immutable.HashMap.size() can be induced to return -1

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I'm using 2.7.1-RC1. this code:

val m = new collection.immutable.HashMap[Int,Int]
println(m.size)
m(1) = 1
println(m.size)

prints:

0
-1

shouldn't the -1 be 0?

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Imported From: https://issues.scala-lang.org/browse/SI-768?orig=1
Reporter: @SethTisue

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@odersky said:
fixed in r14704

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@ijuma said:
It seems like the same bug affects immutable.HashSet too:

    val m = new collection.immutable.HashSet[Int]
    println(m.size)
    m + 1
    println(m.size)

prints exactly the same as the report here. The fix only seems to fix HashMap.

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@odersky said:
Thanks for having spotted this. It's fixed now in HashSet as well.

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@ijuma said:
Thanks. :)

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@ijuma said:
I was curious if the immutable.HashSet part of the fix would have any effect on ticket #454. While testing it, it seems like #454 is the same as this but the immutable.HashSet fix is incorrect. It does:

s += tableSize 

instead of

s += m.tableSize 

So, once you fix the "fix", feel free to close #454 too. :)

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@ijuma said:
Just for reference, this is now completely fixed in r14727.

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@odersky said:
Milestone next_bugfix deleted