6315770: javac inference allows creation of strange types: Integer & Runnable
Summary: Javac does not apply glb correctly as per JLS3 15.12.2.8
Reviewed-by: jjg
--- a/langtools/src/share/classes/com/sun/tools/javac/code/Types.java Tue Jan 27 18:38:39 2009 -0800
+++ b/langtools/src/share/classes/com/sun/tools/javac/code/Types.java Thu Jan 29 12:17:57 2009 +0000
@@ -709,12 +709,31 @@
case UNDETVAR:
if (s.tag == WILDCARD) {
UndetVar undetvar = (UndetVar)t;
- undetvar.inst = glb(upperBound(s), undetvar.inst);
- // We should check instantiated type against any of the
- // undetvar's lower bounds.
- for (Type t2 : undetvar.lobounds) {
- if (!isSubtype(t2, undetvar.inst))
- return false;
+ WildcardType wt = (WildcardType)s;
+ switch(wt.kind) {
+ case UNBOUND: //similar to ? extends Object
+ case EXTENDS: {
+ Type bound = upperBound(s);
+ // We should check the new upper bound against any of the
+ // undetvar's lower bounds.
+ for (Type t2 : undetvar.lobounds) {
+ if (!isSubtype(t2, bound))
+ return false;
+ }
+ undetvar.hibounds = undetvar.hibounds.prepend(bound);
+ break;
+ }
+ case SUPER: {
+ Type bound = lowerBound(s);
+ // We should check the new lower bound against any of the
+ // undetvar's lower bounds.
+ for (Type t2 : undetvar.hibounds) {
+ if (!isSubtype(bound, t2))
+ return false;
+ }
+ undetvar.lobounds = undetvar.lobounds.prepend(bound);
+ break;
+ }
}
return true;
} else {
@@ -2825,6 +2844,16 @@
// </editor-fold>
// <editor-fold defaultstate="collapsed" desc="Greatest lower bound">
+ public Type glb(List<Type> ts) {
+ Type t1 = ts.head;
+ for (Type t2 : ts.tail) {
+ if (t1.isErroneous())
+ return t1;
+ t1 = glb(t1, t2);
+ }
+ return t1;
+ }
+ //where
public Type glb(Type t, Type s) {
if (s == null)
return t;
--- a/langtools/src/share/classes/com/sun/tools/javac/comp/Infer.java Tue Jan 27 18:38:39 2009 -0800
+++ b/langtools/src/share/classes/com/sun/tools/javac/comp/Infer.java Thu Jan 29 12:17:57 2009 +0000
@@ -154,33 +154,15 @@
that.inst = syms.objectType;
else if (that.hibounds.tail.isEmpty())
that.inst = that.hibounds.head;
- else {
- for (List<Type> bs = that.hibounds;
- bs.nonEmpty() && that.inst == null;
- bs = bs.tail) {
- // System.out.println("hibounds = " + that.hibounds);//DEBUG
- if (isSubClass(bs.head, that.hibounds))
- that.inst = types.fromUnknownFun.apply(bs.head);
- }
- if (that.inst == null) {
- int classCount = 0, interfaceCount = 0;
- for (Type t : that.hibounds) {
- if (t.tag == CLASS) {
- if (t.isInterface())
- interfaceCount++;
- else
- classCount++;
- }
- }
- if ((that.hibounds.size() == classCount + interfaceCount) && classCount == 1)
- that.inst = types.makeCompoundType(that.hibounds);
- }
- if (that.inst == null || !types.isSubtypeUnchecked(that.inst, that.hibounds, warn))
- throw ambiguousNoInstanceException
- .setMessage("no.unique.maximal.instance.exists",
- that.qtype, that.hibounds);
- }
+ else
+ that.inst = types.glb(that.hibounds);
}
+ if (that.inst == null ||
+ that.inst.isErroneous() ||
+ !types.isSubtypeUnchecked(that.inst, that.hibounds, warn))
+ throw ambiguousNoInstanceException
+ .setMessage("no.unique.maximal.instance.exists",
+ that.qtype, that.hibounds);
}
//where
private boolean isSubClass(Type t, final List<Type> ts) {
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/langtools/test/tools/javac/generics/inference/6315770/T6315770.java Thu Jan 29 12:17:57 2009 +0000
@@ -0,0 +1,42 @@
+/*
+ * Copyright 2009 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/**
+ * @test
+ * @bug 6315770
+ * @summary javac inference allows creation of strange types: Integer & Runnable
+ * @author Maurizio Cimadamore
+ *
+ * @compile/fail/ref=T6315770.out T6315770.java -XDrawDiagnostics
+ */
+
+class T6315770<V> {
+ <T extends Integer & Runnable> T6315770<T> m() {
+ return null;
+ }
+ void test() {
+ T6315770<?> c1 = m();
+ T6315770<? extends String> c2 = m();
+ T6315770<? super String> c3 = m();
+ }
+}
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/langtools/test/tools/javac/generics/inference/6315770/T6315770.out Thu Jan 29 12:17:57 2009 +0000
@@ -0,0 +1,3 @@
+T6315770.java:39:42: compiler.err.undetermined.type.1: <T>T6315770<T>, (- compiler.misc.no.unique.maximal.instance.exists: T, java.lang.String,java.lang.Integer,java.lang.Runnable)
+T6315770.java:40:40: compiler.err.prob.found.req: (- compiler.misc.incompatible.types.1: (- compiler.misc.no.conforming.instance.exists: T, T6315770<T>, T6315770<? super java.lang.String>)), <T>T6315770<T>, T6315770<? super java.lang.String>
+2 errors