From b30daede72a9efcdde1fe6d706577d6052a2eea9 Mon Sep 17 00:00:00 2001
From: Lilith Orion Hafner <lilithhafner@gmail.com>
Date: Mon, 3 Oct 2022 06:02:17 +0600
Subject: [PATCH] =?UTF-8?q?Replace=20isfinite=20check=20in=20ranges=20with?=
 =?UTF-8?q?=20lo=20=E2=89=A4=20x=20=E2=89=A4=20hi=20(#45646)?=
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Co-authored-by: Viral B. Shah <ViralBShah@users.noreply.github.com>
(cherry picked from commit 58118253c63da7d67b9ddf326d3d3d47738e36d2)
---
 base/range.jl  | 15 +++++++--------
 test/ranges.jl | 33 ++++++++++++++++++++++++++++++---
 2 files changed, 37 insertions(+), 11 deletions(-)

diff --git a/base/range.jl b/base/range.jl
index d12a10518cd7f..404c8eaf5295a 100644
--- a/base/range.jl
+++ b/base/range.jl
@@ -1392,14 +1392,13 @@ function sum(r::AbstractRange{<:Real})
 end
 
 function _in_range(x, r::AbstractRange)
-    if !isfinite(x)
-        return false
-    elseif iszero(step(r))
-        return !isempty(r) && first(r) == x
-    else
-        n = round(Integer, (x - first(r)) / step(r)) + 1
-        return n >= 1 && n <= length(r) && r[n] == x
-    end
+    isempty(r) && return false
+    f, l = first(r), last(r)
+    # check for NaN, Inf, and large x that may overflow in the next calculation
+    f <= x <= l || l <= x <= f || return false
+    iszero(step(r)) && return true
+    n = round(Integer, (x - f) / step(r)) + 1
+    n >= 1 && n <= length(r) && r[n] == x
 end
 in(x::Real, r::AbstractRange{<:Real}) = _in_range(x, r)
 # This method needs to be defined separately since -(::T, ::T) can be implemented
diff --git a/test/ranges.jl b/test/ranges.jl
index c448f4b99e201..b68ab3312f304 100644
--- a/test/ranges.jl
+++ b/test/ranges.jl
@@ -518,8 +518,10 @@ end
         @test !(3.5 in 1:5)
         @test (3 in 1:5)
         @test (3 in 5:-1:1)
-        #@test (3 in 3+0*(1:5))
-        #@test !(4 in 3+0*(1:5))
+        @test (3 in 3 .+ 0*(1:5))
+        @test !(4 in 3 .+ 0*(1:5))
+        @test 0. in (0. .* (1:10))
+        @test !(0.1 in (0. .* (1:10)))
 
         let r = 0.0:0.01:1.0
             @test (r[30] in r)
@@ -536,8 +538,17 @@ end
             x = (NaN16, Inf32, -Inf64, 1//0, -1//0)
             @test !(x in r)
         end
+
+        @test 1e40 ∉ 0:1.0 # Issue #45747
+        @test 1e20 ∉ 0:1e-20:1e-20
+        @test 1e20 ∉ 0:1e-20
+        @test 1.0  ∉ 0:1e-20:1e-20
+        @test 0.5  ∉ 0:1e-20:1e-20
+        @test 1    ∉ 0:1e-20:1e-20
+
+        @test_broken 17.0 ∈ 0:1e40 # Don't support really long ranges
     end
-    @testset "in() works across types, including non-numeric types (#21728)" begin
+    @testset "in() works across types, including non-numeric types (#21728 and #45646)" begin
         @test 1//1 in 1:3
         @test 1//1 in 1.0:3.0
         @test !(5//1 in 1:3)
@@ -558,6 +569,22 @@ end
         @test !(Complex(1, 0) in Date(2017, 01, 01):Dates.Day(1):Date(2017, 01, 05))
         @test !(π in Date(2017, 01, 01):Dates.Day(1):Date(2017, 01, 05))
         @test !("a" in Date(2017, 01, 01):Dates.Day(1):Date(2017, 01, 05))
+
+        # We use Ducks because of their propensity to stand in a row and because we know
+        # that no additional methods (e.g. isfinite) are defined specifically for Ducks.
+        struct Duck
+            location::Int
+        end
+        Base.:+(x::Duck, y::Int) = Duck(x.location + y)
+        Base.:-(x::Duck, y::Int) = Duck(x.location - y)
+        Base.:-(x::Duck, y::Duck) = x.location - y.location
+        Base.isless(x::Duck, y::Duck) = isless(x.location, y.location)
+
+        @test Duck(3) ∈ Duck(1):2:Duck(5)
+        @test Duck(3) ∈ Duck(5):-2:Duck(2)
+        @test Duck(4) ∉ Duck(5):-2:Duck(1)
+        @test Duck(4) ∈ Duck(1):Duck(5)
+        @test Duck(0) ∉ Duck(1):Duck(5)
     end
 end
 @testset "indexing range with empty range (#4309)" begin