Fix promote_type(Union{}, Missing/Nothing) and add tests

Without this Dict(1=>missing, 2=>2) returns a Dict{Int,Any}.
JuliaLang · Feb 10, 2018 · ea96757 · ea96757
1 parent 2e49e39
commit ea96757
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Showing 3 changed files with 12 additions and 8 deletions.
diff --git a/base/promotion.jl b/base/promotion.jl
@@ -117,13 +117,13 @@ Falls back to [`typejoin`](@ref).
 promote_typejoin(@nospecialize(a), @nospecialize(b)) =
     (@_pure_meta; join_types(a, b, promote_typejoin))
 promote_typejoin(::Type{Nothing}, ::Type{T}) where {T} =
-    isconcretetype(T) ? Union{T, Nothing} : Any
+    isconcretetype(T) || T === Union{} ? Union{T, Nothing} : Any
 promote_typejoin(::Type{T}, ::Type{Nothing}) where {T} =
-    isconcretetype(T) ? Union{T, Nothing} : Any
+    isconcretetype(T) || T === Union{} ? Union{T, Nothing} : Any
 promote_typejoin(::Type{Missing}, ::Type{T}) where {T} =
-    isconcretetype(T) ? Union{T, Missing} : Any
+    isconcretetype(T) || T === Union{} ? Union{T, Missing} : Any
 promote_typejoin(::Type{T}, ::Type{Missing}) where {T} =
-    isconcretetype(T) ? Union{T, Missing} : Any
+    isconcretetype(T) || T === Union{} ? Union{T, Missing} : Any
 promote_typejoin(::Type{Nothing}, ::Type{Missing}) = Union{Nothing, Missing}
 promote_typejoin(::Type{Missing}, ::Type{Nothing}) = Union{Nothing, Missing}
 promote_typejoin(::Type{Nothing}, ::Type{Nothing}) = Nothing

diff --git a/test/core.jl b/test/core.jl
@@ -139,6 +139,8 @@ for T in (Nothing, Missing)
     @test Base.promote_typejoin(Int, String) === Any
     @test Base.promote_typejoin(Int, Union{Float64, T}) === Any
     @test Base.promote_typejoin(Int, Union{String, T}) === Any
+    @test Base.promote_typejoin(T, Union{}) === T
+    @test Base.promote_typejoin(Union{}, T) === T
 end
 
 @test promote_type(Bool,Bottom) === Bool

diff --git a/test/dict.jl b/test/dict.jl
@@ -165,10 +165,12 @@ end
     @test Dict(1=>1, 2.0=>2) isa Dict{Real,Int}
     @test Dict(1=>1.0, 2.0=>2) isa Dict{Real,Real}
 
-    @test Dict(1=>1, 2=>missing) isa Dict{Int,Union{Int,Missing}}
-    @test Dict(1=>1, 2=>nothing) isa Dict{Int,Union{Int,Nothing}}
-    @test Dict(1=>1, missing=>2) isa Dict{Union{Int,Missing},Int}
-    @test Dict(1=>1, nothing=>2) isa Dict{Union{Int,Nothing},Int}
+    for T in (Nothing, Missing)
+        @test Dict(1=>1, 2=>T()) isa Dict{Int,Union{Int,T}}
+        @test Dict(1=>T(), 2=>2) isa Dict{Int,Union{Int,T}}
+        @test Dict(1=>1, T()=>2) isa Dict{Union{Int,T},Int}
+        @test Dict(T()=>1, 2=>2) isa Dict{Union{Int,T},Int}
+    end
 end
 
 @test_throws KeyError Dict("a"=>2)[Base.secret_table_token]