[Bug fortran/37746] New: string copy fails, due to changed intent(in) parameter

[Bug fortran/37746] New: string copy fails, due to changed intent(in) parameter

[kloedej at knmi dot nl]

The following testcase of (I think) valid Fortran90 code, shows a strange
error. It copies all characters of a text string except for the first
character, which for some unknown reason is replaced by a space.
The essential element seems to be the use of the expression len(a)+1 to
dimension the size of string b.

subroutine copy(a,b)
  character(len=*),        intent(in)  :: a
  character(len=len(a)+1), intent(out) :: b
  integer :: c
  print *,"inside1: a = ["//trim(a)//"]"
  b(:)=' '
  c=len_trim(a)
  b(1:c)=a(1:c)
  print *,"inside2: a = ["//trim(a)//"]"
  print *,"len_trim(a)=",c
  print *,"inside:  b = ["//trim(b)//"]"    
end subroutine copy

program Test_StrCopy
  character(len=50) :: a,b
  a = "abcdefg"
  call copy(a,b)
end program Test_StrCopy


After compiling with: gfortran -o Test_Copy Test_Copy.F90
I get this result:

>Test_Copy
 inside1: a = [abcdefg]
 inside2: a = [ bcdefg]
 len_trim(a)=           7
 inside:  b = [ bcdefg]
>

Clearly, the problem seems to be that the intent(in) variable a gets modified,
which should never happen.

gfortran version used for testing was:

gfortran -v
Using built-in specs.
Target: i586-pc-linux-gnu
Configured with: /home/fx/gfortran_nightbuild/trunk/configure
--prefix=/home/fx/gfortran_nightbuild/irun-20081005
--enable-languages=c,fortran --build=i586-pc-linux-gnu
--enable-checking=release --with-gmp=/home/fx/gfortran_nightbuild/software
Thread model: posix
gcc version 4.4.0 20081005 (experimental) [trunk revision 140878] (GCC) 
>

Best regards,

Jos de Kloe, KNMI


-- 
           Summary: string copy fails, due to changed intent(in) parameter
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: kloedej at knmi dot nl


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37746

[Bug fortran/37746] string copy fails, due to changed intent(in) parameter

[kargl at gcc dot gnu dot org]

------- Comment #1 from kargl at gcc dot gnu dot org  2008-10-06 14:47 -------
Your code works if you fix the bug.  You have two choices

program Test_StrCopy
  character(len=50) :: a
  character(len=51) :: b
  a = "abcdefg"
  call copy(a,b)
end program Test_StrCopy

or

subroutine copy(a,b)
  character(len=*),       intent(in) :: a
  character(len=len(a)), intent(out) :: b


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37746

[Bug fortran/37746] string copy fails, due to changed intent(in) parameter

[burnus at gcc dot gnu dot org]

------- Comment #2 from burnus at gcc dot gnu dot org  2008-10-06 19:53 -------
I think the true bug is that -fbounds-check misses the problem. NAG f95 prints
at run time:
  CHARACTER actual arg LEN=50 shorter than dummy arg LEN=51
  Program terminated by fatal error


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37746

[Bug fortran/37746] string copy fails, due to changed intent(in) parameter

[kloedej at knmi dot nl]

------- Comment #3 from kloedej at knmi dot nl  2008-10-07 11:23 -------
Hi,

thanks for this discussion.
I do agree now that this code was invalid. I was thinking otherwise because no
compiletime or runtime error was issued by any of the compilers that I tried. 
Checking this during compilation should at least be possible when the interface
of the subroutine is known, so when it is defined inside a module, but gfortran
also accepts that case without complaining.

best regards,

Jos de Kloe.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37746

[Bug fortran/37746] bounds check of string dummy arguments

[tkoenig at gcc dot gnu dot org]

------- Comment #4 from tkoenig at gcc dot gnu dot org  2008-10-12 11:33 -------
Confirm, updated subject, blocks bounds-checking meta-bug.


