unused-import

Flag an explicitly imported name that is never used: import X, import X as Y, and the colon-item forms using X: a / import X: a. The whole-module using X form is exempt, since it attaches exports that resolve elsewhere. A qualified use (X.f) or a re-export counts as a use.

sortperm is imported but never referenced:

using Base: sortperm, sum

println(sum([1, 2, 3]))

example.jl:1:13: warning[unused-import] `sortperm` is imported but never used