incorrect method sorting with union in typevar bound

[srp]

The documentation states that methods are selected based off which is the most specific. While not explicitly stated, this generally also seems to be true of constructors. However on 0.4, the following seems to be functioning off the order the constructors are declared in, rather then which is most specific:

type A{O <: Union(Float64,String)}
    A(a) = println("A(a)")
    A(a::Int) = println("A(a::Int)")
end

type B{O <: Union(Float64,String)}
    B(a::Int) = println("B(a::Int)")
    B(a) = println("B(a)")
end

A{Float64}(1)
B{Float64}(1)

Which produces the following output:

A(a)
B(a::Int)

I can't reproduce this on 0.3, only 0.4. I've also only been able to reproduce this when parameterizing the type with a Union.

[simonster]

This seems like a general method sorting bug not restricted to constructors:

julia> type A{T} end

julia> f{T<:Union(Float64,Int)}(::Type{A{T}}, a) = false;

julia> f{T<:Union(Float64,Int)}(::Type{A{T}}, a::Int) = true;

julia> f(A{Float64}, 1)
false

julia> methods(f)
# 2 methods for generic function "f":
f{T<:Union(Float64,Int64)}(::Type{A{T<:Union(Float64,Int64)}},a) at none:1
f{T<:Union(Float64,Int64)}(::Type{A{T<:Union(Float64,Int64)}},a::Int64) at none:1

In this form it's reproducible on 0.3 as well.

[timholy]

Another likely instance of this can be seen in ColorTypes, depending on whether we precompile or not:

tim@diva:~/.julia/v0.5/ColorTypes/test$ julia -q
julia> using ColorTypes

julia> Gray(0.8)
Gray{Float64}(0.8)

julia> 
tim@diva:~/.julia/v0.5/ColorTypes/test$ julia -q
julia> include("../src/ColorTypes.jl")
ColorTypes

julia> using ColorTypes

julia> Gray(0.8)
------------------------------------------------------------------------------------------
StackOverflowError                                      Stacktrace (most recent call last)
[#1] — ColorTypes.Gray{T<:Union{AbstractFloat,Bool,FixedPointNumbers.FixedPoint}}(::Float64)
       ⌙ at types.jl:369 (repeats 80000 times)

StackOverflowError:

[JeffBezanson]

closed by #18457