Type changes in scalar computation

[lindahua]

On latest commit, I find:

julia> typeof(-int32(1))
Int64

julia> typeof(ones(Int32,1))
Array{Int32,1}

Actually, any arithmetic operation on Int32 scalars yields Int64 scalar, and operations on Int32 arrays yields Int32 array.

Is this supposed the case? or a bug?

[StefanKarpinski]

This is actually intentional. The idea is that arithmetic always promotes to the system int size since that preserves values and you might as well. For arrays, on the other hand, you don't want to blow your result up if you're working with, e.g. Int16s, then you want the result to still be an Int16 array. Intermediate computations are done with Ints though.

[lindahua]

Thanks for the explanation. This makes sense.

[timholy]

Anyone who really wants to break a bunch of packages should tackle this!

I wonder if we can generalize our promotion system at the same time, see #8027.

[JeffBezanson]

closed by #8420