Iteration causes many allocations

[roflmaostc]

Some IFAs such as (rr2, rr, normal) cause allocations.
Strangely, window_hamming doesn't.

using IndexFunArrays


function main_bug(; N=4096)
    els = rr2(Int, (N, N)) 

    s = zero(eltype(els))

    for e in els 
        if e > 100
            s += 1
        end 
    end 
    return s
end

# 
julia> @time main_bug(; N=1000)
  0.061883 seconds (3.00 M allocations: 106.787 MiB, 22.70% gc time)

collecting fixes it, so it is related to IndexFunArrays.

using IndexFunArrays


function main_bug(; N=4096)
    els = collect(rr2(Int, (N, N)))

    s = zero(eltype(els))

    for e in els 
        if e > 100
            s += 1
        end 
    end 
    return s
end

# 
julia> @time main_bug(; N=1000)
  0.007953 seconds (7 allocations: 7.630 MiB, 84.24% gc time)

[RainerHeintzmann]

Maybe we need to write a specialized iterator?
This code does not cause the extra allocations:

julia> @time sum(rr((1000,1000)) .> 100.0)
  0.001440 seconds (4 allocations: 126.406 KiB)