8338301: Error recovery and reporting should be improved for erroneous implicitly declared classes

Reviewed-by: cstein, vromero

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

@@ -457,9 +457,13 @@ public class JavacParser implements Parser {
     }
 
     protected JCErroneous syntaxError(int pos, List<? extends JCTree> errs, Error errorKey) {
+        return syntaxError(pos, errs, errorKey, false);
+    }
+
+    private JCErroneous syntaxError(int pos, List<? extends JCTree> errs, Error errorKey, boolean noEofError) {
         setErrorEndPos(pos);
         JCErroneous err = F.at(pos).Erroneous(errs);
-        reportSyntaxError(err, errorKey);
+        reportSyntaxError(err, errorKey, noEofError);
         if (errs != null) {
             JCTree last = errs.last();
             if (last != null)
@@ -486,9 +490,13 @@ public class JavacParser implements Parser {
      * arguments, unless one was already reported at the same position.
      */
     protected void reportSyntaxError(JCDiagnostic.DiagnosticPosition diagPos, Error errorKey) {
+        reportSyntaxError(diagPos, errorKey, false);
+    }
+
+    private void reportSyntaxError(JCDiagnostic.DiagnosticPosition diagPos, Error errorKey, boolean noEofError) {
         int pos = diagPos.getPreferredPosition();
         if (pos > S.errPos() || pos == Position.NOPOS) {
-            if (token.kind == EOF) {
+            if (token.kind == EOF && !noEofError) {
                 log.error(DiagnosticFlag.SYNTAX, diagPos, Errors.PrematureEof);
             } else {
                 log.error(DiagnosticFlag.SYNTAX, diagPos, errorKey);
@@ -4093,6 +4101,13 @@ public class JavacParser implements Parser {
                     checkSourceLevel(token.pos, Feature.IMPLICIT_CLASSES);
                     defs.appendList(topLevelMethodOrFieldDeclaration(mods, docComment));
                     isImplicitClass = true;
+                } else if (isDefiniteStatementStartToken()) {
+                    int startPos = token.pos;
+                    List<JCStatement> statements = blockStatement();
+                    defs.append(syntaxError(startPos,
+                                            statements,
+                                            Errors.StatementNotExpected,
+                                            true));
                 } else {
                     JCTree def = typeDeclaration(mods, docComment);
                     if (def instanceof JCExpressionStatement statement)
@@ -4325,6 +4340,9 @@ public class JavacParser implements Parser {
             JCDiagnostic.Error error;
             if (parseModuleInfo) {
                 error = Errors.ExpectedModuleOrOpen;
+            } else if (Feature.IMPLICIT_CLASSES.allowedInSource(source) &&
+                       (!preview.isPreview(Feature.IMPLICIT_CLASSES) || preview.isEnabled())) {
+                error = Errors.ClassMethodOrFieldExpected;
             } else if (allowRecords) {
                 error = Errors.Expected4(CLASS, INTERFACE, ENUM, "record");
             } else {
@@ -4907,6 +4925,12 @@ public class JavacParser implements Parser {
 
                 return defs;
             }
+        } else if (token.kind == LPAREN && type.hasTag(IDENT)) {
+            log.error(DiagnosticFlag.SYNTAX, pos, Errors.InvalidMethDeclRetTypeReq);
+
+            return List.of(methodDeclaratorRest(
+                    pos, mods, null, names.init, typarams,
+                    false, true, false, dc));
         }
 
         return List.of(F.Erroneous());

src/jdk.compiler/share/classes/com/sun/tools/javac/resources/compiler.properties

@@ -1619,6 +1619,9 @@ compiler.err.no.java.lang=\
 compiler.err.statement.not.expected=\
     statements not expected outside of methods and initializers
 
+compiler.err.class.method.or.field.expected=\
+    class, interface, annotation type, enum, record, method or field expected
+
 #####
 
