re PR c++/48212 ([C++0x] ICE: in non_const_var_error, at cp/semantics.c:6700 on invalid code)

	PR c++/48212
	* semantics.c (non_const_var_error): Just return if DECL_INITIAL
	is error_mark_node.

From-SVN: r171748

gcc/cp/ChangeLog

 2011-03-30  Jason Merrill  <jason@redhat.com>
 
+	PR c++/48212
+	* semantics.c (non_const_var_error): Just return if DECL_INITIAL
+	is error_mark_node.
+
+2011-03-30  Jason Merrill  <jason@redhat.com>
+
 	PR c++/48369
 	* semantics.c (potential_constant_expression_1): Handle
 	UNORDERED_EXPR and ORDERED_EXPR.

gcc/cp/semantics.c

@@ -6753,6 +6753,9 @@ non_const_var_error (tree r)
   tree type = TREE_TYPE (r);
   error ("the value of %qD is not usable in a constant "
 	 "expression", r);
+  /* Avoid error cascade.  */
+  if (DECL_INITIAL (r) == error_mark_node)
+    return;
   if (DECL_DECLARED_CONSTEXPR_P (r))
     inform (DECL_SOURCE_LOCATION (r),
 	    "%qD used in its own initializer", r);

gcc/testsuite/ChangeLog

 2011-03-30  Jason Merrill  <jason@redhat.com>
 
+	* g++.dg/cpp0x/regress/error-recovery1.C: New.
+
 	* g++.dg/cpp0x/regress/isnan.C: New.
 
 	* g++.dg/cpp0x/initlist46.C: New.

gcc/testsuite/g++.dg/cpp0x/regress/error-recovery1.C

+// PR c++/48212
+// { dg-options -std=c++0x }
+
+template < bool > void
+foo ()
+{
+  const bool b =;		// { dg-error "" }
+  foo < b > ();			// { dg-error "constant expression" }
+};