Failing assertion while multiplying two BigUints

[Armavica]

extern crate num;
use num::CheckedMul;
use num::bigint::BigUint;

fn main() {
    let s = "531137992816767098689588206552468627329593117727031923199444138200403559860852242739162502232636710047537552105951370000796528760829212940754539968588340162273730474622005920097370111";
    let a: BigUint = s.parse().unwrap();
    let b = a.clone();
    let _ = a.checked_mul(&b);
}

The code above crashes at this assertion in num-bigint:

thread '<main>' panicked at 'assertion failed: carry == 0', /home/virgile/.cargo/registry/src/github.com-88ac128001ac3a9a/num-bigint-0.1.32/src/lib.rs:783

while it runs fine with one digit less in s. The same problem occurs with an unchecked multiplication.

I am not sure how to interpret the comment below the assertion; is there an allocation I should make manually?

[cuviper]

This is definitely a bug in the implementation, not something you did or should have done. The comments around that assertion are just development details from #133. In fact, @koverstreet if you see this, I'd appreciate if you can take a look.

FWIW, CheckedMul will always succeed on BigUint (barring bugs like this), so you can just use plain multiplication unless you need to be generic for other types too.

[koverstreet]

I'll dig into it first thing tomorrow.

On Tue, Apr 19, 2016 at 7:37 PM, Josh Stone notifications@github.com
wrote:

This is definitely a bug in the implementation, not something you did or
should have done. The comments around that assertion are just development
details from #133 #133. In fact,
@koverstreet https://github.com/koverstreet if you see this, I'd
appreciate if you can take a look.

FWIW, CheckedMul will always succeed on BigUint (barring bugs like this),
so you can just use plain multiplication unless you need to be generic for
other types too.

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