Fix a bug in blocktype

Author: mtfishman

Project.toml

@@ -1,7 +1,7 @@
 name = "BlockSparseArrays"
 uuid = "2c9a651f-6452-4ace-a6ac-809f4280fbb4"
 authors = ["ITensor developers <[email protected]> and contributors"]
-version = "0.2.13"
+version = "0.2.14"
 
 [deps]
 Adapt = "79e6a3ab-5dfb-504d-930d-738a2a938a0e"

src/blocksparsearrayinterface/blocksparsearrayinterface.jl

@@ -41,29 +41,26 @@ function eachstoredblock(a::AbstractArray)
   return storedvalues(blocks(a))
 end
 
-# TODO: Generalize this, this catches simple cases
-# where the more general definition isn't specific enough.
-blocktype(a::Array) = typeof(a)
-# TODO: Maybe unwrap SubArrays?
 function blocktype(a::AbstractArray)
-  # TODO: Unfortunately, this doesn't always give
-  # a concrete type, even when it could be concrete, i.e.
-  #=
-  ```julia
-  julia> eltype(blocks(BlockArray(randn(2, 2), [1, 1], [1, 1])))
-  Matrix{Float64} (alias for Array{Float64, 2})
-
-  julia> eltype(blocks(BlockedArray(randn(2, 2), [1, 1], [1, 1])))
-  AbstractMatrix{Float64} (alias for AbstractArray{Float64, 2})
-
-  julia> eltype(blocks(randn(2, 2)))
-  AbstractMatrix{Float64} (alias for AbstractArray{Float64, 2})
-  ```
-  =#
   if isempty(blocks(a))
+    # TODO: Unfortunately, this doesn't always give
+    # a concrete type, even when it could be concrete, i.e.
+    #=
+    ```julia
+    julia> eltype(blocks(BlockArray(randn(2, 2), [1, 1], [1, 1])))
+    Matrix{Float64} (alias for Array{Float64, 2})
+
+    julia> eltype(blocks(BlockedArray(randn(2, 2), [1, 1], [1, 1])))
+    AbstractMatrix{Float64} (alias for AbstractArray{Float64, 2})
+
+    julia> eltype(blocks(randn(2, 2)))
+    AbstractMatrix{Float64} (alias for AbstractArray{Float64, 2})
+    ```
+    =#
+    # That is an issue in BlockArrays.jl that we should address.
     return eltype(blocks(a))
   end
-  return eltype(first(blocks(a)))
+  return mapreduce(typeof, promote_type, blocks(a))
 end
 
 abstract type AbstractBlockSparseArrayInterface <: AbstractSparseArrayInterface end

test/test_basics.jl

@@ -132,6 +132,9 @@ arrayts = (Array, JLArray)
       end
     end
   end
+  @testset "blocktype" begin
+    @test blocktype(arrayt(randn(elt, 2, 2))) <: SubArray{elt,2,arrayt{elt,2}}
+  end
   @testset "Basics" begin
     a = dev(BlockSparseArray{elt}([2, 3], [2, 3]))
     @allowscalar @test a == dev(