8235446: confusing error message for records with no parens

Reviewed-by: mcimadamore

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

@@ -3664,23 +3664,29 @@ public class JavacParser implements Parser {
         } else {
             int pos = token.pos;
             List<JCTree> errs;
-            if (LAX_IDENTIFIER.accepts(token.kind)) {
-                errs = List.of(mods, toP(F.at(pos).Ident(ident())));
-                setErrorEndPos(token.pos);
+            if (token.kind == IDENTIFIER && token.name() == names.record && preview.isEnabled()) {
+                checkSourceLevel(Feature.RECORDS);
+                JCErroneous erroneousTree = syntaxError(token.pos, List.of(mods), Errors.RecordHeaderExpected);
+                return toP(F.Exec(erroneousTree));
             } else {
-                errs = List.of(mods);
-            }
-            final JCErroneous erroneousTree;
-            if (parseModuleInfo) {
-                erroneousTree = syntaxError(pos, errs, Errors.ExpectedModuleOrOpen);
-            } else {
-                if (allowRecords) {
-                    erroneousTree = syntaxError(pos, errs, Errors.Expected4(CLASS, INTERFACE, ENUM, "record"));
+                if (LAX_IDENTIFIER.accepts(token.kind)) {
+                    errs = List.of(mods, toP(F.at(pos).Ident(ident())));
+                    setErrorEndPos(token.pos);
                 } else {
-                    erroneousTree = syntaxError(pos, errs, Errors.Expected3(CLASS, INTERFACE, ENUM));
+                    errs = List.of(mods);
                 }
+                final JCErroneous erroneousTree;
+                if (parseModuleInfo) {
+                    erroneousTree = syntaxError(pos, errs, Errors.ExpectedModuleOrOpen);
+                } else {
+                    if (allowRecords) {
+                        erroneousTree = syntaxError(pos, errs, Errors.Expected4(CLASS, INTERFACE, ENUM, "record"));
+                    } else {
+                        erroneousTree = syntaxError(pos, errs, Errors.Expected3(CLASS, INTERFACE, ENUM));
+                    }
+                }
+                return toP(F.Exec(erroneousTree));
             }
-            return toP(F.Exec(erroneousTree));
         }
     }
 

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

@@ -3522,6 +3522,9 @@ compiler.err.instance.initializer.not.allowed.in.records=\
 compiler.err.record.declaration.not.allowed.in.inner.classes=\
     record declarations not allowed in inner classes
 
+compiler.err.record.header.expected=\
+    record header expected
+
 ############################################
 # messages previouly at javac.properties
 

test/langtools/tools/javac/diags/examples/IncorrectRecordDeclaration.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.record.header.expected
+// key: compiler.note.preview.filename
+// key: compiler.note.preview.recompile
+// options: --enable-preview -source ${jdk.version}
+
+record R {}

test/langtools/tools/javac/records/RecordCompilationTests.java

@@ -67,7 +67,7 @@ public class RecordCompilationTests extends CompilationTestCase {
         assertFail("compiler.err.premature.eof", "record R();");
         assertFail("compiler.err.illegal.start.of.type", "record R(,) { }");
         assertFail("compiler.err.illegal.start.of.type", "record R((int x)) { }");
-        assertFail("compiler.err.expected4", "record R { }");
+        assertFail("compiler.err.record.header.expected", "record R { }");
         assertFail("compiler.err.expected", "record R(foo) { }");
         assertFail("compiler.err.expected", "record R(int int) { }");
         assertFail("compiler.err.mod.not.allowed.here", "abstract record R(String foo) { }");