覆盖类型绑定过程的fortran 2003 seg错误

Question

I'm trying to use some of the object-oriented features of Fortran 2003 and I'm running into some trouble. First off, I have an abstract data type sparse_matrix:

type, abstract :: sparse_matrix
    (some data)
contains
    procedure(matrix_vector_multiply), deferred :: matvec
end type sparse_matrix

abstract interface
    subroutine matrix_vector_multiply(A,x,y)
        import :: sparse_matrix
        class (sparse_matrix), intent(in) :: A
        real(kind=8), dimension(:) :: x,y
    end subroutine matrix_vector_multiply
end abstract interface

then I have a concrete data type which inherits from sparse_matrix

type, extends(sparse_matrix) :: csr_sparse_matrix
    (some more data)
contains
    procedure :: matvec => csr_matvec
end type csr_sparse_matrix

and the actual implementation of matvec:

subroutine csr_matvec(A,x,y)
    class (csr_sparse_matrix), intent(in) :: A
    real(kind=8), dimension(:) :: x,y
    (do stuff)
end subroutine csr_matvec

Later, I want to use matvec in a different module, and I don't care which dynamic type I've got:

subroutine solve(A,x,b,tolerance)
    class (sparse_matrix), intent(in) :: A
    real(kind=8), dimension(:), intent(in) :: b
    real(kind=8), dimension(:), intent(out) :: x
    real(kind=8), intent(in) :: tolerance
    real(kind=8), dimension( A%nrow ) :: z

    call A%matvec(b,z)
    (more stuff)
end subroutine solver

My understanding is that everything should work fine, no matter what dynamic type A is, so long as the subroutine matvec has been overridden in the child data type.

This code compiles just fine, but it seg faults when I run it. When I change the declaration of the matrix in the solve procedure as follows:

     class (csr_sparse_matrix), intent(in) :: A

it works just fine. Likewise, if I leave A as a sparse_matrix but use

select type(A)
type is (csr_sparse_matrix)
    (the same stuff)
end select

then everything runs fine too. But this defeats the whole purpose of overriding the procedures of an abstract type in the first place -- the program shouldn't care what kind of matrix I'm using, as long as it can perform a matrix-vector multiplication.

Anyhow, I'm sure it's just a matter of some attribute that I forgot to include, but I can't figure out what it is.

Answer 1

So it was the compiler after all; I was using gfortran 4.6.3, whereas abstract data types were only properly supported as of gfortran 4.7. Unfortunately, this makes my code not so portable, as the long-term support releases of several linux distributions only include version 4.6.