N5N3 · N5N3 · Jul 5, 2021 · Jul 2, 2021 · Jul 2, 2021 · Jul 2, 2021
diff --git a/NEWS.md b/NEWS.md
@@ -39,6 +39,11 @@ New library features
 Standard library changes
 ------------------------
 
+* The `length` function on certain ranges of certain specific element types no longer checks for integer
+  overflow in most cases. The new function `checked_length` is now available, which will try to use checked
+  arithmetic to error if the result may be wrapping. Or use a package such as SaferIntegers.jl when
+  constructing the range. ([#40382])
+
 #### Package Manager
 
 #### LinearAlgebra

diff --git a/README.md b/README.md
@@ -8,7 +8,16 @@
 Documentation:
 [![version 1][docs-img]](https://docs.julialang.org)
 
+Code coverage:
+[![coveralls][coveralls-img]](https://coveralls.io/r/JuliaLang/julia?branch=master)
+[![codecov][codecov-img]](https://codecov.io/github/JuliaLang/julia?branch=master)
+
+Continuous integration: [![Build status](https://badge.buildkite.com/f28e0d28b345f9fad5856ce6a8d64fffc7c70df8f4f2685cd8.svg?branch=master)](https://buildkite.com/julialang/julia)
+
 [docs-img]: https://img.shields.io/badge/docs-v1-blue.svg
+[coveralls-img]: https://img.shields.io/coveralls/github/JuliaLang/julia/master.svg?label=coveralls
+[codecov-img]: https://img.shields.io/codecov/c/github/JuliaLang/julia/master.svg?label=codecov
+
 
 ## The Julia Language
 
@@ -141,19 +150,3 @@ Supported IDEs include: [julia-vscode](https://github.com/JuliaEditorSupport/jul
 Code plugin), [Juno](http://junolab.org/) (Atom plugin). [Jupyter](https://jupyter.org/)
 notebooks are available through the [IJulia](https://github.com/JuliaLang/IJulia.jl) package, and
 [Pluto](https://github.com/fonsp/Pluto.jl) notebooks through the Pluto.jl package.
-
-## Continuous Integration (CI) Builders
-
-Code coverage:
-[![coveralls][coveralls-img]](https://coveralls.io/r/JuliaLang/julia?branch=master)
-[![codecov][codecov-img]](https://codecov.io/github/JuliaLang/julia?branch=master)
-
-| Builder    | Status |
-| ---------- | ------ |
-| Overall    | [![Build status](https://badge.buildkite.com/f28e0d28b345f9fad5856ce6a8d64fffc7c70df8f4f2685cd8.svg?branch=master)](https://buildkite.com/julialang/julia) |
-| analyzegc  | [![Build status](https://badge.buildkite.com/f28e0d28b345f9fad5856ce6a8d64fffc7c70df8f4f2685cd8.svg?branch=master&step=analyzegc)](https://buildkite.com/julialang/julia) |
-| llvmpasses | [![Build status](https://badge.buildkite.com/f28e0d28b345f9fad5856ce6a8d64fffc7c70df8f4f2685cd8.svg?branch=master&step=llvmpasses)](https://buildkite.com/julialang/julia) |
-| coverage   | [![Build status](https://badge.buildkite.com/d5ae34dbbf6fefe615300c4f3118bf63cb4a5ae7fd962263c1.svg?branch=master)](https://buildkite.com/julialang/julia-coverage-linux64) |
-
-[coveralls-img]: https://img.shields.io/coveralls/github/JuliaLang/julia/master.svg?label=coveralls
-[codecov-img]: https://img.shields.io/codecov/c/github/JuliaLang/julia/master.svg?label=codecov
diff --git a/base/Base.jl b/base/Base.jl
@@ -124,11 +124,6 @@ include("refpointer.jl")
 include("checked.jl")
 using .Checked
 
-# SIMD loops
-@pure sizeof(s::String) = Core.sizeof(s)  # needed by gensym as called from simdloop
-include("simdloop.jl")
-using .SimdLoop
-
 # array structures
 include("indices.jl")
 include("array.jl")
@@ -177,6 +172,14 @@ using .MultiplicativeInverses
 include("abstractarraymath.jl")
 include("arraymath.jl")
 
