re PR fortran/48847 (Wrong "unused parameter" warning with interface block)

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.

From-SVN: r183916

gcc/fortran/ChangeLog

+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  Paul Thomas  <pault@gcc.gnu.org>
 
 	* trans-array.c (gfc_array_allocate): Zero memory for all class

gcc/fortran/trans-decl.c

@@ -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

gcc/testsuite/ChangeLog

+2012-02-05  Thomas König  <tkoenig@gcc.gnu.org>
+
+	PR fortran/48847
+	* gfortran.dg/warn_unused_dummy_argument_3.f90:  New test.
+
 2012-02-05  Paul Thomas  <pault@gcc.gnu.org>
 
 	PR fortran/52102

gcc/testsuite/gfortran.dg/warn_unused_dummy_argument_3.f90

+! { 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