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make ReinterpretArray more Offset-safe #58898

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de1c389
make ReinterpretArray more Offset-safe
adienes Jul 4, 2025
6d772ba
whitespace
adienes Jul 4, 2025
e7a3d80
don't touch generic ind2sub
adienes Jul 4, 2025
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15 changes: 15 additions & 0 deletions base/reinterpretarray.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -311,6 +311,7 @@ SimdLoop.simd_inner_length(::SCartesianIndices2{K}, ::Any) where K = K
SCartesianIndex2{K}(I1+1, Ilast)
end

_maybe_reshape(::IndexSCartesian2, A::AbstractArray, I...) = _maybe_reshape(IndexCartesian(), A, I...)
_maybe_reshape(::IndexSCartesian2, A::ReshapedReinterpretArray, I...) = A

# fallbacks
Expand All @@ -329,11 +330,25 @@ function _getindex(::IndexSCartesian2, A::AbstractArray{T,N}, ind::SCartesianInd
J = _ind2sub(tail(axes(A)), ind.j)
getindex(A, ind.i, J...)
end

function _getindex(::IndexSCartesian2{2}, A::AbstractArray{T,2}, ind::SCartesianIndex2) where {T}
@_propagate_inbounds_meta
J = first(axes(A, 2)) + ind.j - 1
getindex(A, ind.i, J)
end

function _setindex!(::IndexSCartesian2, A::AbstractArray{T,N}, v, ind::SCartesianIndex2) where {T,N}
@_propagate_inbounds_meta
J = _ind2sub(tail(axes(A)), ind.j)
setindex!(A, v, ind.i, J...)
end

function _setindex!(::IndexSCartesian2{2}, A::AbstractArray{T,2}, v, ind::SCartesianIndex2) where {T}
@_propagate_inbounds_meta
J = first(axes(A, 2)) + ind.j - 1
setindex!(A, v, ind.i, J)
end

eachindex(style::IndexSCartesian2, A::AbstractArray) = eachindex(style, parent(A))

## AbstractArray interface
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14 changes: 8 additions & 6 deletions test/reinterpretarray.jl
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Expand Up @@ -10,12 +10,14 @@ tslow(a::AbstractArray) = TSlow(a)
wrapper(a::AbstractArray) = WrapperArray(a)
fcviews(a::AbstractArray) = view(a, ntuple(Returns(:),ndims(a)-1)..., axes(a)[end])
fcviews(a::AbstractArray{<:Any, 0}) = view(a)
offset(a::AbstractArray) = OffsetArray(a)
tslow(t::Tuple) = map(tslow, t)
wrapper(t::Tuple) = map(wrapper, t)
fcviews(t::Tuple) = map(fcviews, t)
offset(t::Tuple) = map(offset, t)

test_many_wrappers(testf, A, wrappers) = foreach(w -> testf(w(A)), wrappers)
test_many_wrappers(testf, A) = test_many_wrappers(testf, A, (identity, tslow, wrapper, fcviews))
test_many_wrappers(testf, A) = test_many_wrappers(testf, A, (identity, tslow, wrapper, fcviews, offset))

A = Int64[1, 2, 3, 4]
Ars = Int64[1 3; 2 4]
Expand All @@ -37,10 +39,6 @@ test_many_wrappers(B, (identity, tslow)) do _B
@test @inferred(size(reinterpret(reshape, Int128, _B))) == (3,)
end

test_many_wrappers(C) do Cr
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just folding this into the same at L163

@test reinterpret(reshape, Tuple{Int8, Int}, Cr) == fill((1,1))
end

@test_throws ArgumentError("cannot reinterpret `Int64` as `Vector{Int64}`, type `Vector{Int64}` is not a bits type") reinterpret(Vector{Int64}, A)
@test_throws ArgumentError("cannot reinterpret `Vector{Int32}` as `Int32`, type `Vector{Int32}` is not a bits type") reinterpret(Int32, Av)
@test_throws ArgumentError("cannot reinterpret a zero-dimensional `Int64` array to `Int32` which is of a different size") reinterpret(Int32, reshape([Int64(0)]))
Expand Down Expand Up @@ -160,8 +158,10 @@ test_many_wrappers(A3) do A3_
@test A3[2,1,2] == 400
end

test_many_wrappers(C) do Cr
test_many_wrappers(C) do Cr_
Cr = deepcopy(Cr_)
r = reinterpret(reshape, Tuple{Int, Int}, Cr)
@test r == fill((1,1))
r[] = (2,2)
@test r[] === (2,2)
r[1] = (3,3)
Expand Down Expand Up @@ -378,6 +378,8 @@ let a = rand(ComplexF32, 5)
r = reinterpret(reshape, Float32, a)
ref = Array(r)

@test all(r .== OffsetArray(r)[:, :, :])

@test r[1, :, 1] == ref[1, :]
@test r[1, :, 1, 1, 1] == ref[1, :]
@test r[1, :, UInt8(1)] == ref[1, :]
Expand Down