Assertion functions don't work with wildcard imports · Issue #35004 · microsoft/TypeScript

dfilatov · 2019-11-08T20:09:04.000Z

**TypeScript Version:** 3.7.2 **Search Terms:** assert function import export **Code** ```ts // Module asserts.ts function isNonNullable (obj: T): asserts obj is NonNullable { if(obj === undefined || obj === null) { throw new Error('Must not be a nullable value'); } } export { isNonNullable }; // Module test.ts import * as asserts from './asserts.ts'; function test(obj: string | null): void { asserts.isNonNullable(obj); obj.trim(); } ``` **Expected behavior:** Everything works as expected **Actual behavior:** Error: Assertions require every name in the call target to be declared with an explicit type annotation. If I rewrite test.ts with: ```ts // Module test.ts import { isNonNullable } from './asserts.ts'; function test(obj: string | null): void { isNonNullable(obj); obj.trim(); } ``` then everything compiles without any error

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