8016640: compiler hangs if the generics arity of a base class is wrong

Summary: Check.checkCompatibleConcretes hang when javac creates synthetic supertypes for 269 model API
Reviewed-by: jjg

src/share/classes/com/sun/tools/javac/code/Types.java

@@ -2245,7 +2245,7 @@ public class Types {
 
             @Override
             public Type visitErrorType(ErrorType t, Void ignored) {
-                return t;
+                return Type.noType;
             }
         };
     // </editor-fold>

src/share/classes/com/sun/tools/javadoc/ClassDocImpl.java

@@ -46,6 +46,7 @@ import com.sun.tools.javac.code.Symbol;
 import com.sun.tools.javac.code.Symbol.*;
 import com.sun.tools.javac.code.Type;
 import com.sun.tools.javac.code.Type.ClassType;
+import com.sun.tools.javac.code.TypeTag;
 import com.sun.tools.javac.comp.AttrContext;
 import com.sun.tools.javac.comp.Env;
 import com.sun.tools.javac.tree.JCTree;
@@ -516,7 +517,7 @@ public class ClassDocImpl extends ProgramElementDocImpl implements ClassDoc {
             return null;
         Type sup = env.types.supertype(type);
         return TypeMaker.getType(env,
-                                 (sup != type) ? sup : env.syms.objectType);
+                                 (sup.hasTag(TypeTag.NONE)) ? env.syms.objectType : sup);
     }
 
     /**

test/tools/javac/generics/8016640/T8016640.java

+/*
+ * @test /nodynamiccopyright/
+ * @bug     8016640
+ * @summary compiler hangs if the generics arity of a base class is wrong
+ * @compile/fail/ref=T8016640.out -XDrawDiagnostics T8016640.java
+ */
+class T8016640 {
+    static class Foo<X,Y> { }
+    static class BadFoo<T> extends Foo<T> { }
+}

test/tools/javac/generics/8016640/T8016640.out

+T8016640.java:9:39: compiler.err.wrong.number.type.args: 2
+1 error