add tests

JuliaLang#2552, JuliaLang#8625, JuliaLang#8915, JuliaLang#11407

test/subtype.jl

@@ -915,3 +915,27 @@ ftwoparams(::TwoParams{<:Real,<:Real}) = 3
 # supertype operator
 @test !(Int >: Integer)
 @test Integer >: Int
+
+# #2552
+typealias DiagDict{T} Dict{T,T}
+f2552(::Dict) = 1
+f2552(::DiagDict) = 2
+@test f2552(Dict(1 => "a")) == 1
+@test f2552(Dict(1 => 1)) == 2
+
+# #8625
+typealias CV8625{T<:Real} Vector{Complex{T}}
+@test isa([2.0+3.0im],CV8625)
+
+# #8915
+type D8915{T <: Union{Float32,Float64}}
+    D8915(a) = 1
+    D8915(a::Int) = 2
+end
+@test D8915{Float64}(1) = 2
+
+# #11407
+f11407{K,V}(::Dict{K,V},::Dict{Any,V}) = 1
+f11407{K,V}(::Dict{K,V},::Dict{K,Any}) = 2
+d = Dict{Any,Any}()
+@test_throws MethodError f11407(d,d)