Fix libc++ clang-cl build, swap attribute order

[rnk]

Summary

Clang insists that attribute attributes precede __declspec
attributes. This is a longstanding known issue:
https://llvm.org/pr24559. Re-order the visibility and deprecation macros
to fix the build.

[mstorsjo]

LGTM fwiw, I just looked into the same yesterday, but I guess @ldionne should ack it too.

[ldionne]

LGTM, but we should really fix the clang bug. Please wait for CI to finish before committing.

libcxx/include/__locale

protected:
     virtual bool do_always_noconv() const  _NOEXCEPT;
     virtual int do_length(state_type&, const extern_type* __frm, const extern_type* __end, size_t __mx) const;
     virtual int do_max_length() const  _NOEXCEPT;
 };
 
 // template <> class codecvt<char16_t, char, mbstate_t> // deprecated in C++20
 
 template <>
-class _LIBCPP_TYPE_VIS _LIBCPP_DEPRECATED_IN_CXX20 codecvt<char16_t, char, mbstate_t>
+class _LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_TYPE_VIS codecvt<char16_t, char, mbstate_t>
     : public locale::facet,
       public codecvt_base
 {
 public:
     typedef char16_t  intern_type;
     typedef char      extern_type;
     typedef mbstate_t state_type;
 
protected:
     virtual int do_max_length() const  _NOEXCEPT;
 };
 
 #endif
 
 // template <> class codecvt<char32_t, char, mbstate_t> // deprecated in C++20
 
 template <>
-class _LIBCPP_TYPE_VIS _LIBCPP_DEPRECATED_IN_CXX20 codecvt<char32_t, char, mbstate_t>
+class _LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_TYPE_VIS codecvt<char32_t, char, mbstate_t>
     : public locale::facet,
       public codecvt_base
 {
 public:
     typedef char32_t  intern_type;
     typedef char      extern_type;
     typedef mbstate_t state_type;
 

 template <class _InternT, class _ExternT, class _StateT>
 codecvt_byname<_InternT, _ExternT, _StateT>::~codecvt_byname()
 {
 }
 _LIBCPP_SUPPRESS_DEPRECATED_POP
 
 _LIBCPP_EXTERN_TEMPLATE(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS codecvt_byname<char, char, mbstate_t>)
 _LIBCPP_EXTERN_TEMPLATE(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS codecvt_byname<wchar_t, char, mbstate_t>)
-_LIBCPP_EXTERN_TEMPLATE(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS _LIBCPP_DEPRECATED_IN_CXX20 codecvt_byname<char16_t, char, mbstate_t>) // deprecated in C++20
-_LIBCPP_EXTERN_TEMPLATE(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS _LIBCPP_DEPRECATED_IN_CXX20 codecvt_byname<char32_t, char, mbstate_t>) // deprecated in C++20
+_LIBCPP_EXTERN_TEMPLATE(class _LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS codecvt_byname<char16_t, char, mbstate_t>) // deprecated in C++20
+_LIBCPP_EXTERN_TEMPLATE(class _LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS codecvt_byname<char32_t, char, mbstate_t>) // deprecated in C++20
 #ifndef _LIBCPP_NO_HAS_CHAR8_T
 _LIBCPP_EXTERN_TEMPLATE(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS codecvt_byname<char16_t, char8_t, mbstate_t>) // C++20
 _LIBCPP_EXTERN_TEMPLATE(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS codecvt_byname<char32_t, char8_t, mbstate_t>) // C++20
 #endif
 
 template <size_t _Np>
 struct __narrow_to_utf8
 {

libcxx/src/locale.cpp

 template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS messages<char>;
 template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS messages<wchar_t>;
 
 template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS messages_byname<char>;
 template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS messages_byname<wchar_t>;
 
 template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS codecvt_byname<char, char, mbstate_t>;
 template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS codecvt_byname<wchar_t, char, mbstate_t>;
-template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS _LIBCPP_DEPRECATED_IN_CXX20 codecvt_byname<char16_t, char, mbstate_t>;
-template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS _LIBCPP_DEPRECATED_IN_CXX20 codecvt_byname<char32_t, char, mbstate_t>;
+template class _LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS codecvt_byname<char16_t, char, mbstate_t>;
+template class _LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS codecvt_byname<char32_t, char, mbstate_t>;
 #ifndef _LIBCPP_NO_HAS_CHAR8_T
 template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS codecvt_byname<char16_t, char8_t, mbstate_t>;
 template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS codecvt_byname<char32_t, char8_t, mbstate_t>;
 #endif
 
 _LIBCPP_END_NAMESPACE_STD