As reported by Thomas Robitaille at
http://gcc.gnu.org/ml/fortran/2009-10/msg00220.html
the following code gives wrong-code (segfault/buserror) at run time with GCC
4.2/4.3/4.4/4.5. (4.1 does not support allocatable dummies.)
$ ./a.out
in sub1
Bus error
module test_module
implicit none
contains
subroutine sub2(a)
implicit none
real,allocatable,intent(out),optional :: a(:)
print *,'in sub2'
end subroutine sub2
subroutine sub1(a)
implicit none
real,allocatable,intent(out),optional :: a(:)
print *,'in sub1'
call sub2(a)
end subroutine sub1
end module test_module
program test
use test_module
implicit none
call sub1()
end program
The problem is that the argument can be "NULL" - and there is no check for the
case "a == NULL"; i.e. the INTENT(OUT) autodeallocation block needs to be
enclosed with a "if (a !=NULL)" as remarked by Dennis
(http://gcc.gnu.org/ml/fortran/2009-10/msg00221.html).
sub1 (a)
{
[...snip printing "in sub1" stuff...]
{
struct array1_real(kind=4) * D.555;
if (a->data != 0B)
{
__builtin_free (a->data);
}
a->data = 0B;
D.555 = a != 0B ? a : 0B;
sub2 (D.555);
}
By the way the line "D.555 = a != 0B ? a : 0B;" is redundant - and also not
nice because making the alias analysis for the middle end more difficult.
--
Summary: Wong-code with optional allocatable arrays
Product: gcc
Version: 4.5.0
Status: UNCONFIRMED
Keywords: wrong-code
Severity: normal
Priority: P3
Component: fortran
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: burnus at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41850
