Fix -1 for BigInt factorial - Update gmp.jl (#51497)

Fixes #51488 --------- Co-authored-by: Rafael Fourquet <[email protected]>
JuliaLang · Oct 29, 2023 · d5c30d8 · d5c30d8
1 parent b5b05c8
commit d5c30d8
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diff --git a/base/gmp.jl b/base/gmp.jl
@@ -705,7 +705,7 @@ function prod(arr::AbstractArray{BigInt})
  foldl(MPZ.mul!, arr; init)
 end
 
-factorial(x::BigInt) = isneg(x) ? BigInt(0) : MPZ.fac_ui(x)
+factorial(n::BigInt) = !isneg(n) ? MPZ.fac_ui(n) : throw(DomainError(n, "`n` must not be negative."))
 
 function binomial(n::BigInt, k::Integer)
  k < 0 && return BigInt(0)

diff --git a/test/gmp.jl b/test/gmp.jl
@@ -220,6 +220,8 @@ end
 end
 @testset "combinatorics" begin
  @test factorial(BigInt(40)) == parse(BigInt,"815915283247897734345611269596115894272000000000")
+ @test_throws DomainError factorial(BigInt(-1))
+ @test_throws DomainError factorial(BigInt(rand(-999:-2)))
  @test binomial(BigInt(1), -1) == BigInt(0)
  @test binomial(BigInt(1), 2) == BigInt(0)
  @test binomial(BigInt(-53), 42) == parse(BigInt,"959509335087854414441273718")