[Bug fortran/33544] New: Spurious warning in TRANSFER intrinsic in Sept 24 snapshot of gfortran

[Bug fortran/33544] New: Spurious warning in TRANSFER intrinsic in Sept 24 snapshot of gfortran

[michael dot a dot richmond at nasa dot gov]

When I compile the program listed below with the snapshot version of gfortran
dated September 24 I get the following spurious warning:

pp.f90:3.15:
rft = TRANSFER(' ', 0.0)
              1
Warning: Intrinsic TRANSFER at (1) has partly undefined result: source size 1 <
result size 4

PROGRAM printd
REAL :: rft
rft = TRANSFER(' ', 0.0)
END PROGRAM printd


-- 
           Summary: Spurious warning in TRANSFER intrinsic in Sept 24
                    snapshot of gfortran
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: michael dot a dot richmond at nasa dot gov


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33544

Re: [Bug fortran/33544] New: Spurious warning in TRANSFER intrinsic in Sept 24 snapshot of gfortran

[Andrew Pinski]

On 24 Sep 2007 15:48:19 -0000, michael dot a dot richmond at nasa dot
gov <gcc-bugzilla@gcc.gnu.org> wrote:
> When I compile the program listed below with the snapshot version of gfortran
> dated September 24 I get the following spurious warning:
>
> pp.f90:3.15:
> rft = TRANSFER(' ', 0.0)
>               1
> Warning: Intrinsic TRANSFER at (1) has partly undefined result: source size 1 <
> result size 4

the warning is correct.

[Bug fortran/33544] Spurious warning in TRANSFER intrinsic in Sept 24 snapshot of gfortran

[pinskia at gmail dot com]

------- Comment #1 from pinskia at gmail dot com  2007-09-24 15:53 -------
Subject: Re:  New: Spurious warning in TRANSFER intrinsic in Sept 24 snapshot
of gfortran

On 24 Sep 2007 15:48:19 -0000, michael dot a dot richmond at nasa dot
gov <gcc-bugzilla@gcc.gnu.org> wrote:
> When I compile the program listed below with the snapshot version of gfortran
> dated September 24 I get the following spurious warning:
>
> pp.f90:3.15:
> rft = TRANSFER(' ', 0.0)
>               1
> Warning: Intrinsic TRANSFER at (1) has partly undefined result: source size 1 <
> result size 4

the warning is correct.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33544

[Bug fortran/33544] Spurious warning in TRANSFER intrinsic in Sept 24 snapshot of gfortran

[burnus at gcc dot gnu dot org]

------- Comment #2 from burnus at gcc dot gnu dot org  2007-09-24 17:26 -------
(In reply to comment #0)
> When I compile the program listed below with the snapshot version of gfortran
> dated September 24 I get the following spurious warning:
> pp.f90:3.15:
> rft = TRANSFER(' ', 0.0)
>               1
> Warning: Intrinsic TRANSFER at (1) has partly undefined result:
>          source size 1 < result size 4

pinskia wrote:
> the warning is correct.

To elaborate:
  ' ' is 1 byte long
  0.0 is 4 bytes long
thus transfer initializes only 1 of the 4 bytes of rft, the rest remain
unchanged. You need to use "transfer('    ', 0.0)" to initialize all bytes.

If you have a suggestion how to improve the warning message or if you have any
other suggestion, I would be grateful.

I tried some compiles and the resulting rft is varying a lot:
4.484155086E-44, -4.1234682E-11, -2.4305621E-28, 1.0774349E+12


-- 

burnus 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=33544

[Bug fortran/33544] Spurious warning in TRANSFER intrinsic in Sept 24 snapshot of gfortran

[kargl at gcc dot gnu dot org]

------- Comment #3 from kargl at gcc dot gnu dot org  2007-09-24 18:57 -------
Tobias,

We may want to hide the warning behind a -Wshort-transfer option
(or some other appropriate name).  Afterall, if a programmer 
wrote 'rft = transfer(' ', 0.0)', then s/he probably meant it.


-- 

kargl at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33544

[Bug fortran/33544] Spurious warning in TRANSFER intrinsic in Sept 24 snapshot of gfortran

[burnus at gcc dot gnu dot org]

------- Comment #4 from burnus at gcc dot gnu dot org  2007-09-24 19:17 -------
> We may want to hide the warning behind a -Wshort-transfer option
> (or some other appropriate name).
Maybe; I think having a warning by default would be more reasonable but it
should be hideable.

> Afterall, if a programmer wrote 'rft = transfer(' ', 0.0)',
> then s/he probably meant it.

