re PR c++/6749 (infinite loop with inheritance of abstract classes)

PR c++/6749
	* pt.c (instantiate_pending_templates): Add int parameter.  Don't
	return anything.
	* cp-tree.h (instantiate_pending_templates): Adjust prototype.
	* decl2.c (finish_file): Adjust call to
	instantiate_pending_templates.

	* g++.dg/template/vtable2.C: New test.

From-SVN: r86054

gcc/cp/ChangeLog

@@ -1,3 +1,12 @@
+2004-08-16  Kriang Lerdsuwanakij  <lerdsuwa@users.sourceforge.net>
+
+	PR c++/6749
+	* pt.c (instantiate_pending_templates): Add int parameter.  Don't
+	return anything.
+	* cp-tree.h (instantiate_pending_templates): Adjust prototype.
+	* decl2.c (finish_file): Adjust call to
+	instantiate_pending_templates.
+
 2004-08-15  Roger Sayle  <roger@eyesopen.com>
 
 	* call.c (build_vfield_ref, build_call, build_conditional_expr,

gcc/cp/cp-tree.h

@@ -3990,7 +3990,7 @@ extern void maybe_process_partial_specialization (tree);
 extern void maybe_check_template_type           (tree);
 extern tree most_specialized_instantiation      (tree);
 extern void print_candidates                    (tree);
-extern int instantiate_pending_templates        (void);
+extern void instantiate_pending_templates       (int);
 extern tree tsubst_default_argument             (tree, tree, tree);
 extern tree tsubst_copy_and_build               (tree, tree, tsubst_flags_t, tree, bool);
 extern tree most_general_template		(tree);

gcc/cp/decl2.c

@@ -2721,6 +2721,7 @@ finish_file (void)
   size_t i;
   location_t locus;
   unsigned ssdf_count = 0;
+  int retries = 0;
 
   locus = input_location;
   at_eof = 1;
@@ -2772,7 +2773,7 @@ finish_file (void)
 
       /* If there are templates that we've put off instantiating, do
 	 them now.  */
-      instantiate_pending_templates ();
+      instantiate_pending_templates (retries);
       ggc_collect ();
 
       /* Write out virtual tables as required.  Note that writing out
@@ -2994,6 +2995,8 @@ finish_file (void)
 	reconsider = true;
       if (cgraph_varpool_assemble_pending_decls ())
 	reconsider = true;
+
+      retries++;
     } 
   while (reconsider);
 

gcc/cp/pt.c

@@ -11272,17 +11272,30 @@ out:
 }
 
 /* Run through the list of templates that we wish we could
-   instantiate, and instantiate any we can.  */
+   instantiate, and instantiate any we can.  RETRIES is the
+   number of times we retry pending template instantiation.  */
 
-int
-instantiate_pending_templates (void)
+void
+instantiate_pending_templates (int retries)
 {
   tree *t;
   tree last = NULL_TREE;
-  int instantiated_something = 0;
   int reconsider;
   location_t saved_loc = input_location;
 
+  /* Instantiating templates may trigger vtable generation.  This in turn
+     may require further template instantiations.  We place a limit here
+     to avoid infinite loop.  */
+  if (pending_templates && retries >= max_tinst_depth)
+    {
+      cp_error_at ("template instantiation depth exceeds maximum of %d"
+		   " (use -ftemplate-depth-NN to increase the maximum)"
+		   " instantiating `%+D', possibly from virtual table"
+		   " generation",
+		   max_tinst_depth, TREE_VALUE (pending_templates));
+      return;
+    }
+
   do 
     {
       reconsider = 0;
@@ -11309,11 +11322,8 @@ instantiate_pending_templates (void)
 			instantiate_decl (fn, /*defer_ok=*/0,
 					  /*undefined_ok=*/0);
 		  if (COMPLETE_TYPE_P (instantiation))
-		    {
-		      instantiated_something = 1;
 		    reconsider = 1;
 		}
-		}
 
 	      if (COMPLETE_TYPE_P (instantiation))
 		/* If INSTANTIATION has been instantiated, then we don't
@@ -11334,11 +11344,8 @@ instantiate_pending_templates (void)
 						    /*defer_ok=*/0,
 						    /*undefined_ok=*/0);
 		  if (DECL_TEMPLATE_INSTANTIATED (instantiation))
-		    {
-		      instantiated_something = 1;
 		    reconsider = 1;
 		}
-		}
 
 	      if (DECL_TEMPLATE_SPECIALIZATION (instantiation)
 		  || DECL_TEMPLATE_INSTANTIATED (instantiation))
@@ -11359,7 +11366,6 @@ instantiate_pending_templates (void)
   while (reconsider);
 
   input_location = saved_loc;
-  return instantiated_something;
 }
 
 /* Substitute ARGVEC into T, which is a list of initializers for

gcc/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2004-08-16  Kriang Lerdsuwanakij  <lerdsuwa@users.sourceforge.net>
+
+	PR c++/6749
+	* g++.dg/template/vtable2.C: New test.
+
 2004-08-14  Richard Henderson  <rth@redhat.com>
 
 	* gcc.dg/torture/builtin-attr-1.c: Fix scalbln prototype.

gcc/testsuite/g++.dg/template/vtable2.C

@@ -0,0 +1,18 @@
+// Use a small template instantiation depth to speed up testing 
+// { dg-options "-ftemplate-depth-5" }
+// { dg-do compile }
+
+// Origin: rullo.pat@tiscalinet.it
+//	   Nathanael Nerode <neroden@gcc.gnu.org>
+//	   Wolfgang Bangerth <bangerth@dealii.org>
+
+// PR c++/6749: Infinite loop generating vtable.
+
+template <class T> struct inner {};
+
+template <class T> struct parent {
+  virtual void f()
+    { parent<inner<T> > p; };		// { dg-error "instantiation depth" }
+};
+
+template struct parent<int>;