From c500caa3eef30be5b3d16c65e0a3ff22df7b744a Mon Sep 17 00:00:00 2001
From: Harmen Stoppels <harmenstoppels@gmail.com>
Date: Tue, 26 Jun 2018 13:41:20 +0300
Subject: [PATCH] Fix conversion in getindex (#26615)

* Test more out of bounds errors for the UnitRange type

* Do the conversion in getindex of UnitRange only when returning
---
 base/range.jl  | 18 +++++++++++++++---
 test/ranges.jl |  6 ++++++
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/base/range.jl b/base/range.jl
index 748f8104bd9e1..1aaa5c64235f8 100644
--- a/base/range.jl
+++ b/base/range.jl
@@ -478,11 +478,23 @@ end
 
 ## indexing
 
+_in_unit_range(v::UnitRange, val, i::Integer) = i > 0 && val <= v.stop && val >= v.start
+
 function getindex(v::UnitRange{T}, i::Integer) where T
     @_inline_meta
-    ret = convert(T, first(v) + i - 1)
-    @boundscheck ((i > 0) & (ret <= v.stop) & (ret >= v.start)) || throw_boundserror(v, i)
-    ret
+    val = convert(T, v.start + i - 1)
+    @boundscheck _in_unit_range(v, val, i) || throw_boundserror(v, i)
+    val
+end
+
+const OverflowSafe = Union{Bool,Int8,Int16,Int32,Int64,Int128,
+                           UInt8,UInt16,UInt32,UInt64,UInt128}
+
+function getindex(v::UnitRange{T}, i::Integer) where {T<:OverflowSafe}
+    @_inline_meta
+    val = v.start + i - 1
+    @boundscheck _in_unit_range(v, val, i) || throw_boundserror(v, i)
+    val % T
 end
 
 function getindex(v::OneTo{T}, i::Integer) where T
diff --git a/test/ranges.jl b/test/ranges.jl
index d3575bde6d736..aa0d7980de956 100644
--- a/test/ranges.jl
+++ b/test/ranges.jl
@@ -1286,6 +1286,12 @@ end
     @test x isa StepRangeLen{Float64,Base.TwicePrecision{Float64},Base.TwicePrecision{Float64}}
 end
 
+@testset "Issue #26608" begin
+    @test_throws BoundsError (Int8(-100):Int8(100))[400]
+    @test_throws BoundsError (-100:100)[typemax(UInt)]
+    @test_throws BoundsError (false:true)[3]
+end
+
 module NonStandardIntegerRangeTest
 
 using Test