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 
case Fragment::AND_B: {
                const auto count{1 + subs[0]->ops.count + subs[1]->ops.count};
                const auto sat{subs[0]->ops.sat + subs[1]->ops.sat};
                const auto dsat{subs[0]->ops.dsat + subs[1]->ops.dsat};
                return {count, sat, dsat};
            }
            case Fragment::OR_B: {
                const auto count{1 + subs[0]->ops.count + subs[1]->ops.count};
                const auto sat{(subs[0]->ops.sat + subs[1]->ops.dsat) | (subs[1]->ops.sat + subs[0]->ops.dsat)};
                const auto dsat{subs[0]->ops.dsat + subs[1]->ops.dsat};
                return {count, sat, dsat};
            }
            case Fragment::OR_D: {
                const auto count{3 + subs[0]->ops.count + subs[1]->ops.count};
                const auto sat{subs[0]->ops.sat | (subs[1]->ops.sat + subs[0]->ops.dsat)};
                const auto dsat{subs[0]->ops.dsat + subs[1]->ops.dsat};
                return {count, sat, dsat};
            }
            case Fragment::OR_C: {
                const auto count{2 + subs[0]->ops.count + subs[1]->ops.count};
                const auto sat{subs[0]->ops.sat | (subs[1]->ops.sat + subs[0]->ops.dsat)};
                return {count, sat, {}};
            }
            case Fragment::OR_I: {
                const auto count{3 + subs[0]->ops.count + subs[1]->ops.count};
                const auto sat{subs[0]->ops.sat | subs[1]->ops.sat};
                const auto dsat{subs[0]->ops.dsat | subs[1]->ops.dsat};
                return {count, sat, dsat};
            }
            case Fragment::ANDOR: {