Method with empty arg list not overwritten by definition of keyword-only method (with no defaults)

[klaff]

See https://discourse.julialang.org/t/im-confused-about-methods/48508/4

In the following snippet, when f()=1 is defined, it should overwrite the previous f(;a)=2 (because dispatch should only be performed on the positional arguments and both of these have no positional arguments). The methods function incorrectly indicates the wrong method survived, and both methods appear to be reachable. Per the discourse discussion, there is some debate on these points!

C:\Users\klaff>julia -q
julia> f(;a)=2
f (generic function with 1 method)

julia> f()=1
f (generic function with 1 method)

julia> methods(f)
# 1 method for generic function "f":
[1] f(; a) in Main at REPL[2]:1

julia> f()
1

julia> f(a=1)
2

julia>

[yuyichao]

Dup of #9498