From patchwork Sun Feb  5 10:12:01 2012
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Subject: [fortran] Fix PR 48847, bogus "unused parameter" warning
Date: Sun, 05 Feb 2012 00:12:01 -0000
From: Thomas Koenig <tkoenig@netcologne.de>
X-Patchwork-Id: 139619
Message-Id: <4F2E55F1.2070207@netcologne.de>
To: "fortran@gcc.gnu.org" <fortran@gcc.gnu.org>,
 gcc-patches <gcc-patches@gcc.gnu.org>

Hello world,

the attached, rather obvious patch fixed a bogus "unused parameter"
warning with procedure dummy arguments and warns about these if
they occur.

Regression-tested.  OK for trunk?  Or rather wait until 4.8?

	Thomas

2012-02-05  Thomas König  <tkoenig@gcc.gnu.org>

         PR fortran/48847
         * trans-decl.c:  Warn about unused dummy procedure arguments
         if -Wunused-dummy-argument is specified.  Suppress middle-end
         warnings about procedure arguments.

2012-02-05  Thomas König  <tkoenig@gcc.gnu.org>

         PR fortran/48847
         * gfortran.dg/warn_unused_dummy_argument_3.f90:  New test.
! { dg-do compile }
! { dg-options "-Wunused-dummy-argument -Wunused-parameter" }
! PR 48847 - we used to generate a warning for g(), and none for h()
program main
contains
  function f(g,h)
    interface
       real function g()
       end function g
    end interface
    interface
       real function h()  !  { dg-warning "Unused dummy argument" }
       end function h
    end interface
    real :: f
    f = g()
  end function f
end program main


Index: trans-decl.c
===================================================================
--- trans-decl.c	(Revision 183873)
+++ trans-decl.c	(Arbeitskopie)
@@ -4683,6 +4683,22 @@ generate_local_decl (gfc_symbol * sym)
 	  && sym->ts.type == BT_CHARACTER && sym->ts.is_c_interop
 	  && sym->ns->proc_name != NULL && sym->ns->proc_name->attr.is_bind_c)
 	gfc_conv_scalar_char_value (sym, NULL, NULL);
+
+      /* Unused procedure passed as dummy argument.  */
+      if (sym->attr.flavor == FL_PROCEDURE)
+	{
+	  if (!sym->attr.referenced)
+	    {
+	      if (gfc_option.warn_unused_dummy_argument)
+		gfc_warning ("Unused dummy argument '%s' at %L", sym->name,
+			     &sym->declared_at);	     
+	    }
+
+	  /* Silence bogus "unused parameter" warnings from the
+	     middle end.  */
+	  if (sym->backend_decl != NULL_TREE)
+		TREE_NO_WARNING(sym->backend_decl) = 1;
+	}
     }
 
   /* Make sure we convert the types of the derived types from iso_c_binding