Inconsistent behaviour of argmax

[aplavin]

`findmax` and friends: confusing behaviour to be introduced in 1.7

Several people, including myself, have tried to raise this issue during last months. There were multiple posts on slack, and even a GH issue (https://github.com/JuliaLang/julia/issues/39203). I’ll try to raise it once more, here on discourse, hoping that it gets more traction. The findmax(A) function, which everyone is used to, returns the maximum value in the array A and its index. However, Julia 1.7 will introduce a findmax(f, A) version, that doesn’t return any index at all: julia> A = [5, …