+# SIMD loops
+@pure sizeof(s::String) = Core.sizeof(s)  # needed by gensym as called from simdloop
+include("simdloop.jl")
+using .SimdLoop
+
+# functions for AbstractArray with @simd
+include("abstractarraypatch.jl")
+
 # map-reduce operators
 include("reduce.jl")
 

diff --git a/base/abstractarray.jl b/base/abstractarray.jl
@@ -116,9 +116,6 @@ axes1(A::AbstractArray{<:Any,0}) = OneTo(1)
 axes1(A::AbstractArray) = (@_inline_meta; axes(A)[1])
 axes1(iter) = oneto(length(iter))
 
-unsafe_indices(A) = axes(A)
-unsafe_indices(r::AbstractRange) = (oneto(unsafe_length(r)),) # Ranges use checked_sub for size
-
 """
     keys(a::AbstractArray)
 
@@ -580,14 +577,14 @@ end
 function trailingsize(inds::Indices, n)
     s = 1
     for i=n:length(inds)
-        s *= unsafe_length(inds[i])
+        s *= length(inds[i])
     end
     return s
 end
 # This version is type-stable even if inds is heterogeneous
 function trailingsize(inds::Indices)
     @_inline_meta
-    prod(map(unsafe_length, inds))
+    prod(map(length, inds))
 end
 
 ## Bounds checking ##
@@ -688,7 +685,7 @@ function checkbounds_indices(::Type{Bool}, ::Tuple{}, I::Tuple)
     @_inline_meta
     checkindex(Bool, OneTo(1), I[1])::Bool & checkbounds_indices(Bool, (), tail(I))
 end
-checkbounds_indices(::Type{Bool}, IA::Tuple, ::Tuple{}) = (@_inline_meta; all(x->unsafe_length(x)==1, IA))
+checkbounds_indices(::Type{Bool}, IA::Tuple, ::Tuple{}) = (@_inline_meta; all(x->length(x)==1, IA))
 checkbounds_indices(::Type{Bool}, ::Tuple{}, ::Tuple{}) = true
 
 throw_boundserror(A, I) = (@_noinline_meta; throw(BoundsError(A, I)))
@@ -886,7 +883,35 @@ function copy!(dst::AbstractArray, src::AbstractArray)
 end
 
 ## from general iterable to any array
+
+"""
+    copyto!(dest::AbstractArray, src) -> dest
+
+Copy all elements from collection `src` to array `dest`, whose length must be greater than
+or equal to the length `n` of `src`. The first `n` elements of `dest` are overwritten,
+the other elements are left untouched.
 
+See also [`copy!`](@ref Base.copy!), [`copy`](@ref).
+
+# Examples
+```jldoctest
+julia> x = [1., 0., 3., 0., 5.];
+
+julia> y = zeros(7);
+
+julia> copyto!(y, x);
+
+julia> y
+7-element Vector{Float64}:
+ 1.0
+ 0.0
+ 3.0
+ 0.0
+ 5.0
+ 0.0
+ 0.0
+```
+"""
 function copyto!(dest::AbstractArray, src)
     destiter = eachindex(dest)
     y = iterate(destiter)
@@ -964,87 +989,6 @@ function copyto!(dest::AbstractArray, dstart::Integer, src, sstart::Integer, n::
     return dest
 end
 
