Revert "P0503R0, adopted in Issaquah, rewords some requirements on nullptr_t and istream_iterator. No code changes were needed, but I updated a few tests. Also resolved P0509 and P0521, which required no changes to the library or tests."

This reverts commit r286884, because it breaks the Xcode 7 builders:

  http://lab.llvm.org:8080/green/job/clang-stage1-cmake-RA-expensive/1583

Here is a PR that tracks the issue:
https://llvm.org/bugs/show_bug.cgi?id=31016

llvm-svn: 287004

3 files changed, 3 insertions, 43 deletions

diff --git a/libcxx/test/std/iterators/stream.iterators/istream.iterator/istream.iterator.cons/copy.pass.cpp b/libcxx/test/std/iterators/stream.iterators/istream.iterator/istream.iterator.cons/copy.pass.cpp
index 7f807b63e3c..0d70c7fc9ed 100644
--- a/libcxx/test/std/iterators/stream.iterators/istream.iterator/istream.iterator.cons/copy.pass.cpp
+++ b/libcxx/test/std/iterators/stream.iterators/istream.iterator/istream.iterator.cons/copy.pass.cpp
@@ -12,15 +12,11 @@
 // class istream_iterator
 
 // istream_iterator(const istream_iterator& x);
-//  C++17 says:  If is_trivially_copy_constructible_v<T> is true, then
-//     this constructor shall beis a trivial copy constructor.
 
 #include <iterator>
 #include <sstream>
 #include <cassert>
 
-#include "test_macros.h"
-
 int main()
 {
     {
diff --git a/libcxx/test/std/iterators/stream.iterators/istream.iterator/istream.iterator.cons/default.pass.cpp b/libcxx/test/std/iterators/stream.iterators/istream.iterator/istream.iterator.cons/default.pass.cpp
index 0c6828246af..c1924e4b927 100644
--- a/libcxx/test/std/iterators/stream.iterators/istream.iterator/istream.iterator.cons/default.pass.cpp
+++ b/libcxx/test/std/iterators/stream.iterators/istream.iterator/istream.iterator.cons/default.pass.cpp
@@ -12,32 +12,12 @@
 // class istream_iterator
 
 // constexpr istream_iterator();
-// C++17 says: If is_trivially_default_constructible_v<T> is true, then this 
-//    constructor shall beis a constexpr constructor.
 
 #include <iterator>
 #include <cassert>
-#include <string>
 
 #include "test_macros.h"
 
-struct S { S(); }; // not constexpr
-
-#if TEST_STD_VER > 14
-template <typename T, bool isTrivial = std::is_trivially_default_constructible_v<T>>
-struct test_trivial {
-void operator ()() const {
-    constexpr std::istream_iterator<T> it;
-    }
-};
-
-template <typename T>
-struct test_trivial<T, false> {
-void operator ()() const {}
-};
-#endif
-
-
 int main()
 {
     {
@@ -49,11 +29,4 @@ int main()
 #endif
     }
 
-#if TEST_STD_VER > 14
-    test_trivial<int>()();
-    test_trivial<char>()();
-    test_trivial<double>()();   
-    test_trivial<S>()();
-    test_trivial<std::string>()();
-#endif
 }
diff --git a/libcxx/test/std/iterators/stream.iterators/istream.iterator/types.pass.cpp b/libcxx/test/std/iterators/stream.iterators/istream.iterator/types.pass.cpp
index b1bf75b1195..1250e364d35 100644
--- a/libcxx/test/std/iterators/stream.iterators/istream.iterator/types.pass.cpp
+++ b/libcxx/test/std/iterators/stream.iterators/istream.iterator/types.pass.cpp
@@ -23,18 +23,9 @@
 //     typedef basic_istream<charT,traits> istream_type;
 //     ...
 //
-// Before C++17, we have:
 //   If T is a literal type, then the default constructor shall be a constexpr constructor.
 //   If T is a literal type, then this constructor shall be a trivial copy constructor.
 //   If T is a literal type, then this destructor shall be a trivial destructor.
-// C++17 says:
-//   If is_trivially_default_constructible_v<T> is true, then
-//       this constructor (the default ctor) shall beis a constexpr constructor.
-//   If is_trivially_copy_constructible_v<T> is true, then
-//       this constructor (the copy ctor) shall beis a trivial copy constructor.
-//   If is_trivially_destructible_v<T> is true, then this
-//       destructor shall beis a trivial destructor.
-//  Testing the C++17 ctors for this are in the ctor tests.
 
 #include <iterator>
 #include <type_traits>
@@ -42,7 +33,7 @@
 
 int main()
 {
-    typedef std::istream_iterator<double> I1; // double is trivially destructible
+    typedef std::istream_iterator<double> I1;
     static_assert((std::is_convertible<I1,
         std::iterator<std::input_iterator_tag, double, std::ptrdiff_t,
         const double*, const double&> >::value), "");
@@ -52,7 +43,7 @@ int main()
     static_assert( std::is_trivially_copy_constructible<I1>::value, "");
     static_assert( std::is_trivially_destructible<I1>::value, "");
 
-    typedef std::istream_iterator<unsigned, wchar_t> I2; // unsigned is trivially destructible
+    typedef std::istream_iterator<unsigned, wchar_t> I2;
     static_assert((std::is_convertible<I2,
         std::iterator<std::input_iterator_tag, unsigned, std::ptrdiff_t,
         const unsigned*, const unsigned&> >::value), "");
@@ -62,7 +53,7 @@ int main()
     static_assert( std::is_trivially_copy_constructible<I2>::value, "");
     static_assert( std::is_trivially_destructible<I2>::value, "");
 
-    typedef std::istream_iterator<std::string> I3; // string is NOT trivially destructible
+    typedef std::istream_iterator<std::string> I3;
     static_assert(!std::is_trivially_copy_constructible<I3>::value, "");
     static_assert(!std::is_trivially_destructible<I3>::value, "");
 }