unusedMessageIds

Reports message IDs defined in the messages object that are never used in recognized report calls.

✅ This rule is included in the flint logical presets.

Lint rules often declare a messages object up front and then reference those message IDs from report calls later on. Keeping unused message IDs around makes rules harder to scan and maintain, especially when the message object grows over time.

This rule tracks message usage from context.report() calls and Flint’s built-in reportSourceCode() helper for source-mapped language rules.

Examples

❌ Incorrect

ruleCreator.createRule(_, {
  messages: {
    usedMessage: {
      primary: "This message is used.",
      secondary: [""],
      suggestions: [""],
    },
    unusedMessage: {
      primary: "This message is never used.",
      secondary: [""],
      suggestions: [""],
    },
  },
  setup(context: RuleContext) {
    context.report({
      message: "usedMessage",
    });
  },
});

✅ Correct

ruleCreator.createRule(_, {
  messages: {
    usedMessage: {
      primary: "This message is used.",
      secondary: [""],
      suggestions: [""],
    },
  },
  setup(context: RuleContext) {
    context.report({
      message: "usedMessage",
    });
  },
});

import { reportSourceCode } from "@flint.fyi/volar-language";

ruleCreator.createRule(_, {
  messages: {
    missingKey: {
      primary: "This message is used from source code.",
      secondary: [""],
      suggestions: [""],
    },
  },
  setup(context: RuleContext) {
    reportSourceCode(context, {
      message: "missingKey",
      range,
    });
  },
});

Options

This rule is not configurable.

Equivalents in Other Linters

• ESLint: eslint-plugin-eslint-plugin/no-unused-message-ids