8016702: use of ternary operator in lambda expression gives incorrect results

Constant types erroneously creep in during inference

Reviewed-by: jjg, vromero

langtools/src/share/classes/com/sun/tools/javac/comp/Attr.java

@@ -2392,7 +2392,7 @@ public class Attr extends JCTree.Visitor {
 
             ResultInfo bodyResultInfo = lambdaType.getReturnType() == Type.recoveryType ?
                 recoveryInfo :
-                new ResultInfo(VAL, lambdaType.getReturnType(), funcContext);
+                new LambdaResultInfo(lambdaType.getReturnType(), funcContext);
             localEnv.info.returnResult = bodyResultInfo;
 
             Log.DeferredDiagnosticHandler lambdaDeferredHandler = new Log.DeferredDiagnosticHandler(log);
@@ -2584,6 +2584,28 @@ public class Attr extends JCTree.Visitor {
             }
         }
 
+        class LambdaResultInfo extends ResultInfo {
+
+            LambdaResultInfo(Type pt, CheckContext checkContext) {
+                super(VAL, pt, checkContext);
+            }
+
+            @Override
+            protected Type check(DiagnosticPosition pos, Type found) {
+                return super.check(pos, found.baseType());
+            }
+
+            @Override
+            protected ResultInfo dup(CheckContext newContext) {
+                return new LambdaResultInfo(pt, newContext);
+            }
+
+            @Override
+            protected ResultInfo dup(Type newPt) {
+                return new LambdaResultInfo(newPt, checkContext);
+            }
+        }
+
         /**
         * Lambda compatibility. Check that given return types, thrown types, parameter types
         * are compatible with the expected functional interface descriptor. This means that:

langtools/test/tools/javac/conditional/T8016702.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright (c) 2013, 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 8016702
+ * @summary use of ternary operator in lambda expression gives incorrect results
+ */
+import java.util.Arrays;
+import java.util.List;
+
+public class T8016702 {
+
+    static int assertionCount;
+
+    static void assertTrue(boolean b, String msg) {
+        assertionCount++;
+        if (!b) {
+            throw new AssertionError(msg);
+        }
+    }
+
+    interface IntFunction<Y> {
+        Y m(int x);
+    }
+
+    void test(List<Integer> li) {
+        map(i -> (i % 2 == 0) ? "" : "i="+i, li);
+    }
+
+
+    @SuppressWarnings("unchecked")
+    <R> void map(IntFunction<R> mapper, List<Integer> li) {
+        for (int i : li) {
+            String res = (String)mapper.m(i);
+            assertTrue((i % 2 == 0) ? res.isEmpty() : res.contains("" + i),
+                    "i = " + i + " res = " + res);
+        }
+    }
+
+    public static void main(String[] args) {
+        T8016702 tester = new T8016702();
+        tester.test(Arrays.asList(0, 1, 2, 3, 4, 5, 6, 7, 8, 9));
+        assertTrue(assertionCount == 10, "wrong assertion count: " + assertionCount);
+    }
+}