[Bug fortran/30746] New: 50th Anniversary Bug - scoping error

[Bug fortran/30746] New: 50th Anniversary Bug - scoping error

[pault at gcc dot gnu dot org]

Malcolm Cohen's talk to the BCS 50th anniversary of FORTRAN meeting has this
example:

MODULE m
  REAL :: x(3) = (/ 1.5, 2.5, 3.5 /)
CONTAINS
  SUBROUTINE s
    CALL inner
  CONTAINS
    SUBROUTINE inner
      PRINT *,x(7) ! This is not an error!
    END SUBROUTINE
    FUNCTION x(n)
      x = REAL(n)**n
    END FUNCTION
  END SUBROUTINE
END MODULE
  use m
  call s()
end

to which, gfortran incorrectly returns

      PRINT *,x(7) ! This is not an error!
               1
Warning: Array reference at (1) is out of bounds

unless subroutine inner and function x are interchanged.

Paul


-- 
           Summary: 50th Anniversary Bug - scoping error
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pault at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30746

[Bug fortran/30746] 50th Anniversary Bug - scoping error

[pault at gcc dot gnu dot org]

------- Comment #1 from pault at gcc dot gnu dot org  2007-02-09 15:19 -------
Sorry, I forgot to add the keyword.


-- 

pault at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |rejects-valid


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30746

[Bug fortran/30746] 50th Anniversary Bug - scoping error

[fxcoudert at gcc dot gnu dot org]

------- Comment #2 from fxcoudert at gcc dot gnu dot org  2007-02-09 17:06 -------
Confirmed. Sun and g95 also reject it, while Intel and Portland accept it.


-- 

fxcoudert at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
      Known to fail|                            |4.3.0 4.2.0 4.1.2
   Last reconfirmed|0000-00-00 00:00:00         |2007-02-09 17:06:57
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30746

[Bug fortran/30746] 50th Anniversary Bug - Forward reference to contained function

[pault at gcc dot gnu dot org]

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------- Comment #3 from pault at gcc dot gnu dot org  2007-05-10 09:11 -------
The patch below does the job. Before submitting, I want to check how much the
compile time is hit.  If it is a lot, I will try to streamline detection of the
wrong host association.

Paul

Index: gcc/fortran/gfortran.h
===================================================================
*** gcc/fortran/gfortran.h      (révision 124567)
--- gcc/fortran/gfortran.h      (copie de travail)
*************** bool gfc_check_access (gfc_access, gfc_a
*** 2160,2165 ****
--- 2160,2166 ----
  /* primary.c */
  symbol_attribute gfc_variable_attr (gfc_expr *, gfc_typespec *);
  symbol_attribute gfc_expr_attr (gfc_expr *);
+ match gfc_match_rvalue (gfc_expr **);

  /* trans.c */
  void gfc_generate_code (gfc_namespace *);
Index: gcc/fortran/resolve.c
===================================================================
*** gcc/fortran/resolve.c       (révision 124567)
--- gcc/fortran/resolve.c       (copie de travail)
*************** resolve_variable (gfc_expr *e)
*** 3204,3209 ****
--- 3204,3274 ----
  }


+ /* Checks to see that the correct symbol has been host associated.
+    The only situation where this arises is that in which a contained
+    function is parsed after the host association is made.  Therefore,
+    on detecting this, the line is rematched, having got rid of the
+    existing references and actual_arg_list.  */
+ static bool
+ check_host_association (gfc_expr *e)
+ {
+   gfc_symbol *sym, *old_sym;
+   locus temp_locus;
+   gfc_expr *expr;
+ 
+   old_sym = e->symtree->n.sym;
+   if (!old_sym->attr.use_assoc && old_sym->ns != gfc_current_ns)
+     {
+       gfc_find_symbol (old_sym->name, gfc_current_ns->parent, 1, &sym);
+       if (sym && old_sym != sym && sym->attr.flavor == FL_PROCEDURE)
+       {
+         temp_locus = gfc_current_locus;
+         gfc_current_locus = e->where;
+ 
+         gfc_buffer_error (1);
+ 
+         gfc_free_ref_list (e->ref);
+         e->ref = NULL;
+ 
+         if (e->expr_type == EXPR_FUNCTION)
+           {
+             gfc_free_actual_arglist (e->value.function.actual);
+             e->value.function.actual = NULL;
+           }
+ 
+         if (e->shape != NULL)
+           {
+             for (n = 0; n < e->rank; n++)
+               mpz_clear (e->shape[n]);
+ 
+             gfc_free (e->shape);
+           }
+ 
+ 
+         gfc_match_rvalue (&expr);
+ 
+         gcc_assert (expr && sym == expr->symtree->n.sym);
+ 
+         *e = *expr;
+         gfc_free (expr);
+         sym->refs++;
+ 
+         /* Free the old symbol.  */
+         if (old_sym->ns->proc_name->attr.flavor != FL_MODULE)
+           {
+             old_sym->refs--;
+             if (old_sym->refs == 0)
+               gfc_free_symbol (old_sym);
+           }
+ 
+         gfc_current_locus = temp_locus;
+       }
+     }
+ 
+   return e->expr_type == EXPR_FUNCTION;
+ }
+ 
+ 
  /* Resolve an expression.  That is, make sure that types of operands agree
     with their operators, intrinsic operators are converted to function calls
     for overloaded types and unresolved function references are resolved.  */
*************** gfc_resolve_expr (gfc_expr *e)
*** 3223,3235 ****
        break;

