Legacy standard C library headers and overloaded C++ functions

C++ language standard says in D.5

2 Every C header, each of which has a name of the form name.h, behaves
as if each name placed in the standard library namespace by the
corresponding cname header is placed within the global namespace
scope. It is unspecified whether these names are first declared or
defined within namespace scope (3.3.6) of the namespace std and are
then injected into the global namespace scope by explicit
using-declarations (7.3.3).

3 [ Example: The header
assuredly provides its declarations and definitions within the
namespace std. It may also provide these names within the global
namespace. The header assuredly provides the same
declarations and definitions within the global namespace, much as in
the C Standard. It may also provide these names within the namespace
std. —end example ]

This seems to state rather explicitly ("... each name ...", "...the same declarations...") that the old-style headers must provide the same set of declarations as the new-style headers, but in global namespace. No exception is made for C++-specific overloaded versions of various C functions, for one example.

That appears to mean that must provide three versions of sin function: sin(float), sin(double) and sin(long double) in global namespace. This, in turn, means that the following C++ code should fail overload resolution

#include 

int main() {
  sin(1);
}

It does fail under MSVC++ compiler, but it compiles successfully under GCC and Clang. So, does GCC just ignore the standard requirement with regard to deprecated old-style headers? Or do I somehow misinterpret the wording in the standard?

Answer

Thanks to @hvd's comments I have seen the light, it turns out MSVC is correct and GCC should be complaining about the ambiguity as well.

The only differences between including vs are where the names are originally scoped, which is in namespace std for the former, and the global namespace for the latter (implementations are free to provide the names in the other namespace as well, but this isn't mandated), and the fact that including the .h variants of C headers is deprecated.