For this test case:

program F03_2_9_3_6_2c
! derived from OpenMP test omp3f/F03_2_9_3_6_2c.f90
! REFERENCES
!     OpenMP 3.0, p. 100, lines 10-12
!     OpenMP 3.0, p. 316, lines 18-22
   use omp_lib
   implicit none
   integer, parameter :: NT = 4
   integer :: thread_num1, thread_num2, thread_num3
   integer, allocatable :: thread_num_sums(:)
   integer :: i

   call omp_set_dynamic(.false.)
   call omp_set_num_threads(NT)

   allocate(thread_num_sums(NT))
   thread_num_sums = 0

   !$omp parallel 
      !$omp sections reduction(+:thread_num_sums)
         !$omp section
            thread_num_sums = omp_get_thread_num()
            thread_num1 = omp_get_thread_num()
         !$omp section
            thread_num_sums = omp_get_thread_num()
            thread_num2 = omp_get_thread_num()
         !$omp section
            thread_num_sums = omp_get_thread_num()
            thread_num3 = omp_get_thread_num()
      !$omp end sections
   !$omp end parallel

   do i = 1, NT
      if (thread_num_sums(i) /= thread_num1+thread_num2+thread_num3) then
         write (*,fmt="('FAIL - thread_num_sums(',i2, ') == ',i10,  &
                ' (expected',i2,')')") &
                i, thread_num_sums(i), thread_num1+thread_num2+thread_num3
                                                                     else
         write (*,fmt="('thread',i2,'  thread_num_sums(i) = ',i2)") &
                                 i, thread_num_sums(i)
      end if
   end do
end program F03_2_9_3_6_2c

the compiler aborts:

> gfortran -fopenmp test.f90
test.f90: In function 'f03_2_9_3_6_2c':
test.f90:20: internal compiler error: in single_pred_edge, at basic-block.h:658
Please submit a full bug report,
with preprocessed source if appropriate.


Additional comment from the OpenMP testers:

The GNU gfortran compiler gets an internal error when compiling this
test case when the REDUCTION appears on a SECTIONS.

The OpenMP API version 3 (May 2008) p. 316 lines 18-20 states:

"In Version 3.0, Fortran allocatable arrays may appear in ...
 reduction ... clauses."

The API also states on p. 100 line 10-23:

"An original list item with the ALLOCATABLE attribute must be in the 
 allocated state at entry to the construct containing the reduction clause.
 Additionally, the list item must not be deallocated and/or allocated
 within the region."