propgate inbounds to substring and use it in split (#29557)

* propgate inbounds to substring and use it in split

* remove Base prefix

(cherry picked from commit 18b9fc2)

base/strings/substring.jl

@@ -35,11 +35,11 @@ struct SubString{T<:AbstractString} <: AbstractString
     end
 end
 
-SubString(s::T, i::Int, j::Int) where {T<:AbstractString} = SubString{T}(s, i, j)
-SubString(s::AbstractString, i::Integer, j::Integer=lastindex(s)) = SubString(s, Int(i), Int(j))
-SubString(s::AbstractString, r::UnitRange{<:Integer}) = SubString(s, first(r), last(r))
+@propagate_inbounds SubString(s::T, i::Int, j::Int) where {T<:AbstractString} = SubString{T}(s, i, j)
+@propagate_inbounds SubString(s::AbstractString, i::Integer, j::Integer=lastindex(s)) = SubString(s, Int(i), Int(j))
+@propagate_inbounds SubString(s::AbstractString, r::UnitRange{<:Integer}) = SubString(s, first(r), last(r))
 
-function SubString(s::SubString, i::Int, j::Int)
+@propagate_inbounds function SubString(s::SubString, i::Int, j::Int)
     @boundscheck i ≤ j && checkbounds(s, i:j)
     SubString(s.string, s.offset+i, s.offset+j)
 end

base/strings/util.jl

@@ -323,7 +323,7 @@ function _split(str::AbstractString, splitter, limit::Integer, keepempty::Bool,
         while 0 < j <= n && length(strs) != limit-1
             if i < k
                 if keepempty || i < j
-                    push!(strs, SubString(str,i,prevind(str,j)))
+                    push!(strs, @inbounds SubString(str,i,prevind(str,j)))
                 end
                 i = k
             end
@@ -334,7 +334,7 @@ function _split(str::AbstractString, splitter, limit::Integer, keepempty::Bool,
         end
     end
     if keepempty || i <= ncodeunits(str)
-        push!(strs, SubString(str,i))
+        push!(strs, @inbounds SubString(str,i))
     end
     return strs
 end