8263642: javac emits duplicate checkcast for first bound of intersection type in cast

Reviewed-by: vromero

src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TransTypes.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 2021, 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
@@ -767,7 +767,7 @@ public class TransTypes extends TreeTranslator {
             JCTypeCast typeCast = newExpression.hasTag(Tag.TYPECAST)
                 ? (JCTypeCast) newExpression
                 : null;
-            tree.expr = typeCast != null && types.isSameType(typeCast.type, originalTarget)
+            tree.expr = typeCast != null && types.isSameType(typeCast.type, tree.type)
                 ? typeCast.expr
                 : newExpression;
         }

test/langtools/tools/javac/cast/intersection/DuplicatedCheckcastTest.java

@@ -0,0 +1,108 @@
+/*
+ * Copyright (c) 2021, 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 8263642
+ * @summary javac should not emit duplicate checkcast for first bound of intersection type in cast
+ * @library /tools/lib
+ * @modules jdk.compiler/com.sun.tools.javac.api
+ *          jdk.compiler/com.sun.tools.javac.main
+ *          jdk.jdeps/com.sun.tools.classfile
+ * @build toolbox.ToolBox toolbox.JavacTask
+ * @run main DuplicatedCheckcastTest
+ */
+
+import java.nio.file.Path;
+import java.util.ArrayList;
+
+import com.sun.tools.classfile.ClassFile;
+import com.sun.tools.classfile.Method;
+import com.sun.tools.classfile.Attribute;
+import com.sun.tools.classfile.Code_attribute;
+import com.sun.tools.classfile.Instruction;
+import com.sun.tools.classfile.ConstantPool.CONSTANT_Class_info;
+
+import toolbox.JavacTask;
+import toolbox.TestRunner;
+import toolbox.ToolBox;
+
+public class DuplicatedCheckcastTest extends TestRunner {
+    ToolBox tb;
+    ClassFile cf;
+
+    public DuplicatedCheckcastTest() {
+        super(System.err);
+        tb = new ToolBox();
+    }
+
+    public static void main(String[] args) throws Exception {
+        DuplicatedCheckcastTest t = new DuplicatedCheckcastTest();
+        t.runTests();
+    }
+
+    @Test
+    public void testDuplicatedCheckcast() throws Exception {
+        String code = """
+                class IntersectionTypeTest {
+                    interface I1 { }
+                    static class C1 { }
+                    static Object test(Object o) {
+                        return (C1 & I1) o;
+                    }
+                }""";
+        Path curPath = Path.of(".");
+        new JavacTask(tb)
+                .sources(code)
+                .outdir(curPath)
+                .run();
+        cf = ClassFile.read(curPath.resolve("IntersectionTypeTest.class"));
+        ArrayList<Instruction> checkCastList = new ArrayList<>();
+        for (Method method : cf.methods) {
+            if ("test".equals(method.getName(cf.constant_pool))) {
+                Code_attribute code_attribute = (Code_attribute) method.attributes.get(Attribute.Code);
+                for (Instruction instruction : code_attribute.getInstructions()) {
+                    if ("checkcast".equals(instruction.getMnemonic())) {
+                        checkCastList.add(instruction);
+                    }
+                }
+            }
+        }
+        if (checkCastList.size() != 2) {
+            throw new AssertionError("The number of the instruction 'checkcast' is not right. " +
+                    "Expected number: 2, actual number: " + checkCastList.size());
+        }
+        checkClassName(checkCastList.get(0), "IntersectionTypeTest$I1");
+        checkClassName(checkCastList.get(1), "IntersectionTypeTest$C1");
+    }
+
+    public void checkClassName(Instruction ins, String expected) throws Exception {
+        int classIndex = ins.getUnsignedShort(1);
+        CONSTANT_Class_info classInfo = cf.constant_pool.getClassInfo(classIndex);
+        String className = classInfo.getName();
+        if (!expected.equals(className)) {
+            throw new AssertionError("The type of the 'checkcast' is not right. Expected: " +
+                    expected + ", actual: " + className);
+        }
+    }
+}