diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index c93e39f56915a12ffb1968cee1af3dbdbc5b257d..57c80275bd6c8fe58a2206890dea26b267a5d9a0 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2006-04-30  Volker Reichelt  <reichelt@igpm.rwth-aachen.de>
+
+	PR c++/27278
+	* decl.c (grok_op_properties): Skip operators with invalid args
+	when checking for class-type or enum-type args.
+
 2006-04-29  Volker Reichelt  <reichelt@igpm.rwth-aachen.de>
 
 	PR c++/27279
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 1617a47bbfccfaa5d3f82100cf0e44073e494bf2..e59bd68af8f8dddbdb96b7163c1999a54e5938bc 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -9086,6 +9086,9 @@ grok_op_properties (tree decl, bool complain)
 	      for (p = argtypes; p && p != void_list_node; p = TREE_CHAIN (p))
 		{
 		  tree arg = non_reference (TREE_VALUE (p));
+		  if (arg == error_mark_node)
+		    return;
+
 		  /* IS_AGGR_TYPE, rather than CLASS_TYPE_P, is used
 		     because these checks are performed even on
 		     template functions.  */
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 6d9172c19fbced6f043c1dfe6c0fb159e8577009..b82e646e90de2e932121c099233fdcc26e1ba120 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2006-04-30  Volker Reichelt  <reichelt@igpm.rwth-aachen.de>
+
+	PR c++/27278
+	* g++.dg/parse/operator7.C: New test.
+
 2006-04-29  Volker Reichelt  <reichelt@igpm.rwth-aachen.de>
 
 	PR c++/11471
diff --git a/gcc/testsuite/g++.dg/parse/operator7.C b/gcc/testsuite/g++.dg/parse/operator7.C
new file mode 100644
index 0000000000000000000000000000000000000000..e3464f017da1eb93238fbe259e1b4a7728d6811e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/parse/operator7.C
@@ -0,0 +1,4 @@
+// PR c++/27278
+// { dg-do compile }
+
+int operator+(void,void);  // { dg-error "incomplete type|invalid use" }