more efficient array indexing with AbstractUnitRange (JuliaLang#39896)

Co-authored-by: Sebastian Stock <[email protected]>

base/array.jl

@@ -834,7 +834,7 @@ 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)
@@ -844,6 +844,10 @@ function getindex(A::Array, I::UnitRange{Int})
     end
     return X
 end
+
+# getindex for carrying out logical indexing for AbstractUnitRange{Bool} as Bool <: Integer
+getindex(a::Array, r::AbstractUnitRange{Bool}) = getindex(a, to_index(r))
+
 function getindex(A::Array, c::Colon)
     lI = length(A)
     X = similar(A, lI)

test/abstractarray.jl

@@ -1293,6 +1293,25 @@ end
     @test_throws ArgumentError Int[t...; 3 4 5]
 end
 
+@testset "issue #39896, modified getindex " begin
+    for arr = ([1:10;], reshape([1.0:16.0;],4,4), reshape(['a':'h';],2,2,2))
+        for inds = (2:5, Base.OneTo(5), BigInt(3):BigInt(5), UInt(4):UInt(3))
+            @test arr[inds] == arr[collect(inds)]
+            @test arr[inds] isa AbstractVector{eltype(arr)}
+        end
+    end
+    for arr = ([1], reshape([1.0],1,1), reshape(['a'],1,1,1))
+        @test arr[true:true] == [arr[1]]
+        @test arr[true:true] isa AbstractVector{eltype(arr)}
+        @test arr[false:false] == []
+        @test arr[false:false] isa AbstractVector{eltype(arr)}
+    end
+    for arr = ([1:10;], reshape([1.0:16.0;],4,4), reshape(['a':'h';],2,2,2))
+        @test_throws BoundsError arr[true:true]
+        @test_throws BoundsError arr[false:false]
+    end
+end
+
 @testset "reduce(vcat, ...) inferrence #40277" begin
     x_vecs = ([5, ], [1.0, 2.0, 3.0])
     @test @inferred(reduce(vcat, x_vecs)) == [5.0, 1.0, 2.0, 3.0]