tests/cases/conformance/types/typeRelationships/assignmentCompatibility/callSignatureAssignabilityInInheritance.ts(57,15): error TS2429: Interface 'I2' incorrectly extends interface 'Base2':
  Types of property 'a' are incompatible:
    Type '(x: number) => string' is not assignable to type '(x: number) => number':
      Type 'string' is not assignable to type 'number'.


==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/callSignatureAssignabilityInInheritance.ts (1 errors) ====
    module CallSignature {
        interface Base { // T
            // M's
            (x: number): void;
            (x: number, y: number): void;
        }
    
        // S's
        interface I extends Base {
            // N's
            (x: number): number; // ok because base returns void
            (x: number, y: number): boolean; // ok because base returns void
            <T>(x: T): string; // ok because base returns void
        }
    
        interface Base2 { // T
            // M's
            (x: number): number;
        }
    
        // S's
        interface I2 extends Base2 {
            // N's
            (x: number): string; // error because base returns non-void;
        }
    
        // S's
        interface I3 extends Base2 {
            // N's
            <T>(x: T): string; // ok, adds a new call signature
        }
    }
    
    module MemberWithCallSignature {
        interface Base { // T
            // M's
            a: (x: number) => void;
            a2: (x: number, y: number) => void;
            a3: <T>(x: T) => void;
        }
    
        // S's
        interface I extends Base {
            // N's
            a: (x: number) => number; // ok because base returns void
            a2: (x: number, y: number) => boolean; // ok because base returns void
            a3: <T>(x: T) => string; // ok because base returns void
        }
    
        interface Base2 { // T
            // M's
            a: (x: number) => number;
            a2: <T>(x: T) => T;
        }
    
        // S's
        interface I2 extends Base2 {
                  ~~
!!! error TS2429: Interface 'I2' incorrectly extends interface 'Base2':
!!! error TS2429:   Types of property 'a' are incompatible:
!!! error TS2429:     Type '(x: number) => string' is not assignable to type '(x: number) => number':
!!! error TS2429:       Type 'string' is not assignable to type 'number'.
            // N's
            a: (x: number) => string; // error because base returns non-void;
        }
    
        // S's
        interface I3 extends Base2 {
            // N's
            a2: <T>(x: T) => string; // error because base returns non-void;
        }
    }