[Bug fortran/52774] Derived-type assignment: check required to prevent double deallocation of allocatable component

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52774

Tobias Burnus <burnus at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
           Keywords|                            |wrong-code
   Last reconfirmed|                            |2012-04-02
                 CC|                            |burnus at gcc dot gnu.org,
                   |                            |pault at gcc dot gnu.org
     Ever Confirmed|0                           |1
            Summary|A check is needed to        |Derived-type assignment:
                   |prevent deallocation in     |check required to prevent
                   |realloc-lhs                 |double deallocation of
                   |                            |allocatable component
      Known to fail|                            |4.3.4, 4.7.1, 4.8.0

--- Comment #1 from Tobias Burnus <burnus at gcc dot gnu.org> 2012-04-02 16:36:17 UTC ---
Confirmed.

Remarks:

a) The reduced program in comment 0 is invalid: As "p1%p" is not allocated,
   accessing it with   print *, p1%p   is invalid - and is likely to segfault.
   Solution: Use     print *, allocated (p1%p)   which shall print "F";
   that still gives the expected segfault or "invalid free()" errors from
   valgrind with current gfortran - as expected.

b) The issue is unrelated to realloc on assignment and seems to be related to
   allocatable components (TR 15581, a GCC 4.2 feature). At least the program
   in comment 0 [modified as in comment (a)] also fails with GCC 4.3, using
   -fno-realloc-lhs  does not help, and valgrind shows the same failure.