This is being emitted with [GCC 10.2.1](https://packages.debian.org/bullseye/g++-arm-linux-gnueabihf), in some CI jobs: i.e https://github.com/bitcoin/bitcoin/pull/25972/checks?check_run_id=12423693655, or https://github.com/bitcoin/bitcoin/pull/25972/checks?check_run_id=12423693651 (where we actually turn on all our warning flags with depends builds).
```bash
In file included from test/miniscript_tests.cpp:19:
./script/miniscript.h:1197:71: error: comparison of integers of different signs: 'typename iterator_traits<int *>::difference_type' (aka 'int') and 'const uint32_t' (aka 'const unsigned int') [-Werror,-Wsign-compare]
                    return std::count(subs.begin(), subs.end(), true) >= node.k;
                           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^  ~~~~~~
test/miniscript_tests.cpp:346:34: note: in instantiation of function template specialization 'miniscript::Node<CPubKey>::IsSatisfiable<(lambda at test/miniscript_tests.cpp:346:48)>' requested here
        bool satisfiable = node->IsSatisfiable([](const Node&) { return true; });
                                 ^
1 error generated.
```

cc @darosior 
{
        std::vector<std::pair<const Node<Key>&, const Node<Key>&>> queue;
        queue.emplace_back(node1, node2);
        while (!queue.empty()) {
            const auto& [a, b] = queue.back();
            queue.pop_back();
            if (std::tie(a.fragment, a.k, a.keys, a.data) < std::tie(b.fragment, b.k, b.keys, b.data)) return -1;
            if (std::tie(b.fragment, b.k, b.keys, b.data) < std::tie(a.fragment, a.k, a.keys, a.data)) return 1;
            if (a.subs.size() < b.subs.size()) return -1;
            if (b.subs.size() < a.subs.size()) return 1;
            size_t n = a.subs.size();
            for (size_t i = 0; i < n; ++i) {
                queue.emplace_back(*a.subs[n - 1 - i], *b.subs[n - 1 - i]);
            }
        }
        return 0;
    }
    
    Type CalcType() const {