libstdc++: constexpr priority_queue

This patch makes priority_queue constexpr as part of P3372R3.

libstdc++-v3/ChangeLog:

	* include/bits/stl_queue.h: Add constexpr.
	* testsuite/23_containers/priority_queue/constexpr.cc: New test.

diff --git a/libstdc++-v3/include/bits/stl_queue.h b/libstdc++-v3/include/bits/stl_queue.h
index 5dc846e13e1675d1fc5e1d991178e4631e05f2aa..d9edc4c838de523f23143d4ac0214af687ff23e9 100644 (file)
--- a/libstdc++-v3/include/bits/stl_queue.h
+++ b/libstdc++-v3/include/bits/stl_queue.h
@@ -607,14 +607,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       template<typename _Seq = _Sequence, typename _Requires = typename
               enable_if<__and_<is_default_constructible<_Compare>,
                                is_default_constructible<_Seq>>::value>::type>
+       _GLIBCXX26_CONSTEXPR
        priority_queue()
        : c(), comp() { }
 
+      _GLIBCXX26_CONSTEXPR
       explicit
       priority_queue(const _Compare& __x, const _Sequence& __s)
       : c(__s), comp(__x)
       { std::make_heap(c.begin(), c.end(), comp); }
 
+      _GLIBCXX26_CONSTEXPR
       explicit
       priority_queue(const _Compare& __x, _Sequence&& __s = _Sequence())
       : c(std::move(__s)), comp(__x)
@@ -623,12 +626,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       priority_queue(const priority_queue&) = default;
       priority_queue& operator=(const priority_queue&) = default;
 
+      _GLIBCXX26_CONSTEXPR
       priority_queue(priority_queue&& __q)
       noexcept(__and_<is_nothrow_move_constructible<_Sequence>,
                      is_nothrow_move_constructible<_Compare>>::value)
       : c(std::move(__q.c)), comp(std::move(__q.comp))
       { __q.c.clear(); }
 
+      _GLIBCXX26_CONSTEXPR
       priority_queue&
       operator=(priority_queue&& __q)
       noexcept(__and_<is_nothrow_move_assignable<_Sequence>,
@@ -641,32 +646,38 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       }
 
       template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
+       _GLIBCXX26_CONSTEXPR
        explicit
        priority_queue(const _Alloc& __a)
        : c(__a), comp() { }
 
       template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
+       _GLIBCXX26_CONSTEXPR
        priority_queue(const _Compare& __x, const _Alloc& __a)
        : c(__a), comp(__x) { }
 
       // _GLIBCXX_RESOLVE_LIB_DEFECTS
       // 2537. Constructors [...] taking allocators should call make_heap
       template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
+       _GLIBCXX26_CONSTEXPR
        priority_queue(const _Compare& __x, const _Sequence& __c,
                       const _Alloc& __a)
        : c(__c, __a), comp(__x)
        { std::make_heap(c.begin(), c.end(), comp); }
 
       template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
+       _GLIBCXX26_CONSTEXPR
        priority_queue(const _Compare& __x, _Sequence&& __c, const _Alloc& __a)
        : c(std::move(__c), __a), comp(__x)
        { std::make_heap(c.begin(), c.end(), comp); }
 
       template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
+       _GLIBCXX26_CONSTEXPR
        priority_queue(const priority_queue& __q, const _Alloc& __a)
        : c(__q.c, __a), comp(__q.comp) { }
 
