On Tue, Oct 16, 2012 at 9:49 PM, Ivan Maidanski <iv...@mail.ru> wrote:
> You're right about emptyList() invocation from subList.
> Thanks.
>
> Updated (and rebased) commit:
> https://github.com/ivmai/classpath/commit/ef3af4f38970f7cea3d5b5a7d98a617f7b23da4e
> (branch: https://github.com/ivmai/classpath/tree/ivmai4review-v3)
>
> diff --git a/ChangeLog b/ChangeLog
> index f78f393..5805463 100644
> --- a/ChangeLog
> +++ b/ChangeLog
> @@ -1,3 +1,19 @@
> +2012-10-16  Ivan Maidanski  <iv...@mail.ru>
> +
> +    * java/util/Collections.java:
> +    (emptySet(), EmptySet.iterator(), emptyList(), emptyMap(),
> +    EmptyMap.entrySet(), EmptyMap.keySet(), EmptyMap.values()): Suppress
> +    "unchecked" warnings.
> +    (emptySet(), emptyList(), emptyMap()): Don't create new instance (use
> +    the corresponding immutable container instance); remove FIXME.
> +    (EmptySet.equals(Object), EmptyList.equals(Object),
> +    EmptyMap.entrySet(), EmptyMap.equals(Object), EmptyMap.keySet(),
> +    EmptyMap.values()): Add generic typing.
> +    (SingletonList.subList(int, int)): Use emptyList() instead of
> +    EMPTY_LIST (to eliminate "unchecked" warning).
> +    (SynchronizedCollection.toArray(T[])): Rename T type to E (to
> +    suppress compiler warning about type hiding).
> +
>  2012-10-15  Andrew John Hughes  <gnu_and...@member.fsf.org>
>
>      * configure.ac: Set to 0.99.1pre, as
> diff --git a/java/util/Collections.java b/java/util/Collections.java
> index 828c6ec..b970dd8 100644
> --- a/java/util/Collections.java
> +++ b/java/util/Collections.java
> @@ -120,10 +120,10 @@ public class Collections
>     * @return an empty parameterized set.
>     * @since 1.5
>     */
> +  @SuppressWarnings("unchecked")
>    public static final <T> Set<T> emptySet()
>    {
> -    /* FIXME: Could this be optimized? */
> -    return new EmptySet<T>();
> +    return (Set<T>) EMPTY_SET;
>    }
>
>    /**> Hi Andrew,
>

> @@ -161,6 +161,7 @@ public class Collections
>       * @return A non-iterating iterator.
>       */
>      // This is really cheating! I think it's perfectly valid, though.
> +    @SuppressWarnings("unchecked")
>      public Iterator<T> iterator()
>      {
>        return (Iterator<T>) EMPTY_LIST.iterator();
> @@ -196,7 +197,7 @@ public class Collections
>       */
>      public boolean equals(Object o)
>      {
> -      return o instanceof Set && ((Set) o).isEmpty();
> +      return o instanceof Set<?> && ((Set<?>) o).isEmpty();
>      }
>
>      /**
> @@ -288,10 +289,10 @@ public class Collections
>     * @return an empty parameterized list.
>     * @since 1.5
>     */
> +  @SuppressWarnings("unchecked")
>    public static final <T> List<T> emptyList()
>    {
> -    /* FIXME: Could this be optimized? */
> -    return new EmptyList<T>();
> +    return (List<T>) EMPTY_LIST;
>    }
>
>    /**
> @@ -369,7 +370,7 @@ public class Collections
>       */
>      public boolean equals(Object o)
>      {
> -      return o instanceof List && ((List) o).isEmpty();
> +      return o instanceof List<?> && ((List<?>) o).isEmpty();
>      }
>
>      /**
> @@ -480,10 +481,10 @@ public class Collections
>     * @return an empty parameterized map.
>     * @since 1.5
>     */
> +  @SuppressWarnings("unchecked")
>    public static final <K,V> Map<K,V> emptyMap()
>    {
> -    /* FIXME: Could this be optimized? */
> -    return new EmptyMap<K,V>();
> +    return (Map<K,V>) EMPTY_MAP;
>    }
>
>    /**
> @@ -511,9 +512,10 @@ public class Collections
>       * There are no entries.
>       * @return The empty set.
>       */
> +    @SuppressWarnings("unchecked")
>      public Set<Map.Entry<K, V>> entrySet()
>      {
> -      return EMPTY_SET;
> +      return (Set<Map.Entry<K, V>>) EMPTY_SET;
>      }
>
>      // The remaining methods are optional, but provide a performance
> @@ -546,7 +548,7 @@ public class Collections
>       */
>      public boolean equals(Object o)
>      {
> -      return o instanceof Map && ((Map) o).isEmpty();
> +      return o instanceof Map<?,?> && ((Map<?,?>) o).isEmpty();
>      }
>
>      /**
> @@ -572,9 +574,10 @@ public class Collections
>       * No entries.
>       * @return The empty set.
>       */
> +    @SuppressWarnings("unchecked")
>      public Set<K> keySet()
>      {
> -      return EMPTY_SET;
> +      return (Set<K>) EMPTY_SET;
>      }
>
>      /**
> @@ -601,9 +604,10 @@ public class Collections
>       * Collection, will work. Besides, that's what the JDK uses!
>       * @return The empty set.
>       */
> +    @SuppressWarnings("unchecked")
>      public Collection<V> values()
>      {
> -      return EMPTY_SET;
> +      return (Collection<V>) EMPTY_SET;
>      }
>
>      /**
> @@ -1854,7 +1858,7 @@ public class Collections
>      public List<T> subList(int from, int to)
>      {
>        if (from == to && (to == 0 || to == 1))
> -        return EMPTY_LIST;
> +        return emptyList();
>        if (from == 0 && to == 1)
>          return this;
>        if (from > to)
> @@ -2480,7 +2484,7 @@ public class Collections
>       * @throws ArrayStoreException if the type of any element of the
>       *         collection is not a subtype of the element type of a.
>       */
> -    public <T> T[] toArray(T[] a)
> +    public <E> E[] toArray(E[] a)
>      {
>        synchronized (mutex)
>          {
>
>

Andrew, can you take a look at this, please?

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