Conditional type *without union* behaves differently when inlined

[laughinghan]

TypeScript Version: 3.7.2

Search Terms: inline, generic type, conditional type, Extract

Code

type MyExtract<T, U> = T extends U ? T : never

function foo<T>(a: T) {
  const b: Extract<any[], T> = 0 as any;
  a = b; // ok

  const c: (any[] extends T ? any[] : never) = 0 as any;
  a = c; // FAILS
//^ Type 'any[] extends T ? any[] : never' is not assignable to type 'T'.
//    'any[] extends T ? any[] : never' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
//      Type 'any[]' is not assignable to type 'T'.
//        'any[]' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.(2322)

  const d: MyExtract<any[], T> = 0 as any;
  a = d; // ok

  type CustomType = any[] extends T ? any[] : never;
  const e: CustomType = 0 as any;
  a = e; // FAILS
//^ Type 'CustomType' is not assignable to type 'T'.
//    'CustomType' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
//      Type 'any[]' is not assignable to type 'T'.
//        'any[]' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.(2322)
}

Expected behavior: All assignments typecheck

Actual behavior: Assignments with inlined conditional type all report type error

Playground Link

Related Issues:
These are similar because they involve a generic type behaving differently when inlined, but they're because of the distributive property of conditional types and homomorphic mapped types, which doesn't apply to this issue:

• Conditional types don't work with passed never type #23022 (comment)
• keyof "a" behaves differently when using a type parameter #23345 (comment)