assertion num channels compatible with groups

Author: CarloLucibello

src/layers/conv.jl

@@ -128,6 +128,8 @@ julia> Flux.params(c1) |> length
 """
 function Conv(w::AbstractArray{T,N}, b = true, σ = identity;
               stride = 1, pad = 0, dilation = 1, groups = 1) where {T,N}
+
+  @assert size(w, N) % groups == 0 "Output channel dimension must be divisible by groups."
   stride = expand(Val(N-2), stride)
   dilation = expand(Val(N-2), dilation)
   pad = calc_padding(Conv, pad, size(w)[1:N-2], dilation, stride)
@@ -155,6 +157,8 @@ distribution.
 function convfilter(filter::NTuple{N,Integer}, ch::Pair{<:Integer,<:Integer};
           init = glorot_uniform, groups = 1) where N
   cin, cout = ch
+  @assert cin % groups == 0 "Input channel dimension must be divisible by groups."
+  @assert cout % groups == 0 "Output channel dimension must be divisible by groups."
   init(filter..., cin÷groups, cout)
 end
 

test/layers/conv.jl

@@ -81,6 +81,10 @@ end
     c = Conv((3,4,5), 100 => 25, groups = 5)
     @test size(c.weight) == (3,4,5, 20, 25)
     @test size(c(ip)) == (8,8,8, 25, 2)
+
+    # Test that we cannot ask for non-integer multiplication factors
+    @test_throws AssertionError Conv((2, 2), 3=>10, groups=2)
+    @test_throws AssertionError Conv((2, 2), 2=>9, groups=2)
   end
 end