=== tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithConstructSignatures3.ts === // checking subtype relations for function types as it relates to contextual signature instantiation // error cases, so function calls will all result in 'any' module Errors { >Errors : typeof Errors class Base { foo: string; } >Base : Base >foo : string class Derived extends Base { bar: string; } >Derived : Derived >Base : Base >bar : string class Derived2 extends Derived { baz: string; } >Derived2 : Derived2 >Derived : Derived >baz : string class OtherDerived extends Base { bing: string; } >OtherDerived : OtherDerived >Base : Base >bing : string declare function foo2(a2: new (x: number) => string[]): typeof a2; >foo2 : { (a2: new (x: number) => string[]): new (x: number) => string[]; (a2: any): any; } >a2 : new (x: number) => string[] >x : number >a2 : new (x: number) => string[] declare function foo2(a2: any): any; >foo2 : { (a2: new (x: number) => string[]): new (x: number) => string[]; (a2: any): any; } >a2 : any declare function foo7(a2: new (x: new (arg: Base) => Derived) => new (r: Base) => Derived2): typeof a2; >foo7 : { (a2: new (x: new (arg: Base) => Derived) => new (r: Base) => Derived2): new (x: new (arg: Base) => Derived) => new (r: Base) => Derived2; (a2: any): any; } >a2 : new (x: new (arg: Base) => Derived) => new (r: Base) => Derived2 >x : new (arg: Base) => Derived >arg : Base >Base : Base >Derived : Derived >r : Base >Base : Base >Derived2 : Derived2 >a2 : new (x: new (arg: Base) => Derived) => new (r: Base) => Derived2 declare function foo7(a2: any): any; >foo7 : { (a2: new (x: new (arg: Base) => Derived) => new (r: Base) => Derived2): new (x: new (arg: Base) => Derived) => new (r: Base) => Derived2; (a2: any): any; } >a2 : any declare function foo8(a2: new (x: new (arg: Base) => Derived, y: new (arg2: Base) => Derived) => new (r: Base) => Derived): typeof a2; >foo8 : { (a2: new (x: new (arg: Base) => Derived, y: new (arg2: Base) => Derived) => new (r: Base) => Derived): new (x: new (arg: Base) => Derived, y: new (arg2: Base) => Derived) => new (r: Base) => Derived; (a2: any): any; } >a2 : new (x: new (arg: Base) => Derived, y: new (arg2: Base) => Derived) => new (r: Base) => Derived >x : new (arg: Base) => Derived >arg : Base >Base : Base >Derived : Derived >y : new (arg2: Base) => Derived >arg2 : Base >Base : Base >Derived : Derived >r : Base >Base : Base >Derived : Derived >a2 : new (x: new (arg: Base) => Derived, y: new (arg2: Base) => Derived) => new (r: Base) => Derived declare function foo8(a2: any): any; >foo8 : { (a2: new (x: new (arg: Base) => Derived, y: new (arg2: Base) => Derived) => new (r: Base) => Derived): new (x: new (arg: Base) => Derived, y: new (arg2: Base) => Derived) => new (r: Base) => Derived; (a2: any): any; } >a2 : any declare function foo10(a2: new (...x: Base[]) => Base): typeof a2; >foo10 : { (a2: new (...x: Base[]) => Base): new (...x: Base[]) => Base; (a2: any): any; } >a2 : new (...x: Base[]) => Base >x : Base[] >Base : Base >Base : Base >a2 : new (...x: Base[]) => Base declare function foo10(a2: any): any; >foo10 : { (a2: new (...x: Base[]) => Base): new (...x: Base[]) => Base; (a2: any): any; } >a2 : any declare function foo11(a2: new (x: { foo: string }, y: { foo: string; bar: string }) => Base): typeof a2; >foo11 : { (a2: new (x: { foo: string; }, y: { foo: string; bar: string; }) => Base): new (x: { foo: string; }, y: { foo: string; bar: string; }) => Base; (a2: any): any; } >a2 : new (x: { foo: string; }, y: { foo: string; bar: string; }) => Base >x : { foo: string; } >foo : string >y : { foo: string; bar: string; } >foo : string >bar : string >Base : Base >a2 : new (x: { foo: string; }, y: { foo: string; bar: string; }) => Base declare function foo11(a2: any): any; >foo11 : { (a2: new (x: { foo: string; }, y: { foo: string; bar: string; }) => Base): new (x: { foo: string; }, y: { foo: string; bar: string; }) => Base; (a2: any): any; } >a2 : any declare function foo12(a2: new (x: Array, y: Array) => Array): typeof a2; >foo12 : { (a2: new (x: Base[], y: Derived2[]) => Derived[]): new (x: Base[], y: Derived2[]) => Derived[]; (a2: any): any; } >a2 : new (x: Base[], y: Derived2[]) => Derived[] >x : Base[] >Array : T[] >Base : Base >y : Derived2[] >Array : T[] >Derived2 : Derived2 >Array : T[] >Derived : Derived >a2 : new (x: Base[], y: Derived2[]) => Derived[] declare function foo12(a2: any): any; >foo12 : { (a2: new (x: Base[], y: Derived2[]) => Derived[]): new (x: Base[], y: Derived2[]) => Derived[]; (a2: any): any; } >a2 : any declare function foo15(a2: new (x: { a: string; b: number }) => number): typeof a2; >foo15 : { (a2: new (x: { a: string; b: number; }) => number): new (x: { a: string; b: number; }) => number; (a2: any): any; } >a2 : new (x: { a: string; b: number; }) => number >x : { a: string; b: number; } >a : string >b : number >a2 : new (x: { a: string; b: number; }) => number declare function foo15(a2: any): any; >foo15 : { (a2: new (x: { a: string; b: number; }) => number): new (x: { a: string; b: number; }) => number; (a2: any): any; } >a2 : any declare function foo16(a2: { >foo16 : { (a2: { new (x: { new (a: number): number; new (a?: number): number; }): number[]; new (x: { new (a: boolean): boolean; new (a?: boolean): boolean; }): boolean[]; }): { new (x: { new (a: number): number; new (a?: number): number; }): number[]; new (x: { new (a: boolean): boolean; new (a?: boolean): boolean; }): boolean[]; }; (a2: any): any; } >a2 : { new (x: { new (a: number): number; new (a?: number): number; }): number[]; new (x: { new (a: boolean): boolean; new (a?: boolean): boolean; }): boolean[]; } // type of parameter is overload set which means we can't do inference based on this type new (x: { >x : { new (a: number): number; new (a?: number): number; } new (a: number): number; >a : number new (a?: number): number; >a : number }): number[]; new (x: { >x : { new (a: boolean): boolean; new (a?: boolean): boolean; } new (a: boolean): boolean; >a : boolean new (a?: boolean): boolean; >a : boolean }): boolean[]; }): typeof a2; >a2 : { new (x: { new (a: number): number; new (a?: number): number; }): number[]; new (x: { new (a: boolean): boolean; new (a?: boolean): boolean; }): boolean[]; } declare function foo16(a2: any): any; >foo16 : { (a2: { new (x: { new (a: number): number; new (a?: number): number; }): number[]; new (x: { new (a: boolean): boolean; new (a?: boolean): boolean; }): boolean[]; }): { new (x: { new (a: number): number; new (a?: number): number; }): number[]; new (x: { new (a: boolean): boolean; new (a?: boolean): boolean; }): boolean[]; }; (a2: any): any; } >a2 : any declare function foo17(a2: { >foo17 : { (a2: { new (x: { new (a: T): T; new (a: T): T; }): any[]; new (x: { new (a: T): T; new (a: T): T; }): any[]; }): { new (x: { new (a: T): T; new (a: T): T; }): any[]; new (x: { new (a: T): T; new (a: T): T; }): any[]; }; (a2: any): any; } >a2 : { new (x: { new (a: T): T; new (a: T): T; }): any[]; new (x: { new (a: T): T; new (a: T): T; }): any[]; } new (x: { >x : { new (a: T): T; new (a: T): T; } new (a: T): T; >T : T >Derived : Derived >a : T >T : T >T : T new (a: T): T; >T : T >Base : Base >a : T >T : T >T : T }): any[]; new (x: { >x : { new (a: T): T; new (a: T): T; } new (a: T): T; >T : T >Derived2 : Derived2 >a : T >T : T >T : T new (a: T): T; >T : T >Base : Base >a : T >T : T >T : T }): any[]; }): typeof a2; >a2 : { new (x: { new (a: T): T; new (a: T): T; }): any[]; new (x: { new (a: T): T; new (a: T): T; }): any[]; } declare function foo17(a2: any): any; >foo17 : { (a2: { new (x: { new (a: T): T; new (a: T): T; }): any[]; new (x: { new (a: T): T; new (a: T): T; }): any[]; }): { new (x: { new (a: T): T; new (a: T): T; }): any[]; new (x: { new (a: T): T; new (a: T): T; }): any[]; }; (a2: any): any; } >a2 : any var r1arg1: new (x: T) => U[]; >r1arg1 : new (x: T) => U[] >T : T >U : U >x : T >T : T >U : U var r1arg2: new (x: number) => string[]; >r1arg2 : new (x: number) => string[] >x : number var r1 = foo2(r1arg1); // any >r1 : any >foo2(r1arg1) : any >foo2 : { (a2: new (x: number) => string[]): new (x: number) => string[]; (a2: any): any; } >r1arg1 : new (x: T) => U[] var r1a = [r1arg2, r1arg1]; >r1a : (new (x: T) => U[])[] >[r1arg2, r1arg1] : (new (x: T) => U[])[] >r1arg2 : new (x: number) => string[] >r1arg1 : new (x: T) => U[] var r1b = [r1arg1, r1arg2]; >r1b : (new (x: T) => U[])[] >[r1arg1, r1arg2] : (new (x: T) => U[])[] >r1arg1 : new (x: T) => U[] >r1arg2 : new (x: number) => string[] var r2arg1: new (x: new (arg: T) => U) => new (r: T) => V; >r2arg1 : new (x: new (arg: T) => U) => new (r: T) => V >T : T >Base : Base >U : U >Derived : Derived >V : V >Derived2 : Derived2 >x : new (arg: T) => U >arg : T >T : T >U : U >r : T >T : T >V : V var r2arg2: new (x: new (arg: Base) => Derived) => new (r: Base) => Derived2; >r2arg2 : new (x: new (arg: Base) => Derived) => new (r: Base) => Derived2 >x : new (arg: Base) => Derived >arg : Base >Base : Base >Derived : Derived >r : Base >Base : Base >Derived2 : Derived2 var r2 = foo7(r2arg1); // any >r2 : any >foo7(r2arg1) : any >foo7 : { (a2: new (x: new (arg: Base) => Derived) => new (r: Base) => Derived2): new (x: new (arg: Base) => Derived) => new (r: Base) => Derived2; (a2: any): any; } >r2arg1 : new (x: new (arg: T) => U) => new (r: T) => V var r2a = [r2arg2, r2arg1]; >r2a : (new (x: new (arg: T) => U) => new (r: T) => V)[] >[r2arg2, r2arg1] : (new (x: new (arg: T) => U) => new (r: T) => V)[] >r2arg2 : new (x: new (arg: Base) => Derived) => new (r: Base) => Derived2 >r2arg1 : new (x: new (arg: T) => U) => new (r: T) => V var r2b = [r2arg1, r2arg2]; >r2b : (new (x: new (arg: T) => U) => new (r: T) => V)[] >[r2arg1, r2arg2] : (new (x: new (arg: T) => U) => new (r: T) => V)[] >r2arg1 : new (x: new (arg: T) => U) => new (r: T) => V >r2arg2 : new (x: new (arg: Base) => Derived) => new (r: Base) => Derived2 var r3arg1: new (x: new (arg: T) => U, y: (arg2: { foo: number; }) => U) => new (r: T) => U; >r3arg1 : new (x: new (arg: T) => U, y: (arg2: { foo: number; }) => U) => new (r: T) => U >T : T >Base : Base >U : U >Derived : Derived >x : new (arg: T) => U >arg : T >T : T >U : U >y : (arg2: { foo: number; }) => U >arg2 : { foo: number; } >foo : number >U : U >r : T >T : T >U : U var r3arg2: new (x: (arg: Base) => Derived, y: new (arg2: Base) => Derived) => new (r: Base) => Derived; >r3arg2 : new (x: (arg: Base) => Derived, y: new (arg2: Base) => Derived) => new (r: Base) => Derived >x : (arg: Base) => Derived >arg : Base >Base : Base >Derived : Derived >y : new (arg2: Base) => Derived >arg2 : Base >Base : Base >Derived : Derived >r : Base >Base : Base >Derived : Derived var r3 = foo8(r3arg1); // any >r3 : any >foo8(r3arg1) : any >foo8 : { (a2: new (x: new (arg: Base) => Derived, y: new (arg2: Base) => Derived) => new (r: Base) => Derived): new (x: new (arg: Base) => Derived, y: new (arg2: Base) => Derived) => new (r: Base) => Derived; (a2: any): any; } >r3arg1 : new (x: new (arg: T) => U, y: (arg2: { foo: number; }) => U) => new (r: T) => U var r3a = [r3arg2, r3arg1]; >r3a : ((new (x: new (arg: T) => U, y: (arg2: { foo: number; }) => U) => new (r: T) => U) | (new (x: (arg: Base) => Derived, y: new (arg2: Base) => Derived) => new (r: Base) => Derived))[] >[r3arg2, r3arg1] : ((new (x: new (arg: T) => U, y: (arg2: { foo: number; }) => U) => new (r: T) => U) | (new (x: (arg: Base) => Derived, y: new (arg2: Base) => Derived) => new (r: Base) => Derived))[] >r3arg2 : new (x: (arg: Base) => Derived, y: new (arg2: Base) => Derived) => new (r: Base) => Derived >r3arg1 : new (x: new (arg: T) => U, y: (arg2: { foo: number; }) => U) => new (r: T) => U var r3b = [r3arg1, r3arg2]; >r3b : ((new (x: new (arg: T) => U, y: (arg2: { foo: number; }) => U) => new (r: T) => U) | (new (x: (arg: Base) => Derived, y: new (arg2: Base) => Derived) => new (r: Base) => Derived))[] >[r3arg1, r3arg2] : ((new (x: new (arg: T) => U, y: (arg2: { foo: number; }) => U) => new (r: T) => U) | (new (x: (arg: Base) => Derived, y: new (arg2: Base) => Derived) => new (r: Base) => Derived))[] >r3arg1 : new (x: new (arg: T) => U, y: (arg2: { foo: number; }) => U) => new (r: T) => U >r3arg2 : new (x: (arg: Base) => Derived, y: new (arg2: Base) => Derived) => new (r: Base) => Derived var r4arg1: new (...x: T[]) => T; >r4arg1 : new (...x: T[]) => T >T : T >Derived : Derived >x : T[] >T : T >T : T var r4arg2: new (...x: Base[]) => Base; >r4arg2 : new (...x: Base[]) => Base >x : Base[] >Base : Base >Base : Base var r4 = foo10(r4arg1); // any >r4 : any >foo10(r4arg1) : any >foo10 : { (a2: new (...x: Base[]) => Base): new (...x: Base[]) => Base; (a2: any): any; } >r4arg1 : new (...x: T[]) => T var r4a = [r4arg2, r4arg1]; >r4a : (new (...x: T[]) => T)[] >[r4arg2, r4arg1] : (new (...x: T[]) => T)[] >r4arg2 : new (...x: Base[]) => Base >r4arg1 : new (...x: T[]) => T var r4b = [r4arg1, r4arg2]; >r4b : (new (...x: T[]) => T)[] >[r4arg1, r4arg2] : (new (...x: T[]) => T)[] >r4arg1 : new (...x: T[]) => T >r4arg2 : new (...x: Base[]) => Base var r5arg1: new (x: T, y: T) => T; >r5arg1 : new (x: T, y: T) => T >T : T >Derived : Derived >x : T >T : T >y : T >T : T >T : T var r5arg2: new (x: { foo: string }, y: { foo: string; bar: string }) => Base; >r5arg2 : new (x: { foo: string; }, y: { foo: string; bar: string; }) => Base >x : { foo: string; } >foo : string >y : { foo: string; bar: string; } >foo : string >bar : string >Base : Base var r5 = foo11(r5arg1); // any >r5 : any >foo11(r5arg1) : any >foo11 : { (a2: new (x: { foo: string; }, y: { foo: string; bar: string; }) => Base): new (x: { foo: string; }, y: { foo: string; bar: string; }) => Base; (a2: any): any; } >r5arg1 : new (x: T, y: T) => T var r5a = [r5arg2, r5arg1]; >r5a : (new (x: T, y: T) => T)[] >[r5arg2, r5arg1] : (new (x: T, y: T) => T)[] >r5arg2 : new (x: { foo: string; }, y: { foo: string; bar: string; }) => Base >r5arg1 : new (x: T, y: T) => T var r5b = [r5arg1, r5arg2]; >r5b : (new (x: T, y: T) => T)[] >[r5arg1, r5arg2] : (new (x: T, y: T) => T)[] >r5arg1 : new (x: T, y: T) => T >r5arg2 : new (x: { foo: string; }, y: { foo: string; bar: string; }) => Base var r6arg1: new (x: Array, y: Array) => Array; >r6arg1 : new (x: Base[], y: Derived2[]) => Derived[] >x : Base[] >Array : T[] >Base : Base >y : Derived2[] >Array : T[] >Derived2 : Derived2 >Array : T[] >Derived : Derived var r6arg2: new >(x: Array, y: Array) => T; >r6arg2 : new (x: Base[], y: Base[]) => T >T : T >Array : T[] >Derived2 : Derived2 >x : Base[] >Array : T[] >Base : Base >y : Base[] >Array : T[] >Base : Base >T : T var r6 = foo12(r6arg1); // new (x: Array, y: Array) => Array >r6 : new (x: Base[], y: Derived2[]) => Derived[] >foo12(r6arg1) : new (x: Base[], y: Derived2[]) => Derived[] >foo12 : { (a2: new (x: Base[], y: Derived2[]) => Derived[]): new (x: Base[], y: Derived2[]) => Derived[]; (a2: any): any; } >r6arg1 : new (x: Base[], y: Derived2[]) => Derived[] var r6a = [r6arg2, r6arg1]; >r6a : (new (x: Base[], y: Base[]) => T)[] >[r6arg2, r6arg1] : (new (x: Base[], y: Base[]) => T)[] >r6arg2 : new (x: Base[], y: Base[]) => T >r6arg1 : new (x: Base[], y: Derived2[]) => Derived[] var r6b = [r6arg1, r6arg2]; >r6b : (new (x: Base[], y: Base[]) => T)[] >[r6arg1, r6arg2] : (new (x: Base[], y: Base[]) => T)[] >r6arg1 : new (x: Base[], y: Derived2[]) => Derived[] >r6arg2 : new (x: Base[], y: Base[]) => T var r7arg1: new (x: { a: T; b: T }) => T; >r7arg1 : new (x: { a: T; b: T; }) => T >T : T >x : { a: T; b: T; } >a : T >T : T >b : T >T : T >T : T var r7arg2: new (x: { a: string; b: number }) => number; >r7arg2 : new (x: { a: string; b: number; }) => number >x : { a: string; b: number; } >a : string >b : number var r7 = foo15(r7arg1); // (x: { a: string; b: number }) => number): number; >r7 : any >foo15(r7arg1) : any >foo15 : { (a2: new (x: { a: string; b: number; }) => number): new (x: { a: string; b: number; }) => number; (a2: any): any; } >r7arg1 : new (x: { a: T; b: T; }) => T var r7a = [r7arg2, r7arg1]; >r7a : (new (x: { a: T; b: T; }) => T)[] >[r7arg2, r7arg1] : (new (x: { a: T; b: T; }) => T)[] >r7arg2 : new (x: { a: string; b: number; }) => number >r7arg1 : new (x: { a: T; b: T; }) => T var r7b = [r7arg1, r7arg2]; >r7b : (new (x: { a: T; b: T; }) => T)[] >[r7arg1, r7arg2] : (new (x: { a: T; b: T; }) => T)[] >r7arg1 : new (x: { a: T; b: T; }) => T >r7arg2 : new (x: { a: string; b: number; }) => number var r7arg3: new (x: { a: T; b: T }) => number; >r7arg3 : new (x: { a: T; b: T; }) => number >T : T >Base : Base >x : { a: T; b: T; } >a : T >T : T >b : T >T : T var r7c = foo15(r7arg3); // any >r7c : new (x: { a: string; b: number; }) => number >foo15(r7arg3) : new (x: { a: string; b: number; }) => number >foo15 : { (a2: new (x: { a: string; b: number; }) => number): new (x: { a: