[Bug fortran/86484] New: Undefined symbol when using polymorphic intrinsic assignment

[townsend at astro dot wisc.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86484

            Bug ID: 86484
           Summary: Undefined symbol when using polymorphic intrinsic
                    assignment
           Product: gcc
           Version: 7.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: townsend at astro dot wisc.edu
  Target Milestone: ---

I'm getting an undefined symbol at link time when compiling the following test
program, which involves intrinsic polymorphic assignment:

program test_assign

  implicit none

  type :: foo_t
     real :: a = 1.
  end type foo_t

  type, extends (foo_t) :: bar_t
     real :: b = 2.
  end type bar_t

  class(foo_t), allocatable :: f
  type(bar_t)               :: b

  f = b

  print *, f%a

end program test_assign

From compiling:

% gfortran -O2 -o test_assign test_assign.f90
Undefined symbols for architecture x86_64:
  "___copy_test_assign_Bar_t.3535", referenced from:
      _MAIN__ in ccPjl5CK.o
      ___vtab_test_assign_Bar_t.3533 in ccPjl5CK.o
ld: symbol(s) not found for architecture x86_64
collect2: error: ld returned 1 exit status

This problem seems to exist on both 7.2 and 8.1, and on both Linux and OSX.

cheers,

Rich