Fix Matrix on diagonal and triangular matrices for types without zero

JuliaLang · Jun 12, 2020 · 77e5677 · 77e5677
1 parent 6e7bc68
commit 77e5677
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Showing 5 changed files with 25 additions and 10 deletions.
diff --git a/stdlib/LinearAlgebra/src/bidiag.jl b/stdlib/LinearAlgebra/src/bidiag.jl
@@ -163,7 +163,7 @@ function Matrix{T}(A::Bidiagonal) where T
  B[n,n] = A.dv[n]
  return B
 end
-Matrix(A::Bidiagonal{T}) where {T} = Matrix{T}(A)
+Matrix(A::Bidiagonal{T}) where {T} = Matrix{promote_with_zero(T)}(A)
 Array(A::Bidiagonal) = Matrix(A)
 promote_rule(::Type{Matrix{T}}, ::Type{<:Bidiagonal{S}}) where {T,S} =
  @isdefined(T) && @isdefined(S) ? Matrix{promote_type(T,S)} : Matrix

diff --git a/stdlib/LinearAlgebra/src/dense.jl b/stdlib/LinearAlgebra/src/dense.jl
@@ -299,11 +299,11 @@ function diagm_size(size::Tuple{Int,Int}, kv::Pair{<:Integer,<:AbstractVector}..
  (m ≥ mmax && n ≥ nmax) || throw(DimensionMismatch("invalid size=$size"))
  return m, n
 end
+# For some type `T`, `zero(T)` is not a `T` and `zeros(T, ...)` fails.
+promote_with_zero(T::Type) = promote_type(T, typeof(zero(T)))
 function diagm_container(size, kv::Pair{<:Integer,<:AbstractVector}...)
  T = promote_type(map(x -> eltype(x.second), kv)...)
- # For some type `T`, `zero(T)` is not a `T` and `zeros(T, ...)` fails.
- U = promote_type(T, typeof(zero(T)))
- return zeros(U, diagm_size(size, kv...)...)
+ return zeros(promote_with_zero(T), diagm_size(size, kv...)...)
 end
 diagm_container(size, kv::Pair{<:Integer,<:BitVector}...) =
  falses(diagm_size(size, kv...)...)

diff --git a/stdlib/LinearAlgebra/src/triangular.jl b/stdlib/LinearAlgebra/src/triangular.jl
@@ -31,7 +31,7 @@ for t in (:LowerTriangular, :UnitLowerTriangular, :UpperTriangular,
  Anew = convert(AbstractMatrix{T}, A.data)
  $t(Anew)
  end
- Matrix(A::$t{T}) where {T} = Matrix{T}(A)
+ Matrix(A::$t{T}) where {T} = Matrix{promote_with_zero(T)}(A)
 
  size(A::$t, d) = size(A.data, d)
  size(A::$t) = size(A.data)

diff --git a/stdlib/LinearAlgebra/src/tridiag.jl b/stdlib/LinearAlgebra/src/tridiag.jl
@@ -138,7 +138,7 @@ function Matrix{T}(M::SymTridiagonal) where T
  end
  return Mf
 end
-Matrix(M::SymTridiagonal{T}) where {T} = Matrix{T}(M)
+Matrix(M::SymTridiagonal{T}) where {T} = Matrix{promote_with_zero(T)}(M)
 Array(M::SymTridiagonal) = Matrix(M)
 
 size(A::SymTridiagonal) = (length(A.dv), length(A.dv))
@@ -579,7 +579,7 @@ function Matrix{T}(M::Tridiagonal{T}) where T
  end
  A
 end
-Matrix(M::Tridiagonal{T}) where {T} = Matrix{T}(M)
+Matrix(M::Tridiagonal{T}) where {T} = Matrix{promote_with_zero(T)}(M)
 Array(M::Tridiagonal) = Matrix(M)
 
 # For M<:Tridiagonal, similar(M[, neweltype]) should yield a Tridiagonal matrix.

diff --git a/stdlib/LinearAlgebra/test/dense.jl b/stdlib/LinearAlgebra/test/dense.jl
@@ -943,11 +943,26 @@ struct TypeWithoutZero end
 Base.zero(::Type{TypeWithoutZero}) = TypeWithZero()
 struct TypeWithZero end
 Base.promote_rule(::Type{TypeWithoutZero}, ::Type{TypeWithZero}) = TypeWithZero
-Base.zero(::Type{<:Union{TypeWithoutZero, TypeWithZero}}) = TypeWithZero()
+Base.convert(::Type{TypeWithZero}, ::TypeWithoutZero) = TypeWithZero()
+Base.zero(::Union{TypeWithZero, Type{<:Union{TypeWithoutZero, TypeWithZero}}}) = TypeWithZero()
 Base.:+(x::TypeWithZero, ::TypeWithoutZero) = x
 
-@testset "diagm for type with no zero" begin
- @test diagm(0 => [TypeWithoutZero()]) isa Matrix{TypeWithZero}
+@testset "diagm and Matrix for type with no zero" begin
+ x = TypeWithoutZero()
+ @test (@inferred diagm(0 => [x])) isa Matrix{TypeWithZero}
+ diag = [x, x, x]
+ offdiag = [x, x]
+ X = [x x
+ x x]
+ for A in [
+ Bidiagonal(diag, offdiag, :U),
+ Tridiagonal(offdiag, diag, offdiag),
+ SymTridiagonal(diag, offdiag),
+ LowerTriangular(X),
+ UpperTriangular(X)
+ ]
+ @test (@inferred Matrix(A)) isa Matrix{TypeWithZero}
+ end
 end
 
 end # module TestDense