-## copy between abstract arrays - generally more efficient
-## since a single index variable can be used.
-
-"""
-    copyto!(dest::AbstractArray, src) -> dest
-
-Copy all elements from collection `src` to array `dest`, whose length must be greater than
-or equal to the length `n` of `src`. The first `n` elements of `dest` are overwritten,
-the other elements are left untouched.
-
-See also [`copy!`](@ref Base.copy!), [`copy`](@ref).
-
-# Examples
-```jldoctest
-julia> x = [1., 0., 3., 0., 5.];
-
-julia> y = zeros(7);
-
-julia> copyto!(y, x);
-
-julia> y
-7-element Vector{Float64}:
- 1.0
- 0.0
- 3.0
- 0.0
- 5.0
- 0.0
- 0.0
-```
-"""
-function copyto!(dest::AbstractArray, src::AbstractArray)
-    isempty(src) && return dest
-    src′ = unalias(dest, src)
-    copyto_unaliased!(IndexStyle(dest), dest, IndexStyle(src′), src′)
-end
-
-function copyto!(deststyle::IndexStyle, dest::AbstractArray, srcstyle::IndexStyle, src::AbstractArray)
-    isempty(src) && return dest
-    src′ = unalias(dest, src)
-    copyto_unaliased!(deststyle, dest, srcstyle, src′)
-end
-
-function copyto_unaliased!(deststyle::IndexStyle, dest::AbstractArray, srcstyle::IndexStyle, src::AbstractArray)
-    isempty(src) && return dest
-    length(dest) >= length(src) || throw(BoundsError(dest, LinearIndices(src)))
-    if deststyle isa IndexLinear
-        if srcstyle isa IndexLinear
-            Δi = firstindex(dest) - firstindex(src)
-            for i in eachindex(src)
-                @inbounds dest[i + Δi] = src[i]
-            end
-        else
-            j = firstindex(dest) - 1
-            @inbounds @simd for I in eachindex(src)
-                dest[j+=1] = src[I]
-            end
-        end
-    else
-        if srcstyle isa IndexLinear
-            i = firstindex(src) - 1
-            @inbounds @simd for J in eachindex(dest)
-                dest[J] = src[i+=1]
-            end
-        else
-            iterdest, itersrc = eachindex(dest), eachindex(src)
-            if iterdest == itersrc
-                # Shared-iterator implementation
-                @inbounds @simd for I in itersrc
-                    dest[I] = src[I]
-                end
-            else
-                for (I,J) in zip(itersrc, iterdest)
-                    @inbounds dest[J] = src[I]
-                end
-            end
-        end
-    end
-    return dest
-end
-
 function copyto!(dest::AbstractArray, dstart::Integer, src::AbstractArray)
     copyto!(dest, dstart, src, first(LinearIndices(src)), length(src))
 end
@@ -2497,8 +2441,8 @@ function _sub2ind_recurse(inds, L, ind, i::Integer, I::Integer...)
 end
 
 nextL(L, l::Integer) = L*l
-nextL(L, r::AbstractUnitRange) = L*unsafe_length(r)
-nextL(L, r::Slice) = L*unsafe_length(r.indices)
+nextL(L, r::AbstractUnitRange) = L*length(r)
+nextL(L, r::Slice) = L*length(r.indices)
 offsetin(i, l::Integer) = i-1
 offsetin(i, r::AbstractUnitRange) = i-first(r)
 
@@ -2524,7 +2468,7 @@ end
 _lookup(ind, d::Integer) = ind+1
 _lookup(ind, r::AbstractUnitRange) = ind+first(r)
 _div(ind, d::Integer) = div(ind, d), 1, d
-_div(ind, r::AbstractUnitRange) = (d = unsafe_length(r); (div(ind, d), first(r), d))
+_div(ind, r::AbstractUnitRange) = (d = length(r); (div(ind, d), first(r), d))
 
 # Vectorized forms
 function _sub2ind(inds::Indices{1}, I1::AbstractVector{T}, I::AbstractVector{T}...) where T<:Integer

diff --git a/base/abstractarraypatch.jl b/base/abstractarraypatch.jl
@@ -0,0 +1,55 @@
+# This file is a part of Julia. License is MIT: https://julialang.org/license
+
+## copy between abstract arrays - generally more efficient
+## since a single index variable can be used.
+## copyto_unaliased! use @simd to speed up, so these definition is seperated from abstractarray.jl
+
+function copyto!(dest::AbstractArray, src::AbstractArray)
+    isempty(src) && return dest
+    src′ = unalias(dest, src)
+    copyto_unaliased!(IndexStyle(dest), dest, IndexStyle(src′), src′)
+end
+
+function copyto!(deststyle::IndexStyle, dest::AbstractArray, srcstyle::IndexStyle, src::AbstractArray)
+    isempty(src) && return dest
+    src′ = unalias(dest, src)
+    copyto_unaliased!(deststyle, dest, srcstyle, src′)
+end
+
+function copyto_unaliased!(deststyle::IndexStyle, dest::AbstractArray, srcstyle::IndexStyle, src::AbstractArray)
+    isempty(src) && return dest
+    length(dest) >= length(src) || throw(BoundsError(dest, LinearIndices(src)))
+    if deststyle isa IndexLinear
+        if srcstyle isa IndexLinear
+            Δi = firstindex(dest) - firstindex(src)
+            for i in eachindex(src)
+                @inbounds dest[i + Δi] = src[i]
+            end
+        else
+            j = firstindex(dest) - 1
+            @inbounds @simd for I in eachindex(src)
+                dest[j+=1] = src[I]
+            end
+        end
+    else
+        if srcstyle isa IndexLinear
+            i = firstindex(src) - 1
+            @inbounds @simd for J in eachindex(dest)
+                dest[J] = src[i+=1]
+            end
+        else
+            iterdest, itersrc = eachindex(dest), eachindex(src)
+            if iterdest == itersrc
+                # Shared-iterator implementation
+                @inbounds @simd for I in itersrc
+                    dest[I] = src[I]
+                end
+            else
+                for (I,J) in zip(itersrc, iterdest)
+                    @inbounds dest[J] = src[I]
+                end
+            end
+        end
+    end
+    return dest
+end
diff --git a/base/broadcast.jl b/base/broadcast.jl
@@ -566,7 +566,7 @@ an `Int`.
 """
 Base.@propagate_inbounds newindex(arg, I::CartesianIndex) = CartesianIndex(_newindex(axes(arg), I.I))
 Base.@propagate_inbounds newindex(arg, I::Integer) = CartesianIndex(_newindex(axes(arg), (I,)))
-Base.@propagate_inbounds _newindex(ax::Tuple, I::Tuple) = (ifelse(Base.unsafe_length(ax[1])==1, ax[1][1], I[1]), _newindex(tail(ax), tail(I))...)
+Base.@propagate_inbounds _newindex(ax::Tuple, I::Tuple) = (ifelse(length(ax[1]) == 1, ax[1][1], I[1]), _newindex(tail(ax), tail(I))...)
 Base.@propagate_inbounds _newindex(ax::Tuple{}, I::Tuple) = ()
 Base.@propagate_inbounds _newindex(ax::Tuple, I::Tuple{}) = (ax[1][1], _newindex(tail(ax), ())...)
 Base.@propagate_inbounds _newindex(ax::Tuple{}, I::Tuple{}) = ()

