fix code instability of axes (#119)

* fix code instability of axes

* construct axes using axes of parent array

Author: johnnychen94

src/OffsetArrays.jl

@@ -92,8 +92,8 @@ Base.eachindex(::IndexLinear, A::OffsetVector)   = axes(A, 1)
 @inline Base.size(A::OffsetArray, d) = size(parent(A), d)
 
 @inline Base.axes(A::OffsetArray) = map(IdOffsetRange, axes(parent(A)), A.offsets)
-@inline Base.axes(A::OffsetArray, d) = d <= ndims(A) ? IdOffsetRange(axes(parent(A), d), A.offsets[d]) : Base.OneTo(1)
-@inline Base.axes1(A::OffsetArray{T,0}) where {T} = Base.OneTo(1)  # we only need to specialize this one
+@inline Base.axes(A::OffsetArray, d) = d <= ndims(A) ? IdOffsetRange(axes(parent(A), d), A.offsets[d]) : IdOffsetRange(axes(parent(A), d))
+@inline Base.axes1(A::OffsetArray{T,0}) where {T} = IdOffsetRange(axes(parent(A), 1))  # we only need to specialize this one
 
 const OffsetAxis = Union{Integer, UnitRange, Base.OneTo, IdentityUnitRange, IdOffsetRange, Colon}
 Base.similar(A::OffsetArray, ::Type{T}, dims::Dims) where T =

test/runtests.jl

@@ -160,7 +160,9 @@ end
     A0 = [1 3; 2 4]
     A = OffsetArray(A0, (-1,2))                   # IndexLinear
     S = OffsetArray(view(A0, 1:2, 1:2), (-1,2))   # IndexCartesian
+    @test axes(A) === axes(S)
     @test axes(A) == axes(S) == (0:1, 3:4)
+    @test axes(A, 1) === OffsetArrays.IdOffsetRange(Base.OneTo(2), -1)
     @test size(A) == size(A0)
     @test size(A, 1) == size(A0, 1)
     @test length(A) == length(A0)