IsAny: Fix circular constraint error on TypeScript 5.4+ (#993)

sindresorhus · Dec 2, 2024 · 32d94dd · 32d94dd
1 parent ca449dc
commit 32d94dd
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Showing 2 changed files with 12 additions and 1 deletion.
diff --git a/source/is-any.d.ts b/source/is-any.d.ts
@@ -1,3 +1,7 @@
+// Can eventually be replaced with the built-in once this library supports
+// TS5.4+ only. Tracked in https://github.com/sindresorhus/type-fest/issues/848
+type NoInfer<T> = T extends infer U ? U : never;
+
 /**
 Returns a boolean for whether the given type is `any`.
 
@@ -26,4 +30,4 @@ const anyA = get(anyObject, 'a');
 @category Type Guard
 @category Utilities
 */
-export type IsAny<T> = 0 extends 1 & T ? true : false;
+export type IsAny<T> = 0 extends 1 & NoInfer<T> ? true : false;
diff --git a/test-d/is-any.ts b/test-d/is-any.ts
@@ -18,3 +18,10 @@ expectType<IsAny<void>>(false);
 // Missing generic parameter
 // @ts-expect-error
 type A = IsAny;
+
+// Verify that are no circular reference issues
+// https://github.com/sindresorhus/type-fest/issues/846
+type OnlyAny<T extends IsAny<T> extends true ? any : never> = T;
+type B = OnlyAny<any>;
+// @ts-expect-error
+type C = OnlyAny<string>;