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 
const std::vector<unsigned char> data;
    
    const std::vector<NodeRef<Key>> subs;
private:
    
    const internal::Ops ops;
    
    const internal::StackSize ss;
    
    const Type typ;
    
    const size_t scriptlen;
    
    
    
    
    
    mutable std::optional<bool> has_duplicate_keys;
    
    size_t CalcScriptLen() const {
        size_t subsize = 0;
        for (const auto& sub : subs) {
            subsize += sub->ScriptSize();
        }
        Type sub0type = subs.size() > 0 ? subs[0]->GetType() : ""_mst;
        return internal::ComputeScriptLen(fragment, sub0type, subsize, k, subs.size(), keys.size());
    }
    /* Apply a recursive algorithm to a Miniscript tree, without actual recursive calls.
     *
     * The algorithm is defined by two functions: downfn and upfn. Conceptually, the