Support conv_direct! on custom datatypes (#592)

* Add test for unusual input datatypes

* Add fix to `conv_direct!`

* Only set y to zero if beta is false or zero

* Test output eltype

src/impl/conv_direct.jl

@@ -81,6 +81,11 @@ function conv_direct!(
     # Use `calc_padding_regions` to determine where we do or don't need to worry about padding
     padded_regions, central_region = calc_padding_regions(cdims)
 
+    # Set outputs to zero to support custom datatypes (https://github.com/FluxML/NNlib.jl/issues/490)
+    if iszero(beta)
+        y = fill!(y, zero(yT))
+    end
+
     # Start with the central region
     w_region, h_region, d_region = central_region
     @inbounds for batch in 1:size(x, 5),

test/conv.jl

@@ -2,6 +2,7 @@ using NNlib, Test
 using NNlib: input_size, kernel_size, channels_in, channels_out, channel_multiplier,
              stride, padding, dilation, flipkernel, output_size,
              groupcount
+using Random: AbstractRNG, SamplerType
 
 @testset "ConvDims" begin
     for T in (DenseConvDims, DepthwiseConvDims)
@@ -865,6 +866,44 @@ end
     @test size(NNlib.∇conv_filter_direct!(w, x, y, cdims)) == w_size
 end
 
+# https://github.com/FluxML/NNlib.jl/issues/490
+# https://github.com/FluxML/NNlib.jl/issues/405
+@testset "conv_direct! - Unusual input types" begin
+    # Create test type that can't be indexed when undefined.
+    # This simulates the worst-case scenario for custom types.
+    struct MyFloat <: Real
+        set::Set{Float32}
+    end
+
+    # Test that direct indexing fails when undefined.
+    v = Array{MyFloat}(undef, 3)
+    @test_throws UndefRefError v[1]
+
+    # Define minimal set of functions required for conv_direct!
+    MyFloat(x::MyFloat) = x
+    MyFloat(x::Real) = MyFloat(Set(Float32(x)))
+
+    Base.:+(x::MyFloat, y::MyFloat) = MyFloat(only(x.set) + only(y.set))
+    Base.:*(x::MyFloat, y::MyFloat) = MyFloat(only(x.set) * only(y.set))
+    Base.promote_rule(::Type{MyFloat}, ::Type{Float32})   = MyFloat
+    Base.rand(::AbstractRNG, ::SamplerType{MyFloat}) = MyFloat(rand(Float32))
+    Base.zero(::MyFloat) = MyFloat(zero(Float32))
+    Base.zero(::Type{MyFloat}) = MyFloat(zero(Float32))
+
+    # Test conv_direct!
+    x_size = (6, 7, 8, 5, 3)
+    y_size = (5, 6, 7, 4, 3)
+    w_size = (2, 2, 2, 5, 4)
+    x = rand(MyFloat, x_size);
+    w = randn(Float32, w_size);
+    y = Array{MyFloat}(undef, y_size...);
+    cdims = DenseConvDims(x_size, w_size)
+    y_out = NNlib.conv_direct!(y, x, w, cdims)
+
+    @test eltype(y_out) == MyFloat
+    @test size(y_out) == y_size
+end
+
 @testset "AutoDiff: spatial_rank=$spatial_rank" for spatial_rank in (1, 2, 3)
   x = rand(rng, repeat([5], spatial_rank)..., 3, 2)
   w = rand(rng, repeat([3], spatial_rank)..., 3, 3)