Properly handle reducing complex numbers with abs2

Imitating what is done with `abs`

Author: Sleort

src/mapreduce.jl

@@ -58,6 +58,7 @@ gpu_promote_type(::typeof(Base.mul_prod), ::Type{T}) where {T<:Number} = typeof(
 gpu_promote_type(::typeof(max), ::Type{T}) where {T<: WidenReduceResult} = T
 gpu_promote_type(::typeof(min), ::Type{T}) where {T<: WidenReduceResult} = T
 gpu_promote_type(::typeof(abs), ::Type{Complex{T}}) where {T} = T
+gpu_promote_type(::typeof(abs2), ::Type{Complex{T}}) where {T} = T
 
 import Base.Broadcast: Broadcasted, ArrayStyle
 const GPUSrcArray = Union{Broadcasted{ArrayStyle{AT}}, GPUArray{T, N}} where {T, N, AT<:GPUArray}

test/testsuite/mapreduce.jl

@@ -30,6 +30,8 @@ function test_mapreduce(AT)
                         @test compare(prod, AT, rand(range, dims))
                         @test compare(x -> sum(abs, x),  AT, rand(range, dims))
                         @test compare(x -> prod(abs, x), AT, rand(range, dims))
+                        @test compare(x -> sum(abs2, x),  AT, rand(range, dims))
+                        @test compare(x -> prod(abs2, x), AT, rand(range, dims))
                         ET <: Complex || @test compare(maximum, AT,rand(range, dims))
                         ET <: Complex || @test compare(minimum, AT,rand(range, dims))
                     end