8290379: Parse error with parenthesized pattern and guard using an array

Reviewed-by: jlahoda

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

@@ -3169,7 +3169,8 @@ public class JavacParser implements Parser {
                         lookahead++;
                         break;
                     } else {
-                        return PatternResult.EXPRESSION;
+                        // This is a potential guard, if we are already in a pattern
+                        return pendingResult;
                     }
                 case LPAREN:
                     if (S.token(lookahead + 1).kind == RPAREN) {

test/langtools/tools/javac/T8290379.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2022, 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 8290379
+ * @summary Parse error with parenthesized pattern and guard using an array
+ * @compile --enable-preview -source ${jdk.version} T8290379.java
+ * @run main/othervm --enable-preview T8290379
+ */
+public class T8290379 {
+    public static void main(String... args) {
+        assertEquals(0, test("test"));
+        assertEquals(1, test(Integer.valueOf(42)));
+    }
+
+    public static int test(Object o)
+    {
+        int[] arr = {0, 1};
+
+        return switch (o) {
+            case (String s) when (arr[0] == 0) -> 0;
+            case (Integer i) when arr[1] == 1 -> 1;
+            default -> 2;
+        };
+    }
+
+    static void assertEquals(int expected, int actual) {
+        if (expected != actual) {
+            throw new AssertionError("Expected: " + expected + ", actual: " + actual);
+        }
+    }
+}