fix buggy rand(RandomDevice(), Bool) (JuliaLang#35590)

stdlib/Random/src/RNGs.jl

@@ -25,6 +25,7 @@ else # !windows
  end
 
  rand(rd::RandomDevice, sp::SamplerBoolBitInteger) = read(getfile(rd), sp[])
+ rand(rd::RandomDevice, ::SamplerType{Bool}) = read(getfile(rd), UInt8) % Bool
 
  function getfile(rd::RandomDevice)
  devrandom = rd.unlimited ? DEV_URANDOM : DEV_RANDOM

stdlib/Random/test/runtests.jl

@@ -455,6 +455,38 @@ for rng in [MersenneTwister(), RandomDevice()],
  end
 end
 
+@testset "rand(Bool) uniform distribution" begin
+ for n in [rand(1:8), rand(9:16), rand(17:64)]
+ a = zeros(Bool, n)
+ as = zeros(Int, n)
+ # we will test statistical properties for each position of a,
+ # but also for 3 linear combinations of positions (for the array version)
+ lcs = unique!.([rand(1:n, 2), rand(1:n, 3), rand(1:n, 5)])
+ aslcs = zeros(Int, 3)
+ for rng = (MersenneTwister(), RandomDevice())
+ for scalar = [false, true]
+ fill!(a, 0)
+ fill!(as, 0)
+ fill!(aslcs, 0)
+ for _ = 1:49
+ if scalar
+ for i in eachindex(as)
+ as[i] += rand(rng, Bool)
+ end
+ else
+ as .+= rand!(rng, a)
+ aslcs .+= [xor(getindex.(Ref(a), lcs[i])...) for i in 1:3]
+ end
+ end
+ @test all(x -> 7 <= x <= 42, as) # for each x, fails with proba ≈ 2/35_000_000
+ if !scalar
+ @test all(x -> 7 <= x <= 42, aslcs)
+ end
+ end
+ end
+ end
+end
+
 # test reproducility of methods
 let mta = MersenneTwister(42), mtb = MersenneTwister(42)