diff --git a/base/checked.jl b/base/checked.jl
@@ -6,14 +6,14 @@ module Checked
 
 export checked_neg, checked_abs, checked_add, checked_sub, checked_mul,
        checked_div, checked_rem, checked_fld, checked_mod, checked_cld,
-       add_with_overflow, sub_with_overflow, mul_with_overflow
+       checked_length, add_with_overflow, sub_with_overflow, mul_with_overflow
 
 import Core.Intrinsics:
        checked_sadd_int, checked_ssub_int, checked_smul_int, checked_sdiv_int,
        checked_srem_int,
        checked_uadd_int, checked_usub_int, checked_umul_int, checked_udiv_int,
        checked_urem_int
-import ..no_op_err, ..@_inline_meta, ..@_noinline_meta
+import ..no_op_err, ..@_inline_meta, ..@_noinline_meta, ..checked_length
 
 # define promotion behavior for checked operations
 checked_add(x::Integer, y::Integer) = checked_add(promote(x,y)...)
@@ -349,4 +349,12 @@ The overflow protection may impose a perceptible performance penalty.
 """
 checked_cld(x::T, y::T) where {T<:Integer} = cld(x, y) # Base.cld already checks
 
+"""
+    Base.checked_length(r)
+
+Calculates `length(r)`, but may check for overflow errors where applicable when
+the result doesn't fit into `Union{Integer(eltype(r)),Int}`.
+"""
+checked_length(r) = length(r) # for most things, length doesn't error
+
 end
diff --git a/base/compiler/compiler.jl b/base/compiler/compiler.jl
@@ -70,11 +70,6 @@ add_with_overflow(x::T, y::T) where {T<:SignedInt}   = checked_sadd_int(x, y)
 add_with_overflow(x::T, y::T) where {T<:UnsignedInt} = checked_uadd_int(x, y)
 add_with_overflow(x::Bool, y::Bool) = (x+y, false)
 
-# SIMD loops (The new copyto_unalias! use @simd)
-@pure sizeof(s::String) = Core.sizeof(s)  # needed by gensym as called from simdloop
-include("simdloop.jl")
-using .SimdLoop
-
 # core array operations
 include("indices.jl")
 include("array.jl")

diff --git a/base/deprecated.jl b/base/deprecated.jl
@@ -240,6 +240,9 @@ end
 @deprecate cat_shape(dims, shape::Tuple{}, shapes::Tuple...) cat_shape(dims, shapes) false
 cat_shape(dims, shape::Tuple{}) = () # make sure `cat_shape(dims, ())` do not recursively calls itself
 
+@deprecate unsafe_indices(A) axes(A) false
+@deprecate unsafe_length(r) length(r) false
+
 # END 1.6 deprecations
 
 # BEGIN 1.7 deprecations