[BUG] `call(::BlockSparseArrayInterface, ::typeof(similar), ::BlockSparseArray` is ambiguous

[ogauthe]

This issue is triggered by vector-vector contraction in #95
a_dest, dimnames_dest = contract(a3, (1, 2), a3, (2, 1)) # from test_tensoralgebraext

ERROR: MethodError: call(::BlockSparseArrayInterface, ::typeof(similar), ::BlockSparseArray{…}, ::Type{…}, ::Tuple{…}) is ambiguous.

Candidates:
  call(::AbstractBlockSparseArrayInterface, ::typeof(similar), a::AbstractArray, elt::Type, axes::Tuple)
    @ BlockSparseArrays ~/Documents/itensor/BlockSparseArrays.jl/src/abstractblocksparsearray/wrappedabstractblocksparsearray.jl:230
  call(interface::DerivableInterfaces.AbstractArrayInterface, ::typeof(similar), a::AbstractArray, T::Type, axes::Tuple{Base.OneTo, Vararg{Base.OneTo}})
    @ DerivableInterfaces ~/.julia/packages/DerivableInterfaces/ZNBYA/src/abstractarrayinterface.jl:99

Possible fix, define
  call(::AbstractBlockSparseArrayInterface, ::typeof(similar), ::AbstractArray, ::Type, ::Tuple{Base.OneTo, Vararg{…}})

Stacktrace:
  [1] (::DerivableInterfaces.InterfaceFunction{…})(::BlockSparseArray{…}, ::Vararg{…}; kwargs::@Kwargs{})
    @ DerivableInterfaces ~/.julia/packages/DerivableInterfaces/ZNBYA/src/interface_function.jl:17
  [2] similar(a::BlockSparseArray{…}, elt::Type, axes::Tuple{…})
    @ BlockSparseArrays ~/Documents/itensor/BlockSparseArrays.jl/src/abstractblocksparsearray/wrappedabstractblocksparsearray.jl:323
  [3] similar(a::BlockSparseArray{…}, dims::Tuple{…})
    @ BlockArrays ~/.julia/packages/BlockArrays/XczLX/src/abstractblockarray.jl:37
  [4] blockreshape(a::BlockSparseArray{…}, axes::Tuple{…})
    @ BlockSparseArrays ~/Documents/itensor/BlockSparseArrays.jl/src/BlockArraysExtensions/BlockArraysExtensions.jl:278
  [5] matricize(::BlockSparseArraysTensorAlgebraExt.BlockReshapeFusion, a::BlockSparseArray{…}, biperm::TensorAlgebra.BlockedTrivialPermutation{…})
    @ BlockSparseArraysTensorAlgebraExt ~/Documents/itensor/BlockSparseArrays.jl/ext/BlockSparseArraysTensorAlgebraExt/BlockSparseArraysTensorAlgebraExt.jl:22
  [6] matricize(style::BlockSparseArraysTensorAlgebraExt.BlockReshapeFusion, a::BlockSparseArray{…}, biperm::TensorAlgebra.BlockedPermutation{…})
    @ TensorAlgebra ~/Documents/itensor/TensorAlgebra.jl/src/matricize.jl:64
  [7] matricize(a::BlockSparseArray{…}, biperm::TensorAlgebra.BlockedPermutation{…})
    @ TensorAlgebra ~/Documents/itensor/TensorAlgebra.jl/src/matricize.jl:57
  [8] contract!(::TensorAlgebra.Matricize, a_dest::BlockSparseArray{…}, biperm_dest::TensorAlgebra.BlockedPermutation{…}, a1::BlockSparseMatrix{…}, biperm1::TensorAlgebra.BlockedPermutation{…}, a2::BlockSparseMatrix{…}, biperm2::TensorAlgebra.BlockedPermutation{…}, α::Bool, β::Bool)
    @ TensorAlgebra ~/Documents/itensor/TensorAlgebra.jl/src/contract/contract_matricize/contract.jl:14
  [9] contract(alg::TensorAlgebra.Matricize, biperm_dest::TensorAlgebra.BlockedPermutation{…}, a1::BlockSparseMatrix{…}, biperm1::TensorAlgebra.BlockedPermutation{…}, a2::BlockSparseMatrix{…}, biperm2::TensorAlgebra.BlockedPermutation{…}, α::Bool; kwargs::@Kwargs{})
    @ TensorAlgebra ~/Documents/itensor/TensorAlgebra.jl/src/contract/contract.jl:122
 [10] contract(alg::TensorAlgebra.Matricize, biperm_dest::TensorAlgebra.BlockedPermutation{…}, a1::BlockSparseMatrix{…}, biperm1::TensorAlgebra.BlockedPermutation{…}, a2::BlockSparseMatrix{…}, biperm2::TensorAlgebra.BlockedPermutation{…}, α::Bool)
    @ TensorAlgebra ~/Documents/itensor/TensorAlgebra.jl/src/contract/contract.jl:111
 [11] contract(alg::TensorAlgebra.Matricize, labels_dest::Tuple{}, a1::BlockSparseMatrix{…}, labels1::Tuple{…}, a2::BlockSparseMatrix{…}, labels2::Tuple{…}, α::Bool; kwargs::@Kwargs{})
    @ TensorAlgebra ~/Documents/itensor/TensorAlgebra.jl/src/contract/contract.jl:92
 [12] contract(alg::TensorAlgebra.Matricize, labels_dest::Tuple{}, a1::BlockSparseMatrix{…}, labels1::Tuple{…}, a2::BlockSparseMatrix{…}, labels2::Tuple{…}, α::Bool)
    @ TensorAlgebra ~/Documents/itensor/TensorAlgebra.jl/src/contract/contract.jl:81
 [13] contract(alg::TensorAlgebra.Matricize, a1::BlockSparseMatrix{…}, labels1::Tuple{…}, a2::BlockSparseMatrix{…}, labels2::Tuple{…}, α::Bool; kwargs::@Kwargs{})
    @ TensorAlgebra ~/Documents/itensor/TensorAlgebra.jl/src/contract/contract.jl:49
 [14] contract
    @ ~/Documents/itensor/TensorAlgebra.jl/src/contract/contract.jl:39 [inlined]
 [15] #contract#27
    @ ~/Documents/itensor/TensorAlgebra.jl/src/contract/contract.jl:36 [inlined]
 [16] contract
    @ ~/Documents/itensor/TensorAlgebra.jl/src/contract/contract.jl:27 [inlined]
 [17] contract(a1::BlockSparseMatrix{…}, labels1::Tuple{…}, a2::BlockSparseMatrix{…}, labels2::Tuple{…})
    @ TensorAlgebra ~/Documents/itensor/TensorAlgebra.jl/src/contract/contract.jl:27
 [18] top-level scope
    @ REPL[75]:1
Some type information was truncated. Use `show(err)` to see complete types.

