Fix rand!/randn! dispatch for non-Number array eltypes

Project.toml

@@ -1,6 +1,6 @@
 name = "GPUArrays"
 uuid = "0c68f7d7-f131-5f86-a1c3-88cf8149b2d7"
-version = "11.5.8"
+version = "11.5.9"
 
 [workspace]
 projects = ["lib/GPUArraysCore", "lib/JLArrays", "test", "docs"]

src/host/random.jl

@@ -447,7 +447,7 @@ end
     end
 end
 
-function Random.rand!(rng::RNG, A::AnyGPUArray{T}) where T <: Number
+function Random.rand!(rng::RNG, A::AnyGPUArray{T}) where T
     isempty(A) && return A
     rand_generic_kernel!(get_backend(A))(rng.seed, rng.counter, A; ndrange=length(A))
     advance_counter!(rng)
@@ -586,7 +586,8 @@ function Random.rand!(rng::RNG{AT}, A::AbstractArray{T}) where {AT, T}
     Random.rand!(rng, B)
     copyto!(A, B)
 end
-function Random.randn!(rng::RNG{AT}, A::AbstractArray{T}) where {AT, T}
+function Random.randn!(rng::RNG{AT}, A::AbstractArray{T}) where {AT, T<:Union{AbstractFloat,
+                                                                             Complex{<:AbstractFloat}}}
     isempty(A) && return A
     B = similar(AT{T}, size(A))
     Random.randn!(rng, B)

test/testsuite/random.jl

@@ -1,3 +1,14 @@
+# A non-`Number` isbits eltype with a custom sampler, mirroring how ColorTypes
+# hooks colorants into the Random API. Exercises the generic element-wise rand!
+# path; regression cover for JuliaGPU/CUDA.jl#3179.
+struct RGBTriplet
+    r::Float32
+    g::Float32
+    b::Float32
+end
+Random.rand(rng::AbstractRNG, ::Random.SamplerType{RGBTriplet}) =
+    RGBTriplet(rand(rng, Float32), rand(rng, Float32), rand(rng, Float32))
+
 @testsuite "random" (AT, eltypes)->begin
     rng = if AT <: AbstractGPUArray
         GPUArrays.RNG{AT}()
@@ -88,4 +99,21 @@
             @test (randn!(cpu_rng, A); true)
         end
     end
+
+    # non-`Number` eltypes with a custom sampler must generate element-wise
+    # rather than hit an ambiguous fallback (JuliaGPU/CUDA.jl#3179)
+    if AT <: AbstractGPUArray
+        @testset "non-Number eltype" begin
+            A = AT{RGBTriplet}(undef, 1024)
+            rand!(rng, A)
+            h = Array(A)
+            @test all(t -> 0f0 <= t.r <= 1f0 && 0f0 <= t.g <= 1f0 && 0f0 <= t.b <= 1f0, h)
+            @test any(t -> t.r != h[1].r, h)
+        end
+
+        # randn! on a non-float eltype must error cleanly, not recurse forever
+        @testset "randn! rejects non-float" begin
+            @test_throws MethodError randn!(rng, AT{Int32}(undef, 4))
+        end
+    end
 end