==== tests/cases/compiler/extendedInterfacesWithDuplicateTypeParameters.ts (3 errors) ====
    interface InterfaceWithMultipleTypars<A, A> { // should error
                                             ~
!!! Duplicate identifier 'A'.
    	bar(): void;
    }
    
    interface InterfaceWithSomeTypars<B> { // should not error
    	bar(): void;
    }
    
    interface InterfaceWithSomeTypars<C, C> { // should error
              ~~~~~~~~~~~~~~~~~~~~~~~
!!! All declarations of an interface must have identical type parameters.
                                         ~
!!! Duplicate identifier 'C'.
    	bar2(): void;
    }