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8042656: Inference produces spurious error for intersection type bounds check

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Fix subtyping for intersections involving capture variables

Reviewed-by: vromero
This commit is contained in:
Dan Smith 2014-05-09 14:56:59 -06:00
parent 1ad5b0eee1
commit f799e8d6fc
2 changed files with 63 additions and 14 deletions
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28
langtools/src/share/classes/com/sun/tools/javac/code/Types.java
View File

@ -821,8 +821,9 @@ public class Types {
}
// 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 @@ public class Types {
@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 @@ public class Types {
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;

49
langtools/test/tools/javac/generics/typevars/IntersectionSubVar.java Normal file
View File

@ -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>
}
}