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tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability3.ts(14,5): error TS2322: Type 'U' is not assignable to type 'T'.
'U' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint 'Foo'.
tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability3.ts(15,5): error TS2322: Type 'T' is not assignable to type 'U'.
'T' is assignable to the constraint of type 'U', but 'U' could be instantiated with a different subtype of constraint 'Foo'.
tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability3.ts(22,9): error TS2322: Type 'U' is not assignable to type 'T'.
'U' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint 'Foo'.
tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability3.ts(23,9): error TS2322: Type 'T' is not assignable to type 'U'.
'T' is assignable to the constraint of type 'U', but 'U' could be instantiated with a different subtype of constraint 'Foo'.
==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability3.ts (4 errors) ====
// type parameters are not assignable to one another unless directly or indirectly constrained to one another
class Foo { foo: string; }
function foo<T extends Foo, U extends Foo>(t: T, u: U) {
var a: T;
var b: U;
t = a; // ok
a = t; // ok
b = u; // ok
u = b; // ok
t = u; // error
~
!!! error TS2322: Type 'U' is not assignable to type 'T'.
!!! error TS2322: 'U' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint 'Foo'.
u = t; // error
~
!!! error TS2322: Type 'T' is not assignable to type 'U'.
!!! error TS2322: 'T' is assignable to the constraint of type 'U', but 'U' could be instantiated with a different subtype of constraint 'Foo'.
}
class C<T extends Foo, U extends Foo> {
t: T;
u: U;
r = () => {
this.t = this.u; // error
~~~~~~
!!! error TS2322: Type 'U' is not assignable to type 'T'.
!!! error TS2322: 'U' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint 'Foo'.
this.u = this.t; // error
~~~~~~
!!! error TS2322: Type 'T' is not assignable to type 'U'.
!!! error TS2322: 'T' is assignable to the constraint of type 'U', but 'U' could be instantiated with a different subtype of constraint 'Foo'.
}
}
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