🐛 Bug

When I try the following transactional test code, I see a failure writing the file format. What's odd is that it's not happening due to having too many local variables, but in serialize_signature_size() (298 cannot exceed 255). The bytecode printed shows 298 local variables, but only 255 are actually used. Why would the signature size vary? How is the signature generated?

Note that this failure is occurring with move-compiler (V1), but it may be useful for V2 to understand how this might happen.

//# publish --print-bytecode
module 0xcafe::vectors {
    use std::vector;

    fun make_big_vector(a: u64): vector<u64> {
        let x = vector[a,
            {a = a + 1; a},
            ... <297 more identical lines: 298 total>
            ];
        let y = x;
        y
    }

    fun sum(a: &vector<u64>): u64 {
        let sum = 0;
        vector::for_each_ref(a, |elt| { sum = sum + *elt});
        sum
    }

    public fun test_big_vector() {
        let v = make_big_vector(0);
        let len = vector::length(&v);
        let sum = sum(&v);
        assert!(len == 300, len);
        assert!(sum == (len * (len -1)) / 2, sum);
    }
}

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