fix inf rational (#39063)

JuliaLang · Jan 4, 2021 · 1a333a9 · 1a333a9 · nanosoldier · Jan 5, 2021
1 parent ee66728
commit 1a333a9
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Showing 2 changed files with 31 additions and 1 deletion.
diff --git a/base/rational.jl b/base/rational.jl
@@ -278,13 +278,35 @@ function -(x::Rational{T}) where T<:Unsigned
  x
 end
 
-for (op,chop) in ((:+,:checked_add), (:-,:checked_sub), (:rem,:rem), (:mod,:mod))
+function +(x::Rational, y::Rational)
+ xp, yp = promote(x, y)
+ if isinf(x) && x == y
+ return xp
+ end
+ xd, yd = divgcd(promote(x.den, y.den)...)
+ Rational(checked_add(checked_mul(x.num,yd), checked_mul(y.num,xd)), checked_mul(x.den,yd))
+end
+
+function -(x::Rational, y::Rational)
+ xp, yp = promote(x, y)
+ if isinf(x) && x == -y
+ return xp
+ end
+ xd, yd = divgcd(promote(x.den, y.den)...)
+ Rational(checked_sub(checked_mul(x.num,yd), checked_mul(y.num,xd)), checked_mul(x.den,yd))
+end
+
+for (op,chop) in ((:rem,:rem), (:mod,:mod))
  @eval begin
  function ($op)(x::Rational, y::Rational)
  xd, yd = divgcd(promote(x.den, y.den)...)
  Rational(($chop)(checked_mul(x.num,yd), checked_mul(y.num,xd)), checked_mul(x.den,yd))
  end
+ end
+end
 
+for (op,chop) in ((:+,:checked_add), (:-,:checked_sub), (:rem,:rem), (:mod,:mod))
+ @eval begin
  function ($op)(x::Rational, y::Integer)
  unsafe_rational(($chop)(x.num, checked_mul(x.den, y)), x.den)
  end

diff --git a/test/rational.jl b/test/rational.jl
@@ -116,6 +116,14 @@ using Test
  @test abs(one(Rational{UInt})) === one(Rational{UInt})
  @test abs(one(Rational{Int})) === one(Rational{Int})
  @test abs(-one(Rational{Int})) === one(Rational{Int})
+
+ # inf addition
+ @test 1//0 + 1//0 == 1//0
+ @test -1//0 - 1//0 == -1//0
+ @test_throws DivideError 1//0 - 1//0
+ @test_throws DivideError -1//0 + 1//0
+ @test Int128(1)//0 + 1//0 isa Rational{Int128}
+ @test 1//0 + Int128(1)//0 isa Rational{Int128}
 end
 
 @testset "Rational methods" begin