jmx-dev

[Alan Bateman]

I don't know if the JMX  team or the JavaBeans maintainers are on the
core-libs-dev mailing list.


When trying to compile OpenJDK with the Eclipse compiler, I noticed two
compiler errors related to generics. It turned out that the code there
is invalid and only javac (incorrectly) accepts it. See the following
bug reports for details:

https://bugs.eclipse.org/bugs/show_bug.cgi?id=212147
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6400189

The attached changeset fixes the problem. Could this be included?

/Roman

--
Dipl.-Inform. (FH) Roman Kennke, Software Engineer, http://kennke.org
aicas Allerton Interworks Computer Automated Systems GmbH
Haid-und-Neu-Straße 18 * D-76131 Karlsruhe * Germany
http://www.aicas.com   * Tel: [phone]
USt-Id: DE216375633, Handelsregister HRB 109481, AG Karlsruhe
Geschäftsführer: Dr. James J. Hunt

[openjdk-compile.patch]

---

# HG changeset patch
# User Roman Kennke <kennke@...>
# Date 1197988258 -3600
# Node ID 2b6c2ce8cd88445d9e3ea709069bf26d53039223
# Parent  37a05a11f281b4d238e2f9e7ebb67c63f64d0e77
Fix compiler problem.

diff -r 37a05a11f281 -r 2b6c2ce8cd88 src/share/classes/com/sun/jmx/mbeanserver/OpenConverter.java
--- a/src/share/classes/com/sun/jmx/mbeanserver/OpenConverter.java Sat Dec 01 00:00:00 2007 +0000
+++ b/src/share/classes/com/sun/jmx/mbeanserver/OpenConverter.java Tue Dec 18 15:30:58 2007 +0100
@@ -1152,7 +1152,7 @@ public abstract class OpenConverter {
             // Also remember the set of properties in that constructor
             // so we can test unambiguity.
             Set<BitSet> getterIndexSets = newSet();
-            for (Constructor constr : annotatedConstrList) {
+            for (Constructor<?> constr : annotatedConstrList) {
                 String[] propertyNames =
                     constr.getAnnotation(propertyNamesClass).value();
 
diff -r 37a05a11f281 -r 2b6c2ce8cd88 src/share/classes/java/beans/MetaData.java
--- a/src/share/classes/java/beans/MetaData.java Sat Dec 01 00:00:00 2007 +0000
+++ b/src/share/classes/java/beans/MetaData.java Tue Dec 18 15:30:58 2007 +0100
@@ -1563,7 +1563,7 @@ class MetaData {
         return names;
     }
 
-    private static String[] getAnnotationValue(Constructor constructor) {
+    private static String[] getAnnotationValue(Constructor<?> constructor) {
         ConstructorProperties annotation = constructor.getAnnotation(ConstructorProperties.class);
         return (annotation != null)
                 ? annotation.value()

---

[eamonn.mcmanus]

Thanks for bringing this to our attention, Alan. Roman is right - the code in question should not compile and we should change it as he suggests so that it is correct.

(For people interested in the gory details, the method
<T extends Annotation> T getAnnotation(Class<T> annotationClass)
returns T only if it is called on a properly generic variable, such as a Constructor<?> or Constructor<? extends Foo> or Constructor<E>. If it is called on a plain Constructor with no type parameter, then that is a "raw type", and the return type is "erased" to Annotation. So something like
ConstructorProperties annotation = constructor.getAnnotation(ConstructorProperties.class)
should not compile if constructor is declared as Constructor rather than Constructor<?> or whatever.)

Alan Bateman wrote:

I don't know if the JMX  team or the JavaBeans maintainers are on the core-libs-dev mailing list.

---

Subject:

Fix compiler problem

From:

Roman Kennke roman.kennke@...

Date:

Tue, 18 Dec 2007 15:32:06 +0100

To:

Core-Libs-Dev core-libs-dev@...

To:

Core-Libs-Dev core-libs-dev@...

When trying to compile OpenJDK with the Eclipse compiler, I noticed two
compiler errors related to generics. It turned out that the code there
is invalid and only javac (incorrectly) accepts it. See the following
bug reports for details:

https://bugs.eclipse.org/bugs/show_bug.cgi?id=212147
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6400189

The attached changeset fixes the problem. Could this be included?

/Roman

  

[sergey.malenkov]

Hi,

Thank you for explanation.
I'll fix it soon.

Thanks,
SAM

Eamonn McManus wrote:

> Thanks for bringing this to our attention, Alan. Roman is right - the
> code in question should not compile and we should change it as he
> suggests so that it is correct.
>
> (For people interested in the gory details, the method
> <T extends Annotation> T getAnnotation
> <http://java.sun.com/javase/6/docs/api/java/lang/reflect/Constructor.html#getAnnotation%28java.lang.Class%29>(Class<T>
> annotationClass)
> returns T only if it is called on a properly generic variable, such as a
> Constructor<?> or Constructor<? extends Foo> or Constructor<E>. If it is
> called on a plain Constructor with no type parameter, then that is a
> "raw type", and the return type is "erased" to Annotation. So something like
> ConstructorProperties annotation =
> constructor.getAnnotation(ConstructorProperties.class)
> should not compile if constructor is declared as Constructor rather than
> Constructor<?> or whatever.)
>
> Éamonn McManus   JMX Spec Lead   http://weblogs.java.net/blog/emcmanus/
>
>
>
> Alan Bateman wrote:
>>
>> I don't know if the JMX  team or the JavaBeans maintainers are on the
>> core-libs-dev mailing list.
>>
>>
>> ------------------------------------------------------------------------
>>
>> Subject:
>> Fix compiler problem
>> From:
>> Roman Kennke <roman.kennke@...>
>> Date:
>> Tue, 18 Dec 2007 15:32:06 +0100
>> To:
>> Core-Libs-Dev <core-libs-dev@...>
>>
>> To:
>> Core-Libs-Dev <core-libs-dev@...>
>>
>>
>> When trying to compile OpenJDK with the Eclipse compiler, I noticed two
>> compiler errors related to generics. It turned out that the code there
>> is invalid and only javac (incorrectly) accepts it. See the following
>> bug reports for details:
>>
>> https://bugs.eclipse.org/bugs/show_bug.cgi?id=212147
>> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6400189
>>
>> The attached changeset fixes the problem. Could this be included?
>>
>> /Roman
>>
>>