permit AbstractUnitRange for setindex!,deleteat!,splice! (#41809)

Author: mkitti

base/array.jl

@@ -895,7 +895,7 @@ function getindex end
 @eval getindex(A::Array, i1::Int) = arrayref($(Expr(:boundscheck)), A, i1)
 @eval getindex(A::Array, i1::Int, i2::Int, I::Int...) = (@_inline_meta; arrayref($(Expr(:boundscheck)), A, i1, i2, I...))
 
-# Faster contiguous indexing using copyto! for UnitRange and Colon
+# Faster contiguous indexing using copyto! for AbstractUnitRange and Colon
 function getindex(A::Array, I::AbstractUnitRange{<:Integer})
     @_inline_meta
     @boundscheck checkbounds(A, I)
@@ -955,7 +955,7 @@ function setindex!(A::Array, X::AbstractArray, I::AbstractVector{Int})
 end
 
 # Faster contiguous setindex! with copyto!
-function setindex!(A::Array{T}, X::Array{T}, I::UnitRange{Int}) where T
+function setindex!(A::Array{T}, X::Array{T}, I::AbstractUnitRange{Int}) where T
     @_inline_meta
     @boundscheck checkbounds(A, I)
     lI = length(I)
@@ -1455,7 +1455,7 @@ julia> deleteat!([6, 5, 4, 3, 2, 1], 2)
 """
 deleteat!(a::Vector, i::Integer) = (_deleteat!(a, i, 1); a)
 
-function deleteat!(a::Vector, r::UnitRange{<:Integer})
+function deleteat!(a::Vector, r::AbstractUnitRange{<:Integer})
     n = length(a)
     isempty(r) || _deleteat!(a, first(r), length(r))
     return a
@@ -1621,14 +1621,17 @@ Remove items at specified indices, and return a collection containing
 the removed items.
 Subsequent items are shifted left to fill the resulting gaps.
 If specified, replacement values from an ordered collection will be spliced in
-place of the removed items; in this case, `indices` must be a `UnitRange`.
+place of the removed items; in this case, `indices` must be a `AbstractUnitRange`.
 
 To insert `replacement` before an index `n` without removing any items, use
 `splice!(collection, n:n-1, replacement)`.
 
 !!! compat "Julia 1.5"
     Prior to Julia 1.5, `indices` must always be a `UnitRange`.
 
+!!! compat "Julia 1.8"
+    Prior to Julia 1.8, `indices` must be a `UnitRange` if splicing in replacement values.
+
 # Examples
 ```jldoctest
 julia> A = [-1, -2, -3, 5, 4, 3, -1]; splice!(A, 4:3, 2)
@@ -1646,7 +1649,7 @@ julia> A
  -1
 ```
 """
-function splice!(a::Vector, r::UnitRange{<:Integer}, ins=_default_splice)
+function splice!(a::Vector, r::AbstractUnitRange{<:Integer}, ins=_default_splice)
     v = a[r]
     m = length(ins)
     if m == 0