More constexpr from P0202. count and count_if. Also fix a comment that Morwenn noted.

llvm-svn: 322506

diff --git a/libcxx/include/algorithm b/libcxx/include/algorithm
index ee06250..44a3d10 100644 (file)
--- a/libcxx/include/algorithm
+++ b/libcxx/include/algorithm
@@ -79,11 +79,11 @@ template <class ForwardIterator, class BinaryPredicate>
     adjacent_find(ForwardIterator first, ForwardIterator last, BinaryPredicate pred);
 
 template <class InputIterator, class T>
-    typename iterator_traits<InputIterator>::difference_type
+    constexpr typename iterator_traits<InputIterator>::difference_type  // constexpr in C++20
     count(InputIterator first, InputIterator last, const T& value);
 
 template <class InputIterator, class Predicate>
-    typename iterator_traits<InputIterator>::difference_type
+    constexpr typename iterator_traits<InputIterator>::difference_type // constexpr in C++20
     count_if(InputIterator first, InputIterator last, Predicate pred);
 
 template <class InputIterator1, class InputIterator2>
@@ -333,11 +333,11 @@ template <class ForwardIterator, class Compare>
     is_sorted(ForwardIterator first, ForwardIterator last, Compare comp);
 
 template<class ForwardIterator>
-    ForwardIterator
+    constexpr ForwardIterator    // constexpr in C++20
     is_sorted_until(ForwardIterator first, ForwardIterator last);
 
 template <class ForwardIterator, class Compare>
-    ForwardIterator
+    constexpr ForwardIterator    // constexpr in C++20
     is_sorted_until(ForwardIterator first, ForwardIterator last, Compare comp);
 
 template <class RandomAccessIterator>
@@ -1240,7 +1240,7 @@ adjacent_find(_ForwardIterator __first, _ForwardIterator __last)
 // count
 
 template <class _InputIterator, class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
 typename iterator_traits<_InputIterator>::difference_type
 count(_InputIterator __first, _InputIterator __last, const _Tp& __value_)
 {
@@ -1254,7 +1254,7 @@ count(_InputIterator __first, _InputIterator __last, const _Tp& __value_)
 // count_if
 
 template <class _InputIterator, class _Predicate>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
 typename iterator_traits<_InputIterator>::difference_type
 count_if(_InputIterator __first, _InputIterator __last, _Predicate __pred)
 {

diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.count/count.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.count/count.pass.cpp
index 260e5ed..bce1095 100644 (file)
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.count/count.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.count/count.pass.cpp
@@ -11,14 +11,25 @@
 
 // template<InputIterator Iter, class T>
 //   requires HasEqualTo<Iter::value_type, T>
-//   Iter::difference_type
+//   constexpr Iter::difference_type   // constexpr after C++17
 //   count(Iter first, Iter last, const T& value);
 
 #include <algorithm>
 #include <cassert>
 
+#include "test_macros.h"
 #include "test_iterators.h"
 
+#if TEST_STD_VER > 17
+TEST_CONSTEXPR bool test_constexpr() {
+    int ia[] = {0, 1, 2, 2, 0, 1, 2, 3};
+    int ib[] = {1, 2, 3, 4, 5, 6};
+    return    (std::count(std::begin(ia), std::end(ia), 2) == 3)
+           && (std::count(std::begin(ib), std::end(ib), 9) == 0)
+           ;
+    }
+#endif
+
 int main()
 {
     int ia[] = {0, 1, 2, 2, 0, 1, 2, 3};
@@ -29,4 +40,8 @@ int main()
                       input_iterator<const int*>(ia + sa), 7) == 0);
     assert(std::count(input_iterator<const int*>(ia),
                       input_iterator<const int*>(ia), 2) == 0);
+
+#if TEST_STD_VER > 17
+    static_assert(test_constexpr());
+#endif
 }

diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.count/count_if.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.count/count_if.pass.cpp
index b837a0e..ff3b688 100644 (file)
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.count/count_if.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.count/count_if.pass.cpp
@@ -11,21 +11,31 @@
 
 // template<InputIterator Iter, Predicate<auto, Iter::value_type> Pred>
 //   requires CopyConstructible<Pred>
-//   Iter::difference_type
+//   constexpr Iter::difference_type   // constexpr after C++17
 //   count_if(Iter first, Iter last, Pred pred);
 
 #include <algorithm>
 #include <functional>
 #include <cassert>
 
+#include "test_macros.h"
 #include "test_iterators.h"
 
 struct eq {
-    eq (int val) : v(val) {}
-    bool operator () (int v2) const { return v == v2; }
+    TEST_CONSTEXPR eq (int val) : v(val) {}
+    TEST_CONSTEXPR bool operator () (int v2) const { return v == v2; }
     int v;
     };
 
+#if TEST_STD_VER > 17
+TEST_CONSTEXPR bool test_constexpr() {
+    int ia[] = {0, 1, 2, 2, 0, 1, 2, 3};
+    int ib[] = {1, 2, 3, 4, 5, 6};
+    return    (std::count_if(std::begin(ia), std::end(ia), eq(2)) == 3)
+           && (std::count_if(std::begin(ib), std::end(ib), eq(9)) == 0)
+           ;
+    }
+#endif
 
 int main()
 {
@@ -40,4 +50,8 @@ int main()
     assert(std::count_if(input_iterator<const int*>(ia),
                          input_iterator<const int*>(ia),
                          eq(2)) == 0);
+
+#if TEST_STD_VER > 17
+    static_assert(test_constexpr());
+#endif
 }