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distributions/uniform: fix panic in gen_range(0..=MAX) #1087

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Merged
merged 2 commits into from
Jan 13, 2021
Merged

distributions/uniform: fix panic in gen_range(0..=MAX) #1087

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distributions/uniform: fix panic in gen_range(0..=MAX)
mautier Jan 12, 2021
2c9085a
Bump to 0.8.2 and update changelog
mautier Jan 12, 2021
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11 changes: 11 additions & 0 deletions src/distributions/uniform.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -521,6 +521,12 @@ macro_rules! uniform_int_impl {
let high = *high_b.borrow();
assert!(low <= high, "UniformSampler::sample_single_inclusive: low > high");
let range = high.wrapping_sub(low).wrapping_add(1) as $unsigned as $u_large;
// If the above resulted in wrap-around to 0, the range is $ty::MIN..=$ty::MAX,
// and any integer will do.
if range == 0 {
return rng.gen();
}

let zone = if ::core::$unsigned::MAX <= ::core::u16::MAX as $unsigned {
// Using a modulus is faster than the approximation for
// i8 and i16. I suppose we trade the cost of one
Expand Down Expand Up @@ -1235,6 +1241,11 @@ mod tests {
let v = <$ty as SampleUniform>::Sampler::sample_single(low, high, &mut rng);
assert!($le(low, v) && $lt(v, high));
}

for _ in 0..1000 {
let v = <$ty as SampleUniform>::Sampler::sample_single_inclusive(low, high, &mut rng);
assert!($le(low, v) && $le(v, high));
}
}
}};

Expand Down