RFR: 8180352: Add Stream.toList() method [v3]

[Rémi Forax]

On Thu, 5 Nov 2020 17:26:48 GMT, Stuart Marks <smarks at openjdk.org> wrote:

>> src/java.base/share/classes/java/util/ImmutableCollections.java line 199:
>> 
>>> 197:      * safely reused as the List's internal storage, avoiding a defensive copy. Declared
>>> 198:      * with Object... instead of E... as the parameter type so that varargs calls don't
>>> 199:      * accidentally create an array of type other than Object[].
>> 
>> Why would that be a problem? If the resulting list is immutable, then the actual array type doesn't really matter, right?
>
> It's an implementation invariant that the internal array be Object[]. Having it be something other than Object[] can lead to subtle bugs. See [JDK-6260652](https://bugs.openjdk.java.net/browse/JDK-6260652) for example.

you can still calls the varargs with an already created array
listFromTrustedArray(new String[] { "foo" });

I think at least an assert is missing
assert input.getClass() == Object.class;

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PR: https://git.openjdk.java.net/jdk/pull/1026