Conditional types don't work through other types

[falsandtru]

cc @ahejlsberg

TypeScript Version: master

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Code

type Eq_<T, U> = T extends U ? U extends T ? true : false : false;
(): true => true as Eq_<true, true>;
(): false => true as Eq_<true, false>;
(): false => true as Eq_<false, true>;
(): true => true as Eq_<false, false>;

type Eq<T, U> = Eq_<T, U> extends false ? false : true;
(): true => true as Eq<true, true>;
(): false => true as Eq<true, false>;
(): false => true as Eq<false, true>;
(): true => true as Eq<false, false>;

also

type Eq<T, U> = If<T extends U ? U extends T ? true : false : false, true, false>;
type If<S, T, U> = S extends false ? U : T;

Expected behavior:

pass

Actual behavior:

$ node built/local/tsc.js --noEmit index.ts
index.ts(9,14): error TS2322: Type 'true' is not assignable to type 'false'.
index.ts(10,14): error TS2322: Type 'true' is not assignable to type 'false'.

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