[PATCH] PR fortran/82796 -- common entity in equivalence in pure routine

[PATCH] PR fortran/82796 -- common entity in equivalence in pure routine

[Steve Kargl]

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The attached patch fixes a regression where gfortran was
issuing an error for an entity in a common block within
a module when it appears in equivalence, and the entity
*is not* use associated in a pure subprogram.  OK to 
commit?


2017-11-01  Steven G. Kargl  <kargl@gcc.gnu.org>

	PR fortran/82796
	* resolve.c (resolve_equivalence): An entity in a common block within
 	a module cannot appear in an equivalence statement if the entity is
	with a pure procedure.

2017-11-01  Steven G. Kargl  <kargl@gcc.gnu.org>

	PR fortran/82796
	* gfortran.dg/equiv_pure.f90: New test.

-- 
Steve

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Index: gcc/fortran/resolve.c
===================================================================
--- gcc/fortran/resolve.c	(revision 254241)
+++ gcc/fortran/resolve.c	(working copy)
@@ -15936,9 +15936,22 @@ resolve_equivalence (gfc_equiv *eq)
 	  && sym->ns->proc_name->attr.pure
 	  && sym->attr.in_common)
 	{
-	  gfc_error ("Common block member %qs at %L cannot be an EQUIVALENCE "
-		     "object in the pure procedure %qs",
-		     sym->name, &e->where, sym->ns->proc_name->name);
+	  /* Need to check for symbols that may have entered the pure
+	     procedure via a USE statement.  */
+	  bool saw_sym = false;
+	  if (sym->ns->use_stmts)
+	    {
+	      gfc_use_rename *r;
+	      for (r = sym->ns->use_stmts->rename; r; r = r->next)
+		if (strcmp(r->use_name, sym->name) == 0) saw_sym = true; 
+	    }
+	  else
+	    saw_sym = true;
+
+	  if (saw_sym)
+	    gfc_error ("COMMON block member %qs at %L cannot be an "
+		       "EQUIVALENCE object in the pure procedure %qs",
+		       sym->name, &e->where, sym->ns->proc_name->name);
 	  break;
 	}
 
Index: gcc/testsuite/gfortran.dg/equiv_pure.f90
===================================================================
--- gcc/testsuite/gfortran.dg/equiv_pure.f90	(nonexistent)
+++ gcc/testsuite/gfortran.dg/equiv_pure.f90	(working copy)
@@ -0,0 +1,50 @@
+! { dg-do compile }
+module eq
+   implicit none
+   integer :: n1, n2
+   integer, dimension(2) :: a
+   equivalence (a(1), n1)
+   equivalence (a(2), n2)
+   common /a/ a
+end module eq
+
+module m
+   use eq
+   implicit none
+   type, public :: t
+     integer :: i
+   end type t
+end module m
+
+module p
+   implicit none
+   contains
+   pure integer function d(h)
+     use m
+     implicit none
+     integer, intent(in) :: h
+     d = h
+   end function
+end module p
+
+module q
+   implicit none
+   contains
+   pure integer function d(h)
+     use m, only : t
+     implicit none
+     integer, intent(in) :: h
+     d = h
+   end function
+end module q
+
+module r
+   implicit none
+   contains
+   pure integer function d(h)
+     use m, only : a          ! { dg-error "cannot be an EQUIVALENCE object" }
+     implicit none
+     integer, intent(in) :: h
+     d = h
+   end function
+end module r

Re: [PATCH] PR fortran/82796 -- common entity in equivalence in pure routine

[Paul Richard Thomas]

Hi Steve,

I read the correspondence on clf and your earlier posting here. With
those in mind, the patch looks to be OK to commit.

Thanks

Paul

On 2 November 2017 at 01:09, Steve Kargl
<sgk@troutmask.apl.washington.edu> wrote:
> The attached patch fixes a regression where gfortran was
> issuing an error for an entity in a common block within
> a module when it appears in equivalence, and the entity
> *is not* use associated in a pure subprogram.  OK to
> commit?
>
>
> 2017-11-01  Steven G. Kargl  <kargl@gcc.gnu.org>
>
>         PR fortran/82796
>         * resolve.c (resolve_equivalence): An entity in a common block within
>         a module cannot appear in an equivalence statement if the entity is
>         with a pure procedure.
>
> 2017-11-01  Steven G. Kargl  <kargl@gcc.gnu.org>
>
>         PR fortran/82796
>         * gfortran.dg/equiv_pure.f90: New test.
>
> --
> Steve



-- 
"If you can't explain it simply, you don't understand it well enough"
- Albert Einstein

Re: [PATCH] PR fortran/82796 -- common entity in equivalence in pure routine

[Steve Kargl]

On Thu, Nov 02, 2017 at 11:48:36AM +0000, Paul Richard Thomas wrote:
> Hi Steve,
> 
> I read the correspondence on clf and your earlier posting here. With
> those in mind, the patch looks to be OK to commit.
> 
> Thanks
> 

Thanks.  The c.l.f posting is addressing a different issue.
This patch simply fixes a regression that was introduced
ages ago.  Here, one needs the combination of COMMON,
EQUIVALENCE, and a PURE subprogram.  From F2003, it comes
from C1272.  The problem is that gfortran was issuing an
error when it should not have.  The patch suppresses that
error.

-- 
Steve