string; b: number; }) => number; (a2: any): any; } >r7arg3 : new (x: { a: T; b: T; }) => number var r7d = [r7arg2, r7arg3]; >r7d : (new (x: { a: string; b: number; }) => number)[] >[r7arg2, r7arg3] : (new (x: { a: string; b: number; }) => number)[] >r7arg2 : new (x: { a: string; b: number; }) => number >r7arg3 : new (x: { a: T; b: T; }) => number var r7e = [r7arg3, r7arg2]; >r7e : (new (x: { a: string; b: number; }) => number)[] >[r7arg3, r7arg2] : (new (x: { a: string; b: number; }) => number)[] >r7arg3 : new (x: { a: T; b: T; }) => number >r7arg2 : new (x: { a: string; b: number; }) => number var r8arg: new (x: new (a: T) => T) => T[]; >r8arg : new (x: new (a: T) => T) => T[] >T : T >x : new (a: T) => T >a : T >T : T >T : T >T : T var r8 = foo16(r8arg); // any >r8 : any >foo16(r8arg) : any >foo16 : { (a2: { new (x: { new (a: number): number; new (a?: number): number; }): number[]; new (x: { new (a: boolean): boolean; new (a?: boolean): boolean; }): boolean[]; }): { new (x: { new (a: number): number; new (a?: number): number; }): number[]; new (x: { new (a: boolean): boolean; new (a?: boolean): boolean; }): boolean[]; }; (a2: any): any; } >r8arg : new (x: new (a: T) => T) => T[] var r9arg: new (x: new (a: T) => T) => any[]; >r9arg : new (x: new (a: T) => T) => any[] >T : T >x : new (a: T) => T >a : T >T : T >T : T var r9 = foo17(r9arg); // // (x: { (a: T): T; (a: T): T; }): any[]; (x: { (a: T): T; (a: T): T; }): any[]; >r9 : { new (x: { new (a: T): T; new (a: T): T; }): any[]; new (x: { new (a: T): T; new (a: T): T; }): any[]; } >foo17(r9arg) : { new (x: { new (a: T): T; new (a: T): T; }): any[]; new (x: { new (a: T): T; new (a: T): T; }): any[]; } >foo17 : { (a2: { new (x: { new (a: T): T; new (a: T): T; }): any[]; new (x: { new (a: T): T; new (a: T): T; }): any[]; }): { new (x: { new (a: T): T; new (a: T): T; }): any[]; new (x: { new (a: T): T; new (a: T): T; }): any[]; }; (a2: any): any; } >r9arg : new (x: new (a: T) => T) => any[] } module WithGenericSignaturesInBaseType { >WithGenericSignaturesInBaseType : typeof WithGenericSignaturesInBaseType declare function foo2(a2: new (x: T) => T[]): typeof a2; >foo2 : { (a2: new (x: T) => T[]): new (x: T) => T[]; (a2: any): any; } >a2 : new (x: T) => T[] >T : T >x : T >T : T >T : T >a2 : new (x: T) => T[] declare function foo2(a2: any): any; >foo2 : { (a2: new (x: T) => T[]): new (x: T) => T[]; (a2: any): any; } >a2 : any var r2arg2: new (x: T) => string[]; >r2arg2 : new (x: T) => string[] >T : T >x : T >T : T var r2 = foo2(r2arg2); // (x:T) => T[] since we can infer from generic signatures now >r2 : new (x: T) => T[] >foo2(r2arg2) : new (x: T) => T[] >foo2 : { (a2: new (x: T) => T[]): new (x: T) => T[]; (a2: any): any; } >r2arg2 : new (x: T) => string[] declare function foo3(a2: new (x: T) => string[]): typeof a2; >foo3 : { (a2: new (x: T) => string[]): new (x: T) => string[]; (a2: any): any; } >a2 : new (x: T) => string[] >T : T >x : T >T : T >a2 : new (x: T) => string[] declare function foo3(a2: any): any; >foo3 : { (a2: new (x: T) => string[]): new (x: T) => string[]; (a2: any): any; } >a2 : any var r3arg2: new (x: T) => T[]; >r3arg2 : new (x: T) => T[] >T : T >x : T >T : T >T : T var r3 = foo3(r3arg2); // any >r3 : any >foo3(r3arg2) : any >foo3 : { (a2: new (x: T) => string[]): new (x: T) => string[]; (a2: any): any; } >r3arg2 : new (x: T) => T[] }