tuple_size does not work on clang

Works both for gcc and msvc, but not clang.

https://godbolt.org/z/bcochYz5P

```#include
#include
#include
#include
#include
#include

using Boolean = bool;
using Integer = std::int64_t;
using Float = double;
using String = std::string;

template
using Optional = std::optional;
template
using Ptr = std::unique_ptr;
template
using Variant = std::variant;
template
using Vector = std::vector;

// This object represents one button of the reply keyboard. For simple text buttons, String can be used instead of this object to specify the button text. The optional fields web_app, request_users, request_chat, request_contact, request_location, and request_poll are mutually exclusive.
struct KeyboardButton
{
// Text of the button. If none of the optional fields are used, it will be sent as a message when the button is pressed
String text;
// Optional. If True, the user's phone number will be sent as a contact when the button is pressed. Available in private chats only.
Optional request_contact;
// Optional. If True, the user's current location will be sent when the button is pressed. Available in private chats only.
Optional request_location;
};

// This object represents a custom keyboard with reply options (see Introduction to bots for details and examples).
struct ReplyKeyboardMarkup
{
// Array of button rows, each represented by an Array of KeyboardButton objects
Vector>> keyboard;
};

struct sendAnimationRequest
{
// Additional interface options. A JSON-serialized object for an inline keyboard, custom reply keyboard, instructions to remove a reply keyboard or to force a reply from the user. Not supported for messages sent on behalf of a business account
Optional> reply_markup;
};

int main() {
return boost::pfr::tuple_size::value;
}
```

```
In file included from :1:
In file included from /opt/compiler-explorer/gcc-13.2.0/lib/gcc/x86_64-linux-gnu/13.2.0/../../../../include/c++/13.2.0/string:42:
In file included from /opt/compiler-explorer/gcc-13.2.0/lib/gcc/x86_64-linux-gnu/13.2.0/../../../../include/c++/13.2.0/bits/char_traits.h:57:
/opt/compiler-explorer/gcc-13.2.0/lib/gcc/x86_64-linux-gnu/13.2.0/../../../../include/c++/13.2.0/bits/stl_construct.h:115:4: error: no matching function for call to 'construct_at'
115 | std::construct_at(__p, std::forward<_Args>(__args)...);
| ^~~~~~~~~~~~~~~~~
/opt/compiler-explorer/gcc-13.2.0/lib/gcc/x86_64-linux-gnu/13.2.0/../../../../include/c++/13.2.0/bits/stl_uninitialized.h:120:11: note: in instantiation of function template specialization 'std::_Construct, const std::unique_ptr &>' requested here
120 | std::_Construct(std::__addressof(*__cur), *__first);
| ^
/opt/compiler-explorer/gcc-13.2.0/lib/gcc/x86_64-linux-gnu/13.2.0/../../../../include/c++/13.2.0/bits/stl_uninitialized.h:371:14: note: in instantiation of function template specialization 'std::__do_uninit_copy<__gnu_cxx::__normal_iterator *, std::vector>>, std::unique_ptr *>' requested here
371 | return std::__do_uninit_copy(__first, __last, __result);
| ^
/opt/compiler-explorer/gcc-13.2.0/lib/gcc/x86_64-linux-gnu/13.2.0/../../../../include/c++/13.2.0/bits/stl_vector.h:603:9: note: in instantiation of function template specialization 'std::__uninitialized_copy_a<__gnu_cxx::__normal_iterator *, std::vector>>, std::unique_ptr *, std::unique_ptr>' requested here
603 | std::__uninitialized_copy_a(__x.begin(), __x.end(),
| ^
/opt/compiler-explorer/gcc-13.2.0/lib/gcc/x86_64-linux-gnu/13.2.0/../../../../include/c++/13.2.0/bits/stl_construct.h:97:39: note: in instantiation of member function 'std::vector>::vector' requested here
97 | { return ::new((void*)__location) _Tp(std::forward<_Args>(__args)...); }
| ^
/opt/compiler-explorer/gcc-13.2.0/lib/gcc/x86_64-linux-gnu/13.2.0/../../../../include/c++/13.2.0/bits/stl_construct.h:115:9: note: in instantiation of function template specialization 'std::construct_at>, const std::vector> &>' requested here
115 | std::construct_at(__p, std::forward<_Args>(__args)...);
| ^
