From 8b7c13310ee40302fe4a479cf6c338c53e84b2bd Mon Sep 17 00:00:00 2001
From: Matt Bauman <mbauman@juliacomputing.com>
Date: Thu, 28 Jan 2021 14:51:35 -0500
Subject: [PATCH] =?UTF-8?q?fix=20#39379,=20use=20first=E2=88=98LinearIndic?=
 =?UTF-8?q?es=20instead=20of=201=20(#39393)?=
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(cherry picked from commit 9de107a63a56f9ca922497991a7eb9dcd027dc06)
---
 base/abstractarray.jl | 2 +-
 test/offsetarray.jl   | 9 +++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/base/abstractarray.jl b/base/abstractarray.jl
index 383814ff38ddc..a880b4eecfd3f 100644
--- a/base/abstractarray.jl
+++ b/base/abstractarray.jl
@@ -1193,7 +1193,7 @@ function _getindex(::IndexLinear, A::AbstractArray, I::Vararg{Int,M}) where M
 end
 _to_linear_index(A::AbstractArray, i::Integer) = i
 _to_linear_index(A::AbstractVector, i::Integer, I::Integer...) = i
-_to_linear_index(A::AbstractArray) = 1
+_to_linear_index(A::AbstractArray) = first(LinearIndices(A))
 _to_linear_index(A::AbstractArray, I::Integer...) = (@_inline_meta; _sub2ind(A, I...))
 
 ## IndexCartesian Scalar indexing: Canonical method is full dimensionality of Ints
diff --git a/test/offsetarray.jl b/test/offsetarray.jl
index bb0b4b13b8da4..07f2e12999f90 100644
--- a/test/offsetarray.jl
+++ b/test/offsetarray.jl
@@ -715,6 +715,15 @@ end
     @test axes(S) == (OffsetArrays.IdOffsetRange(0:1), Base.OneTo(2), OffsetArrays.IdOffsetRange(2:5))
 end
 
+@testset "Zero-index indexing" begin
+    @test OffsetArray([6], 2:2)[] == 6
+    @test OffsetArray(fill(6, 1, 1), 2:2, 3:3)[] == 6
+    @test OffsetArray(fill(6))[] == 6
+    @test_throws BoundsError OffsetArray([6,7], 2:3)[]
+    @test_throws BoundsError OffsetArray([6 7], 2:2, 2:3)[]
+    @test_throws BoundsError OffsetArray([], 2:1)[]
+end
+
 @testset "IdentityUnitRange indexing" begin
     a = OffsetVector(3:4, 2:3)
     ax = IdentityUnitRange(2:3)