`methods` and `methodswith` asymmetry

[endremborza]

Hello!

I opened a thread on discourse and I was advised to open an issue as well, as it is really difficult to explain behavior:

struct A end

struct B
    a::A
end

println("finds constructor with A param:")
B |> methods |> println
println("does not find constructor with A:")
A |> methodswith |> println

outputs

finds constructor with A param:
# 2 methods for type constructor:
[1] B(a::A) in Main at In[1]:4
[2] B(a) in Main at In[1]:4
does not find constructor with A:
Method[]

this was run on 1.5 but it is clearly present on master as it was pointed out to me to be the result of this line

julia/stdlib/InteractiveUtils/src/InteractiveUtils.jl

Line 192 in 2280efe

if isa(f, Function)

because isa(B, Function) == false as B is a DataType

but technically there is a method with A, so I would classify this as a bug:

bm = methods(B) |> collect |> (x -> x[1])
println(bm |> typeof)
println(bm.sig)

outputs

Method
Tuple{Type{B},A}

I think I'll attempt a PR but I haven't contributed to Julia yet so it will not be straightforward