I sincerely doubt that the programmer meant that this piece of code produces
different results depending on the compiler and possibly some random value in
memory. For the given example, many compilers seem to initialize the result
with zero; example:

PROGRAM printd
REAL :: rft
rft = TRANSFER(' ', 0.0)
print *, rft
rft = TRANSFER(' '//achar(0)//achar(0)//achar(0), 0.0)
print *, rft
END PROGRAM printd

The second transfer produces: 4.4841551E-44
g95, ifort and openf95 seem to produce the same result also for the first
TRANSFER.
gfortran, NAG f95 and sunf95 have, however, a different result every time.

Thus, if one wants to argue that the programmer intended a certain value, I
would argue that it is the one using a zero-padded SOURCE.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33544

[Bug fortran/33544] Spurious warning in TRANSFER intrinsic in Sept 24 snapshot of gfortran

[sgk at troutmask dot apl dot washington dot edu]

------- Comment #5 from sgk at troutmask dot apl dot washington dot edu  2007-09-24 19:59 -------
Subject: Re:  Spurious warning in TRANSFER intrinsic in Sept 24 snapshot of
gfortran

On Mon, Sep 24, 2007 at 07:17:54PM -0000, burnus at gcc dot gnu dot org wrote:
> 
> 
> ------- Comment #4 from burnus at gcc dot gnu dot org  2007-09-24 19:17 -------
> > We may want to hide the warning behind a -Wshort-transfer option
> > (or some other appropriate name).
> Maybe; I think having a warning by default would be more reasonable but it
> should be hideable.

I don't fell strongly either way, but I do agree one should be able to
turn off/on the warning.

> > Afterall, if a programmer wrote 'rft = transfer(' ', 0.0)',
> > then s/he probably meant it.
> 
> I sincerely doubt that the programmer meant that this piece of code produces
> different results depending on the compiler and possibly some random value in
> memory.

It may not produce random values each time (see below).  Michael (a user) 
did file a bug report, and knowing him for previous bug reports and posts
elsewhere on the net, I suspect he did intend the short transfer.

> For the given example, many compilers seem to initialize the result
> with zero; example:
> 
> PROGRAM printd
> REAL :: rft
> rft = TRANSFER(' ', 0.0)
> print *, rft
> rft = TRANSFER(' '//achar(0)//achar(0)//achar(0), 0.0)
> print *, rft
> END PROGRAM printd
> 
> The second transfer produces: 4.4841551E-44
> g95, ifort and openf95 seem to produce the same result also for the first
> TRANSFER.
> gfortran, NAG f95 and sunf95 have, however, a different result every time.
> 
> Thus, if one wants to argue that the programmer intended a certain value, I
> would argue that it is the one using a zero-padded SOURCE.

The programmer for whatever reason could be using rft as temporary storage.
Yes, I know it's a hypothetical situation, but the following is legal code
and should not give a warning.

program m
  character c
  real rft
  rft = transfer(' ', 0.)
!  print *, rft              <-- Uncommenting may make this invalid code
  c = transfer(rft, c)
  if (c .eq. ' ') print *, 'space'
end program

Note, if I uncomment the print statement, on x86_64-*-freebsd, it prints
a NaN every time I execute the program.  


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33544

Re: [Bug fortran/33544] Spurious warning in TRANSFER intrinsic in Sept 24 snapshot of gfortran

[Andrew Pinski]

On 24 Sep 2007 19:59:37 -0000, sgk at troutmask dot apl dot washington
dot edu <gcc-bugzilla@gcc.gnu.org> wrote:
> The programmer for whatever reason could be using rft as temporary storage.
> Yes, I know it's a hypothetical situation, but the following is legal code
> and should not give a warning.

Though I will argue that is just bad coding.

-- Pinski

[Bug fortran/33544] Spurious warning in TRANSFER intrinsic in Sept 24 snapshot of gfortran

[pinskia at gmail dot com]

------- Comment #6 from pinskia at gmail dot com  2007-09-24 21:26 -------
Subject: Re:  Spurious warning in TRANSFER intrinsic in Sept 24 snapshot of
gfortran

On 24 Sep 2007 19:59:37 -0000, sgk at troutmask dot apl dot washington
dot edu <gcc-bugzilla@gcc.gnu.org> wrote:
> The programmer for whatever reason could be using rft as temporary storage.
> Yes, I know it's a hypothetical situation, but the following is legal code
> and should not give a warning.

Though I will argue that is just bad coding.

