[Bug fortran/98016] New: Host association problem

[Bug fortran/98016] New: Host association problem

[juergen.reuter at desy dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98016

            Bug ID: 98016
           Summary: Host association problem
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: juergen.reuter at desy dot de
  Target Milestone: ---

Discussed on c.l.f. today, the following value from host association is falsely
rejected by gfortran, persistent since at least v4.8.5:
program p
  real :: y(3)
  n=3
  y = func(0.)
  stop
contains
  function func(x) result (y)
    real y(n)
    y=x
  end function func
end program p

Rejected with message:
8.11:

    real y(n)
           1
Error: Variable 'n' cannot appear in the expression at (1)

[Bug fortran/98016] Host association problem

[tkoenig at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98016

Thomas Koenig <tkoenig at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2020-11-26
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |WAITING
                 CC|                            |tkoenig at gcc dot gnu.org

--- Comment #1 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
Seems to be fixed on current trunk:

$ cat bug.f90 
program p
  real :: y(3)
  n=3
  y = func(0.)
  stop
contains
  function func(x) result (y)
    real y(n)
    y=x
  end function func
end program p
$ gfortran bug.f90 
$ gfortran -v
Es werden eingebaute Spezifikationen verwendet.
COLLECT_GCC=gfortran
COLLECT_LTO_WRAPPER=/home/ig25/lib/gcc/x86_64-pc-linux-gnu/11.0.0/lto-wrapper
Ziel: x86_64-pc-linux-gnu
Konfiguriert mit: ../trunk/configure --prefix=/home/ig25
--enable-languages=c,c++,fortran
Thread-Modell: posix
Unterstützte LTO-Kompressionsalgorithmen: zlib
gcc-Version 11.0.0 20201112 (experimental) [master revision
d33bc98f5bc:79fa060941e:87b7d45e358e4df93b6a93b2e7a55b123ea76f5d] (GCC) 

Can you confirm that?  If so, we can commit a test case and close.

[Bug fortran/98016] Host association problem

[juergen.reuter at desy dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98016

--- Comment #2 from Jürgen Reuter <juergen.reuter at desy dot de> ---
(In reply to Thomas Koenig from comment #1)

> gcc-Version 11.0.0 20201112 (experimental) [master revision
> d33bc98f5bc:79fa060941e:87b7d45e358e4df93b6a93b2e7a55b123ea76f5d] (GCC) 
> 
> Can you confirm that?  If so, we can commit a test case and close.

Hm, no, just made git pull, and recompiled:
$ gfortran clf_20201126.f90 
clf_20201126.f90:8:16:

    8 |     dimension y(n)
      |                1
Error: Variable ‘n’ cannot appear in the expression at (1)
$ gfortran -v
Using built-in specs.
COLLECT_GCC=gfortran
COLLECT_LTO_WRAPPER=/scratch/reuter/local/libexec/gcc/x86_64-pc-linux-gnu/11.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../configure --prefix=/scratch/reuter/local/
--with-gmp=/scratch/reuter/local --with-mpfr=/scratch/reuter/local
--with-mpc=/scratch/reuter/local --disable-multilib
--enable-languages=c,c++,fortran,lto
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 11.0.0 20201126 (experimental) (GCC) 

Still present.

[Bug fortran/98016] Host association problem

[juergen.reuter at desy dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98016

--- Comment #3 from Jürgen Reuter <juergen.reuter at desy dot de> ---
Ah wait, the version I committed works, the original version from c.l.f. still
fails, because it uses implicit typing, so not real :: y(3)
and real :: y(n), but 
dimension y(3)

$ cat clf_20201126.f90
program is_it_valid
  dimension y(3)
  n=3
  y=func(0.)
  stop
contains
  function func(x) result (y)
    dimension y(n)
    y=x
  end function func
end program is_it_valid

[Bug fortran/98016] Host association problem

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98016

--- Comment #4 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
I confirm that the test in comment O compiles without any error.
However if I replace

    real y(n)

with

    dimension y(n)

I get the error

Error: Variable 'n' cannot appear in the expression at (1)

[Bug fortran/98016] Host association problem

[kargl at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98016

--- Comment #5 from kargl at gcc dot gnu.org ---
Index: gcc/gcc/fortran/expr.c
===================================================================
--- gcc/gcc/fortran/expr.c      (revision 280157)
+++ gcc/gcc/fortran/expr.c      (working copy)
@@ -3380,24 +3382,41 @@ check_restricted (gfc_expr *e)
         This mechanism also does the same for the specification expressions
         of array-valued functions.  */
       if (e->error
-           || sym->attr.in_common
-           || sym->attr.use_assoc
-           || sym->attr.dummy
-           || sym->attr.implied_index
-           || sym->attr.flavor == FL_PARAMETER
-           || is_parent_of_current_ns (sym->ns)
-           || (sym->ns->proc_name != NULL
-                 && sym->ns->proc_name->attr.flavor == FL_MODULE)
-           || (gfc_is_formal_arg () && (sym->ns == gfc_current_ns)))
+         || sym->attr.in_common
+         || sym->attr.use_assoc
+         || sym->attr.dummy
+         || sym->attr.implied_index
+         || sym->attr.flavor == FL_PARAMETER
+         || is_parent_of_current_ns (sym->ns)
+         || (sym->ns->proc_name != NULL
+             && sym->ns->proc_name->attr.flavor == FL_MODULE)
+         || (gfc_is_formal_arg () && (sym->ns == gfc_current_ns)))
        {
          t = true;
          break;
        }

