re PR fortran/52668 (Incorrect unused warning for USE associating variable in common block)

2012-04-06  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/52668
	* module.c:  Only mark symbols as use_only if they have been
	imported via an only list.

2012-04-06  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/52668
	* gfortran.dg/use_only_6.f90: New test.

From-SVN: r186199

gcc/fortran/ChangeLog

+2012-04-06  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+	PR fortran/52668
+	* module.c:  Only mark symbols as use_only if they have been
+	imported via an only list.
+
 2012-03-28  Paul Thomas  <pault@gcc.gnu.org>
 	Tobias Burnus  <burnus@gcc.gnu.org>
 
@@ -5,7 +11,7 @@
 	* match.c (gfc_match_allocate, gfc_match_deallocate): Change
 	"not.. or" to "neither.. nor".
 	* parse.c (decode_specification_statement): Correct error in
-	chpice of matching function for "allocatable". 
+	chpice of matching function for "allocatable".
 
 2012-03-23  Janne Blomqvist  <jb@gcc.gnu.org>
 

gcc/fortran/module.c

@@ -4389,9 +4389,24 @@ load_needed (pointer_info *p)
 
   /* Mark as only or rename for later diagnosis for explicitly imported
      but not used warnings; don't mark internal symbols such as __vtab,
-     __def_init etc.  */
+     __def_init etc. Only mark them if they have been explicitly loaded.  */
+
   if (only_flag && sym->name[0] != '_' && sym->name[1] != '_')
-    sym->attr.use_only = 1;
+    {
+      gfc_use_rename *u;
+
+      /* Search the use/rename list for the variable; if the variable is
+	 found, mark it.  */
+      for (u = gfc_rename_list; u; u = u->next)
+	{
+	  if (strcmp (u->use_name, sym->name) == 0)
+	    {
+	      sym->attr.use_only = 1;
+	      break;
+	    }
+	}
+    }
+
   if (p->u.rsym.renamed)
     sym->attr.use_rename = 1;
 

gcc/testsuite/ChangeLog

+2012-04-06  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+	PR fortran/52668
+	* gfortran.dg/use_only_6.f90: New test.
+
+2012-04-06  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+	PR fortran/52668
+	* gfortran.dg/use_only_6.f90: New test.
 2012-04-06  Mike Stump  <mikestump@comcast.net>
 
 	PR testsuite/50722

gcc/testsuite/gfortran.dg/use_only_6.f90

+! { dg-do compile }
+! PR 52668 - there used to be a bogus warning about not using b.
+! Original test case by Arnaud Desitter.
+module mm
+  integer :: a, b
+  common /mm1/ a, b
+end module mm
+
+subroutine aa()
+  use mm, only: a
+  implicit none
+  a = 1
+end subroutine aa