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tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(9,1): error TS2322: Type 'Covariant<unknown>' is not assignable to type 'Covariant<string>'.
Type 'unknown' is not assignable to type 'string'.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(18,1): error TS2322: Type 'Contravariant<string>' is not assignable to type 'Contravariant<unknown>'.
Type 'unknown' is not assignable to type 'string'.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(28,1): error TS2322: Type 'Invariant<string>' is not assignable to type 'Invariant<unknown>'.
Types of property 'f' are incompatible.
Type '(x: string) => string' is not assignable to type '(x: unknown) => unknown'.
Types of parameters 'x' and 'x' are incompatible.
Type 'unknown' is not assignable to type 'string'.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(29,1): error TS2322: Type 'Invariant<unknown>' is not assignable to type 'Invariant<string>'.
The types returned by 'f(...)' are incompatible between these types.
Type 'unknown' is not assignable to type 'string'.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(33,10): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(34,10): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(35,10): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(35,17): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(36,10): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(40,17): error TS2636: Type 'Covariant1<super-T>' is not assignable to type 'Covariant1<sub-T>' as implied by variance annotation.
Types of property 'x' are incompatible.
Type 'super-T' is not assignable to type 'sub-T'.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(44,21): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(46,21): error TS2636: Type 'Contravariant2<sub-T>' is not assignable to type 'Contravariant2<super-T>' as implied by variance annotation.
Types of property 'f' are incompatible.
Type '(x: sub-T) => void' is not assignable to type '(x: super-T) => void'.
Types of parameters 'x' and 'x' are incompatible.
Type 'super-T' is not assignable to type 'sub-T'.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(50,17): error TS2636: Type 'Invariant1<super-T>' is not assignable to type 'Invariant1<sub-T>' as implied by variance annotation.
The types returned by 'f(...)' are incompatible between these types.
Type 'super-T' is not assignable to type 'sub-T'.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(54,17): error TS2636: Type 'Invariant2<sub-T>' is not assignable to type 'Invariant2<super-T>' as implied by variance annotation.
Types of property 'f' are incompatible.
Type '(x: sub-T) => sub-T' is not assignable to type '(x: super-T) => super-T'.
Types of parameters 'x' and 'x' are incompatible.
Type 'super-T' is not assignable to type 'sub-T'.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(60,11): error TS2636: Type 'Foo1<super-T>' is not assignable to type 'Foo1<sub-T>' as implied by variance annotation.
Types of property 'x' are incompatible.
Type 'super-T' is not assignable to type 'sub-T'.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(71,11): error TS2636: Type 'Foo2<sub-T>' is not assignable to type 'Foo2<super-T>' as implied by variance annotation.
Types of property 'f' are incompatible.
Type 'FooFn2<sub-T>' is not assignable to type 'FooFn2<super-T>'.
Type 'super-T' is not assignable to type 'sub-T'.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(95,10): error TS1273: 'public' modifier cannot appear on a type parameter
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(96,10): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(96,17): error TS1030: 'in' modifier already seen.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(97,10): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(97,17): error TS1030: 'out' modifier already seen.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(98,10): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(98,14): error TS1029: 'in' modifier must precede 'out' modifier.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(100,21): error TS1274: 'in' modifier can only appear on a type parameter of a class, interface or type alias
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(101,21): error TS1274: 'out' modifier can only appear on a type parameter of a class, interface or type alias
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(104,5): error TS1274: 'in' modifier can only appear on a type parameter of a class, interface or type alias
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(105,5): error TS1274: 'out' modifier can only appear on a type parameter of a class, interface or type alias
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(116,1): error TS2322: Type 'Baz<string>' is not assignable to type 'Baz<unknown>'.
Type 'unknown' is not assignable to type 'string'.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(117,1): error TS2322: Type 'Baz<unknown>' is not assignable to type 'Baz<string>'.
Type 'unknown' is not assignable to type 'string'.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(136,7): error TS2322: Type 'Parent<unknown>' is not assignable to type 'Parent<string>'.
Type 'unknown' is not assignable to type 'string'.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(160,68): error TS2345: Argument of type 'ActionObject<{ type: "PLAY"; value: number; }>' is not assignable to parameter of type 'ActionObject<{ type: "PLAY"; value: number; } | { type: "RESET"; }>'.
Types of property 'exec' are incompatible.
Type '(meta: StateNode<any, { type: "PLAY"; value: number; }>) => void' is not assignable to type '(meta: StateNode<any, { type: "PLAY"; value: number; } | { type: "RESET"; }>) => void'.
Types of parameters 'meta' and 'meta' are incompatible.
Type 'StateNode<any, { type: "PLAY"; value: number; } | { type: "RESET"; }>' is not assignable to type 'StateNode<any, { type: "PLAY"; value: number; }>'.
Types of property '_storedEvent' are incompatible.
Type '{ type: "PLAY"; value: number; } | { type: "RESET"; }' is not assignable to type '{ type: "PLAY"; value: number; }'.
Type '{ type: "RESET"; }' is not assignable to type '{ type: "PLAY"; value: number; }'.
==== tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts (31 errors) ====
type Covariant<out T> = {
x: T;
}
declare let super_covariant: Covariant<unknown>;
declare let sub_covariant: Covariant<string>;
super_covariant = sub_covariant;
sub_covariant = super_covariant; // Error
~~~~~~~~~~~~~
!!! error TS2322: Type 'Covariant<unknown>' is not assignable to type 'Covariant<string>'.
!!! error TS2322: Type 'unknown' is not assignable to type 'string'.
type Contravariant<in T> = {
f: (x: T) => void;
}
declare let super_contravariant: Contravariant<unknown>;
declare let sub_contravariant: Contravariant<string>;
super_contravariant = sub_contravariant; // Error
~~~~~~~~~~~~~~~~~~~
!!! error TS2322: Type 'Contravariant<string>' is not assignable to type 'Contravariant<unknown>'.
!!! error TS2322: Type 'unknown' is not assignable to type 'string'.
sub_contravariant = super_contravariant;
type Invariant<in out T> = {
f: (x: T) => T;
}
declare let super_invariant: Invariant<unknown>;
declare let sub_invariant: Invariant<string>;
super_invariant = sub_invariant; // Error
~~~~~~~~~~~~~~~
!!! error TS2322: Type 'Invariant<string>' is not assignable to type 'Invariant<unknown>'.
!!! error TS2322: Types of property 'f' are incompatible.
!!! error TS2322: Type '(x: string) => string' is not assignable to type '(x: unknown) => unknown'.
!!! error TS2322: Types of parameters 'x' and 'x' are incompatible.
!!! error TS2322: Type 'unknown' is not assignable to type 'string'.
sub_invariant = super_invariant; // Error
~~~~~~~~~~~~~
!!! error TS2322: Type 'Invariant<unknown>' is not assignable to type 'Invariant<string>'.
!!! error TS2322: The types returned by 'f(...)' are incompatible between these types.
!!! error TS2322: Type 'unknown' is not assignable to type 'string'.
// Variance of various type constructors
type T10<out T> = T;
~~~~~
!!! error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
type T11<in T> = keyof T;
~~~~
!!! error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
type T12<out T, out K extends keyof T> = T[K];
~~~~~
!!! error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
~~~~~~~~~~~~~~~~~~~~~
!!! error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
type T13<in out T> = T[keyof T];
~~~~~~~~
!!! error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
// Variance annotation errors
type Covariant1<in T> = { // Error
~~~~
!!! error TS2636: Type 'Covariant1<super-T>' is not assignable to type 'Covariant1<sub-T>' as implied by variance annotation.
!!! error TS2636: Types of property 'x' are incompatible.
!!! error TS2636: Type 'super-T' is not assignable to type 'sub-T'.
x: T;
}
type Contravariant1<out T> = keyof T; // Error
~~~~~
!!! error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
type Contravariant2<out T> = { // Error
~~~~~
!!! error TS2636: Type 'Contravariant2<sub-T>' is not assignable to type 'Contravariant2<super-T>' as implied by variance annotation.
!!! error TS2636: Types of property 'f' are incompatible.
!!! error TS2636: Type '(x: sub-T) => void' is not assignable to type '(x: super-T) => void'.
!!! error TS2636: Types of parameters 'x' and 'x' are incompatible.
!!! error TS2636: Type 'super-T' is not assignable to type 'sub-T'.
f: (x: T) => void;
}
type Invariant1<in T> = { // Error
~~~~
!!! error TS2636: Type 'Invariant1<super-T>' is not assignable to type 'Invariant1<sub-T>' as implied by variance annotation.
!!! error TS2636: The types returned by 'f(...)' are incompatible between these types.
!!! error TS2636: Type 'super-T' is not assignable to type 'sub-T'.
f: (x: T) => T;
}
type Invariant2<out T> = { // Error
~~~~~
!!! error TS2636: Type 'Invariant2<sub-T>' is not assignable to type 'Invariant2<super-T>' as implied by variance annotation.
!!! error TS2636: Types of property 'f' are incompatible.
!!! error TS2636: Type '(x: sub-T) => sub-T' is not assignable to type '(x: super-T) => super-T'.
!!! error TS2636: Types of parameters 'x' and 'x' are incompatible.
!!! error TS2636: Type 'super-T' is not assignable to type 'sub-T'.
f: (x: T) => T;
}
// Variance in circular types
type Foo1<in T> = { // Error
~~~~
!!! error TS2636: Type 'Foo1<super-T>' is not assignable to type 'Foo1<sub-T>' as implied by variance annotation.
!!! error TS2636: Types of property 'x' are incompatible.
!!! error TS2636: Type 'super-T' is not assignable to type 'sub-T'.
x: T;
f: FooFn1<T>;
}
type FooFn1<T> = (foo: Bar1<T[]>) => void;
type Bar1<T> = {
value: Foo1<T[]>;
}
type Foo2<out T> = { // Error
~~~~~
!!! error TS2636: Type 'Foo2<sub-T>' is not assignable to type 'Foo2<super-T>' as implied by variance annotation.
!!! error TS2636: Types of property 'f' are incompatible.