-- Pinski


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33544

[Bug fortran/33544] Spurious warning in TRANSFER intrinsic in Sept 24 snapshot of gfortran

[sgk at troutmask dot apl dot washington dot edu]

------- Comment #7 from sgk at troutmask dot apl dot washington dot edu  2007-09-24 21:49 -------
Subject: Re:  Spurious warning in TRANSFER intrinsic in Sept 24 snapshot of
gfortran

On Mon, Sep 24, 2007 at 09:26:01PM -0000, pinskia at gmail dot com wrote:
> On 24 Sep 2007 19:59:37 -0000, sgk at troutmask dot apl dot washington
> dot edu <gcc-bugzilla@gcc.gnu.org> wrote:
> > The programmer for whatever reason could be using rft as temporary storage.
> > Yes, I know it's a hypothetical situation, but the following is legal code
> > and should not give a warning.
> 
> Though I will argue that is just bad coding.
> 

It doesn't matter if it's bad coding (which I can agree).
AFAIK, the standard says the code is legal.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33544

[Bug fortran/33544] Spurious warning in TRANSFER intrinsic in Sept 24 snapshot of gfortran

[michael dot a dot richmond at nasa dot gov]

------- Comment #8 from michael dot a dot richmond at nasa dot gov  2007-09-26 15:36 -------
An analogous message appears when I compile the program listed below with the
flag "-fdefault-real-8":

qq.f90:3.15:
rft = TRANSFER('abcd', 0.0)
              1
Warning: Intrinsic TRANSFER at (1) has partly undefined result: source size 4 <
result size 8

PROGRAM printd
REAL :: rft
rft = TRANSFER('abcd', 0.0)
END PROGRAM printd


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33544

[Bug fortran/33544] [4.3 only] Warning in TRANSFER intrinsic should be made optional

[fxcoudert at gcc dot gnu dot org]

------- Comment #9 from fxcoudert at gcc dot gnu dot org  2007-09-27 12:27 -------
(In reply to comment #7)
> It doesn't matter if it's bad coding (which I can agree).
> AFAIK, the standard says the code is legal.

After reading the standard, I concur. I think a warning option should be added,
maybe -Wshort-transfer, maybe -Wsurprising...


-- 

fxcoudert at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |fxcoudert at gcc dot gnu dot
                   |                            |org
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
           Keywords|                            |diagnostic
   Last reconfirmed|0000-00-00 00:00:00         |2007-09-27 12:27:35
               date|                            |
            Summary|Spurious warning in TRANSFER|[4.3 only] Warning in
                   |intrinsic in Sept 24        |TRANSFER intrinsic should be
                   |snapshot of gfortran        |made optional
   Target Milestone|---                         |4.3.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33544

[Bug fortran/33544] [4.3 only] Warning in TRANSFER intrinsic should be made optional

[mmitchel at gcc dot gnu dot org]

-- 

mmitchel at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P5


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33544

[Bug fortran/33544] [4.3 only] Warning in TRANSFER intrinsic should be made optional

[jvdelisle at gcc dot gnu dot org]

------- Comment #10 from jvdelisle at gcc dot gnu dot org  2007-10-19 04:58 -------
This does the trick.  I am checking the testsuite for any side effects.


Index: simplify.c
===================================================================
--- simplify.c  (revision 129465)
+++ simplify.c  (working copy)
@@ -4065,7 +4065,7 @@ gfc_simplify_transfer (gfc_expr *source,
       result_size = result_elt_size;
     }

-  if (source_size < result_size)
+  if (gfc_option.warn_surprising && source_size < result_size)
     gfc_warning("Intrinsic TRANSFER at %L has partly undefined result: "
                "source size %ld < result size %ld", &source->where,
                (long) source_size, (long) result_size);


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33544

[Bug fortran/33544] [4.3 only] Warning in TRANSFER intrinsic should be made optional

[jvdelisle at gcc dot gnu dot org]

------- Comment #11 from jvdelisle at gcc dot gnu dot org  2007-10-19 14:06 -------
Subject: Bug 33544

Author: jvdelisle
Date: Fri Oct 19 14:06:05 2007
New Revision: 129488

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=129488
Log:
2007-10-19  Jerry DeLisle  <jvdelisle@gcc.gnu.org>

        PR fortran/33544
        * simplify.c (gfc_simplify_transfer): Only warn for short transfer when
        -Wsurprising is given.
        * invoke.texi: Document revised behavior.

Modified:
    trunk/gcc/fortran/ChangeLog
    trunk/gcc/fortran/invoke.texi
    trunk/gcc/fortran/simplify.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33544

[Bug fortran/33544] [4.3 only] Warning in TRANSFER intrinsic should be made optional

[jvdelisle at gcc dot gnu dot org]

------- Comment #12 from jvdelisle at gcc dot gnu dot org  2007-10-19 14:09 -------
Subject: Bug 33544

Author: jvdelisle
Date: Fri Oct 19 14:09:27 2007
New Revision: 129489

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=129489
Log:
2007-10-19  Jerry DeLisle  <jvdelisle@gcc.gnu.org>

        PR libfortran/33544
        * gfortran.dg/transfer_check_1.f90: Adjust options.

Modified:
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/gfortran.dg/transfer_check_1.f90


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33544

[Bug fortran/33544] [4.3 only] Warning in TRANSFER intrinsic should be made optional

[jvdelisle at gcc dot gnu dot org]

------- Comment #13 from jvdelisle at gcc dot gnu dot org  2007-10-19 14:10 -------
Fixed.


-- 

jvdelisle at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33544