Disable `default-case` ESLint rule for type-checked TypeScript files (#94316)
`@typescript-eslint/switch-exhaustiveness-check` (enabled in
eslint.cli.config.mjs) already guarantees complete switch coverage on
enums and discriminated unions, so requiring an additional default case
on those switches in TypeScript just forced dead branches.
We turn on its `requireDefaultForNonUnion` option so that switches on
plain types such as `string` or `number` still require a default,
preserving the coverage that `default-case` previously gave us. We scope
the `default-case: off` override to exactly the files where the
type-checked rule runs — the same `files` and `ignores` as the
switch-exhaustiveness check — and cross-reference the two config blocks
so the globs stay in sync. That way `default-case` stays enabled for
JavaScript files, `.mts` files, and the directories the type-checked
config skips, so no switch is left unchecked.
The two `// eslint-disable-next-line default-case` directives in
`postcss-loader` and `head.tsx` are no longer the right escape hatch:
with `requireDefaultForNonUnion` the exhaustiveness check now wants
those switches handled, and a directive for that rule would be reported
as unused under the editor config where it does not run. We give each
switch an explicit `default` case instead, which both rules accept and
which makes the previously implicit fall-through behavior explicit.
next.js
4fff8f42 - Disable `default-case` ESLint rule for type-checked TypeScript files (#94316)
