8315458: Implement JEP 463: Implicitly Declared Classes and Instance Main Method (Second Preview)

Reviewed-by: jlahoda, mcimadamore, vromero, rriggs, alanb, mchung

test/langtools/tools/javac/ImplicitClass/ImplicitClassRecovery.java

@@ -0,0 +1,8 @@
+/**
+ * @test /nodynamiccopyright/
+ * @compile/fail/ref=ImplicitClassRecovery.out -XDrawDiagnostics --enable-preview --source ${jdk.version} ImplicitClassRecovery.java
+ */
+public void main() {
+    //the following is intentionally missing a semicolon:
+    System.err.println("Hello!")
+}