Memory allocations regression in julia 1.9 for Tuple{String, String}

[armdavtyan]

Hi there, I’ve come across a notable regression issue in Julia 1.9.3. Would anyone happen to have any insights on this?
Interestingly, the script below doesn’t allocate any memory in Julia 1.8.1, but it leads to 200.00k allocations: 6.104 MiB in Julia 1.9.3.
This seems to be fixed in 1.10-beta3.

function f(arr)
    s = 0
    for el in arr
        if el ∈ ("1", "2")
            s+=1
        end
    end
    return s
end
a = string.(rand(Int, 100000));
@time f(a) # Compilation consumes the majority of the time.
@time f(a) # So, we need to run it a second time

I have investigated the problem and found that the reason for the allocations is the presence of ("1", "2"). To confirm this, you can run the second example.

function g(arr, arg)
    s = 0
    for el in arr
        if el ∈ arg
            s+=1
        end
    end
    return s
end
a = string.(rand(Int, 100000));
b = ("1", "2")
@time g(a, b)
@time g(a, b) # In Julia 1.9.3, allocations will be reduced to 0.

[KristofferC]

Seems fixed on 1.10 at least.

[vtjnash]

The fix was probably #51573