re PR fortran/66993 (Spurious ambiguous symbol error with submodules)

2015-09-10  Paul Thomas  <pault@gcc.gnu.org>

	PR fortran/66993
	* module.c (read_module): If a symtree exists and the symbol has
	been associated in a submodule from a parent (sub)module, attach
	the symbol to a 'unique symtree' and the new symbol to the
	existing symtree.

2015-09-10  Paul Thomas  <pault@gcc.gnu.org>

	PR fortran/66993
	* gfortran.dg/submodule_11.f08: New test.

From-SVN: r227648

gcc/fortran/ChangeLog

+2015-09-10  Paul Thomas  <pault@gcc.gnu.org>
+
+	PR fortran/66993
+	* module.c (read_module): If a symtree exists and the symbol has
+	been associated in a submodule from a parent (sub)module, attach
+	the symbol to a 'unique symtree' and the new symbol to the
+	existing symtree.
+
 2015-09-04  Francois-Xavier Coudert  <fxcoudert@gcc.gnu.org>
 
 	* intrinsic.h (gfc_simplify_mvbits): Remove.

gcc/fortran/module.c

@@ -5132,7 +5132,8 @@ read_module (void)
 
 	  st = gfc_find_symtree (gfc_current_ns->sym_root, p);
 
-	  if (st != NULL)
+	  if (st != NULL
+	      && !(st->n.sym && st->n.sym->attr.used_in_submodule))
 	    {
 	      /* Check for ambiguous symbols.  */
 	      if (check_for_ambiguous (st, info))
@@ -5142,14 +5143,23 @@ read_module (void)
 	    }
 	  else
 	    {
-	      st = gfc_find_symtree (gfc_current_ns->sym_root, name);
-
-	      /* Create a symtree node in the current namespace for this
-		 symbol.  */
-	      st = check_unique_name (p)
-		   ? gfc_get_unique_symtree (gfc_current_ns)
-		   : gfc_new_symtree (&gfc_current_ns->sym_root, p);
-	      st->ambiguous = ambiguous;
+	      if (st)
+		{
+		  /* This symbol is host associated from a module in a
+		     submodule.  Hide it with a unique symtree.  */
+		  gfc_symtree *s = gfc_get_unique_symtree (gfc_current_ns);
+		  s->n.sym = st->n.sym;
+		  st->n.sym = NULL;
+		}
+	      else
+		{
+		  /* Create a symtree node in the current namespace for this
+		     symbol.  */
+		  st = check_unique_name (p)
+		       ? gfc_get_unique_symtree (gfc_current_ns)
+		       : gfc_new_symtree (&gfc_current_ns->sym_root, p);
+		  st->ambiguous = ambiguous;
+		}
 
 	      sym = info->u.rsym.sym;
 

gcc/testsuite/ChangeLog

+2015-09-10  Paul Thomas  <pault@gcc.gnu.org>
+
+	PR fortran/66993
+	* gfortran.dg/submodule_11.f08: New test.
+
 2015-09-10  Oleg Endo  <olegendo@gcc.gnu.org>
 
 	PR target/67506
@@ -476,7 +481,7 @@
 
 2015-08-28  Andrew Bennett  <andrew.bennett@imgtec.com>
 
-	* gcc.target/mips/madd-8.c: Add lo register to clobber list. 
+	* gcc.target/mips/madd-8.c: Add lo register to clobber list.
 	* gcc.target/mips/msub-8.c: Ditto
 
 2015-08-27  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>

gcc/testsuite/gfortran.dg/submodule_11.f08

+! { dg-do run }
+! Test the fix for PR66993, in which the use associated version of 'i'
+! was incorrectly determined to be ambiguous with the 'i', host associated
+! in submodule 'sm' from the module 'm'. The principle has been tested with
+! the function 'time_two' in addition.
+!
+! Contributed by Mikael Morin  <mikael.morin@sfr.fr>
+!
+module m
+  integer, parameter :: i = -1
+  interface
+    module subroutine show_i
+    end subroutine show_i
+  end interface
+contains
+  integer function times_two (arg)
+    integer :: arg
+    times_two = -2*arg
+  end function
+end module m
+
+module n
+  integer, parameter :: i = 2
+contains
+  integer function times_two (arg)
+    integer :: arg
+    times_two = 2*arg
+  end function
+end module n
+
+submodule (m) sm
+  use n
+contains
+  module subroutine show_i
+    if (i .ne. 2) call abort
+    if (times_two (i) .ne. 4) call abort
+  end subroutine show_i
+end submodule sm
+
+program p
+  use m
+  call show_i
+  if (i .ne. -1) call abort
+  if (times_two (i) .ne. 2) call abort
+end program