8253584: Redunant errors for partial member selects

Reviewed-by: vromero

Author: lahodaj

src/jdk.compiler/share/classes/com/sun/tools/javac/parser/JavacParser.java

@@ -567,7 +567,7 @@ public Name ident() {
         return ident(false);
     }
 
-    protected Name ident(boolean advanceOnErrors) {
+    protected Name ident(boolean allowClass) {
         if (token.kind == IDENTIFIER) {
             Name name = token.name();
             nextToken();
@@ -603,8 +603,9 @@ protected Name ident(boolean advanceOnErrors) {
             return name;
         } else {
             accept(IDENTIFIER);
-            if (advanceOnErrors) {
+            if (allowClass && token.kind == CLASS) {
                 nextToken();
+                return names._class;
             }
             return names.error;
         }

test/langtools/tools/javac/parser/JavacParserTest.java

@@ -23,7 +23,7 @@
 
 /*
  * @test
- * @bug 7073631 7159445 7156633 8028235 8065753 8205418 8205913 8228451 8237041
+ * @bug 7073631 7159445 7156633 8028235 8065753 8205418 8205913 8228451 8237041 8253584
  * @summary tests error and diagnostics positions
  * @author  Jan Lahoda
  * @modules jdk.compiler/com.sun.tools.javac.api
@@ -1564,6 +1564,53 @@ public class B {
         assertEquals("Unexpected AST, got:\n" + ast, expected, ast);
     }
 
+    @Test //JDK-8253584
+    void testElseRecovery() throws IOException {
+        //verify the errors and AST form produced for member selects which are
+        //missing the selected member name:
+        String code = """
+                      package t;
+                      class Test {
+                          void t() {
+                              if (true) {
+                                  s().
+                              } else {
+                              }
+                          }
+                          String s() {
+                              return null;
+                          }
+                      }
+                      """;
+        StringWriter out = new StringWriter();
+        JavacTaskImpl ct = (JavacTaskImpl) tool.getTask(out, fm, null, List.of("-XDrawDiagnostics"),
+                null, Arrays.asList(new MyFileObject(code)));
+        String ast = ct.parse().iterator().next().toString().replaceAll("\\R", "\n");
+        String expected = """
+                          package t;
+                          \n\
+                          class Test {
+                              \n\
+                              void t() {
+                                  if (true) {
+                                      (ERROR);
+                                  } else {
+                                  }
+                              }
+                              \n\
+                              String s() {
+                                  return null;
+                              }
+                          } """;
+        assertEquals("Unexpected AST, got:\n" + ast, expected, ast);
+        assertEquals("Unexpected errors, got:\n" + out.toString(),
+                     out.toString(),
+                     """
+                     Test.java:5:17: compiler.err.expected: token.identifier
+                     Test.java:5:16: compiler.err.not.stmt
+                     """);
+    }
+
     void run(String[] args) throws Exception {
         int passed = 0, failed = 0;
         final Pattern p = (args != null && args.length > 0)