Memory leak in intrinsic assignment of allocatable function result

[Damian Rouson <damian at rouson dot net>]

Gfortran developers,

I am assisting my staff member Karla Morris (cc'd) in demonstrating a
gfortran memory leak.  In my version of her code below, it's possible
I have oversimplified the situation.  I'm not sure the leak valgrind
is reporting is associated with the right-hand-side function result in
"a = bar()" or with the left-hand side "a".  If valgrind is reporting
a leak associated with "a", then I presume it's not really a leak
because the compiler is not obligated to free deallocate objects
declared in a main program.  If valgrind is reporting a leak
associated with a function result, then this test code is sufficient
to demonstrate at least part of the problem we've encountered.

In Karla's actual application, the "bar" procedure is type-bound and
is invoked via a type-bound generic operator that appears in a longer
expression composed of various user-defined operators.

If the results below do in fact demonstrate a leak, I'd love to know
exactly what the one leaky bite holds.  Please advise.

Damian

$ gfortran --version
GNU Fortran (MacPorts gcc48 4.8-20121202_0) 4.8.0 20121202 (experimental)

$ cat leak.f90
  type foo
  end type
  type(foo) a
  a = bar()
contains
  function bar()
    type(foo), allocatable :: bar
    allocate(bar)
  end function
end
$ gfortran leak.f90
$ valgrind ./a.out
==5151== Memcheck, a memory error detector
==5151== Copyright (C) 2002-2012, and GNU GPL'd, by Julian Seward et al.
==5151== Using Valgrind-3.8.1 and LibVEX; rerun with -h for copyright info
==5151== Command: ./a.out
==5151==
--5151-- ./a.out:
--5151-- dSYM directory is missing; consider using --dsymutil=yes
==5151==
==5151== HEAP SUMMARY:
==5151==     in use at exit: 1,998 bytes in 33 blocks
==5151==   total heap usage: 49 allocs, 16 frees, 5,706 bytes allocated
==5151==
==5151== LEAK SUMMARY:
==5151==    definitely lost: 1 bytes in 1 blocks
==5151==    indirectly lost: 0 bytes in 0 blocks
==5151==      possibly lost: 0 bytes in 0 blocks
==5151==    still reachable: 1,997 bytes in 32 blocks
==5151==         suppressed: 0 bytes in 0 blocks
==5151== Rerun with --leak-check=full to see details of leaked memory
==5151==
==5151== For counts of detected and suppressed errors, rerun with: -v
==5151== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)