Interval(1..2, 3..4) crashes Julia

[dpsanders]

[Mistake for IntervalBox.]

[dpsanders]

On 0.6; IA on Julia 0.7 is currently broken.

[Kolaru]

It seems to be a display issue:

julia> Interval(1..2, 3..4)
Error showing value of type IntervalArithmetic.Interval{IntervalArithmetic.Interval{Float64}}:
ERROR: StackOverflowError:

julia> setformat(:full)
6

julia> Interval(1..2, 3..4)
Interval(Interval(1.0, 2.0), Interval(3.0, 4.0))

It doesn't crash the REPL for me (Julia 0.6.4 on Windows) thought.

The StackOverflowError probably means there is an infinite recursive call somewhere, I will try to hunt it down.

[Kolaru]

The crash comes from here:

round_string(x::Real, digits::Int, r::RoundingMode) = round_string(big(x), digits, r)

If x is an Interval, it is a real as well, but big(x) is still an interval. Therefore big(x) never becomes a BigFloat which is needed to switch to another method, hence the infinite recursion.

However, we should probably not silently accept something like Interval(1..2, 3..4)... we could be lenient and return an IntervalBox, which would be very misleading, but works fine, or we could just return an error.

Interestingly enough, this boils down to the fact that since Intervals (and others) are Real we can not assume that Real only means the Integer, Float and BigFloat families, which is related to #181.

[dpsanders]

Thanks for finding the problem!

I think this should just give an error.