Fix bug in converting Zeros matrix to Diagonal (#389)

* Fix bug in converting Zeros matrix to Diagonal

* Update runtests.jl

* only overload diagonal/convert for ≤v1.11-

Author: dlfivefifty

src/FillArrays.jl

@@ -554,11 +554,13 @@ for (Typ, funcs, func) in ((:AbstractZeros, :zeros, :zero), (:AbstractOnes, :one
     end
 end
 
-# temporary patch. should be a PR(#48895) to LinearAlgebra
-Diagonal{T}(A::AbstractFillMatrix) where T = Diagonal{T}(diag(A))
-function convert(::Type{T}, A::AbstractFillMatrix) where T<:Diagonal
-    checksquare(A)
-    isdiag(A) ? T(A) : throw(InexactError(:convert, T, A))
+if VERSION < v"1.11-"
+    # temporary patch. should be a PR(#48895) to LinearAlgebra
+    Diagonal{T}(A::AbstractFillMatrix) where T = Diagonal{T}(diag(A))
+    function convert(::Type{T}, A::AbstractFillMatrix) where T<:Diagonal
+        checksquare(A)
+        isdiag(A) ? T(diag(A)) : throw(InexactError(:convert, T, A))
+    end
 end
 
 Base.StepRangeLen(F::AbstractFillVector{T}) where T = StepRangeLen(getindex_value(F), zero(T), length(F))

test/runtests.jl

@@ -2977,6 +2977,13 @@ end
     @test tril(Z, 2) === Z
 end
 
+@testset "Diagonal conversion (#389)" begin
+    @test convert(Diagonal{Int, Vector{Int}}, Zeros(5,5)) isa Diagonal{Int,Vector{Int}}
+    @test convert(Diagonal{Int, Vector{Int}}, Zeros(5,5)) == zeros(5,5)
+    @test Diagonal{Int}(Zeros(5,5)) ≡ Diagonal(Zeros{Int}(5))
+    @test Diagonal{Int}(Ones(5,5)) ≡ Diagonal(Ones{Int}(5))
+end
+
 @testset "sqrt/cbrt" begin
     F = Fill(4, 4, 4)
     A = Array(F)