 # Fatal Errors

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

@@ -0,0 +1,222 @@
+/*
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/**
+ * @test
+ * @bug 8338301
+ * @summary Verify error recovery and reporting related to implicitly declared classes
+ * @library /tools/lib
+ * @modules jdk.compiler/com.sun.tools.javac.api
+ *          jdk.compiler/com.sun.tools.javac.main
+ *          jdk.compiler/com.sun.tools.javac.util
+ * @build toolbox.ToolBox toolbox.JavacTask
+ * @run main ErrorRecovery
+*/
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.List;
+import java.util.Objects;
+
+import toolbox.TestRunner;
+import toolbox.JavacTask;
+import toolbox.JavaTask;
+import toolbox.Task;
+import toolbox.Task.OutputKind;
+import toolbox.ToolBox;
+
+public class ErrorRecovery extends TestRunner {
+
+    private static final String SOURCE_VERSION = System.getProperty("java.specification.version");
+    private ToolBox tb;
+
+    public static void main(String... args) throws Exception {
+        new ErrorRecovery().runTests();
+    }
+
+    ErrorRecovery() {
+        super(System.err);
+        tb = new ToolBox();
+    }
+
+    public void runTests() throws Exception {
+        runTests(m -> new Object[] { Paths.get(m.getName()) });
+    }
+
+    @Test
+    public void testMethodNoReturnType(Path base) throws Exception {
+        Path current = base.resolve(".");
+        Path src = current.resolve("src");
+        Path classes = current.resolve("classes");
+        tb.writeFile(src.resolve("Test.java"),
+                     """
+                     main() {}
+                     """);
+
+        Files.createDirectories(classes);
+
+        List<String> log = new JavacTask(tb)
+            .options("-XDrawDiagnostics",
+                     "--enable-preview", "--release", SOURCE_VERSION)
+            .outdir(classes)
+            .files(tb.findJavaFiles(src))
+            .run(Task.Expect.FAIL)
+            .writeAll()
+            .getOutputLines(OutputKind.DIRECT);
+        List<String> expected = List.of(
+            "Test.java:1:1: compiler.err.invalid.meth.decl.ret.type.req",
+            "- compiler.note.preview.filename: Test.java, DEFAULT",
+            "- compiler.note.preview.recompile",
+            "1 error"
+        );
+        if (!Objects.equals(expected, log)) {
+            throw new AssertionError("Unexpected output: " + log +
+                                     ", while expecting: " + expected);
+        }
+    }
+
+    @Test
+    public void testStatement(Path base) throws Exception {
+        Path current = base.resolve(".");
+        Path src = current.resolve("src");
+        Path classes = current.resolve("classes");
+        tb.writeFile(src.resolve("Test.java"),
+                     """
+                     if (true) {int var = 0;}
+                     """);
+
+        Files.createDirectories(classes);
+
+        List<String> log = new JavacTask(tb)
+            .options("-XDrawDiagnostics",
+                     "-XDshould-stop.at=FLOW",
+                     "--enable-preview", "--release", SOURCE_VERSION)
+            .outdir(classes)
+            .files(tb.findJavaFiles(src))
+            .run(Task.Expect.FAIL)
+            .writeAll()
+            .getOutputLines(OutputKind.DIRECT);
+        List<String> expected = List.of(
+            "Test.java:1:1: compiler.err.statement.not.expected",
+            "1 error"
+        );
+        if (!Objects.equals(expected, log)) {
+            throw new AssertionError("Unexpected output: " + log +
+                                     ", while expecting: " + expected);
+        }
+    }
+
+    @Test
+    public void testExtraSemi(Path base) throws Exception {
+        Path current = base.resolve(".");
+        Path src = current.resolve("src");
+        Path classes = current.resolve("classes");
+        tb.writeFile(src.resolve("Test.java"),
+                     """
+                     class C {};
+                     void main() {};
+                     """);
+
+        Files.createDirectories(classes);
+
+        new JavacTask(tb)
+            .options("-XDrawDiagnostics",
+                     "--enable-preview", "--release", SOURCE_VERSION)
+            .outdir(classes)
+            .files(tb.findJavaFiles(src))
+            .run(Task.Expect.SUCCESS)
+            .writeAll();
+    }
+
+    @Test
+    public void testVeryBroken(Path base) throws Exception {
+        Path current = base.resolve(".");
+        Path src = current.resolve("src");
+        Path classes = current.resolve("classes");
+        tb.writeFile(src.resolve("Test.java"),
+                     """
+                     "neither-of-class-method-file-statement"
+                     """);
+
+        Files.createDirectories(classes);
+
+        List<String> log;
+        List<String> expected;
+
+        log = new JavacTask(tb)
+                .options("-XDrawDiagnostics",
+                        "--enable-preview", "--release", SOURCE_VERSION)
+                .outdir(classes)
+                .files(tb.findJavaFiles(src))
+                .run(Task.Expect.FAIL)
+                .writeAll()
+                .getOutputLines(OutputKind.DIRECT);
+        expected = List.of(
+                "Test.java:1:1: compiler.err.class.method.or.field.expected",
+                "1 error"
+        );
+
+        if (!Objects.equals(expected, log)) {
+            throw new AssertionError("Unexpected output: " + log +
+                                     ", while expecting: " + expected);
+        }
+
+        log = new JavacTask(tb)
+                .options("-XDrawDiagnostics")
+                .outdir(classes)
+                .files(tb.findJavaFiles(src))
+                .run(Task.Expect.FAIL)
+                .writeAll()
+                .getOutputLines(OutputKind.DIRECT);
+        expected = List.of(
+                "Test.java:1:1: compiler.err.expected4: class, interface, enum, record",
+                "1 error"
+        );
+
+        if (!Objects.equals(expected, log)) {
+            throw new AssertionError("Unexpected output: " + log +
+                                     ", while expecting: " + expected);
+        }
+
+        log = new JavacTask(tb)
+                .options("-XDrawDiagnostics",
+                         "--release", "17")
+                .outdir(classes)
+                .files(tb.findJavaFiles(src))
+                .run(Task.Expect.FAIL)
+                .writeAll()
+                .getOutputLines(OutputKind.DIRECT);
+        expected = List.of(
+                "Test.java:1:1: compiler.err.expected4: class, interface, enum, record",
+                "1 error"
+        );
+
+        if (!Objects.equals(expected, log)) {
+            throw new AssertionError("Unexpected output: " + log +
+                                     ", while expecting: " + expected);
+        }
+    }
+
+}

test/langtools/tools/javac/diags/examples/ClassMethodOrFieldExpected.java

@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+// key: compiler.err.class.method.or.field.expected
+// options: --enable-preview --source ${jdk.version}
+
+"neither-of-class-method-file-statement"