8042656: Inference produces spurious error for intersection type bounds check
Summary: Fix subtyping for intersections involving capture variables
Reviewed-by: vromero
--- a/langtools/src/share/classes/com/sun/tools/javac/code/Types.java Fri May 09 09:28:47 2014 -0400
+++ b/langtools/src/share/classes/com/sun/tools/javac/code/Types.java Fri May 09 14:56:59 2014 -0600
@@ -821,8 +821,9 @@
}
// Generally, if 's' is a type variable, recur on lower bound; but
- // for alpha <: CAP, alpha should get upper bound CAP
- if (!t.hasTag(UNDETVAR)) {
+ // for inference variables and intersections, we need to keep 's'
+ // (see JLS 4.10.2 for intersections and 18.2.3 for inference vars)
+ if (!t.hasTag(UNDETVAR) && !t.isCompound()) {
// TODO: JDK-8039198, bounds checking sometimes passes in a wildcard as s
Type lower = cvarLowerBound(wildLowerBound(s));
if (s != lower)
@@ -913,14 +914,11 @@
@Override
public Boolean visitClassType(ClassType t, Type s) {
Type sup = asSuper(t, s.tsym);
- return sup != null
- && sup.tsym == s.tsym
- // You're not allowed to write
- // Vector<Object> vec = new Vector<String>();
- // But with wildcards you can write
- // Vector<? extends Object> vec = new Vector<String>();
- // which means that subtype checking must be done
- // here instead of same-type checking (via containsType).
+ if (sup == null) return false;
+ // If t is an intersection, sup might not be a class type
+ if (!sup.hasTag(CLASS)) return isSubtypeNoCapture(sup, s);
+ return sup.tsym == s.tsym
+ // Check type variable containment
&& (!s.isParameterized() || containsTypeRecursive(s, sup))
&& isSubtypeNoCapture(sup.getEnclosingType(),
s.getEnclosingType());
@@ -1970,16 +1968,18 @@
return t;
Type st = supertype(t);
- if (st.hasTag(CLASS) || st.hasTag(TYPEVAR) || st.hasTag(ERROR)) {
+ if (st.hasTag(CLASS) || st.hasTag(TYPEVAR)) {
Type x = asSuper(st, sym);
if (x != null)
return x;
}
if ((sym.flags() & INTERFACE) != 0) {
for (List<Type> l = interfaces(t); l.nonEmpty(); l = l.tail) {
- Type x = asSuper(l.head, sym);
- if (x != null)
- return x;
+ if (!l.head.hasTag(ERROR)) {
+ Type x = asSuper(l.head, sym);
+ if (x != null)
+ return x;
+ }
}
}
return null;
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/langtools/test/tools/javac/generics/typevars/IntersectionSubVar.java Fri May 09 14:56:59 2014 -0600
@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2014, 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 8042656
+ * @summary Subtyping for intersection types containing type variables
+ * @compile IntersectionSubVar.java
+ */
+
+class IntersectionSubVar {
+
+ interface Box<T> {
+ void set(T arg);
+ T get();
+ }
+
+ <I> Box<I> glb(Box<? super I> arg1, Box<? super I> arg2) {
+ return null;
+ }
+
+ <E extends Cloneable> void takeBox(Box<? super E> box) {}
+
+ <T> void test(Box<T> arg1, Box<Cloneable> arg2, Box<? super T> arg3) {
+ T t = glb(arg1, arg2).get(); // assign T&Cloneable to T
+ takeBox(arg3); // inference tests Box<CAP> <: Box<? super CAP&Cloneable>
+ }
+
+}