fix: support typescript 7 — widen peer range and fix Trans ns inference under TS7 (#1927)

Author: adrai

CHANGELOG.md

@@ -1,3 +1,8 @@
+## 17.0.9
+
+- fix: allow TypeScript 7 in the optional `typescript` peer dependency range (`^5 || ^6 || ^7`). With `typescript@7.0.2` in a project, `npm install` failed with an `ERESOLVE` peer conflict. Fixes [#1927](https://github.com/i18next/react-i18next/issues/1927), thanks @andikapradanaarif.
+- fix(types): `<Trans t={t} ns="ns" …>` with a `t` from `useTranslation(['ns'])` now typechecks under TypeScript 7. TS7 intersects the `Ns` inference candidates coming from the `t` prop (`readonly ['ns']`) and the `ns` prop (`'ns'`) into an unsatisfiable `'ns' & readonly ['ns']`, where TS6 resolved them. The `ns` prop on `TransProps`, `TransSelectorProps` and `IcuTransWithoutContextProps` now also accepts a single namespace out of an array-typed `Ns` (`Ns | (Ns extends readonly (infer S extends string)[] ? S : never)`) — which matches runtime behavior and is unchanged under TS5/TS6.
+
 ## 17.0.8
 
 - fix(types): `<Trans i18nKey={$ => ...}>` now typechecks under `enableSelector: 'strict'`. The `Trans` component's conditional type was gated on `_EnableSelector extends true | 'optimize'`, excluding `'strict'` and falling back to the legacy string-key signature. Runtime was already correct (it calls `keyFromSelector(i18nKey)` whenever `typeof i18nKey === 'function'`); this is a type-only fix that widens the conditional to include `'strict'`. Thanks @Faithfinder ([#1921](https://github.com/i18next/react-i18next/pull/1921))

TransWithoutContext.d.ts

@@ -42,7 +42,9 @@ export type TransProps<
   defaults?: string;
   i18n?: i18n;
   i18nKey?: Key | Key[];
-  ns?: Ns;
+  // allow a single namespace from an array-typed `t` (e.g. useTranslation(['ns'])); TS7 intersects
+  // inference candidates from `t` and `ns`, so a bare `Ns` here rejects ns="ns" when t is passed
+  ns?: Ns | (Ns extends readonly (infer S extends string)[] ? S : never);
   parent?: string | React.ComponentType<any> | null; // used in React.createElement if not null
   tOptions?: TOpt;
   values?: InterpolationMap<Ret>;
@@ -82,7 +84,8 @@ export interface TransSelectorProps<
   defaults?: string | Key;
   i18n?: i18n;
   i18nKey?: Key | readonly Key[];
-  ns?: Ns;
+  // see TransProps.ns: keep single-namespace values assignable when `t` fixes Ns to an array
+  ns?: Ns | (Ns extends readonly (infer S extends string)[] ? S : never);
   parent?: string | React.ComponentType<any> | null; // used in React.createElement if not null
   tOptions?: TOpt;
   values?: Key extends (...args: any[]) => infer R ? InterpolationMap<R> : {};

index.d.ts

@@ -62,7 +62,8 @@ export type IcuTransWithoutContextProps<
   /** Declaration tree describing React components and their props */
   content: IcuTransContentDeclaration[];
   /** Optional namespace(s) for the translation */
-  ns?: Ns;
+  // see TransProps.ns: keep single-namespace values assignable when `t` fixes Ns to an array
+  ns?: Ns | (Ns extends readonly (infer S extends string)[] ? S : never);
   /** Optional values for ICU variable interpolation */
   values?: Record<string, any>;
   /** i18next instance. If not provided, uses global instance */

package.json

@@ -74,7 +74,7 @@
   "peerDependencies": {
     "i18next": ">= 26.2.0",
     "react": ">= 16.8.0",
-    "typescript": "^5 || ^6"
+    "typescript": "^5 || ^6 || ^7"
   },
   "peerDependenciesMeta": {
     "react-dom": {