more efficient array indexing with AbstractUnitRange

base/array.jl

@@ -803,7 +803,7 @@ function getindex end
 @eval getindex(A::Array, i1::Int, i2::Int, I::Int...) = (@_inline_meta; arrayref($(Expr(:boundscheck)), A, i1, i2, I...))
 
 # Faster contiguous indexing using copyto! for UnitRange and Colon
-function getindex(A::Array, I::UnitRange{Int})
+function getindex(A::Array, I::AbstractUnitRange{<:Integer})
     @_inline_meta
     @boundscheck checkbounds(A, I)
     lI = length(I)

test/abstractarray.jl

@@ -1280,3 +1280,26 @@ end
     @test Int[0 t...; t... 0] == [0 1 2; 1 2 0]
     @test_throws ArgumentError Int[t...; 3 4 5]
 end
+
+@testset "issue #39896, modified getindex " begin
+    a=collect(1:10)
+    ax=axes(a,1)
+    @test a==a[ax]
+    a=reshape(collect(1:100),(10,10))
+    @test a==a[ax,ax]
+    a=collect(1:10)
+    ax=Base.OneTo(8)
+    @test a[1:8]==a[ax]
+    a=reshape(collect(1:100),(10,10))
+    ay=Base.OneTo(7)
+    @test a[1:8,1:7]==a[ax,ay]
+    ax=UnitRange(1,10)
+    @test a[ax]==collect(1:10)
+    @test a[ax,ax]==reshape(collect(1:100),(10,10))
+    a=collect(1:BigInt(10))
+    ax=UnitRange(1,10)
+    @test a[ax]== collect(1:BigInt(10))
+    a=reshape(collect(1:BigInt(100)),(10,10))
+    @test a[ax,ax]==reshape(collect(1:BigInt(100)),(10,10))
+end
+