re PR fortran/54107 ([F03] Memory hog with abstract interface)

fortran/
	PR fortran/54107
	* trans-types.c (gfc_get_function_type): Change a NULL backend_decl
	to error_mark_node on entry.  Detect recursive types.  Build a variadic
	procedure type if the type is recursive.  Restore the initial
	backend_decl.

testsuite/
	PR fortran/54107
	* gfortran.dg/recursive_interface_2.f90: New test.

From-SVN: r195890

gcc/fortran/ChangeLog

+2013-02-08  Mikael Morin  <mikael@gcc.gnu.org>
+
+	PR fortran/54107
+	* trans-types.c (gfc_get_function_type): Change a NULL backend_decl
+	to error_mark_node on entry.  Detect recursive types.  Build a variadic
+	procedure type if the type is recursive.  Restore the initial
+	backend_decl.
+
 2013-02-07  Tobias Burnus  <burnus@net-b.de>
 
 	PR fortran/54339 

gcc/fortran/trans-types.c

@@ -2711,19 +2711,23 @@ gfc_get_function_type (gfc_symbol * sym)
   gfc_formal_arglist *f;
   gfc_symbol *arg;
   int alternate_return;
-  bool is_varargs = true;
+  bool is_varargs = true, recursive_type = false;
 
   /* Make sure this symbol is a function, a subroutine or the main
      program.  */
   gcc_assert (sym->attr.flavor == FL_PROCEDURE
 	      || sym->attr.flavor == FL_PROGRAM);
 
-  if (sym->backend_decl)
-    {
-      if (sym->attr.proc_pointer)
-	return TREE_TYPE (TREE_TYPE (sym->backend_decl));
-      return TREE_TYPE (sym->backend_decl);
-    }
+  /* To avoid recursing infinitely on recursive types, we use error_mark_node
+     so that they can be detected here and handled further down.  */
+  if (sym->backend_decl == NULL)
+    sym->backend_decl = error_mark_node;
+  else if (sym->backend_decl == error_mark_node)
+    recursive_type = true;
+  else if (sym->attr.proc_pointer)
+    return TREE_TYPE (TREE_TYPE (sym->backend_decl));
+  else
+    return TREE_TYPE (sym->backend_decl);
 
   alternate_return = 0;
   typelist = NULL;
@@ -2775,6 +2779,13 @@ gfc_get_function_type (gfc_symbol * sym)
 
 	  if (arg->attr.flavor == FL_PROCEDURE)
 	    {
+	      /* We don't know in the general case which argument causes
+		 recursion.  But we know that it is a procedure.  So we give up
+		 creating the procedure argument type list at the first
+		 procedure argument.  */
+	      if (recursive_type)
+	        goto arg_type_list_done;
+
 	      type = gfc_get_function_type (arg);
 	      type = build_pointer_type (type);
 	    }
@@ -2828,6 +2839,11 @@ gfc_get_function_type (gfc_symbol * sym)
       || sym->attr.if_source != IFSRC_UNKNOWN)
     is_varargs = false;
 
+arg_type_list_done:
+
+  if (!recursive_type && sym->backend_decl == error_mark_node)
+    sym->backend_decl = NULL_TREE;
+
   if (alternate_return)
     type = integer_type_node;
   else if (!sym->attr.function || gfc_return_by_reference (sym))
@@ -2865,7 +2881,7 @@ gfc_get_function_type (gfc_symbol * sym)
   else
     type = gfc_sym_type (sym);
 
-  if (is_varargs)
+  if (is_varargs || recursive_type)
     type = build_varargs_function_type_vec (type, typelist);
   else
     type = build_function_type_vec (type, typelist);

gcc/testsuite/ChangeLog

+2013-02-08  Mikael Morin  <mikael@gcc.gnu.org>
+
+	PR fortran/54107
+	* gfortran.dg/recursive_interface_2.f90: New test.
+
 2013-02-08  Jakub Jelinek  <jakub@redhat.com>
 
 	PR tree-optimization/56250

gcc/testsuite/gfortran.dg/recursive_interface_2.f90

+! { dg-do compile }
+!
+! PR fortran/54107
+! Recursive interfaces used to lead to an infinite recursion during
+! translation.
+
+module m
+ contains
+  subroutine foo (arg) 
+    procedure(foo) :: arg 
+  end subroutine 
+  function foo2 (arg) result(r)
+    procedure(foo2) :: arg
+    procedure(foo2), pointer :: r
+  end function 
+  subroutine bar (arg) 
+    procedure(baz) :: arg 
+  end subroutine 
+  subroutine baz (arg) 
+    procedure(bar) :: arg 
+  end subroutine 
+end module m