CODEWITHSUNDEEP
fortrangfortrantype-definition
GammaSQ
GammaSQ

Reputation: 391

Length-parameterized passed object to type-bound procedure has gfortran complain

I'm learning Fortran and I'd like to encapsulate an array and a subroutine in a type. The problem appears to be in the type definition of the self-object.

This is the minimal test case I came up with:

module testing
  implicit none

  type test(para)
    integer, len :: para
    real, dimension(para) :: weights

  contains
    procedure :: testing => testing_test
  end type
contains
  subroutine testing_test(self)
    class(test(*)) :: self
  end subroutine
end module

Compiling this with gfortran raises this error:

module_test.f08:9:23:

  procedure :: testing => testing_test
          1
Error: Argument ‘self’ of ‘testing_test’ with PASS(self) at (1) must be of the derived-type ‘test’

It works when the array-length is fixed (so type%para doesn't exist)

Is what I'm trying to do (type with array of variable size and bound procedure) plain impossible or am I missing something regarding dummy argument definition?

Upvotes: 7

Views: 620

Answers (3)

Jonatan Öström
Jonatan Öström

Reputation: 2629

This is not really an answer but may provide a solution for some. gfortran-10 still has the same problem. However flang-7 compiles this example and it is available for Ubuntu since 19.10, and maybe other OS:es.

Upvotes: 3

francescalus
francescalus

Reputation: 32451

A previous answer points to a bug report and patch for gfortran. It is worth saying, though, that this is standard Fortran (2003) code.

What we have here is a type-bound procedure with passed-object dummy argument. The main restrictions of such an argument are that it is a:

  • scalar,
  • nonallocatable,
  • nonpointer object,
  • with all length-type parameters assumed.

Further, as the type is extensible the passed-object dummy argument must be polymorphic.

For the example of the question, all of the conditions are met.

Upvotes: 1

GammaSQ
GammaSQ

Reputation: 391

Thanks to @Rodrigo for the idea, I finally found this bug (and patch): https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82943

To fix the issue, download the source, apply the mentioned patch and compile your own gfortran. (Or wait until it's in the repositories)

Upvotes: 6

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