      case EXPR_FUNCTION:
-       t = resolve_function (e);
-       break;
- 
      case EXPR_VARIABLE:
!       t = resolve_variable (e);
!       if (t == SUCCESS)
!       expression_rank (e);
        break;

      case EXPR_SUBSTRING:
--- 3288,3303 ----
        break;

      case EXPR_FUNCTION:
      case EXPR_VARIABLE:
! 
!       if (check_host_association (e))
!       t = resolve_function (e);
!       else
!       {
!         t = resolve_variable (e);
!         if (t == SUCCESS)
!           expression_rank (e);
!       }
        break;

      case EXPR_SUBSTRING:
Index: gcc/fortran/match.h
===================================================================
*** gcc/fortran/match.h (révision 124567)
--- gcc/fortran/match.h (copie de travail)
*************** match gfc_match_volatile (void);
*** 153,159 ****

  /* primary.c */
  match gfc_match_structure_constructor (gfc_symbol *, gfc_expr **);
- match gfc_match_rvalue (gfc_expr **);
  match gfc_match_variable (gfc_expr **, int);
  match gfc_match_equiv_variable (gfc_expr **);
  match gfc_match_actual_arglist (int, gfc_actual_arglist **);
--- 153,158 ----
Index: gcc/testsuite/gfortran.dg/host_assoc_function_1.f90
===================================================================
*** gcc/testsuite/gfortran.dg/host_assoc_function_1.f90 (révision 0)
--- gcc/testsuite/gfortran.dg/host_assoc_function_1.f90 (révision 0)
***************
*** 0 ****
--- 1,26 ----
+ ! { dg-do run }
+ ! Tests the fix for the bug PR30746, in which the reference to 'x'
+ ! in 'inner' wrongly host-associated with the variable 'x' rather
+ ! than the function.
+ !
+ ! Testcase is due to Malcolm Cohen, NAG.
+ !
+ MODULE m
+   REAL :: x(3) = (/ 1.5, 2.5, 3.5 /)
+ CONTAINS
+   SUBROUTINE s
+     CALL inner
+   CONTAINS
+     SUBROUTINE inner
+       i = 7
+       if (x(7) .ne. real (7)**7) call abort ()
+     END SUBROUTINE
+     FUNCTION x(n)
+       x = REAL(n)**n
+     END FUNCTION
+   END SUBROUTINE
+ END MODULE
+   use m
+   call s()
+ end
+ ! { dg-final { cleanup-modules "m" } }



-- 

pault at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |pault at gcc dot gnu dot org
                   |dot org                     |
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2007-02-09 17:06:57         |2007-05-10 09:11:58
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30746

[Bug fortran/30746] 50th Anniversary Bug - Forward reference to contained function

[pault at gcc dot gnu dot org]

------- Comment #4 from pault at gcc dot gnu dot org  2007-05-10 12:19 -------
(In reply to comment #3)
> The patch below does the job.

Not quite - apart from 'n' not being declared, this patch causes a couple of
regressions.  These are easily fixed.  However, if the function x has a
different number of arguments to the rank of variable 'x', an error ensues. 
This is going to require a bit more work but it is promising.

Paul


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30746

[Bug fortran/30746] 50th Anniversary Bug - Forward reference to contained function

[patchapp at dberlin dot org]

------- Comment #5 from patchapp at dberlin dot org  2007-05-10 21:10 -------
Subject: Bug number PR30746

A patch for this bug has been added to the patch tracker.
The mailing list url for the patch is
http://gcc.gnu.org/ml/gcc-patches/2007-05/msg00746.html


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30746

[Bug fortran/30746] 50th Anniversary Bug - Forward reference to contained function

[pault at gcc dot gnu dot org]

------- Comment #6 from pault at gcc dot gnu dot org  2007-05-12 07:19 -------
Subject: Bug 30746

Author: pault
Date: Sat May 12 06:19:43 2007
New Revision: 124633

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=124633
Log:
2007-05-12  Paul Thomas  <pault@gcc.gnu.org>

        PR fortran/30746
        * resolve.c (check_host_association): New function that detects
        incorrect host association and corrects it.
        (gfc_resolve_expr): Call the new function for variables and
        functions.
        * match.h : Remove prototype for gfc_match_rvalue.
        * gfortran.h : Add prototype for gfc_match_rvalue.

2007-05-12  Paul Thomas  <pault@gcc.gnu.org>

        PR fortran/30746
        * gfortran.dg/host_assoc_function_1.f90: New test.

Added:
    trunk/gcc/testsuite/gfortran.dg/host_assoc_function_1.f90
    trunk/gcc/testsuite/gfortran.dg/recursive_reference_1.f90
Modified:
    trunk/gcc/fortran/ChangeLog
    trunk/gcc/fortran/gfortran.h
    trunk/gcc/fortran/match.h
    trunk/gcc/fortran/resolve.c
    trunk/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30746

[Bug fortran/30746] 50th Anniversary Bug - Forward reference to contained function

[pault at gcc dot gnu dot org]

------- Comment #7 from pault at gcc dot gnu dot org  2007-05-12 07:22 -------
Fixed on trunk.

Please note that recursive_reference_1.f90 was replaced, accidentally, by an
identical copy of itself.

Paul


-- 

pault at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30746