http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53956
Bug #: 53956
Summary: Proc-pointer w/ interface: Bogus "EXTERNAL attribute
conflicts with FUNCTION attribute"
Classification: Unclassified
Product: gcc
Version: 4.8.0
Status: UNCONFIRMED
Keywords: rejects-valid
Severity: normal
Priority: P3
Component: fortran
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: bur...@gcc.gnu.org
CC: ja...@gcc.gnu.org
Found at comp.lang.fortran,
cf. http://www.rhinocerus.net/forum/lang-fortran/709699-sort-2d-matrix-2.html
or
https://groups.google.com/forum/?fromgroups#!topic/comp.lang.fortran/kfOR7y1bI0Q
The original example has been written by James Van Buskirk - see thread.
The following program gives the bogus error when the procedure pointer is
invoked. Without procedure pointer or - for the dummy argument - using
"procedure(integer)" instead of "integer, external" (which is semantically
identically), works.
program testme
1
Error: EXTERNAL attribute conflicts with FUNCTION attribute in 'comparator2' at
(1)
module m
contains
function compare()
integer :: compare
compare = 42
end function compare
subroutine print_it(x)
procedure(integer) :: x
print *, x()
end subroutine print_it
end module m
program testme
use m
implicit none
interface
subroutine sub(comparator2) ! <<< related to those
integer, external :: comparator2 ! <<< lines
end subroutine sub
end interface
procedure(sub), pointer :: fp ! << but the interface might be involved
fp => print_it
call fp (compare) ! <<< Triggers the error
end program testme
