when there is a named export collision. Look for how the rule collects exports and whether it differentiates between type only re exports. A fix may involve checking if the re export is type only and excluding non type exports from the check.