Implement n3789; constexpr support in named function objects

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@191626 91177308-0d34-0410-b5e6-96231b3b80d8

test/utilities/function.objects/comparisons/equal_to.pass.cpp

@@ -29,5 +29,11 @@ int main()
     assert(!f2(36, 6));
     assert(f2(36, 36.0));
     assert(f2(36.0, 36L));
+
+    constexpr bool foo = std::equal_to<int> () (36, 36);
+    static_assert ( foo, "" );
+
+    constexpr bool bar = std::equal_to<> () (36.0, 36);
+    static_assert ( bar, "" );
 #endif
 }

test/utilities/function.objects/comparisons/greater.pass.cpp

@@ -33,5 +33,11 @@ int main()
     assert( f2(36.0, 6));
     assert(!f2(6, 36.0));
     assert(!f2(6.0, 36));
+
+    constexpr bool foo = std::greater<int> () (36, 36);
+    static_assert ( !foo, "" );
+
+    constexpr bool bar = std::greater<> () (36.0, 36);
+    static_assert ( !bar, "" );
 #endif
 }

test/utilities/function.objects/comparisons/greater_equal.pass.cpp

@@ -33,5 +33,11 @@ int main()
     assert( f2(36.0, 6));
     assert(!f2(6, 36.0));
     assert(!f2(6.0, 36));
+
+    constexpr bool foo = std::greater_equal<int> () (36, 36);
+    static_assert ( foo, "" );
+
+    constexpr bool bar = std::greater_equal<> () (36.0, 36);
+    static_assert ( bar, "" );
 #endif
 }

test/utilities/function.objects/comparisons/less.pass.cpp

@@ -33,5 +33,11 @@ int main()
     assert(!f2(36.0, 6));
     assert( f2(6, 36.0));
     assert( f2(6.0, 36));
+
+    constexpr bool foo = std::less<int> () (36, 36);
+    static_assert ( !foo, "" );
+
+    constexpr bool bar = std::less<> () (36.0, 36);
+    static_assert ( !bar, "" );
 #endif
 }

test/utilities/function.objects/comparisons/less_equal.pass.cpp

@@ -33,5 +33,11 @@ int main()
     assert(!f2(36.0, 6));
     assert( f2(6, 36.0));
     assert( f2(6.0, 36));
+
+    constexpr bool foo = std::less_equal<int> () (36, 36);
+    static_assert ( foo, "" );
+
+    constexpr bool bar = std::less_equal<> () (36.0, 36);
+    static_assert ( bar, "" );
 #endif
 }

test/utilities/function.objects/comparisons/not_equal_to.pass.cpp

@@ -31,5 +31,11 @@ int main()
     assert( f2(36.0, 6));
     assert(!f2(36.0, 36));
     assert(!f2(36, 36.0));
+
+    constexpr bool foo = std::not_equal_to<int> () (36, 36);
+    static_assert ( !foo, "" );
+
+    constexpr bool bar = std::not_equal_to<> () (36.0, 36);
+    static_assert ( !bar, "" );
 #endif
 }