Performance tips recommend invalid use of `@inbounds`

[LilithHafner]

https://docs.julialang.org/en/v1/manual/performance-tips/#man-performance-annotations (still broken on master)

includes

@noinline function inner(x, y)
    s = zero(eltype(x))
    for i=eachindex(x)
        @inbounds s += x[i]*y[i]
    end
    return s
end

which is UB because eachindex(x) may be out of bounds in y and @inbounds applies to all possible inputs to inner.

It should be eachindex(x, y). Making an issue instead of a PR to avoid conflict with #54211