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// @strict: true
// from https://github.com/microsoft/TypeScript/issues/30706
type ConditionalType<T> = T extends string ? string : number;
function ConditionalOrUndefined<T>(): ConditionalType<T> | undefined {
return 0 as any;
}
function JustConditional<T>(): ConditionalType<T> {
return ConditionalOrUndefined<T>()!; // shouldn't error
}
// For comparison...
function genericOrUndefined<T>(): T | undefined {
return 0 as any;
}
function JustGeneric<T>(): T {
return genericOrUndefined<T>()!; // no error
}
// Simplified example:
function f<T>() {
type One = T extends string ? string : string;
type A = T extends number ? One : never;
const x: One = null as any as A;
}
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