-- 

tkoenig at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
OtherBugsDependingO|                            |27766
              nThis|                            |
           Severity|normal                      |enhancement
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2008-10-12 11:33:42
               date|                            |
            Summary|string copy fails, due to   |bounds check of string dummy
                   |changed intent(in) parameter|arguments


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37746

[Bug fortran/37746] bounds check of string dummy arguments

[domob at gcc dot gnu dot org]

-- 

domob at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |domob at gcc dot gnu dot org
                   |dot org                     |
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2008-10-12 11:33:42         |2008-12-20 19:08:02
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37746

[Bug fortran/37746] bounds check of string dummy arguments

[domob at gcc dot gnu dot org]

------- Comment #5 from domob at gcc dot gnu dot org  2009-01-04 08:40 -------
*** Bug 35943 has been marked as a duplicate of this bug. ***


-- 

domob at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |burnus at gcc dot gnu dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37746

[Bug fortran/37746] bounds check of string dummy arguments

[domob at gcc dot gnu dot org]

------- Comment #6 from domob at gcc dot gnu dot org  2009-01-04 08:41 -------
Here's a patch: http://gcc.gnu.org/ml/fortran/2008-12/msg00273.html


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37746

[Bug fortran/37746] bounds check of string dummy arguments

[domob at gcc dot gnu dot org]

------- Comment #7 from domob at gcc dot gnu dot org  2009-04-11 16:44 -------
Subject: Bug 37746

Author: domob
Date: Sat Apr 11 16:44:37 2009
New Revision: 145958

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=145958
Log:
2009-04-11  Daniel Kraft  <d@domob.eu>

        PR fortran/37746
        * gfortran.h (struct gfc_charlen): New field `passed_length' to store
        the actual passed string length for dummy arguments.
        * trans-decl.c (gfc_create_string_length): Formatting fixes and added
        assertion, moved a local variable into the innermost block it is
needed.
        (create_function_arglist): Removed TODO about the check being
        implemented and initialize cl->passed_length here.
        (add_argument_checking): New method.
        (gfc_generate_function_code): Call the argument checking method.

2009-04-11  Daniel Kraft  <d@domob.eu>

        PR fortran/37746
        * gfortran.dg/bounds_check_strlen_1.f90: New test.
        * gfortran.dg/bounds_check_strlen_2.f90: New test.
        * gfortran.dg/bounds_check_strlen_3.f90: New test.
        * gfortran.dg/bounds_check_strlen_4.f90: New test.
        * gfortran.dg/bounds_check_strlen_5.f90: New test.
        * gfortran.dg/bounds_check_strlen_6.f90: New test.
        * gfortran.dg/bounds_check_strlen_7.f90: New test.
        * gfortran.fortran-torture/execute/intrinsic_index.f90: Fix wrong
        expected string length that failed with -fbounds-check now.
        * gfortran.fortran-torture/execute/intrinsic_trim.f90: Ditto.

Added:
    trunk/gcc/testsuite/gfortran.dg/bounds_check_strlen_1.f90
    trunk/gcc/testsuite/gfortran.dg/bounds_check_strlen_2.f90
    trunk/gcc/testsuite/gfortran.dg/bounds_check_strlen_3.f90
    trunk/gcc/testsuite/gfortran.dg/bounds_check_strlen_4.f90
    trunk/gcc/testsuite/gfortran.dg/bounds_check_strlen_5.f90
    trunk/gcc/testsuite/gfortran.dg/bounds_check_strlen_6.f90
    trunk/gcc/testsuite/gfortran.dg/bounds_check_strlen_7.f90
Modified:
    trunk/gcc/fortran/ChangeLog
    trunk/gcc/fortran/gfortran.h
    trunk/gcc/fortran/trans-decl.c
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/gfortran.fortran-torture/execute/intrinsic_index.f90
    trunk/gcc/testsuite/gfortran.fortran-torture/execute/intrinsic_trim.f90


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37746

[Bug fortran/37746] bounds check of string dummy arguments

[domob at gcc dot gnu dot org]

------- Comment #8 from domob at gcc dot gnu dot org  2009-04-11 16:46 -------
Fixed on trunk.


-- 

domob at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37746