[External] Mono gives an incorrect result for BigInteger --> int64 conversion in an obscure case

[ghost]

This is very corner case!!

Mono should raise a System.OverflowException for this obscure case when converting a large negative biginteger to an int64. Instead it returns a positive int64.

open System.Numerics

let x = -1I * BigInteger.Pow(2I,63)
int64 (x - 1I)

// The value is -9223372036854775809
// Mono gives: val it : int64 = 9223372036854775807L
// .NET gives: System.OverflowException

[migueldeicaza]

hello Don,

Why was this issue closed?

[ghost]

Recorded as mono bug https://bugzilla.xamarin.com/show_bug.cgi?id=16526