Fix inference on getindex

Author: timholy

src/OffsetArrays.jl

@@ -133,15 +133,13 @@ Base.fill(x, inds::Tuple{UnitRange,Vararg{UnitRange}}) =
 ### Low-level utilities ###
 
 # Computing a shifted index (subtracting the offset)
-@inline offset(offsets::NTuple{N,Int}, inds::NTuple{N,Int}) where {N} = _offset((), offsets, inds)
-_offset(out, ::Tuple{}, ::Tuple{}) = out
-@inline _offset(out, offsets, inds) =
-    _offset((out..., inds[1]-offsets[1]), Base.tail(offsets), Base.tail(inds))
+@inline offset(offsets::NTuple{N,Int}, inds::NTuple{N,Int}) where {N} =
+    (inds[1]-offsets[1], offset(Base.tail(offsets), Base.tail(inds))...)
+offset(::Tuple{}, ::Tuple{}) = ()
 
 # Support trailing 1s
 @inline offset(offsets::Tuple{Vararg{Int}}, inds::Tuple{Vararg{Int}}) =
     (offset(offsets, Base.front(inds))..., inds[end])
-offset(offsets::Tuple{}, inds::Tuple{}) = ()
 offset(offsets::Tuple{Vararg{Int}}, inds::Tuple{}) = error("inds cannot be shorter than offsets")
 
 indexoffset(r::AbstractRange) = first(r) - 1

test/runtests.jl

@@ -45,7 +45,7 @@ S = OffsetArray(view(A0, 1:2, 1:2), (-1,2))   # IndexCartesian
 @test_throws DimensionMismatch OffsetArray(A0, 0:1, 2:4)
 
 # Scalar indexing
-@test A[0,3] == A[0,3,1] == A[1] == S[0,3] == S[0,3,1] == S[1] == 1
+@test @inferred(A[0,3]) == @inferred(A[0,3,1]) == @inferred(A[1]) == @inferred(S[0,3]) == @inferred(S[0,3,1]) == @inferred(S[1]) == 1
 @test A[1,3] == A[1,3,1] == A[2] == S[1,3] == S[1,3,1] == S[2] == 2
 @test A[0,4] == A[0,4,1] == A[3] == S[0,4] == S[0,4,1] == S[3] == 3
 @test A[1,4] == A[1,4,1] == A[4] == S[1,4] == S[1,4,1] == S[4] == 4