[Bug fortran/34547] New: NULL(): Fortran 2003 changes, accepts invalid, ICE on invalid

[Bug fortran/34547] New: NULL(): Fortran 2003 changes, accepts invalid, ICE on invalid

[burnus at gcc dot gnu dot org]

The following gives an ICE:

  print *, NULL()

The program is invalid as the MOLD of NULL([MOLD]) is required in this context
(see F2003, 13.7.88): "If MOLD is absent, the characteristics of the result are
determined by the entity with which the reference is associated. See Table
13.1. MOLD shall not be absent in any other context."

Table 13.1 contains: rhs of pointer assignment; initialization of an object in
a declaration; default component init; struct constr; actual argument; in a
DATA statement.

Likewise for Fortran 97, see 7.1.4.1 around Table 7.2 - and 13.14.79.

---------------------

 integer, allocatable :: i(:)
 print *, NULL(i)

Prints: Error: 'mold' argument of 'null' intrinsic at (1) must be a POINTER.

While Fortran 97 has: "MOLD shall be a pointer and may be of any type."
Fortran 2003 has: "MOLD shall be a pointer or allocatable. It may be of any
type or may be a procedure pointer".

----

NULL as actual argument:

  external foo
  call foo(NULL())

is invalid without a MOLD as (F2003, similar in F97):
"If any type parameters of the contextual entity are deferred, those type
parameters of the result are deferred. If any type parameters of the contextual
entity are assumed, MOLD shall be present.
If the context of the reference to NULL is an actual argument to a generic
procedure, MOLD shall be present if the type, type parameters, or rank is
required to resolve the generic reference. MOLD shall also be present if the
reference appears as an actual argument corresponding to a dummy argument with
assumed character length."

---

Someone could also check whether we do the right thing for:
http://groups.google.com/group/comp.lang.fortran/browse_thread/thread/5a1e0cc2c7eb95cc/


-- 
           Summary: NULL(): Fortran 2003 changes, accepts invalid, ICE on
                    invalid
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Keywords: ice-on-invalid-code, rejects-valid, accepts-invalid,
                    diagnostic
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: burnus at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34547

[Bug fortran/34547] NULL(): Fortran 2003 changes, accepts invalid, ICE on invalid

[burnus at gcc dot gnu dot org]

------- Comment #1 from burnus at gcc dot gnu dot org  2008-01-16 21:20 -------
See also
http://groups.google.com/group/comp.lang.fortran/browse_thread/thread/f014195ccf7b93e6/
for some other possible diagnostic issues.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34547

[Bug fortran/34547] NULL(): Fortran 2003 changes, accepts invalid, ICE on invalid

[fxcoudert at gcc dot gnu dot org]

-- 

fxcoudert at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2009-03-29 08:19:05
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34547

[Bug fortran/34547] NULL(): Fortran 2003 changes, accepts invalid, ICE on invalid

[mikael at gcc dot gnu dot org]

------- Comment #2 from mikael at gcc dot gnu dot org  2010-05-31 17:36 -------
*** Bug 44349 has been marked as a duplicate of this bug. ***


-- 

mikael at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |zeccav at gmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34547

[Bug fortran/34547] NULL(): Fortran 2003 changes, accepts invalid, ICE on invalid

[dominiq at lps dot ens.fr]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34547

--- Comment #6 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
> However, one should go through the lengthy, convoluted thread at
>
> http://groups.google.com/group/comp.lang.fortran/browse_thread/thread/f014195ccf7b93e6/
>to check whether it contains some still-unfixed issues.

The thread is too convoluted for me. Is this still an issue?

[Bug fortran/34547] NULL(): Fortran 2003 changes, accepts invalid, ICE on invalid

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34547

--- Comment #5 from Tobias Burnus <burnus at gcc dot gnu.org> 2011-09-14 07:19:03 UTC ---
The patch fixes the issues of comment 0.

However, one should go through the lengthy, convoluted thread at
 
http://groups.google.com/group/comp.lang.fortran/browse_thread/thread/f014195ccf7b93e6/
to check whether it contains some still-unfixed issues.

[Bug fortran/34547] NULL(): Fortran 2003 changes, accepts invalid, ICE on invalid

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34547

--- Comment #3 from Tobias Burnus <burnus at gcc dot gnu.org> 2011-09-14 06:26:13 UTC ---
Author: burnus
Date: Wed Sep 14 06:26:07 2011
New Revision: 178841

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=178841
Log:
2011-09-14  Tobias Burnus  <burnus@net-b.de>

        PR fortran/34547
        PR fortran/50375
        * check.c (gfc_check_null): Allow allocatables as MOLD to NULL.
        * resolve.c (resolve_transfer): Reject NULL without MOLD.
        * interface.c (gfc_procedure_use): Reject NULL without MOLD
        if no explicit interface is known.
        (gfc_search_interface): Reject NULL without MOLD if it would
        lead to ambiguity.

2011-09-14  Tobias Burnus  <burnus@net-b.de>

        PR fortran/34547
        PR fortran/50375
        * gfortran.dg/null_5.f90: New.
        * gfortran.dg/null_6.f90: New.


Modified:
    trunk/gcc/fortran/ChangeLog
    trunk/gcc/fortran/check.c
    trunk/gcc/fortran/interface.c
    trunk/gcc/fortran/resolve.c
    trunk/gcc/testsuite/ChangeLog

[Bug fortran/34547] NULL(): Fortran 2003 changes, accepts invalid, ICE on invalid

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34547

--- Comment #4 from Tobias Burnus <burnus at gcc dot gnu.org> 2011-09-14 06:27:30 UTC ---
Author: burnus
Date: Wed Sep 14 06:27:25 2011
New Revision: 178842

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=178842
Log:
Really add:

2011-09-14  Tobias Burnus  <burnus@net-b.de>

        PR fortran/34547
        PR fortran/50375
        * gfortran.dg/null_5.f90: New.
        * gfortran.dg/null_6.f90: New.


Added:
    trunk/gcc/testsuite/gfortran.dg/null_5.f90
    trunk/gcc/testsuite/gfortran.dg/null_6.f90