8257236: can't use var with a class named Z

Reviewed-by: sundar

Author: lahodaj

src/jdk.jshell/share/classes/jdk/jshell/Wrap.java

@@ -107,11 +107,16 @@ public static Wrap varWrap(String source, Wrap wtype, String brackets,
                 // }
                 // in do_it method:
                 //return do_itAux();
+                //find an unused name:
+                String scratchName = "$";
+                while (winit.wrapped().contains(scratchName)) {
+                    scratchName += "$";
+                }
                 Wrap waux = new CompoundWrap(
-                        "    private static <Z> Z ", DOIT_METHOD_NAME + "Aux", "() throws Throwable {\n",
-                        wtype, brackets + " ", wname, "_ =\n        ", winit, semi(winit),
-                        "        @SuppressWarnings(\"unchecked\") Z ", wname, "__ = (Z)", wname, "_;\n",
-                        "        return ", wname, "__;\n",
+                        "    private static <" + scratchName + "> " + scratchName +" ", DOIT_METHOD_NAME + "Aux", "() throws Throwable {\n",
+                        wtype, brackets + " ", scratchName, "_ =\n        ", winit, semi(winit),
+                        "        @SuppressWarnings(\"unchecked\") ", scratchName, " ", scratchName, "__ = (", scratchName, ")", scratchName, "_;\n",
+                        "        return ", scratchName, "__;\n",
                         "}"
                 );
                 components.add(waux);

test/langtools/jdk/jshell/VariablesTest.java

@@ -23,7 +23,7 @@
 
 /*
  * @test
- * @bug 8144903 8177466 8191842 8211694 8213725 8239536
+ * @bug 8144903 8177466 8191842 8211694 8213725 8239536 8257236
  * @summary Tests for EvaluationState.variables
  * @library /tools/lib
  * @modules jdk.compiler/com.sun.tools.javac.api
@@ -400,6 +400,13 @@ public void lvti() {
         assertEval("r15a.add(\"a\");");
         assertEval("var r15b = r15a.get(0);");
         assertEval("r15b", "\"a\"");
+        assertEval("class Z { }");
+        assertEval("var r16a = new Z();");
+        assertEval("var r16b = (Runnable) () -> {int r16b_; int r16b__;};");
+        assertEval("class $ { }");
+        assertEval("var r16c = new $();");
+        assertEval("$ r16d() { return null; }");
+        assertEval("var r16d = r16d();");
     }
 
     public void test8191842() {