Very large arrays

General Usage
2 
julia> v = Vector{Char}(undef, typemax(Int))
ERROR: invalid Array size

julia> v = Vector{Char}(undef, typemax(UInt32))
4294967295-element Vector{Char}:
...

julia> v = Vector{Char}(undef, 16typemax(UInt32))
ERROR: OutOfMemoryError() # I have 64Gb

ERROR: invalid Array size

is generated by

https://github.com/JuliaLang/julia/blob/master/src/array.c#L107

while the actual check jl_array_validate_dims is done in

https://github.com/JuliaLang/julia/blob/master/src/array.c#L79-L96

and that error is from

   wideint_t prod = (wideint_t)elsz * (wideint_t)_nel;
   if (prod >= (wideint_t) MAXINTVAL)
        return 2;