Catching deprecated keyword arguments (with Parameters.jl)

General Usage
1

Consider a struct like

@with_kw struct MyStruct
    a::Int = 3
    b::Int = 5
end

b is no longer needed, so I am looking to deprecate it in the future, changing to

@with_kw struct MyStruct
    a::Int = 3
end

Now, if someone uses MyStruct(b=1), this obviously results in MethodError: no method matching MyStruct(; b=3). There is a somewhat similar question here. I know I could just leave b in the struct for some time (preventing the error), but I am looking for a “nice” way to trigger a warning. Is there anything in Parameters.jl that I could use?

(I thought about using a custom constructor, but since I’m not using positional arguments, that seems impossible since Parameters.jl states: no zero-positional arguments constructor is defined)