[Bug libfortran/20074] New: reshape of pointer array segfaults at runtime

[Thomas dot Koenig at online dot de]

>From a posting to comp.lang.fortran.

$ cat tryresh.f90
! From: "Alfredo Buttari" <pitagoras@tin.it>
! Newsgroups: comp.lang.fortran
! Subject: reshape problem
! Date: 18 Feb 2005 09:54:35 -0800

program tryreshape

  integer,allocatable :: vect1(:),resh1(:,:)
  integer,pointer :: vect(:),resh(:,:)
  integer :: vect2(2*4), resh2(2,4)
  integer :: r, s(2)

  r=2;  nb=4

  s(:)=(/r,nb/)

  allocate(vect(nb*r),vect1(nb*r))
  allocate(resh(r,nb),resh1(r,nb))

  vect =1
  vect1=1
  vect2=1

  write(*,'("Reshaping to  ",1(i1.1,"x"),i2.2)')s

! THIS WORKS
  resh2 = reshape(vect2,s)
  write(*,'("resh2: ",1(i3,2x))')resh2(1,1)

! THIS WORKS
  resh1 = reshape(vect1,s)
  write(*,'("resh1: ",1(i3,2x))')resh1(1,1)

! THIS DOESN'T
  resh = reshape(vect,s)
  write(*,'("resh : ",1(i3,2x))')resh(1,1)

end program tryreshape
$ gfortran -g tryresh.f90
$ ./a.out
Reshaping to  2x04
resh2:   1
resh1:   1
Segmentation fault
$ gdb ./a.out
GNU gdb 6.3-debian
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welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
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This GDB was configured as "i386-linux"...Using host libthread_db library
"/lib/tls/libthread_db.so.1".

(gdb) r
Starting program: /home/ig25/Krempel/a.out
Reshaping to  2x04
resh2:   1
resh1:   1

Program received signal SIGSEGV, Segmentation fault.
0x40127cef in memcpy () from /lib/tls/libc.so.6
(gdb) bt
#0  0x40127cef in memcpy () from /lib/tls/libc.so.6
#1  0x40056f08 in *_gfortrani_reshape_packed (ret=0x0, rsize=32,
    source=0x20 <Address 0x20 out of bounds>, ssize=32, pad=0x0, psize=4)
    at ../../../gcc/libgfortran/intrinsics/reshape_packed.c:45
#2  0x40044b8b in *_gfortran_reshape_4 (ret=0xbffff4c4, source=Variable "source"
is not available.
)
    at ../../../gcc/libgfortran/generated/reshape_i4.c:160
#3  0x08048d6f in MAIN__ () at tryresh.f90:35
#4  0x08048f43 in main (argc=32, argv=0x20)
    at ../../../gcc/libgfortran/fmain.c:18
(gdb) q
The program is running.  Exit anyway? (y or n) y
$ gfortran -v
Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: ../gcc/configure --prefix=/home/ig25 --enable-languages=c,f95
Thread model: posix
gcc version 4.0.0 20050219 (experimental)

-- 
           Summary: reshape of pointer array segfaults at runtime
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: libfortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: Thomas dot Koenig at online dot de
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20074