Fix copyto! when supports don't match (#216)

* Fix copyto! when supports don't match

* Add tests

Author: dlfivefifty

Project.toml

@@ -1,6 +1,6 @@
 name = "BlockArrays"
 uuid = "8e7c35d0-a365-5155-bbbb-fb81a777f24e"
-version = "0.16.18"
+version = "0.16.19"
 
 [deps]
 ArrayLayouts = "4c555306-a7a7-4459-81d9-ec55ddd5c99a"

src/BlockArrays.jl

@@ -40,7 +40,7 @@ import LinearAlgebra: lmul!, rmul!, AbstractTriangular, HermOrSym, AdjOrTrans,
 import ArrayLayouts: _fill_lmul!, MatMulVecAdd, MatMulMatAdd, MatLmulVec, MatLdivVec,
                         materialize!, MemoryLayout, sublayout, transposelayout, conjlayout,
                         triangularlayout, triangulardata, _inv, _copyto!, axes_print_matrix_row,
-                        colsupport, rowsupport, sub_materialize
+                        colsupport, rowsupport, sub_materialize, zero!
 
 include("blockindices.jl")
 include("blockaxis.jl")

src/blockindices.jl

@@ -40,6 +40,7 @@ Block(n::NTuple{N, T}) where {N,T} = Block{N, T}(n)
 # iterate and broadcast like Number
 length(b::Block) = 1
 size(b::Block) = ()
+last(b::Block) = b
 iterate(x::Block) = (x, nothing)
 iterate(x::Block, ::Any) = nothing
 isempty(x::Block) = false

src/blocklinalg.jl

@@ -138,8 +138,18 @@ function _copyto!(_, ::AbstractBlockLayout, dest::AbstractMatrix, src::AbstractM
         return dest
     end
 
-    @inbounds for J = blockaxes(src,2),K = blockcolsupport(src,J)
-        copyto!(view(dest,K,J), view(src,K,J))
+    @inbounds for J = blockaxes(src,2)
+        CS_s = blockcolsupport(src,J)
+        CS_d = blockcolsupport(dest,J)
+        for K = first(CS_d):first(CS_s)-Block(1)
+            zero!(view(dest,K,J))
+        end
+        for K = CS_s 
+            copyto!(view(dest,K,J), view(src,K,J))
+        end
+        for K = last(CS_s)+Block(1):last(CS_d)
+            zero!(view(dest,K,J))
+        end
     end
     dest
 end

test/test_blockarrayinterface.jl

@@ -125,6 +125,7 @@ end
     @test A[Block(1, 2)] == [0 0]
     @test_throws BlockBoundsError A[Block(1, 3)]
     @test A == [1 2 0 0; 0 0 1 2]
+    @test BlockArray(A) == A
 
     N = 3
     D = Diagonal(mortar(Fill.(-(0:N) - (0:N) .^ 2, 1:2:2N+1)))