[Bug fortran/51175] New: Memory Leak with Transfer intrinsic

[Bug fortran/51175] New: Memory Leak with Transfer intrinsic

[stefano.borini at ferrara dot linux.it]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51175

             Bug #: 51175
           Summary: Memory Leak with Transfer intrinsic
    Classification: Unclassified
           Product: gcc
           Version: 4.6.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: stefano.borini@ferrara.linux.it


Hello,

I am using gfortran 4.6.2 on MacOSX 10.7. 
It appears that this code involving transfer generates a memory leak

module LeakModule
   implicit none

contains


   subroutine Leaking(stringdata, string)
      character(len=1), intent(in)  :: stringdata(:)
      character(len=*), intent(out) :: string
      character(len=1)                                  :: singleChar(1)
      !integer                                     :: numChars
      !numChars = size(transfer(stringdata,singleChar))
      !string = ''
      string = transfer(stringdata, string)
      !string(numChars+1:) = ' '
   end subroutine

   subroutine Foo()
      character(len=1) :: stringdata(3)
      character(len=20) :: outstring

      stringdata(1) = 'H'
      stringdata(2) = 'i'
      stringdata(3) = '!'

      call Leaking(stringdata, outstring)
      print *, outstring
   end subroutine

end module
program test
   use LeakModule

   call foo()

end 

According to the produced assembler, malloc gets called inside the Leaking
routine, but the asm of the caller never issues a free of that allocated
memory. The same happens even if the string is a local variable with specified
len. 

The commented code (calculating the size of the data involved) correctly issues
one malloc and one free.

Thanks

[Bug fortran/51175] Memory Leak with Transfer intrinsic

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51175

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |wrong-code
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2011-11-16
                 CC|                            |burnus at gcc dot gnu.org
     Ever Confirmed|0                           |1

--- Comment #1 from Tobias Burnus <burnus at gcc dot gnu.org> 2011-11-16 17:15:31 UTC ---
(In reply to comment #0)
> I am using gfortran 4.6.2 on MacOSX 10.7. 
> It appears that this code involving transfer generates a memory leak

Indeed, valgrind shows:

==3168== 20 bytes in 1 blocks are definitely lost in loss record 1 of 1
==3168==    at 0x4A0610C: malloc (vg_replace_malloc.c:195)
==3168==    by 0x4009BF: __leakmodule_MOD_leaking (test.f90:14)
==3168==    by 0x400889: __leakmodule_MOD_foo (test.f90:26)
==3168==    by 0x400A5B: MAIN__ (test.f90:34)
==3168==    by 0x400A91: main (test.f90:32)


>       print *, outstring

Use:
  print *, outstring(1:3)
otherwise you access uninitialized memory.


> According to the produced assembler, malloc gets called inside the Leaking
> routine, but the asm of the caller never issues a free of that allocated
> memory.

Easier than studying the assembler: Use -fdump-tree-original  (or
-fdump-tree-optimized) which creates a file of the internal representation with
C-like syntax. [Note: The dump does not contain all details.]

[Bug fortran/51175] Memory Leak with Transfer intrinsic

[xiaoyuanbo at yeah dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51175

xiaoyuanbo <xiaoyuanbo at yeah dot net> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |xiaoyuanbo at yeah dot net

--- Comment #2 from xiaoyuanbo <xiaoyuanbo at yeah dot net> 2012-02-22 12:46:16 UTC ---
set char two privilage

[Bug fortran/51175] Memory Leak with Transfer intrinsic

[fxcoudert at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=51175

Francois-Xavier Coudert <fxcoudert at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |fxcoudert at gcc dot gnu.org
         Resolution|---                         |FIXED
   Target Milestone|---                         |4.7.0

--- Comment #3 from Francois-Xavier Coudert <fxcoudert at gcc dot gnu.org> ---
This was fixed in 4.7 and later.