add repr for empty multidimensional arrays

[stevengj]

Fixes #19840.

julia> print(Array{Int}(0))
Int64[]
julia> print(Array{Int}(0,0))
Array{Int64}(0,0)
julia> print(Array{Int}(0,5))
Array{Int64}(0,5)

[ararslan]

For consistency with how we print non-empy arrays, should the number of dimensions also be included in the brackets? That is,

julia> print(Array{Int}(0,0))
Array{Int64,2}(0,0)

[stevengj]

@ararslan, for non-empty arrays print does not display {...} at all.

julia> print(Array{Bool}(2,3,2))
Bool[false true true; false false false]

Bool[false false false; false false false]

[stevengj]

Note that this patch does not affect the summary header in the multi-line output:

julia> Array{Int}(0,0,0)
0×0×0 Array{Int64,3}

It only affects the show(io, x) output (e.g. for repr, print, etcetera), which otherwise was printing nothing.

[stevengj]

(Which is not to say we can't print the number of dimensions in the repr, just that there is no need to do so for consistency's sake. I chose not to print it because it was redundant.)

[ararslan]

Okay, thanks for the explanation. That makes sense. I guess I was thinking of the summary header in the multiline output, which doesn't correspond directly to this.

[stevengj]

Should be good to merge; the Travis failure is the unrelated x86 problem we are having nowadays.