8220041: NullPointerException at jdk.compiler/com.sun.tools.javac.jvm.Code.emitop0
Summary: LambdaToMethod must correctly capture local variables inside switch expressions inside local variable initializers.
Reviewed-by: mcimadamore, vromero
--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/LambdaToMethod.java Wed Jul 10 09:43:35 2019 +0800
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/LambdaToMethod.java Wed Jul 10 09:04:42 2019 +0200
@@ -1709,8 +1709,9 @@
}
break;
case VARDEF:
- if (((JCVariableDecl)block.tree).sym == sym &&
- sym.owner.kind == MTH) { //only locals are captured
+ if ((((JCVariableDecl)block.tree).sym == sym &&
+ sym.owner.kind == MTH) || //only locals are captured
+ (block.locals != null && block.locals.contains(sym))) {
return currentDepth > depth ? null : block.tree;
}
break;
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/test/langtools/tools/javac/switchexpr/LambdaCapture.java Wed Jul 10 09:04:42 2019 +0200
@@ -0,0 +1,108 @@
+/*
+ * 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.
+ */
+
+/*
+ * @test
+ * @bug 8220041
+ * @summary Verify variable capture works inside switch expressions which are
+ * inside variable declarations
+ * @compile --enable-preview -source ${jdk.version} LambdaCapture.java
+ */
+
+import java.util.Objects;
+
+public class LambdaCapture {
+ public static void main(String... args) {
+ new LambdaCapture().run();
+ }
+
+ void run() {
+ assertEquals("00", lambdaCapture1(0).t());
+ assertEquals("12", lambdaCapture1(1).t());
+ assertEquals("D", lambdaCapture1(2).t());
+ assertEquals("D", lambdaCapture1(3).t());
+ assertEquals("00", lambdaCapture2(0).t());
+ assertEquals("12", lambdaCapture2(1).t());
+ assertEquals("D", lambdaCapture2(2).t());
+ assertEquals("D", lambdaCapture2(3).t());
+ }
+
+ I<String> lambdaCapture1(int i) {
+ int j = i + 1;
+ I<String> r = switch (i) {
+ case 0 -> () -> "0" + i; //capture parameter
+ case 1 -> () -> "1" + j; //capture local variable
+ default -> {
+ String k = "D";
+ yield () -> k; //capture local from the switch expr.
+ }
+ };
+
+ return r;
+ }
+
+ I<String> lambdaCapture2(int i) {
+ int j = i + 1;
+
+ return switch (i) {
+ case 0 -> () -> "0" + i; //capture parameter
+ case 1 -> () -> "1" + j; //capture local variable
+ default -> {
+ String k = "D";
+ yield () -> k; //capture local from the switch expr.
+ }
+ };
+ }
+
+ {
+ int j1 = 1;
+ I<String> r1 = switch (j1) {
+ case 1 -> () -> "1" + j1; //capture local variable
+ default -> {
+ String k = "D";
+ yield () -> k; //capture local from the switch expr.
+ }
+ };
+ assertEquals("11", r1.t());
+
+ int j2 = 2;
+ I<String> r2 = switch (j2) {
+ case 1 -> () -> "1" + j2; //capture local variable
+ default -> {
+ String k = "D";
+ yield () -> k; //capture local from the switch expr.
+ }
+ };
+ assertEquals("D", r2.t());
+ }
+
+ private void assertEquals(Object expected, Object actual) {
+ if (!Objects.equals(expected, actual)) {
+ throw new AssertionError("Unexpected value: " + actual);
+ }
+ }
+
+ interface I<T> {
+ public T t();
+ }
+}