a[:,Block.(1:0)] is now empty (#305)

Author: dlfivefifty

Project.toml

@@ -1,6 +1,6 @@
 name = "BlockArrays"
 uuid = "8e7c35d0-a365-5155-bbbb-fb81a777f24e"
-version = "0.16.37"
+version = "0.16.38"
 
 [deps]
 ArrayLayouts = "4c555306-a7a7-4459-81d9-ec55ddd5c99a"

src/views.jl

@@ -11,7 +11,8 @@ function unblock(A, inds, I)
 end
 # Allow `ones(2)[Block(1)[1:1], Block(1)[1:1]]` which is
 # similar to `ones(2)[1:1, 1:1]`.
-unblock(A, ::Tuple{}, I) = BlockSlice(first(I),Base.OneTo(1))
+# Need to check the length of I in case its empty
+unblock(A, ::Tuple{}, I) = BlockSlice(first(I),Base.OneTo(length(I[1])))
 
 to_index(::Block) = throw(ArgumentError("Block must be converted by to_indices(...)"))
 to_index(::BlockIndex) = throw(ArgumentError("BlockIndex must be converted by to_indices(...)"))

test/test_blockarrays.jl

@@ -700,4 +700,12 @@ end
         c = resize!(b,Block(0))
         @test isempty(c)
     end
+
+    @testset "empty indexing of vectors" begin
+        a = mortar([1:3, 2:6])
+        @test size(a[:,Block.(1:0)]) == size(PseudoBlockVector(a)[:,Block.(1:0)]) == (8,0)
+        @test size(a[:,Block.(1:1)]) == size(PseudoBlockVector(a)[:,Block.(1:1)]) == size(a[:,Block(1)]) == (8,1)
+        @test_throws BoundsError a[:,Block.(1:2)]
+        @test size(a[:,1]) == (8,)
+    end
 end