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Re: [linuxtools-dev] Eclipse Build 0.6.0?
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After bringing all the dependencies up to date and jumping through the usual hoops, I get hit with this:
@dot:
[mkdir] Created dir: /var/tmp/portage/dev-util/eclipse-sdk-3.6.0/work/eclipse-build-0.6.0/build/eclipse-3.6.0-src/plugins/org.eclipse.equinox.p2.metadata/@dot
[javac] Compiling 140 source files to /var/tmp/portage/dev-util/eclipse-sdk-3.6.0/work/eclipse-build-0.6.0/build/eclipse-3.6.0-src/plugins/org.eclipse.equinox.p2.metadata/@dot
[javac] /var/tmp/portage/dev-util/eclipse-sdk-3.6.0/work/eclipse-build-0.6.0/build/eclipse-3.6.0-src/plugins/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/expression/CompoundIterator.java:28: type parameters of <T>T cannot be determined; no unique maximal instance exists for type variable T with upper bounds T,java.lang.Object
[javac] private T nextObject = noElement();
[javac] ^
[javac] /var/tmp/portage/dev-util/eclipse-sdk-3.6.0/work/eclipse-build-0.6.0/build/eclipse-3.6.0-src/plugins/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/expression/CompoundIterator.java:51: type parameters of <T>T cannot be determined; no unique maximal instance exists for type variable T with upper bounds T,java.lang.Object
[javac] nextObject = noElement();
[javac] ^
[javac] /var/tmp/portage/dev-util/eclipse-sdk-3.6.0/work/eclipse-build-0.6.0/build/eclipse-3.6.0-src/plugins/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/expression/MatchIteratorFilter.java:24: type parameters of <T>T cannot be determined; no unique maximal instance exists for type variable T with upper bounds T,java.lang.Object
[javac] private T nextObject = noElement();
[javac] ^
[javac] /var/tmp/portage/dev-util/eclipse-sdk-3.6.0/work/eclipse-build-0.6.0/build/eclipse-3.6.0-src/plugins/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/expression/MatchIteratorFilter.java:39: type parameters of <T>T cannot be determined; no unique maximal instance exists for type variable T with upper bounds T,java.lang.Object
[javac] nextObject = noElement();
[javac] ^
[javac] Note: Some input files use or override a deprecated API.
[javac] Note: Recompile with -Xlint:deprecation for details.
[javac] Note: /var/tmp/portage/dev-util/eclipse-sdk-3.6.0/work/eclipse-build-0.6.0/build/eclipse-3.6.0-src/plugins/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/expression/Everything.java uses unchecked or unsafe operations.
[javac] Note: Recompile with -Xlint:unchecked for details.
[javac] 4 errors
The code referenced by the errors above looks pretty sketchy. The noElement() methods are examples of the "returns an instance of any type you think it should" anti-pattern:
private static <T> T noElement() {
return (T) NO_ELEMENT;
}
Unless NO_ELEMENT is null (which it isn't), that code cannot possibly be correct. The compiler is right to complain about it. Please see the attached patch for a correct implementation that compiles cleanly.
After applying the attached patch, Eclipse 3.6 builds successfully on Gentoo. :-)
On Monday, 9 August 2010, at 4:43 pm, Andrew Overholt wrote:
> * Matt Whitlock <matt@xxxxxxxxxxxxx> [2010-08-09 16:39]:
> > Linux Tools 0.6.0 has been out for a while, but there is still no Eclipse Build 0.6.0?
>
> I'm going to tag it tomorrow :) In the meantime, can you build from SVN
> trunk with this tarball and see if it all works on Gentoo?
>
> http://www.eclipse.org/downloads/download.php?file=/technology/linuxtools/eclipse-build/e36-branch/eclipse-3.6.0-src-noxpt.tar.bz2
--- plugins/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/expression/CompoundIterator.java~ 2010-02-19 12:12:49.000000000 +0000
+++ plugins/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/expression/CompoundIterator.java 2010-08-09 23:16:39.201246659 +0000
@@ -25,7 +25,7 @@
private final Iterator<? extends Object> iteratorIterator;
private Iterator<T> currentIterator;
- private T nextObject = noElement();
+ private Object nextObject = NO_ELEMENT;
/**
* Creates a compound iterator that will iterated over the elements
@@ -47,8 +47,9 @@
if (!positionNext())
throw new NoSuchElementException();
- T nxt = nextObject;
- nextObject = noElement();
+ @SuppressWarnings("unchecked")
+ T nxt = (T) nextObject;
+ nextObject = NO_ELEMENT;
return nxt;
}
@@ -76,9 +77,4 @@
nextObject = currentIterator.next();
return true;
}
-
- @SuppressWarnings("unchecked")
- private static <T> T noElement() {
- return (T) NO_ELEMENT;
- }
-}
\ No newline at end of file
+}
--- plugins/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/expression/MatchIteratorFilter.java~ 2010-02-19 12:12:48.000000000 +0000
+++ plugins/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/expression/MatchIteratorFilter.java 2010-08-09 23:20:33.572246380 +0000
@@ -21,7 +21,7 @@
private final Iterator<? extends T> innerIterator;
- private T nextObject = noElement();
+ private Object nextObject = NO_ELEMENT;
public MatchIteratorFilter(Iterator<? extends T> iterator) {
this.innerIterator = iterator;
@@ -35,8 +35,9 @@
if (!positionNext())
throw new NoSuchElementException();
- T nxt = nextObject;
- nextObject = noElement();
+ @SuppressWarnings("unchecked")
+ T nxt = (T) nextObject;
+ nextObject = NO_ELEMENT;
return nxt;
}
@@ -63,9 +64,4 @@
}
return false;
}
-
- @SuppressWarnings("unchecked")
- private static <T> T noElement() {
- return (T) NO_ELEMENT;
- }
-}
\ No newline at end of file
+}