       template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
+       _GLIBCXX26_CONSTEXPR
        priority_queue(priority_queue&& __q, const _Alloc& __a)
        : c(std::move(__q.c), __a), comp(std::move(__q.comp))
        { __q.c.clear(); }
@@ -704,6 +715,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       // 3529. priority_queue(first, last) should construct c with (first, last)
       template<typename _InputIterator,
               typename = std::_RequireInputIter<_InputIterator>>
+       _GLIBCXX26_CONSTEXPR
        priority_queue(_InputIterator __first, _InputIterator __last,
                       const _Compare& __x = _Compare())
        : c(__first, __last), comp(__x)
@@ -713,6 +725,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       // 3522. Missing requirement on InputIterator template parameter
       template<typename _InputIterator,
               typename = std::_RequireInputIter<_InputIterator>>
+       _GLIBCXX26_CONSTEXPR
        priority_queue(_InputIterator __first, _InputIterator __last,
                       const _Compare& __x, const _Sequence& __s)
        : c(__s), comp(__x)
@@ -724,6 +737,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
       template<typename _InputIterator,
               typename = std::_RequireInputIter<_InputIterator>>
+       _GLIBCXX26_CONSTEXPR
        priority_queue(_InputIterator __first, _InputIterator __last,
                       const _Compare& __x, _Sequence&& __s)
        : c(std::move(__s)), comp(__x)
@@ -741,6 +755,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       template<typename _InputIterator, typename _Alloc,
               typename = std::_RequireInputIter<_InputIterator>,
               typename _Requires = _Uses<_Alloc>>
+       _GLIBCXX26_CONSTEXPR
        priority_queue(_InputIterator __first, _InputIterator __last,
                       const _Alloc& __alloc)
        : c(__first, __last, __alloc), comp()
@@ -749,6 +764,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       template<typename _InputIterator, typename _Alloc,
               typename = std::_RequireInputIter<_InputIterator>,
               typename _Requires = _Uses<_Alloc>>
+       _GLIBCXX26_CONSTEXPR
        priority_queue(_InputIterator __first, _InputIterator __last,
                       const _Compare& __x, const _Alloc& __alloc)
        : c(__first, __last, __alloc), comp(__x)
@@ -757,6 +773,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       template<typename _InputIterator, typename _Alloc,
               typename = std::_RequireInputIter<_InputIterator>,
               typename _Requires = _Uses<_Alloc>>
+       _GLIBCXX26_CONSTEXPR
        priority_queue(_InputIterator __first, _InputIterator __last,
                       const _Compare& __x, const _Sequence& __s,
                       const _Alloc& __alloc)
@@ -769,6 +786,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
       template<typename _InputIterator, typename _Alloc,
               typename _Requires = _Uses<_Alloc>>
+       _GLIBCXX26_CONSTEXPR
        priority_queue(_InputIterator __first, _InputIterator __last,
                       const _Compare& __x, _Sequence&& __s,
                       const _Alloc& __alloc)
@@ -788,18 +806,21 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        * @{
        */
       template<__detail::__container_compatible_range<_Tp> _Rg>
+       _GLIBCXX26_CONSTEXPR
        priority_queue(from_range_t, _Rg&& __rg,
                       const _Compare& __x = _Compare())
        : c(ranges::to<_Sequence>(std::forward<_Rg>(__rg))), comp(__x)
        { std::make_heap(c.begin(), c.end(), comp); }
 
       template<__detail::__container_compatible_range<_Tp> _Rg, typename _Alloc>
+       _GLIBCXX26_CONSTEXPR
        priority_queue(from_range_t, _Rg&& __rg, const _Compare& __x,
                       const _Alloc& __a)
        : c(ranges::to<_Sequence>(std::forward<_Rg>(__rg), __a)), comp(__x)
        { std::make_heap(c.begin(), c.end(), comp); }
 
       template<__detail::__container_compatible_range<_Tp> _Rg, typename _Alloc>
+       _GLIBCXX26_CONSTEXPR
        priority_queue(from_range_t, _Rg&& __rg, const _Alloc& __a)
        : c(ranges::to<_Sequence>(std::forward<_Rg>(__rg), __a)), comp()
        { std::make_heap(c.begin(), c.end(), comp); }
@@ -809,12 +830,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       /**
        *  Returns true if the %queue is empty.
        */
-      _GLIBCXX_NODISCARD bool
+      _GLIBCXX_NODISCARD _GLIBCXX26_CONSTEXPR
+      bool
       empty() const
       { return c.empty(); }
 