/opt/compiler-explorer/gcc-13.2.0/lib/gcc/x86_64-linux-gnu/13.2.0/../../../../include/c++/13.2.0/bits/stl_uninitialized.h:120:11: note: (skipping 23 contexts in backtrace; use -ftemplate-backtrace-limit=0 to see all)
120 | std::_Construct(std::__addressof(*__cur), *__first);
| ^
/opt/compiler-explorer/libs/boost_1_84_0/boost/pfr/detail/fields_count.hpp:183:11: note: in instantiation of default argument for 'enable_if_constructible_helper_t' required here
183 | constexpr auto detect_fields_count(detail::multi_element_range, long) noexcept
| ^~~~
/opt/compiler-explorer/libs/boost_1_84_0/boost/pfr/detail/fields_count.hpp:246:12: note: while substituting explicitly-specified template arguments into function template 'detect_fields_count'
246 | return detail::detect_fields_count(detail::multi_element_range{}, 1L);
| ^
/opt/compiler-explorer/libs/boost_1_84_0/boost/pfr/detail/fields_count.hpp:305:44: note: in instantiation of function template specialization 'boost::pfr::detail::detect_fields_count_dispatch' requested here
305 | constexpr std::size_t result = detail::detect_fields_count_dispatch(size_t_{}, 1L, 1L);
| ^
/opt/compiler-explorer/libs/boost_1_84_0/boost/pfr/tuple_size.hpp:33:57: note: in instantiation of function template specialization 'boost::pfr::detail::fields_count' requested here
33 | using tuple_size = detail::size_t_< boost::pfr::detail::fields_count() >;
| ^
:47:24: note: in instantiation of template type alias 'tuple_size' requested here
47 | return boost::pfr::tuple_size::value;
| ^
/opt/compiler-explorer/gcc-13.2.0/lib/gcc/x86_64-linux-gnu/13.2.0/../../../../include/c++/13.2.0/bits/stl_construct.h:94:5: note: candidate template ignored: substitution failure [with _Tp = std::unique_ptr, _Args = &>]: call to deleted constructor of 'std::unique_ptr'
94 | construct_at(_Tp* __location, _Args&&... __args)
| ^
95 | noexcept(noexcept(::new((void*)0) _Tp(std::declval<_Args>()...)))
96 | -> decltype(::new((void*)0) _Tp(std::declval<_Args>()...))
| ~~~
/opt/compiler-explorer/gcc-13.2.0/lib/gcc/x86_64-linux-gnu/13.2.0/../../../../include/c++/13.2.0/bits/stl_construct.h:119:25: error: call to deleted constructor of 'std::unique_ptr'
119 | ::new((void*)__p) _Tp(std::forward<_Args>(__args)...);
| ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~
/opt/compiler-explorer/gcc-13.2.0/lib/gcc/x86_64-linux-gnu/13.2.0/../../../../include/c++/13.2.0/bits/unique_ptr.h:522:7: note: 'unique_ptr' has been explicitly marked deleted here
522 | unique_ptr(const unique_ptr&) = delete;
| ^
In file included from :4:
In file included from /opt/compiler-explorer/gcc-13.2.0/lib/gcc/x86_64-linux-gnu/13.2.0/../../../../include/c++/13.2.0/vector:65:
/opt/compiler-explorer/gcc-13.2.0/lib/gcc/x86_64-linux-gnu/13.2.0/../../../../include/c++/13.2.0/bits/stl_uninitialized.h:90:21: error: static assertion failed due to requirement 'is_constructible>, const std::unique_ptr> &>::value': result type must be constructible from input type
90 | static_assert(is_constructible<_ValueType, _Tp>::value,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/opt/compiler-explorer/gcc-13.2.0/lib/gcc/x86_64-linux-gnu/13.2.0/../../../../include/c++/13.2.0/bits/stl_uninitialized.h:182:4: note: in instantiation of function template specialization 'std::__check_constructible, const std::unique_ptr &>' requested here
182 | = _GLIBCXX_USE_ASSIGN_FOR_INIT(_ValueType2, _From);
| ^
/opt/compiler-explorer/gcc-13.2.0/lib/gcc/x86_64-linux-gnu/13.2.0/../../../../include/c++/13.2.0/bits/stl_uninitialized.h:101:13: note: expanded from macro '_GLIBCXX_USE_ASSIGN_FOR_INIT'
101 | && std::__check_constructible()
| ^
/opt/compiler-explorer/gcc-13.2.0/lib/gcc/x86_64-linux-gnu/13.2.0/../../../../include/c++/13.2.0/bits/stl_uninitialized.h:373:19: note: in instantiation of function template specialization 'std::uninitialized_copy<__gnu_cxx::__normal_iterator *, std::vector>>, std::unique_ptr *>' requested here
373 | return std::uninitialized_copy(__first, __last, __result);
| ^
3 errors generated.
Compiler returned: 1
```