[erlang-bugs] Bug in random seed (definition?) and random:uniform_s/2

[Heinz Nikolaus Gies]

This might not be critical any more since seed is deprecated but I encountered a problem with random today when passing in hand crafted seeds.

The definition of a seed is: {integer(), integer(), integer()}

The seed was generated by the method suggested in random:seed:
{erlang:phash2([node()]),
 erlang:monotonic_time(),
 erlang:unique_integer()}
This resulted in the seed:

{128631525,-576302453291645741,-576460752303421854}

That seed is valid based on the type specification of seed.

Now entered random:uniform_s/2, by specification it returns a value 1 <= N <= (passed argument) BUT it doesn’t with this seed:

random:uniform_s(10, {128631525,-576302453291645741,-576460752303421854}).
{-1,{23048,-115,-29427}}


Yes I know that  constructing and passing a seed like this is evil,  please don’t get hung on that, it is not my code it’s code I am debugging - I fully agree that it probably should be changed to rand and be done with it, still it looks is a bug.

Cheers,
Heinz

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