// C++N4741 Committee Draft, Standard for Programming Language C++
// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/n741.pdf
const char* msg= "C++N4741(270)23.17.5.1 duration constructors [time.duration.cons]p662.cpp";
// Edited by Dr. Ogawa Kiyoshi. Compile procedure and results record.

#include <iostream>
#include <cstdlib>
#include <chrono>

using namespace std;
using namespace std::chrono;

duration<int, milli> d(3); // OK
duration<int, milli> d(3.5); // error

duration<int, milli> ms(3);
duration<int, micro> us = ms; // OK
duration<int, milli> ms2 = us; // error

int main() {
//  http://ja.cppreference.com/w/cpp/chrono/duration
  cout << std::chrono::duration_cast<std::chrono::microseconds>(us).count()<<endl;

  cout << msg << endl;
  return EXIT_SUCCESS;
}

$ ../c1.sh p662
$ clang++ p662.cpp  -std=c++2a -Wall
p662.cpp:14:22: error: redefinition of 'd'
duration<int, milli> d(3.5); // error
                     ^
p662.cpp:13:22: note: previous definition is here
duration<int, milli> d(3); // OK
                     ^
p662.cpp:18:22: error: no viable conversion from 'duration<[...], ratio<[...], 1000000>>'
      to 'duration<[...], ratio<[...], 1000>>'
duration<int, milli> ms2 = us; // error
                     ^     ~~
/usr/local/Cellar/llvm/6.0.0/include/c++/v1/chrono:491:28: note: candidate constructor (the
      implicit copy constructor) not viable: no known conversion from 'duration<int,
      std::__1::micro>' (aka 'duration<int, ratio<1LL, 1000000LL> >') to 'const
      std::__1::chrono::duration<int, std::__1::ratio<1, 1000> > &' for 1st argument
class _LIBCPP_TEMPLATE_VIS duration
                           ^
/usr/local/Cellar/llvm/6.0.0/include/c++/v1/chrono:491:28: note: candidate constructor (the
      implicit move constructor) not viable: no known conversion from 'duration<int,
      std::__1::micro>' (aka 'duration<int, ratio<1LL, 1000000LL> >') to
      'std::__1::chrono::duration<int, std::__1::ratio<1, 1000> > &&' for 1st argument
/usr/local/Cellar/llvm/6.0.0/include/c++/v1/chrono:555:9: note: candidate template ignored:
      requirement '__no_overflow<ratio<1, 1000000>, period>::value &&
      (treat_as_floating_point<rep>::value || (__no_overflow<ratio<1, 1000000>,
      period>::type::den == 1 && !treat_as_floating_point<int>::value))' was not satisfied
      [with _Rep2 = int, _Period2 = std::__1::ratio<1, 1000000>]
        duration(const duration<_Rep2, _Period2>& __d,
        ^
2 errors generated.

// C++N4741 Committee Draft, Standard for Programming Language C++
// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/n741.pdf
const char* msg= "C++N4741(270)23.17.5.1 duration constructors [time.duration.cons]p662.cpp";
// Edited by Dr. Ogawa Kiyoshi. Compile procedure and results record.

#include <iostream>
#include <cstdlib>
#include <chrono>

using namespace std;
using namespace std::chrono;

duration<int, milli> d(3); // OK
///duration<int, milli> d(3.5); // error

duration<int, milli> ms(3);
duration<int, micro> us = ms; // OK
///duration<int, milli> ms2 = us; // error

int main() {
//  http://ja.cppreference.com/w/cpp/chrono/duration
  cout << std::chrono::duration_cast<std::chrono::microseconds>(us).count()<<endl;

  cout << msg << endl;
  return EXIT_SUCCESS;
}

$ ../cpla.sh p662a
$ clang++ p662a.cpp -std=c++03 -Wall
3000
C++N4741(270)23.17.5.1 duration constructors [time.duration.cons]p662.cpp
$ clang++ p662a.cpp -std=c++2a -Wall
3000
C++N4741(270)23.17.5.1 duration constructors [time.duration.cons]p662.cpp

$ g++-8 p662a.cpp -std=c++03  -Wall
In file included from /usr/local/Cellar/gcc/8.1.0/include/c++/8.1.0/chrono:35,
                 from p662a.cpp:8:
/usr/local/Cellar/gcc/8.1.0/include/c++/8.1.0/bits/c++0x_warning.h:32:2: error: #error This file requires compiler and library support for the ISO C++ 2011 standard. This support must be enabled with the -std=c++11 or -std=gnu++11 compiler options.
 #error This file requires compiler and library support \
  ^~~~~
p662a.cpp:11:22: error: 'chrono' is not a namespace-name
 using namespace std::chrono;
                      ^~~~~~
p662a.cpp:11:28: error: expected namespace-name before ';' token
 using namespace std::chrono;
                            ^
p662a.cpp:13:1: error: 'duration' does not name a type; did you mean 'daemon'?
 duration<int, milli> d(3); // OK
 ^~~~~~~~
 daemon
p662a.cpp:16:1: error: 'duration' does not name a type; did you mean 'daemon'?
 duration<int, milli> ms(3);
 ^~~~~~~~
 daemon
p662a.cpp:17:1: error: 'duration' does not name a type; did you mean 'daemon'?
 duration<int, micro> us = ms; // OK
 ^~~~~~~~
 daemon
p662a.cpp: In function 'int main()':
p662a.cpp:22:16: error: 'std::chrono' has not been declared
   cout << std::chrono::duration_cast<std::chrono::microseconds>(us).count()<<endl;
                ^~~~~~
p662a.cpp:22:43: error: 'std::chrono' has not been declared
   cout << std::chrono::duration_cast<std::chrono::microseconds>(us).count()<<endl;
                                           ^~~~~~
p662a.cpp:22:65: error: 'us' was not declared in this scope
   cout << std::chrono::duration_cast<std::chrono::microseconds>(us).count()<<endl;
                                                                 ^~

$ g++-8 p662a.cpp -std=c++2a  -Wall
3000
C++N4741(270)23.17.5.1 duration constructors [time.duration.cons]p662.cpp