-      gfc_error ("Variable %qs cannot appear in the expression at %L",
-                sym->name, &e->where);
-      /* Prevent a repetition of the error.  */
-      e->error = 1;
+      for (gfc_namespace *ns = sym->ns->parent; ns; ns = ns->parent)
+       if (sym->ns == ns)
+         {
+           t = true;
+           break;
+         }
+
+      for (gfc_namespace *ns = sym->ns->contained->parent; ns; ns =
ns->parent)
+       if (sym->ns == ns)
+         {
+           t = true;
+           break;
+         }
+
+      if (!t)
+       {
+         gfc_error ("Variable %qs cannot appear in the expression at %L",
+                    sym->name, &e->where);
+         /* Prevent a repetition of the error.  */
+         e->error = 1;
+       }
       break;

     case EXPR_NULL:

[Bug fortran/98016] Host association problem

[pault at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98016

Paul Thomas <pault at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |pault at gcc dot gnu.org
           Assignee|unassigned at gcc dot gnu.org      |pault at gcc dot gnu.org
             Status|WAITING                     |NEW

--- Comment #6 from Paul Thomas <pault at gcc dot gnu.org> ---
Created attachment 49645
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=49645&action=edit
Fix for the PR

This fix is rather different to Steve's. It exploits the existing mechanism for
formal arguments. In this context, the function result is equivalent to formal
arguments.

It even regtests OK :-)

Unless there are objections, I will commit as 'obvious' after I fix the last of
the nits with PR83118 or, at least, towards the end of the week.

Cheers

Paul

[Bug fortran/98016] Host association problem

[drikosev at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98016

--- Comment #7 from Ev Drikos <drikosev at gmail dot com> ---
Created attachment 49659
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=49659&action=edit
attachment for pr98016-07

(In reply to Paul Thomas from comment #6)
> Created attachment 49645 [details]
> Fix for the PR
> 
> Unless there are objections, ...

Not an objection, rather just an observation:

1. This code is inside "resolve_symbol" and the
   following double declaration seems redundant:

   bool saved_specification_expr

   The reason I'm mentioning it is that I debugged
   the example with gcc-4.8 and the debugger makes
   this call:

   gfc_resolve_array_spec (sym->as, check_constant)

   So, the declaration below could be at the top of
   the function declarations like the code below

[Bug fortran/98016] Host association problem

[pault at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98016

--- Comment #8 from Paul Thomas <pault at gcc dot gnu.org> ---
(In reply to Ev Drikos from comment #7)
> Created attachment 49659 [details]
> attachment for pr98016-07
> 
> (In reply to Paul Thomas from comment #6)
> > Created attachment 49645 [details]
> > Fix for the PR
> > 
> > Unless there are objections, ...
> 
> Not an objection, rather just an observation:
> 
> 1. This code is inside "resolve_symbol" and the
>    following double declaration seems redundant:
> 
>    bool saved_specification_expr
> 
>    The reason I'm mentioning it is that I debugged
>    the example with gcc-4.8 and the debugger makes
>    this call:
> 
>    gfc_resolve_array_spec (sym->as, check_constant)
> 
>    So, the declaration below could be at the top of
>    the function declarations like the code below
Hi There,

The multiple declarations (5 in resolve.c) come about because of the
possibility of rather torturous recursion paths. I guess that we could replace
the boolean with a counter but this doesn't seem to be much of an improvement.

I am just now preparing for a commit this evening.

Thanks for the comment.

Paul

[Bug fortran/98016] Host association problem

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98016

--- Comment #9 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Paul Thomas <pault@gcc.gnu.org>:

https://gcc.gnu.org/g:7ae210d5db5eb96989b2f639e65678b5597e61f0

commit r11-5759-g7ae210d5db5eb96989b2f639e65678b5597e61f0
Author: Paul Thomas <pault@gcc.gnu.org>
Date:   Sat Dec 5 14:14:19 2020 +0000

    Fortran: flag formal argument before resolving an array spec [PR98016].

    2020-12-05  Paul Thomas  <pault@gcc.gnu.org>

    gcc/fortran
            PR fortran/98016
            * resolve.c (resolve_symbol): Set formal_arg_flag before
            resolving an array spec and restore value afterwards.

    gcc/testsuite/
            PR fortran/98016
            * gfortran.dg/pr98016.f90: New test.

[Bug fortran/98016] Host association problem

[pault at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98016

Paul Thomas <pault at gcc dot gnu.org> changed:

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

--- Comment #10 from Paul Thomas <pault at gcc dot gnu.org> ---
Fixed on master. Closing.

Thanks for posting it Juergen.

Paul