8194554: filterArguments runs multiple filters in the wrong order

Reviewed-by: psandoz, jrose

src/java.base/share/classes/java/lang/invoke/MethodHandles.java

@@ -3766,6 +3766,7 @@ assertEquals("xy", h3.invoke("x", "y", 1, "a", "b", "c"));
      * specified in the elements of the {@code filters} array.
      * The first element of the filter array corresponds to the {@code pos}
      * argument of the target, and so on in sequence.
+     * The filter functions are invoked in left to right order.
      * <p>
      * Null arguments in the array are treated as identity functions,
      * and the corresponding arguments left unchanged.
@@ -3836,11 +3837,12 @@ assertEquals("XY", (String) f2.invokeExact("x", "y")); // XY
     MethodHandle filterArguments(MethodHandle target, int pos, MethodHandle... filters) {
         filterArgumentsCheckArity(target, pos, filters);
         MethodHandle adapter = target;
-        int curPos = pos-1;  // pre-incremented
-        for (MethodHandle filter : filters) {
-            curPos += 1;
+        // process filters in reverse order so that the invocation of
+        // the resulting adapter will invoke the filters in left-to-right order
+        for (int i = filters.length - 1; i >= 0; --i) {
+            MethodHandle filter = filters[i];
             if (filter == null)  continue;  // ignore null elements of filters
-            adapter = filterArgument(adapter, curPos, filter);
+            adapter = filterArgument(adapter, pos + i, filter);
         }
         return adapter;
     }

test/jdk/java/lang/invoke/FilterArgumentsTest.java

@@ -0,0 +1,132 @@
+/*
+ * Copyright (c) 2018, 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 8194554
+ * @run testng/othervm test.java.lang.invoke.FilterArgumentsTest
+ */
+
+package test.java.lang.invoke;
+
+import java.lang.invoke.MethodHandle;
+import java.lang.invoke.MethodHandles;
+import java.util.ArrayList;
+import java.util.List;
+
+import static java.lang.invoke.MethodHandles.*;
+import static java.lang.invoke.MethodType.methodType;
+
+import org.testng.annotations.*;
+import static org.testng.Assert.*;
+
+public class FilterArgumentsTest {
+
+    @Test
+    public static void testFilterA_B_C() throws Throwable {
+        FilterTest test = new FilterTest(
+            filterArguments(MH_TEST, 0, MH_FILTER_A, MH_FILTER_B, MH_FILTER_C));
+        test.run(List.of("A", "B", "C"));
+    }
+
+    @Test
+    public static void testFilterA_B() throws Throwable {
+        FilterTest test = new FilterTest(
+            filterArguments(MH_TEST, 0, MH_FILTER_A, MH_FILTER_B));
+        test.run(List.of("A", "B"));
+    }
+
+    @Test
+    public static void testFilterB_C() throws Throwable {
+        FilterTest test = new FilterTest(
+            filterArguments(MH_TEST, 1, MH_FILTER_B, MH_FILTER_C));
+        test.run(List.of("B", "C"));
+    }
+
+    @Test
+    public static void testFilterB() throws Throwable {
+        FilterTest test = new FilterTest(filterArguments(MH_TEST, 1, MH_FILTER_B));
+        test.run(List.of("B"));
+    }
+
+    @Test
+    public static void testFilterC() throws Throwable {
+        FilterTest test = new FilterTest(filterArguments(MH_TEST, 2, MH_FILTER_C));
+        test.run(List.of("C"));
+    }
+
+    static class FilterTest {
+        static List<String> filters = new ArrayList<>();
+
+        final MethodHandle mh;
+        FilterTest(MethodHandle mh) {
+            this.mh = mh;
+        }
+
+        void run(List<String> expected) throws Throwable {
+            filters.clear();
+            assertEquals("x-0-z", (String)mh.invokeExact("x", 0, 'z'));
+            assertEquals(expected, filters);
+        }
+
+        static String filterA(String s) {
+            filters.add("A");
+            return s;
+        }
+
+        static int filterB(int value) {
+            filters.add("B");
+            return value;
+        }
+
+        static char filterC(char c) {
+            filters.add("C");
+            return c;
+        }
+
+        static String test(String s, int i, char c) {
+            return s + "-" + i + "-" + c;
+        }
+    }
+
+    static final MethodHandle MH_TEST;
+    static final MethodHandle MH_FILTER_A;
+    static final MethodHandle MH_FILTER_B;
+    static final MethodHandle MH_FILTER_C;
+    static final Lookup LOOKUP = MethodHandles.lookup();
+
+    static {
+        try {
+            MH_TEST = LOOKUP.findStatic(FilterTest.class, "test",
+                methodType(String.class, String.class, int.class, char.class));
+            MH_FILTER_A = LOOKUP.findStatic(FilterTest.class, "filterA",
+                methodType(String.class, String.class));
+            MH_FILTER_B = LOOKUP.findStatic(FilterTest.class, "filterB",
+                methodType(int.class, int.class));
+            MH_FILTER_C = LOOKUP.findStatic(FilterTest.class, "filterC",
+                methodType(char.class, char.class));
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+}