!!! error TS2636: Type 'FooFn2<sub-T>' is not assignable to type 'FooFn2<super-T>'.
!!! error TS2636: Type 'super-T' is not assignable to type 'sub-T'.
x: T;
f: FooFn2<T>;
}
type FooFn2<T> = (foo: Bar2<T[]>) => void;
type Bar2<T> = {
value: Foo2<T[]>;
}
type Foo3<in out T> = {
x: T;
f: FooFn3<T>;
}
type FooFn3<T> = (foo: Bar3<T[]>) => void;
type Bar3<T> = {
value: Foo3<T[]>;
}
// Wrong modifier usage
type T20<public T> = T; // Error
~~~~~~
!!! error TS1273: 'public' modifier cannot appear on a type parameter
type T21<in out in T> = T; // Error
~~~~~~~~~~~
!!! error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
~~
!!! error TS1030: 'in' modifier already seen.
type T22<in out out T> = T; // Error
~~~~~~~~~~~~
!!! error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
~~~
!!! error TS1030: 'out' modifier already seen.
type T23<out in T> = T; // Error
~~~~~~~~
!!! error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
~~
!!! error TS1029: 'in' modifier must precede 'out' modifier.
declare function f1<in T>(x: T): void; // Error
~~
!!! error TS1274: 'in' modifier can only appear on a type parameter of a class, interface or type alias
declare function f2<out T>(): T; // Error
~~~
!!! error TS1274: 'out' modifier can only appear on a type parameter of a class, interface or type alias
class C {
in a = 0; // Error
~~
!!! error TS1274: 'in' modifier can only appear on a type parameter of a class, interface or type alias
out b = 0; // Error
~~~
!!! error TS1274: 'out' modifier can only appear on a type parameter of a class, interface or type alias
}
// Interface merging
interface Baz<out T> {}
interface Baz<in T> {}
declare let baz1: Baz<unknown>;
declare let baz2: Baz<string>;
baz1 = baz2; // Error
~~~~
!!! error TS2322: Type 'Baz<string>' is not assignable to type 'Baz<unknown>'.
!!! error TS2322: Type 'unknown' is not assignable to type 'string'.
baz2 = baz1; // Error
~~~~
!!! error TS2322: Type 'Baz<unknown>' is not assignable to type 'Baz<string>'.
!!! error TS2322: Type 'unknown' is not assignable to type 'string'.
// Repro from #44572
interface Parent<out A> {
child: Child<A> | null;
parent: Parent<A> | null;
}
interface Child<A, B = unknown> extends Parent<A> {
readonly a: A;
readonly b: B;
}
function fn<A>(inp: Child<A>) {
const a: Child<unknown> = inp;
}
const pu: Parent<unknown> = { child: { a: 0, b: 0, child: null, parent: null }, parent: null };
const notString: Parent<string> = pu; // Error
~~~~~~~~~
!!! error TS2322: Type 'Parent<unknown>' is not assignable to type 'Parent<string>'.
!!! error TS2322: Type 'unknown' is not assignable to type 'string'.
// Repro from comment in #44572
declare class StateNode<TContext, in out TEvent extends { type: string }> {
_storedEvent: TEvent;
_action: ActionObject<TEvent>;
_state: StateNode<TContext, any>;
}
interface ActionObject<TEvent extends { type: string }> {
exec: (meta: StateNode<any, TEvent>) => void;
}
declare function createMachine<TEvent extends { type: string }>(action: ActionObject<TEvent>): StateNode<any, any>;
declare function interpret<TContext>(machine: StateNode<TContext, any>): void;
const machine = createMachine({} as any);
interpret(machine);
declare const qq: ActionObject<{ type: "PLAY"; value: number }>;
createMachine<{ type: "PLAY"; value: number } | { type: "RESET" }>(qq); // Error
~~
!!! error TS2345: Argument of type 'ActionObject<{ type: "PLAY"; value: number; }>' is not assignable to parameter of type 'ActionObject<{ type: "PLAY"; value: number; } | { type: "RESET"; }>'.
!!! error TS2345: Types of property 'exec' are incompatible.
!!! error TS2345: Type '(meta: StateNode<any, { type: "PLAY"; value: number; }>) => void' is not assignable to type '(meta: StateNode<any, { type: "PLAY"; value: number; } | { type: "RESET"; }>) => void'.
!!! error TS2345: Types of parameters 'meta' and 'meta' are incompatible.
!!! error TS2345: Type 'StateNode<any, { type: "PLAY"; value: number; } | { type: "RESET"; }>' is not assignable to type 'StateNode<any, { type: "PLAY"; value: number; }>'.
!!! error TS2345: Types of property '_storedEvent' are incompatible.
!!! error TS2345: Type '{ type: "PLAY"; value: number; } | { type: "RESET"; }' is not assignable to type '{ type: "PLAY"; value: number; }'.
!!! error TS2345: Type '{ type: "RESET"; }' is not assignable to type '{ type: "PLAY"; value: number; }'.
// Repros from #48618
let Anon = class <out T> {
foo(): InstanceType<(typeof Anon<T>)> {
return this;
}
}
let OuterC = class C<out T> {
foo(): C<T> {
return this;
}
}
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