6995200: JDK 7 compiler crashes when type-variable is inferred from expected primitive type

15.12.2.8 should use boxing when expected type in assignment context is a primitive type

Reviewed-by: jjg

langtools/src/share/classes/com/sun/tools/javac/code/Types.java

@@ -2772,6 +2772,8 @@ public class Types {
     public Type glb(Type t, Type s) {
         if (s == null)
             return t;
+        else if (t.isPrimitive() || s.isPrimitive())
+            return syms.errType;
         else if (isSubtypeNoCapture(t, s))
             return t;
         else if (isSubtypeNoCapture(s, t))
@@ -2927,6 +2929,15 @@ public class Types {
         return reader.enterClass(syms.boxedName[t.tag]);
     }
 
+    /**
+     * Return the boxed type if 't' is primitive, otherwise return 't' itself.
+     */
+    public Type boxedTypeOrType(Type t) {
+        return t.isPrimitive() ?
+            boxedClass(t).type :
+            t;
+    }
+
     /**
      * Return the primitive type corresponding to a boxed type.
      */

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

@@ -305,7 +305,8 @@ public class Infer {
             uv.hibounds = hibounds.toList();
         }
         Type qtype1 = types.subst(that.qtype, that.tvars, undetvars);
-        if (!types.isSubtype(qtype1, to)) {
+        if (!types.isSubtype(qtype1,
+                qtype1.tag == UNDETVAR ? types.boxedTypeOrType(to) : to)) {
             throw unambiguousNoInstanceException
                 .setMessage("infer.no.conforming.instance.exists",
                             that.tvars, that.qtype, to);

langtools/test/tools/javac/generics/inference/6638712/T6638712a.java

@@ -10,7 +10,7 @@ import java.util.*;
 
 class T6638712a {
 
-    <T> Comparator<T> compound(Iterable<? extends Comparator<? super T>> it) {}
+    <T> Comparator<T> compound(Iterable<? extends Comparator<? super T>> it) { return null; }
 
     public void test(List<Comparator<?>> x) {
         Comparator<String> c3 = compound(x);

langtools/test/tools/javac/generics/inference/6995200/T6995200.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2010, 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 6995200
+ *
+ * @summary JDK 7 compiler crashes when type-variable is inferred from expected primitive type
+ * @author mcimadamore
+ * @compile T6995200.java
+ *
+ */
+
+import java.util.List;
+
+class T6995200 {
+    static <T> T getValue() {
+        return null;
+    }
+
+    <X> void test() {
+        byte v1 = getValue();
+        short v2 = getValue();
+        int v3 = getValue();
+        long v4 = getValue();
+        float v5 = getValue();
+        double v6 = getValue();
+        String v7 = getValue();
+        String[] v8 = getValue();
+        List<String> v9 = getValue();
+        List<String>[] v10 = getValue();
+        List<? extends String> v11 = getValue();
+        List<? extends String>[] v12 = getValue();
+        List<? super String> v13 = getValue();
+        List<? super String>[] v14 = getValue();
+        List<?> v15 = getValue();
+        List<?>[] v16 = getValue();
+        X v17 = getValue();
+        X[] v18 = getValue();
+        List<X> v19 = getValue();
+        List<X>[] v20 = getValue();
+        List<? extends X> v21 = getValue();
+        List<? extends X>[] v22 = getValue();
+        List<? super X> v23 = getValue();
+        List<? super X>[] v24 = getValue();
+    }
+}