Check for zero length index in copyto! and same length of the indices (#169)

* Check for zero length index in copyto! and same length of the indices

The check for the same length of the indices is copied from the behaviour of copyto! on normal arrays.

* Remove println

* Replace any(==(0)) with isempty

Co-authored-by: Fabian Gans <[email protected]>

---------

Co-authored-by: Fabian Gans <[email protected]>

Author: felixcremer

src/array.jl

@@ -61,8 +61,18 @@ function _copyto!(dest::AbstractArray, source::AbstractArray)
     reshape(dest, size(source)) .= source
     return dest
 end
-_copyto!(dest, Rdest, src, Rsrc) = view(dest, Rdest) .= view(src, Rsrc)
 
+function _copyto!(dest, Rdest, src, Rsrc)
+    if size(Rdest) != size(Rsrc)
+        throw(ArgumentError("source and destination must have same size (got $(size(Rsrc)) and $(size(Rdest)))"))
+    end
+
+    if isempty(Rdest)
+        # This check is here to catch #168
+        return dest
+    end
+    view(dest, Rdest) .= view(src, Rsrc)
+end
 # Use a view for lazy reverse
 _reverse(a, ::Colon) = _reverse(a, ntuple(identity, ndims(a)))
 _reverse(a, dims::Int) = _reverse(a, (dims,))

test/runtests.jl

@@ -663,6 +663,12 @@ end
         copyto!(x, a_disk)
         @test x == a
         copyto!(x, CartesianIndices((1:3, 1:2)), a_disk, CartesianIndices((8:10, 8:9)))
+        # Test copyto! with zero length index
+        x_empty = Matrix{Int64}(undef, 0,2)
+        copyto!(x_empty, CartesianIndices((1:0, 1:2)), a_disk, CartesianIndices((8:7, 8:9)))
+        # copyto! with different length should throw an error
+        @test_throws ArgumentError copyto!(x, CartesianIndices((1:1, 1:2)), a_disk, CartesianIndices((4:6, 8:9)))
+
     end
 
     @test collect(reverse(a_disk)) == reverse(a)