Fix case where elements are matrices

JuliaLang · Jun 16, 2020 · 421f029 · 421f029
1 parent 77e5677
commit 421f029
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Showing 2 changed files with 6 additions and 2 deletions.
diff --git a/stdlib/LinearAlgebra/src/dense.jl b/stdlib/LinearAlgebra/src/dense.jl
@@ -300,7 +300,11 @@ function diagm_size(size::Tuple{Int,Int}, kv::Pair{<:Integer,<:AbstractVector}..
  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)))
+# `zero_type(T::Type) = typeof(zero(T))` would not work for types such
+# as `Array` for which `zero(::T)` is defined but not `zero(::Type{T})`
+# so we use `promote_op` instead.
+zero_type(T::Type) = promote_op(zero, T)
+promote_with_zero(T::Type) = promote_type(T, zero_type(T))
 function diagm_container(size, kv::Pair{<:Integer,<:AbstractVector}...)
  T = promote_type(map(x -> eltype(x.second), kv)...)
  return zeros(promote_with_zero(T), diagm_size(size, kv...)...)

diff --git a/stdlib/LinearAlgebra/test/dense.jl b/stdlib/LinearAlgebra/test/dense.jl
@@ -940,7 +940,7 @@ end
 end
 
 struct TypeWithoutZero end
-Base.zero(::Type{TypeWithoutZero}) = TypeWithZero()
+Base.zero(::Union{TypeWithoutZero, Type{TypeWithoutZero}}) = TypeWithZero()
 struct TypeWithZero end
 Base.promote_rule(::Type{TypeWithoutZero}, ::Type{TypeWithZero}) = TypeWithZero
 Base.convert(::Type{TypeWithZero}, ::TypeWithoutZero) = TypeWithZero()