23 lines
1,000 B
Plaintext
23 lines
1,000 B
Plaintext
==== tests/cases/conformance/types/typeParameters/typeArgumentLists/typeParameterAsTypeParameterConstraint2.ts (2 errors) ====
|
|
// using a type parameter as a constraint for a type parameter is invalid
|
|
// these should be errors unless otherwise noted
|
|
|
|
function foo<T, U extends T>(x: T, y: U): U { return y; } // this is now an error
|
|
~~~~~~~~~~~
|
|
!!! Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
|
|
|
|
foo(1, '');
|
|
foo(1, {});
|
|
|
|
interface NumberVariant extends Number {
|
|
x: number;
|
|
}
|
|
var n: NumberVariant;
|
|
var r3 = foo(1, n);
|
|
|
|
function foo2<T, U extends { length: T }>(x: T, y: U) { return y; } // this is now an error
|
|
~~~~~~~~~~~~~~~~~~~~~~~
|
|
!!! Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
|
|
foo2(1, { length: '' });
|
|
foo2(1, { length: {} });
|
|
foo2([], ['']); |