8228647: Broken enum produce inconvenient errors and AST

Improving error recovery for misplace members in enums.

Reviewed-by: vromero

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

@@ -3756,23 +3756,59 @@ public class JavacParser implements Parser {
     List<JCTree> enumBody(Name enumName) {
         accept(LBRACE);
         ListBuffer<JCTree> defs = new ListBuffer<>();
+        boolean wasSemi = false;
+        boolean hasStructuralErrors = false;
+        boolean wasError = false;
         if (token.kind == COMMA) {
             nextToken();
-        } else if (token.kind != RBRACE && token.kind != SEMI) {
+            if (token.kind == SEMI) {
-            defs.append(enumeratorDeclaration(enumName));
+                wasSemi = true;
-            while (token.kind == COMMA) {
-                nextToken();
-                if (token.kind == RBRACE || token.kind == SEMI) break;
-                defs.append(enumeratorDeclaration(enumName));
-            }
-            if (token.kind != SEMI && token.kind != RBRACE) {
-                defs.append(syntaxError(token.pos, Errors.Expected3(COMMA, RBRACE, SEMI)));
                 nextToken();
+            } else if (token.kind != RBRACE) {
+                reportSyntaxError(S.prevToken().endPos,
+                                  Errors.Expected2(RBRACE, SEMI));
+                wasError = true;
             }
         }
-        if (token.kind == SEMI) {
+        while (token.kind != RBRACE && token.kind != EOF) {
-            nextToken();
+            if (token.kind == SEMI) {
-            while (token.kind != RBRACE && token.kind != EOF) {
+                accept(SEMI);
+                wasSemi = true;
+                if (token.kind == RBRACE || token.kind == EOF) break;
+            }
+            EnumeratorEstimate memberType = estimateEnumeratorOrMember(enumName);
+            if (memberType == EnumeratorEstimate.UNKNOWN) {
+                memberType = wasSemi ? EnumeratorEstimate.MEMBER
+                                     : EnumeratorEstimate.ENUMERATOR;
+            }
+            if (memberType == EnumeratorEstimate.ENUMERATOR) {
+                wasError = false;
+                if (wasSemi && !hasStructuralErrors) {
+                    reportSyntaxError(token.pos, Errors.EnumConstantNotExpected);
+                    hasStructuralErrors = true;
+                }
+                defs.append(enumeratorDeclaration(enumName));
+                if (token.pos <= endPosTable.errorEndPos) {
+                    // error recovery
+                   skip(false, true, true, false);
+                } else {
+                    if (token.kind != RBRACE && token.kind != SEMI && token.kind != EOF) {
+                        if (token.kind == COMMA) {
+                            nextToken();
+                        } else {
+                            setErrorEndPos(token.pos);
+                            reportSyntaxError(S.prevToken().endPos,
+                                              Errors.Expected3(COMMA, RBRACE, SEMI));
+                            wasError = true;
+                        }
+                    }
+                }
+            } else {
+                if (!wasSemi && !hasStructuralErrors && !wasError) {
+                    reportSyntaxError(token.pos, Errors.EnumConstantExpected);
+                    hasStructuralErrors = true;
+                }
+                wasError = false;
                 defs.appendList(classOrInterfaceBodyDeclaration(enumName,
                                                                 false));
                 if (token.pos <= endPosTable.errorEndPos) {
@@ -3785,6 +3821,28 @@ public class JavacParser implements Parser {
         return defs.toList();
     }
 
+    private EnumeratorEstimate estimateEnumeratorOrMember(Name enumName) {
+        if (token.kind == TokenKind.IDENTIFIER && token.name() != enumName) {
+            Token next = S.token(1);
+            switch (next.kind) {
+                case LPAREN: case LBRACE: case COMMA: case SEMI:
+                    return EnumeratorEstimate.ENUMERATOR;
+            }
+        }
+        switch (token.kind) {
+            case IDENTIFIER: case MONKEYS_AT: case LT:
+                return EnumeratorEstimate.UNKNOWN;
+            default:
+                return EnumeratorEstimate.MEMBER;
+        }
+    }
+
+    private enum EnumeratorEstimate {
+        ENUMERATOR,
+        MEMBER,
+        UNKNOWN;
+    }
+
     /** EnumeratorDeclaration = AnnotationsOpt [TypeArguments] IDENTIFIER [ Arguments ] [ "{" ClassBody "}" ]
      */
     JCTree enumeratorDeclaration(Name enumName) {

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

@@ -2158,6 +2158,12 @@ compiler.err.expected3=\
 compiler.err.premature.eof=\
     reached end of file while parsing
 