[mtfishman]

Thanks for the report, looking into it now.

[mtfishman]

It seems like the issue is caused by the fact that this line: https://github.com/ogauthe/BlockSparseArrays.jl/blob/6c2204bf9b18e53bb9c9c11827681c91bce8222c/ext/BlockSparseArraysTensorAlgebraExt/BlockSparseArraysTensorAlgebraExt.jl#L21 constructs axes (Base.OneTo(1), Base.OneTo(1)), since the input axes are empty so that's the best guess that trivial_axis has in this line: https://github.com/ITensor/TensorAlgebra.jl/blob/e235d04e685e84f84ab33676422c06c612954581/src/matricize.jl#L36.

Maybe there could be a version of fuseaxes and trivial_axis that accepts the array as an input, so then we can customize them to output blockedrange([1]) in this case.

[mtfishman]

Fundamentally, the error is being thrown because that similar call on BlockSparseArray doesn't anticipate that a non-blocked range (Base.OneTo) might be passed, we can and should handle that case more gracefully but I think that is a bit orthogonal to this issue, and we should pass a blocked range in this case in the first place.

[mtfishman]

I was able to fix the original issue with just changes to this package, see #99. But I think we should also make TensorAlgebra.fuseaxes and TensorAlgebra.trivial_axis more customizable.

Maybe for now you can incorporate #99 into #95.

[ogauthe]

There are similar issues with graded arrays, I will work on fuseaxes.

[ogauthe]

minimal example that triggers error on main:

using BlockSparseArrays: BlockSparseArray
a = BlockSparseArray{Float64}(undef)
similar(a, Float64, (Base.OneTo(1),))

ERROR: MethodError: call(::BlockSparseArrays.BlockSparseArrayInterface, ::typeof(similar), ::BlockSparseArray{…}, ::Type{…}, ::Tuple{…}) is ambiguous.

Candidates:
  call(::BlockSparseArrays.AbstractBlockSparseArrayInterface, ::typeof(similar), a::AbstractArray, elt::Type, axes::Tuple)
    @ BlockSparseArrays ~/.julia/packages/BlockSparseArrays/1g9zF/src/abstractblocksparsearray/wrappedabstractblocksparsearray.jl:230
  call(interface::DerivableInterfaces.AbstractArrayInterface, ::typeof(similar), a::AbstractArray, T::Type, axes::Tuple{Base.OneTo, Vararg{Base.OneTo}})
    @ DerivableInterfaces ~/.julia/packages/DerivableInterfaces/ZNBYA/src/abstractarrayinterface.jl:99

Possible fix, define
  call(::BlockSparseArrays.AbstractBlockSparseArrayInterface, ::typeof(similar), ::AbstractArray, ::Type, ::Tuple{…})

Stacktrace:
 [1] (::DerivableInterfaces.InterfaceFunction{…})(::BlockSparseArray{…}, ::Vararg{…}; kwargs::@Kwargs{})
   @ DerivableInterfaces ~/.julia/packages/DerivableInterfaces/ZNBYA/src/interface_function.jl:17
 [2] similar(a::BlockSparseArray{…}, elt::Type, axes::Tuple{…})
   @ BlockSparseArrays ~/.julia/packages/BlockSparseArrays/1g9zF/src/abstractblocksparsearray/wrappedabstractblocksparsearray.jl:323
 [3] top-level scope
   @ REPL[3]:1
Some type information was truncated. Use `show(err)` to see complete types.

[mtfishman]

That should be fixed by #99.