Define promotion and conversion for CartesianIndices and LinearIndices (

#28084)

base/indices.jl

@@ -357,6 +357,17 @@ LinearIndices(inds::NTuple{N,Union{<:Integer,AbstractUnitRange{<:Integer}}}) whe
  LinearIndices(map(i->first(i):last(i), inds))
 LinearIndices(A::Union{AbstractArray,SimpleVector}) = LinearIndices(axes(A))
 
+promote_rule(::Type{LinearIndices{N,R1}}, ::Type{LinearIndices{N,R2}}) where {N,R1,R2} =
+ LinearIndices{N,indices_promote_type(R1,R2)}
+
+function indices_promote_type(::Type{Tuple{R1,Vararg{R1,N}}}, ::Type{Tuple{R2,Vararg{R2,N}}}) where {R1,R2,N}
+ R = promote_type(R1, R2)
+ Tuple{R,Vararg{R,N}}
+end
+
+convert(::Type{LinearIndices{N,R}}, inds::LinearIndices{N}) where {N,R} =
+ LinearIndices(convert(R, inds.indices))
+
 # AbstractArray implementation
 IndexStyle(::Type{<:LinearIndices}) = IndexLinear()
 axes(iter::LinearIndices) = map(axes1, iter.indices)

base/multidimensional.jl

@@ -4,7 +4,7 @@
 module IteratorsMD
  import .Base: eltype, length, size, first, last, in, getindex,
  setindex!, IndexStyle, min, max, zero, one, isless, eachindex,
- ndims, IteratorSize, convert, show, iterate
+ ndims, IteratorSize, convert, show, iterate, promote_rule
 
  import .Base: +, -, *
  import .Base: simd_outer_range, simd_inner_length, simd_index
@@ -228,6 +228,9 @@ module IteratorsMD
 
  CartesianIndices(A::AbstractArray) = CartesianIndices(axes(A))
 
+ promote_rule(::Type{CartesianIndices{N,R1}}, ::Type{CartesianIndices{N,R2}}) where {N,R1,R2} =
+ CartesianIndices{N,Base.indices_promote_type(R1,R2)}
+
  convert(::Type{Tuple{}}, R::CartesianIndices{0}) = ()
  convert(::Type{NTuple{N,AbstractUnitRange{Int}}}, R::CartesianIndices{N}) where {N} =
  R.indices
@@ -246,6 +249,9 @@ module IteratorsMD
  convert(::Type{Tuple{Vararg{UnitRange}}}, R::CartesianIndices) =
  convert(Tuple{Vararg{UnitRange{Int}}}, R)
 
+ convert(::Type{CartesianIndices{N,R}}, inds::CartesianIndices{N}) where {N,R} =
+ CartesianIndices(convert(R, inds.indices))
+
  # AbstractArray implementation
  Base.axes(iter::CartesianIndices{N,R}) where {N,R} = map(Base.axes1, iter.indices)
  Base.IndexStyle(::Type{CartesianIndices{N,R}}) where {N,R} = IndexCartesian()

test/abstractarray.jl

@@ -887,6 +887,14 @@ end
 
  @test CartesianIndices(fill(1., 2, 3)) == CartesianIndices((2,3))
  @test LinearIndices((2,3)) == [1 3 5; 2 4 6]
+
+ for IType in (CartesianIndices, LinearIndices)
+ I1 = IType((Base.OneTo(3),))
+ I2 = IType((1:3,))
+ @test !(I1 === I2)
+ J1, J2 = @inferred(promote(I1, I2))
+ @test J1 === J2
+ end
 end
 
 @testset "issue #25770" begin