Initialize parametric-size array of parameterized derived type in Fortran?

Question

Fortran allows parametrizing the size of elements of derived types. However, where fixed-size elements can have a default value assigned in the type declaration, there doesn't seem to be a way for parametrized entries:

PROGRAM main
  IMPLICIT NONE

  TYPE data1
     INTEGER :: array(5) = 2   ! allowed
  END type data1

  TYPE data2(n)
     INTEGER, LEN :: n
     INTEGER :: array(n) = 2   ! incorrect: error #8737 with intel fortran 19,
  END type data2               !            ignored by gfortran 8.2.1

END PROGRAM main

Assigning default values is convenient, as it allows avoiding repeating the initialization every time the type is used, but for parametric-sized fields it isn't allowed; Gfortran just ignores the default value silently, and Intel Fortran issues an error

error #8737: For a default initialized component every type parameter and array bound
             must be a constant expression.   [ARRAY]

Is there any syntax, that would allow defining a default value after all?

Answer 1

There can be no default initialization for such components.

As the Intel Fortran error message states, the array bounds for a component with an initialization expression must be constant expressions (this is constraint C762 of Fortran 2018). The length type parameter is not usable as a constant expression.

There is no other syntax to specify a default value for the component.

A kind type parameter can feature in a constant expression, so components with bounds given by a kind parameter of that type can have default initialization.