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tests/cases/compiler/varianceMeasurement.ts(10,7): error TS2322: Type 'Foo1<string>' is not assignable to type 'Foo1<"a">'.
Type 'string' is not assignable to type '"a"'.
tests/cases/compiler/varianceMeasurement.ts(21,7): error TS2322: Type 'Foo2<string>' is not assignable to type 'Foo2<"a">'.
Types of property 'x' are incompatible.
Type 'string' is not assignable to type '"a"'.
tests/cases/compiler/varianceMeasurement.ts(22,7): error TS2322: Type 'Foo2<string>' is not assignable to type 'Foo2<unknown>'.
The types of 'y.x' are incompatible between these types.
Type '(arg: string) => void' is not assignable to type '(arg: unknown) => void'.
Types of parameters 'arg' and 'arg' are incompatible.
Type 'unknown' is not assignable to type 'string'.
tests/cases/compiler/varianceMeasurement.ts(33,7): error TS2322: Type 'Foo3<string>' is not assignable to type 'Foo3<"a">'.
Type 'string' is not assignable to type '"a"'.
tests/cases/compiler/varianceMeasurement.ts(44,7): error TS2322: Type 'Foo4<string>' is not assignable to type 'Foo4<"a">'.
Types of property 'x' are incompatible.
Type 'string' is not assignable to type '"a"'.
tests/cases/compiler/varianceMeasurement.ts(45,7): error TS2322: Type 'Foo4<string>' is not assignable to type 'Foo4<unknown>'.
The types of 'y.x' are incompatible between these types.
Type '(arg: string) => void' is not assignable to type '(arg: unknown) => void'.
Types of parameters 'arg' and 'arg' are incompatible.
Type 'unknown' is not assignable to type 'string'.
tests/cases/compiler/varianceMeasurement.ts(57,7): error TS2322: Type 'Fn<string, number>' is not assignable to type 'Fn<unknown, number>'.
Type 'unknown' is not assignable to type 'string'.
tests/cases/compiler/varianceMeasurement.ts(62,7): error TS2322: Type 'Fn<string, number>' is not assignable to type 'Fn<string, 0>'.
Type 'number' is not assignable to type '0'.
tests/cases/compiler/varianceMeasurement.ts(75,7): error TS2322: Type 'C<unknown, number>' is not assignable to type 'C<unknown, string>'.
Type 'number' is not assignable to type 'string'.
==== tests/cases/compiler/varianceMeasurement.ts (9 errors) ====
// The type below should be invariant in T but is measured as covariant because
// we don't analyze recursive references.
interface Foo1<T> {
x: T;
y: Foo1<(arg: T) => void>;
}
declare const f10: Foo1<string>;
const f11: Foo1<'a'> = f10;
~~~
!!! error TS2322: Type 'Foo1<string>' is not assignable to type 'Foo1<"a">'.
!!! error TS2322: Type 'string' is not assignable to type '"a"'.
const f12: Foo1<unknown> = f10;
// The type below is invariant in T and is measured as such.
interface Foo2<T> {
x: T;
y: { x: (arg: T) => void, y: Foo2<(arg: T) => void>; }
}
declare const f20: Foo2<string>;
const f21: Foo2<'a'> = f20;
~~~
!!! error TS2322: Type 'Foo2<string>' is not assignable to type 'Foo2<"a">'.
!!! error TS2322: Types of property 'x' are incompatible.
!!! error TS2322: Type 'string' is not assignable to type '"a"'.
const f22: Foo2<unknown> = f20;
~~~
!!! error TS2322: Type 'Foo2<string>' is not assignable to type 'Foo2<unknown>'.
!!! error TS2322: The types of 'y.x' are incompatible between these types.
!!! error TS2322: Type '(arg: string) => void' is not assignable to type '(arg: unknown) => void'.
!!! error TS2322: Types of parameters 'arg' and 'arg' are incompatible.
!!! error TS2322: Type 'unknown' is not assignable to type 'string'.
// The type below should be invariant in T but is measured as covariant because
// we don't analyze recursive references.
type Foo3<T> = {
x: T;
y: Foo3<(arg: T) => void>;
}
declare const f30: Foo3<string>;
const f31: Foo3<'a'> = f30;
~~~
!!! error TS2322: Type 'Foo3<string>' is not assignable to type 'Foo3<"a">'.
!!! error TS2322: Type 'string' is not assignable to type '"a"'.
const f32: Foo3<unknown> = f30;
// The type below is invariant in T and is measured as such.
type Foo4<T> = {
x: T;
y: { x: (arg: T) => void, y: Foo4<(arg: T) => void>; }
}
declare const f40: Foo4<string>;
const f41: Foo4<'a'> = f40;
~~~
!!! error TS2322: Type 'Foo4<string>' is not assignable to type 'Foo4<"a">'.
!!! error TS2322: Types of property 'x' are incompatible.
!!! error TS2322: Type 'string' is not assignable to type '"a"'.
const f42: Foo4<unknown> = f40;
~~~
!!! error TS2322: Type 'Foo4<string>' is not assignable to type 'Foo4<unknown>'.
!!! error TS2322: The types of 'y.x' are incompatible between these types.
!!! error TS2322: Type '(arg: string) => void' is not assignable to type '(arg: unknown) => void'.
!!! error TS2322: Types of parameters 'arg' and 'arg' are incompatible.
!!! error TS2322: Type 'unknown' is not assignable to type 'string'.
// Repro from #3580
interface Fn<A, B> {
(a: A): B;
then<C>(next: Fn<B, C>): Fn<A, C>;
}
declare const fn: Fn<string, number>;
// Contravariant in A
const fn1: Fn<unknown, number> = fn; // Error
~~~
!!! error TS2322: Type 'Fn<string, number>' is not assignable to type 'Fn<unknown, number>'.
!!! error TS2322: Type 'unknown' is not assignable to type 'string'.
const fn2: Fn<'a', number> = fn;
// Covariant in B
const fn3: Fn<string, unknown> = fn;
const fn4: Fn<string, 0> = fn; // Error
~~~
!!! error TS2322: Type 'Fn<string, number>' is not assignable to type 'Fn<string, 0>'.
!!! error TS2322: Type 'number' is not assignable to type '0'.
// Repro from #39947
interface I<Dummy, V> {
c: C<Dummy, V>;
}
class C<Dummy, V> {
declare sub: I<Dummy, V>;
declare covariance: V;
}
const c1: C<unknown, string> = new C<unknown, number>(); // Error
~~
!!! error TS2322: Type 'C<unknown, number>' is not assignable to type 'C<unknown, string>'.
!!! error TS2322: Type 'number' is not assignable to type 'string'.
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