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 
};
enum class Availability {
    NO,
    YES,
    MAYBE,
};
namespace internal {
Type ComputeType(Fragment fragment, Type x, Type y, Type z, const std::vector<Type>& sub_types, uint32_t k, size_t data_size, size_t n_subs, size_t n_keys);
size_t ComputeScriptLen(Fragment fragment, Type sub0typ, size_t subsize, uint32_t k, size_t n_subs, size_t n_keys);
Type SanitizeType(Type x);
struct InputStack {
    /** Whether this stack is valid for its intended purpose (satisfaction or dissatisfaction of a Node).
     *  The MAYBE value is used for size estimation, when keys/preimages may actually be unavailable,
     *  but may be available at signing time. This makes the InputStack structure and signing logic,
     *  filled with dummy signatures/preimages usable for witness size estimation.
     */
    Availability available = Availability::YES;
    
    bool has_sig = false;
    
    bool malleable = false;
    
    
    bool non_canon = false;
    
    size_t size = 0;
    
    std::vector<std::vector<unsigned char>> stack;
    
    InputStack() {}