+compiler.err.enum.constant.expected=\
+    enum constant expected here
+
+compiler.err.enum.constant.not.expected=\
+    enum constant not expected here
+
 ## The following are related in form, but do not easily fit the above paradigm.
 compiler.err.expected.module=\
     ''module'' expected

test/langtools/tools/javac/T4994049/T4994049.java

@@ -10,5 +10,8 @@ public enum T4994049 {
     FOO {
     }
 
-    BAR;
+    BAR1,
+    BAR2(),
+    BAR3 {},
+    BAR4() {};
 }

test/langtools/tools/javac/T4994049/T4994049.out

@@ -1,2 +1,2 @@
-T4994049.java:13:5: compiler.err.expected3: ',', '}', ';'
+T4994049.java:11:6: compiler.err.expected3: ',', '}', ';'
 1 error

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

@@ -0,0 +1,30 @@
+/*
+ * Copyright (c) 2019, 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.enum.constant.expected
+
+enum EnumConstantExpected {
+    A,
+    void test() {}
+    ;
+}

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

@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2019, 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.enum.constant.not.expected
+
+enum EnumConstantNotExpected {
+    ;
+    A;
+}

test/langtools/tools/javac/enum/EnumMembersOrder.out

@@ -1,7 +1,4 @@
 EnumMembersOrder.java:11:16: compiler.err.expected: ')'
-EnumMembersOrder.java:11:17: compiler.err.expected3: ',', '}', ';'
+EnumMembersOrder.java:11:18: compiler.err.expected3: ',', '}', ';'
-EnumMembersOrder.java:11:18: compiler.err.expected: '}'
+EnumMembersOrder.java:11:20: compiler.err.enum.constant.expected
-EnumMembersOrder.java:11:31: compiler.err.expected3: class, interface, enum
+3 errors
-EnumMembersOrder.java:17:13: compiler.err.expected3: class, interface, enum
-EnumMembersOrder.java:19:1: compiler.err.expected3: class, interface, enum
-6 errors

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

@@ -1291,6 +1291,179 @@ public class JavacParserTest extends TestCase {
         assertTrue("testAnalyzeParensWithComma2", found[0]);
     }
 
