From 9d896dc9f1f105b33aa50ad07bb41d4061e2d439 Mon Sep 17 00:00:00 2001
From: Nathan Zimmerberg <39104088+nhz2@users.noreply.github.com>
Date: Tue, 20 Feb 2024 23:07:45 -0500
Subject: [PATCH] Throw OverflowError on `copysign(typemin(Int)//1, 1)`
 (#53395)

The default `copysign(x::Real, y::Real)` in `number.jl` works, so the
incorrect method in `rational.jl` isn't needed.

Here is a benchmark of the new version.
```julia
using BenchmarkTools
function foo!(c,a,b)
    c .= copysign.(a, b)
    nothing
end
N = 1000
@btime foo!(c,a,b) setup=(c=zeros(Rational{Int},N); a=rand(Int,N).//rand(Int,N); b=fill(-1,N))
```
On master: 406.215 ns (0 allocations: 0 bytes)
On this PR: 869.327 ns (0 allocations: 0 bytes)
---
 base/rational.jl | 2 --
 test/numbers.jl  | 3 +++
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/base/rational.jl b/base/rational.jl
index b27baf5973d3b..bd1633bd3dd28 100644
--- a/base/rational.jl
+++ b/base/rational.jl
@@ -315,8 +315,6 @@ denominator(x::Rational) = x.den
 
 sign(x::Rational) = oftype(x, sign(x.num))
 signbit(x::Rational) = signbit(x.num)
-copysign(x::Rational, y::Real) = unsafe_rational(copysign(x.num, y), x.den)
-copysign(x::Rational, y::Rational) = unsafe_rational(copysign(x.num, y.num), x.den)
 
 abs(x::Rational) = unsafe_rational(checked_abs(x.num), x.den)
 
diff --git a/test/numbers.jl b/test/numbers.jl
index 922fa0da3337e..47d7e87753b11 100644
--- a/test/numbers.jl
+++ b/test/numbers.jl
@@ -679,6 +679,9 @@ end
     @test copysign(big(-1), 0x02) == 1
     @test copysign(big(-1.0), 0x02) == 1.0
     @test copysign(-1//2, 0x01) == 1//2
+
+    # Verify overflow is checked with rational
+    @test_throws OverflowError copysign(typemin(Int)//1, 1)
 end
 
 @testset "isnan/isinf/isfinite" begin