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::OR_C:
                case Fragment::OR_D:
                case Fragment::OR_I:
                    return subs[0] || subs[1];
                case Fragment::THRESH:
                    return std::count(subs.begin(), subs.end(), true) >= node.k;
                default: 
                    assert(subs.size() == 1);
                    return subs[0];
            }
        });
    }
    
    bool IsValid() const { return !(GetType() == ""_mst) && ScriptSize() <= MAX_STANDARD_P2WSH_SCRIPT_SIZE; }
    
    bool IsValidTopLevel() const { return IsValid() && GetType() << "B"_mst; }
    
    bool IsNonMalleable() const { return GetType() << "m"_mst; }
    
    bool NeedsSignature() const { return GetType() << "s"_mst; }
    
    bool CheckTimeLocksMix() const { return GetType() << "k"_mst; }
    
    bool CheckDuplicateKey() const { return has_duplicate_keys && !*has_duplicate_keys; }
    
    bool ValidSatisfactions() const { return IsValid() && CheckOpsLimit() && CheckStackSize(); }
    
    bool IsSaneSubexpression() const { return ValidSatisfactions() && IsNonMalleable() && CheckTimeLocksMix() && CheckDuplicateKey(); }
    
    bool IsSane() const { return IsValidTopLevel() && IsSaneSubexpression() && NeedsSignature(); }