       /**  Returns the number of elements in the %queue.  */
-      _GLIBCXX_NODISCARD
+      _GLIBCXX_NODISCARD _GLIBCXX26_CONSTEXPR
       size_type
       size() const
       { return c.size(); }
@@ -823,7 +845,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        *  Returns a read-only (constant) reference to the data at the first
        *  element of the %queue.
        */
-      _GLIBCXX_NODISCARD
+      _GLIBCXX_NODISCARD _GLIBCXX26_CONSTEXPR
       const_reference
       top() const
       {
@@ -839,6 +861,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        *  The time complexity of the operation depends on the underlying
        *  sequence.
        */
+      _GLIBCXX26_CONSTEXPR
       void
       push(const value_type& __x)
       {
@@ -847,6 +870,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       }
 
 #if __cplusplus >= 201103L
+      _GLIBCXX26_CONSTEXPR
       void
       push(value_type&& __x)
       {
@@ -855,6 +879,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       }
 
       template<typename... _Args>
+       _GLIBCXX26_CONSTEXPR
        void
        emplace(_Args&&... __args)
        {
@@ -865,6 +890,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
 #if __glibcxx_containers_ranges // C++ >= 23
       template<__detail::__container_compatible_range<_Tp> _Rg>
+       _GLIBCXX26_CONSTEXPR
        void
        push_range(_Rg&& __rg)
        {
@@ -887,6 +913,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        *  data is needed, it should be retrieved before pop() is
        *  called.
        */
+      _GLIBCXX26_CONSTEXPR
       void
       pop()
       {
@@ -896,6 +923,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       }
 
 #if __cplusplus >= 201103L
+      _GLIBCXX26_CONSTEXPR
       void
       swap(priority_queue& __pq)
       noexcept(__and_<
@@ -964,6 +992,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
 #if __cplusplus >= 201103L
   template<typename _Tp, typename _Sequence, typename _Compare>
+    _GLIBCXX26_CONSTEXPR
     inline
 #if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
     // Constrained free swap overload, see p0185r1

diff --git a/libstdc++-v3/testsuite/23_containers/priority_queue/constexpr.cc b/libstdc++-v3/testsuite/23_containers/priority_queue/constexpr.cc
new file mode 100644 (file)
index 0000000..fe85617
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/priority_queue/constexpr.cc
@@ -0,0 +1,43 @@
+// { dg-do compile { target c++26 } }
+#include <queue>
+
+constexpr bool test_constexpr_priority_queue() {
+  std::priority_queue<int> pq;
+  if (!pq.empty()) return false;
+  if (pq.size() != 0) return false;
+
+  pq.push(10);
+  if (pq.empty()) return false;
+  if (pq.size() != 1) return false;
+  if (pq.top() != 10) return false;
+
+  pq.emplace(30);
+  pq.emplace(20);
+  if (pq.size() != 3) return false;
+  if (pq.top() != 30) return false;
+
+  pq.pop();
+  if (pq.size() != 2) return false;
+  if (pq.top() != 20) return false;
+
+  std::priority_queue<int> pq2;
+  pq2 = pq;
+  if (pq2.size() != 2) return false;
+  if (pq2.top() != 20) return false;
+
+  std::priority_queue<int> pq3;
+  pq3.push(100);
+  pq.swap(pq3);
+  if (pq.size() != 1 || pq.top() != 100) return false;
+  if (pq3.size() != 2 || pq3.top() != 20) return false;
+
+  int arr[] = {50, 200, 10};
+  pq.push_range(arr);
+  if (pq.size() != 4) return false;
+  if (pq.top() != 200) return false;
+
+  return true;
+}
+
+static_assert(test_constexpr_priority_queue(),
+              "constexpr priority_queue test failed!");