+    @Test
+    void testBrokenEnum1() throws IOException {
+        assert tool != null;
+
+        String code = "package test; class Test { enum E { A, B, C. D, E, F; } }";
+        StringWriter output = new StringWriter();
+        JavacTaskImpl ct = (JavacTaskImpl) tool.getTask(output, fm, null, List.of("-XDrawDiagnostics"),
+                null, Arrays.asList(new MyFileObject(code)));
+        CompilationUnitTree cut = ct.parse().iterator().next();
+        List<String> actual = List.of(output.toString().split("\r?\n"));
+        List<String> expected = List.of("Test.java:1:44: compiler.err.expected3: ',', '}', ';'");
+
+        assertEquals("The expected and actual errors do not match, actual errors: " + actual,
+                     actual,
+                     expected);
+
+        String actualAST = cut.toString().replaceAll("\r*\n", "\n");
+        String expectedAST = "package test;\n" +
+                             "\n" +
+                             "class Test {\n" +
+                             "    \n" +
+                             "    enum E {\n" +
+                             "        /*public static final*/ A /* = new E() */ /*enum*/ ,\n" +
+                             "        /*public static final*/ B /* = new E() */ /*enum*/ ,\n" +
+                             "        /*public static final*/ C /* = new E() */ /*enum*/ ,\n" +
+                             "        /*public static final*/ D /* = new E() */ /*enum*/ ,\n" +
+                             "        /*public static final*/ E /* = new E() */ /*enum*/ ,\n" +
+                             "        /*public static final*/ F /* = new E() */ /*enum*/ ;\n" +
+                             "        (ERROR) <error>;\n" +
+                             "    }\n" +
+                             "}";
+        assertEquals("The expected and actual AST do not match, actual AST: " + actualAST,
+                     actualAST,
+                     expectedAST);
+    }
+
+    @Test
+    void testBrokenEnum2() throws IOException {
+        assert tool != null;
+
+        String code = "package test; class Test { enum E { A, B, C void t() {} } }";
+        StringWriter output = new StringWriter();
+        JavacTaskImpl ct = (JavacTaskImpl) tool.getTask(output, fm, null, List.of("-XDrawDiagnostics"),
+                null, Arrays.asList(new MyFileObject(code)));
+        CompilationUnitTree cut = ct.parse().iterator().next();
+        List<String> actual = List.of(output.toString().split("\r?\n"));
+        List<String> expected = List.of("Test.java:1:44: compiler.err.expected3: ',', '}', ';'");
+
+        assertEquals("The expected and actual errors do not match, actual errors: " + actual,
+                     actual,
+                     expected);
+
+        String actualAST = cut.toString().replaceAll("\r*\n", "\n");
+        String expectedAST = "package test;\n" +
+                             "\n" +
+                             "class Test {\n" +
+                             "    \n" +
+                             "    enum E {\n" +
+                             "        /*public static final*/ A /* = new E() */ /*enum*/ ,\n" +
+                             "        /*public static final*/ B /* = new E() */ /*enum*/ ,\n" +
+                             "        /*public static final*/ C /* = new E() */ /*enum*/ ;\n" +
+                             "        \n" +
+                             "        void t() {\n" +
+                             "        }\n" +
+                             "    }\n" +
+                             "}";
+        assertEquals("The expected and actual AST do not match, actual AST: " + actualAST,
+                     actualAST,
+                     expectedAST);
+    }
+
+    @Test
+    void testBrokenEnum3() throws IOException {
+        assert tool != null;
+
+        String code = "package test; class Test { enum E { , void t() {} } }";
+        StringWriter output = new StringWriter();
+        JavacTaskImpl ct = (JavacTaskImpl) tool.getTask(output, fm, null, List.of("-XDrawDiagnostics"),
+                null, Arrays.asList(new MyFileObject(code)));
+        CompilationUnitTree cut = ct.parse().iterator().next();
+        List<String> actual = List.of(output.toString().split("\r?\n"));
+        List<String> expected = List.of("Test.java:1:38: compiler.err.expected2: '}', ';'");
+
+        assertEquals("The expected and actual errors do not match, actual errors: " + actual,
+                     actual,
+                     expected);
+
+        String actualAST = cut.toString().replaceAll("\r*\n", "\n");
+        String expectedAST = "package test;\n" +
+                             "\n" +
+                             "class Test {\n" +
+                             "    \n" +
+                             "    enum E {\n" +
+                             ";\n" +
+                             "        \n" +
+                             "        void t() {\n" +
+                             "        }\n" +
+                             "    }\n" +
+                             "}";
+        assertEquals("The expected and actual AST do not match, actual AST: " + actualAST,
+                     actualAST,
+                     expectedAST);
+    }
+
+    @Test
+    void testBrokenEnum4() throws IOException {
+        assert tool != null;
+
+        String code = "package test; class Test { enum E { A, B, C, void t() {} } }";
+        StringWriter output = new StringWriter();
+        JavacTaskImpl ct = (JavacTaskImpl) tool.getTask(output, fm, null, List.of("-XDrawDiagnostics"),
+                null, Arrays.asList(new MyFileObject(code)));
+        CompilationUnitTree cut = ct.parse().iterator().next();
+        List<String> actual = List.of(output.toString().split("\r?\n"));
+        List<String> expected = List.of("Test.java:1:46: compiler.err.enum.constant.expected");
+
+        assertEquals("The expected and actual errors do not match, actual errors: " + actual,
+                     actual,
+                     expected);
+
+        String actualAST = cut.toString().replaceAll("\r*\n", "\n");
+        String expectedAST = "package test;\n" +
+                             "\n" +
+                             "class Test {\n" +
+                             "    \n" +
+                             "    enum E {\n" +
+                             "        /*public static final*/ A /* = new E() */ /*enum*/ ,\n" +
+                             "        /*public static final*/ B /* = new E() */ /*enum*/ ,\n" +
+                             "        /*public static final*/ C /* = new E() */ /*enum*/ ;\n" +
+                             "        \n" +
+                             "        void t() {\n" +
+                             "        }\n" +
+                             "    }\n" +
+                             "}";
+        assertEquals("The expected and actual AST do not match, actual AST: " + actualAST,
+                     actualAST,
+                     expectedAST);
+    }
+
+    @Test
+    void testBrokenEnum5() throws IOException {
+        assert tool != null;
+
+        String code = "package test; class Test { enum E { A; void t() {} B; } }";
+        StringWriter output = new StringWriter();
+        JavacTaskImpl ct = (JavacTaskImpl) tool.getTask(output, fm, null, List.of("-XDrawDiagnostics"),
+                null, Arrays.asList(new MyFileObject(code)));
+        CompilationUnitTree cut = ct.parse().iterator().next();
+        List<String> actual = List.of(output.toString().split("\r?\n"));
+        List<String> expected = List.of("Test.java:1:52: compiler.err.enum.constant.not.expected");
+
+        assertEquals("The expected and actual errors do not match, actual errors: " + actual,
+                     actual,
+                     expected);
+
+        String actualAST = cut.toString().replaceAll("\r*\n", "\n");
+        String expectedAST = "package test;\n" +
+                             "\n" +
+                             "class Test {\n" +
+                             "    \n" +
+                             "    enum E {\n" +
+                             "        /*public static final*/ A /* = new E() */ /*enum*/ ,\n" +
+                             "        /*public static final*/ B /* = new E() */ /*enum*/ ;\n" +
+                             "        \n" +
+                             "        void t() {\n" +
+                             "        }\n" +
+                             "    }\n" +
+                             "}";
+        assertEquals("The expected and actual AST do not match, actual AST: " + actualAST,
+                     actualAST,
+                     expectedAST);
+    }
+
     void run(String[] args) throws Exception {
         int passed = 0, failed = 0;
         final Pattern p = (args != null && args.length > 0)