https://github.com/ClickHouse/ClickHouse/blob/9a48cf0da8badfc5f3da08611eb44961aa28e3f6/src/Functions/FunctionsHashing.h#L669-L671

There's a call to `blake3_free_char_pointer` that passes ownership of the pointer back to Rust (which then frees the memory), then there's a call to `std::string`'s constructor that accepts that now-freed pointer.
if constexpr (first)
            {
                vec_to.assign(size, h);
            }
            else
            {
                for (size_t i = 0; i < size; ++i)
                    vec_to[i] = Impl::combineHashes(vec_to[i], h);
            }
        }
        else
            throw Exception("Illegal column " + column->getName()
                + " of argument of function " + getName(),
                ErrorCodes::ILLEGAL_COLUMN);
    }
    template <bool first>
    void executeGeneric(const IColumn * column, typename ColumnVector<ToType>::Container & vec_to) const
    {
        for (size_t i = 0, size = column->size(); i < size; ++i)
        {
            StringRef bytes = column->getDataAt(i);
            const ToType h = Impl::apply(bytes.data, bytes.size);
            if constexpr (first)
                vec_to[i] = h;
            else
                vec_to[i] = Impl::combineHashes(vec_to[i], h);
        }
    }
    template <bool first>
    void executeString(const IColumn * column, typename ColumnVector<ToType>::Container & vec_to) const