make union(::Tuple,...) work again (fix #25338) (#25354)

Author: rfourquet

base/abstractarray.jl

@@ -595,6 +595,7 @@ empty(a::AbstractVector{T}, ::Type{U}=T) where {T,U} = Vector{U}()
 
 # like empty, but should return a mutable collection, a Vector by default
 emptymutable(a::AbstractVector{T}, ::Type{U}=T) where {T,U} = Vector{U}()
+emptymutable(itr, ::Type{U}) where {U} = Vector{U}()
 
 ## from general iterable to any array
 
@@ -2043,4 +2044,4 @@ function hash(a::AbstractArray{T}, h::UInt) where T
     end
     !isequal(x2, x1) && (h = hash(x2, h))
     return h
-end
+end

test/arrayops.jl

@@ -941,6 +941,15 @@ end
     @test isequal(symdiff([1,2,3], Float64[]), Float64[1.0,2,3])
     @test isequal(symdiff(Int64[], [1,2,3]), Int64[1,2,3])
     @test isequal(symdiff(Int64[]), Int64[])
+    @testset "tuples" begin # Issue #25338
+        @test union((1, 2), (3)) == [1, 2, 3]
+        u = union((1, 0x2), [3])
+        @test eltype(u) == Integer
+        @test u == [1, 2, 3]
+        @test intersect((1, 2), (3, 2)) == [2]
+        @test setdiff((1, 2), (3, 2)) == [1]
+        @test symdiff((1, 2), (3, 2)) == [1, 3]
+    end
 end
 
 @testset "mapslices" begin