Fix colon-reshaping of OffsetVector (#33890)

* Fix colon-reshaping of OffsetVector
* reshape(::AbstractVector, ::Colon) is a no-op

Author: timholy

base/reshapedarray.jl

@@ -112,6 +112,7 @@ reshape(parent::AbstractArray, shp::Tuple{Union{Integer,OneTo}, Vararg{Union{Int
 reshape(parent::AbstractArray, dims::Dims)        = _reshape(parent, dims)
 
 # Allow missing dimensions with Colon():
+reshape(parent::AbstractVector, ::Colon) = parent
 reshape(parent::AbstractArray, dims::Int...) = reshape(parent, dims)
 reshape(parent::AbstractArray, dims::Union{Int,Colon}...) = reshape(parent, dims)
 reshape(parent::AbstractArray, dims::Tuple{Vararg{Union{Int,Colon}}}) = _reshape(parent, _reshape_uncolon(parent, dims))
@@ -220,6 +221,8 @@ dataids(A::ReshapedArray) = dataids(A.parent)
     d, r = divrem(ind, strds[1])
     (_ind2sub_rs(front(ax), tail(strds), r)..., d + first(ax[end]))
 end
+offset_if_vec(i::Integer, axs::Tuple{<:AbstractUnitRange}) = i + first(axs[1]) - 1
+offset_if_vec(i::Integer, axs::Tuple) = i
 
 @inline function getindex(A::ReshapedArrayLF, index::Int)
     @boundscheck checkbounds(A, index)
@@ -237,8 +240,9 @@ end
 end
 
 @inline function _unsafe_getindex(A::ReshapedArray{T,N}, indices::Vararg{Int,N}) where {T,N}
-    i = Base._sub2ind(size(A), indices...)
-    I = ind2sub_rs(axes(A.parent), A.mi, i)
+    axp = axes(A.parent)
+    i = offset_if_vec(Base._sub2ind(size(A), indices...), axp)
+    I = ind2sub_rs(axp, A.mi, i)
     _unsafe_getindex_rs(parent(A), I)
 end
 @inline _unsafe_getindex_rs(A, i::Integer) = (@inbounds ret = A[i]; ret)
@@ -260,7 +264,9 @@ end
 end
 
 @inline function _unsafe_setindex!(A::ReshapedArray{T,N}, val, indices::Vararg{Int,N}) where {T,N}
-    @inbounds parent(A)[ind2sub_rs(axes(A.parent), A.mi, Base._sub2ind(size(A), indices...))...] = val
+    axp = axes(A.parent)
+    i = offset_if_vec(Base._sub2ind(size(A), indices...), axp)
+    @inbounds parent(A)[ind2sub_rs(axes(A.parent), A.mi, i)...] = val
     val
 end
 

test/offsetarray.jl

@@ -495,6 +495,19 @@ A = OffsetArray(rand(4,4), (-3,5))
 @test vec(A) == reshape(A, :) == reshape(A, 16) == reshape(A, Val(1)) == A[:] == vec(A.parent)
 A = OffsetArray(view(rand(4,4), 1:4, 4:-1:1), (-3,5))
 @test vec(A) == reshape(A, :) == reshape(A, 16) == reshape(A, Val(1)) == A[:] == vec(A.parent)
+# issue #33614
+A = OffsetArray(-1:0, (-2,))
+@test reshape(A, :) === A
+Arsc = reshape(A, :, 1)
+Arss = reshape(A, 2, 1)
+@test Arsc[1,1] == Arss[1,1] == -1
+@test Arsc[2,1] == Arss[2,1] == 0
+@test_throws BoundsError Arsc[0,1]
+@test_throws BoundsError Arss[0,1]
+A = OffsetArray([-1,0], (-2,))
+Arsc = reshape(A, :, 1)
+Arsc[1,1] = 5
+@test first(A) == 5
 
 # broadcast
 a = [1]