type/no-duplicate-type-constituents

Disallow duplicate union or intersection constituents.

Applies to: Type information in Vue SFC scripts and templates, for the constructs shown below.

This rule reads type information from your TypeScript project (tsconfig.json), so the configuration sets typeAware: true. typeAware does not turn on opt-in rules by itself.

Bad

string appears twice in the same union, so the second constituent adds nothing.

<script setup lang="ts">
type Dup = string | string;
</script>

Good

The alias keeps a single string constituent.

<script setup lang="ts">
type Dup = string;
</script>

Configuration (Vite+)

import { defineConfig } from "@vizejs/vite-plugin/vite-plus";

export default defineConfig({}).withVue({
  linter: {
    "preset": "incremental",
    "rules": {
      "type/no-duplicate-type-constituents": "warn"
    },
    "typeAware": true
  },
});

Then run vp run lint.

Related

• Type and script rules
• Rule options
• All rules
• Source code