Fix \ for sparse matrices with LayoutArray right-hand sides

Project.toml

@@ -1,6 +1,6 @@
 name = "ArrayLayouts"
 uuid = "4c555306-a7a7-4459-81d9-ec55ddd5c99a"
-version = "1.15"
+version = "1.15.1"
 authors = ["Sheehan Olver <solver@mac.com>"]
 
 [deps]

ext/ArrayLayoutsSparseArraysExt.jl

@@ -6,6 +6,7 @@ using SparseArrays
 # Specifying the full namespace is necessary because of https://github.com/JuliaLang/julia/issues/48533
 # See https://github.com/JuliaStats/LogExpFunctions.jl/pull/63
 import ArrayLayouts.LinearAlgebra
+using ArrayLayouts.LinearAlgebra: Adjoint, Transpose, Symmetric, Hermitian, Diagonal, UpperTriangular, UnitUpperTriangular, LowerTriangular, UnitLowerTriangular
 
 import Base: copyto!, ==
 
@@ -23,6 +24,22 @@ copyto!(dest::SubArray{<:Any,2,<:LayoutMatrix}, src::SparseArrays.AbstractSparse
 	ArrayLayouts.dot(a,b)
 
 
+# ambiguity between \ for sparse matrices and the layout overloads of \ (see @layoutldiv).
+# SparseArrays' solvers need strided right-hand sides, so convert to Array.
+# Symmetric/Hermitian are included since CHOLMOD does not support ldiv! with other arrays.
+const LayoutLdivRHS = Any[:LayoutVector, :LayoutMatrix]
+for Tri in (:UpperTriangular, :UnitUpperTriangular, :LowerTriangular, :UnitLowerTriangular),
+		Par in (:(LayoutMatrix{T}), :(SubArray{T,2,<:LayoutMatrix{T}}), :(Adjoint{T,<:LayoutMatrix{T}}), :(Transpose{T,<:LayoutMatrix{T}}))
+	push!(LayoutLdivRHS, :($Tri{T,<:$Par} where T))
+end
+for Sp in (:(SparseArrays.AbstractSparseMatrixCSC),
+			:(Adjoint{<:Any,<:SparseArrays.AbstractSparseMatrixCSC}), :(Transpose{<:Any,<:SparseArrays.AbstractSparseMatrixCSC}),
+			:(Symmetric{<:Any,<:SparseArrays.AbstractSparseMatrixCSC}), :(Hermitian{<:Any,<:SparseArrays.AbstractSparseMatrixCSC})),
+		Typ in LayoutLdivRHS
+	@eval Base.:\(A::$Sp, B::$Typ) = A \ convert(Array, B)
+	Typ === :LayoutVector && @eval Base.:\(A::$Sp, B::Diagonal{<:Any,<:LayoutVector}) = A \ Diagonal(convert(Array, B.diag))
+end
+
 # ambiguity from SparseArrays.ReadOnly
 if isdefined(SparseArrays, :ReadOnly)
 	==(A::SparseArrays.ReadOnly, B::LayoutVector) = equals_layout(A, B)

test/test_layoutarray.jl

@@ -619,6 +619,18 @@ BroadcastStyle(::Type{<:MyVector2{T}}) where {T} = MyBroadcastStyle{1}()
             copyto!(view(M, :, :), S)
             @test S == M2
         end
+        @testset "ldiv" begin
+            S = sparse([4.0 1 0; 1 4 1; 0 1 4])
+            b = [1.0, 2, 3]
+            X = [1.0 2 0; 2 3 1; 3 4 2]
+            for A in (S, S', transpose(S), Symmetric(S), Hermitian(S), Symmetric(S, :L))
+                for B in (MyVector(b), MyMatrix(X), Diagonal(MyVector(b)),
+                          UpperTriangular(MyMatrix(X)), UnitLowerTriangular(view(MyMatrix(X), :, :)),
+                          LowerTriangular(MyMatrix(X)'), UnitUpperTriangular(transpose(MyMatrix(X))))
+                    @test A \ B ≈ Matrix(A) \ Array(B)
+                end
+            end
+        end
     end
 
     @testset "mul! with subarrays" begin