8141613: Compiler fails to infer generic type
Summary: Repeated capture of same expression leads to erroneous inference constraints
Reviewed-by: vromero
--- a/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Attr.java Mon Nov 09 16:03:30 2015 +0000
+++ b/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Attr.java Tue Nov 10 11:49:14 2015 +0000
@@ -1890,7 +1890,8 @@
// Check that value of resulting type is admissible in the
// current context. Also, capture the return type
- result = check(tree, capture(restype), KindSelector.VAL, resultInfo);
+ Type capturedRes = resultInfo.checkContext.inferenceContext().cachedCapture(tree, restype, true);
+ result = check(tree, capturedRes, KindSelector.VAL, resultInfo);
}
chk.validate(tree.typeargs, localEnv);
}
--- a/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Infer.java Mon Nov 09 16:03:30 2015 +0000
+++ b/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Infer.java Tue Nov 10 11:49:14 2015 +0000
@@ -372,6 +372,9 @@
resultInfo, inferenceContext);
}
}
+ } else if (rsInfoInfContext.free(resultInfo.pt)) {
+ //propagation - cache captured vars
+ qtype = inferenceContext.asUndetVar(rsInfoInfContext.cachedCapture(tree, from, false));
}
Assert.check(allowGraphInference || !rsInfoInfContext.free(to),
"legacy inference engine cannot handle constraints on both sides of a subtyping assertion");
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/langtools/test/tools/javac/generics/inference/8141613/T8141613.java Tue Nov 10 11:49:14 2015 +0000
@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2015, 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. Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * 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 8141613
+ * @summary Compiler fails to infer generic type
+ * @compile T8141613.java
+ */
+class T8141613 {
+
+ static class Sub<V, L> implements Sup<V, L> {
+ Sub(Bar<V> barv) { }
+ }
+
+ interface Bar<V> { }
+
+ interface Sup<V, L> { }
+
+ <L> void test() {
+ Sup<?, L> res1 = makeSub(makeBar());
+ Sup<?, L> res2 = new Sub<>(makeBar());
+ }
+
+ <S, U> Sub<S, U> makeSub(Bar<S> bars) { return null; }
+
+ <B> Bar<?> makeBar() {
+ return null;
+ }
+}