std::array not working with gcc-9.1 / c++17

[SimonEbner]

The following piece of code fails to compile:

#include <vector>
#include <array>
#include <dbg.h>

int main() {
 std::array<unsigned int, 256> x{};
 dbg(x);
}

The problem boils down to

dbg.h: In substitution of ‘template<class T> using detect_size_t = decltype (dbg_macro::detail::{anonymous}::size(declval<T>())) [with T = std::array<unsigned int, 256>]’:
test.cc:12:39:   required from here
dbg.h:205:36: error: call of overloaded ‘size(std::array<unsigned int, 256>)’ is ambiguous
  205 | using detect_size_t = decltype(size(std::declval<T>()));
      |                                ~~~~^~~~~~~~~~~~~~~~~~~
dbg.h:189:16: note: candidate: ‘constexpr decltype (c.size()) dbg_macro::detail::{anonymous}::size(const T&) [with T = std::array<unsigned int, 256>; decltype (c.size()) = long unsigned int]’
  189 | constexpr auto size(const T& c) -> decltype(c.size()) {
      |                ^~~~
In file included from /usr/include/c++/9/string:54,
                 from /usr/include/c++/9/stdexcept:39,
                 from /usr/include/c++/9/array:39,
                 from test.cc:1:
/usr/include/c++/9/bits/range_access.h:242:5: note: candidate: ‘constexpr decltype (__cont.size()) std::size(const _Container&) [with _Container = std::array<unsigned int, 256>; decltype (__cont.size()) = long unsigned int]’
  242 |     size(const _Container& __cont) noexcept(noexcept(__cont.size()))
      |     ^~~~

Changing line 204 from:

template <typename T>
using detect_size_t = decltype(size(std::declval<T>()));

to

template <typename T>
using detect_size_t = decltype(std::declval<T>().size());

solves the problem for me