Implement LWG-3778 vector<bool> missing exception specifications (#…

…3332) Co-authored-by: Casey Carter <[email protected]>
microsoft · Jan 12, 2023 · ed9a3a0 · ed9a3a0
1 parent dc14f49
commit ed9a3a0
Show file tree

Hide file tree

Showing 3 changed files with 37 additions and 14 deletions.
diff --git a/stl/inc/vector b/stl/inc/vector
@@ -882,7 +882,7 @@ private:
         // insert range [_First, _Last) at end
 
         // For one-at-back, provide strong guarantee.
-        // Otherwise, provide basic guarantee (despite N4659 26.3.11.5 [vector.modifiers]/1).
+        // Otherwise, provide basic guarantee (despite N4928 [vector.modifiers]/2).
         // Performance note: except for one-at-back, _Emplace_one_at_back()'s strong guarantee is unnecessary here.
 
         for (; _First != _Last; ++_First) {
@@ -1764,7 +1764,7 @@ public:
         if (_Myfirst == _Mylast) { // already empty, nothing to do
             // This is an optimization for debug mode: we can avoid taking the debug lock to invalidate iterators.
             // Note that when clearing an empty vector, this will preserve past-the-end iterators, which is allowed by
-            // N4901 [tab:container.seq.req] "a.clear() [...] may invalidate the past-the-end iterator".
+            // N4928 [sequence.reqmts]/54 "a.clear() [...] may invalidate the past-the-end iterator".
             return;
         }
 
@@ -2776,8 +2776,7 @@ public:
         this->_Alloc_proxy(_GET_PROXY_ALLOCATOR(_Alvbase, _Getal()));
     }
 
-    _CONSTEXPR20 _Vb_val(const _Alloc& _Al) noexcept(is_nothrow_constructible_v<_Vectype, _Alvbase>)
-        : _Myvec(static_cast<_Alvbase>(_Al)), _Mysize(0) {
+    _CONSTEXPR20 _Vb_val(const _Alloc& _Al) noexcept : _Myvec(static_cast<_Alvbase>(_Al)), _Mysize(0) {
         this->_Alloc_proxy(_GET_PROXY_ALLOCATOR(_Alvbase, _Getal()));
     }
 
@@ -2876,12 +2875,9 @@ public:
     static const int _VBITS = _STD _VBITS;
     enum { _EEN_VBITS = _VBITS }; // helper for expression evaluator
 
-    _CONSTEXPR20 vector() noexcept(is_nothrow_default_constructible_v<_Mybase>) // strengthened
-        : _Mybase() {}
+    _CONSTEXPR20 vector() noexcept(is_nothrow_default_constructible_v<_Alloc>) : _Mybase(_Alloc()) {}
 
-    _CONSTEXPR20 explicit vector(const _Alloc& _Al) noexcept(
-        is_nothrow_constructible_v<_Mybase, const _Alloc&>) // strengthened
-        : _Mybase(_Al) {}
+    _CONSTEXPR20 explicit vector(const _Alloc& _Al) noexcept : _Mybase(_Al) {}
 
     _CONSTEXPR20 explicit vector(_CRT_GUARDOVERFLOW size_type _Count, const _Alloc& _Al = _Alloc())
         : _Mybase(_Count, false, _Al) {
@@ -2915,13 +2911,12 @@ public:
     }
 #endif // _HAS_CXX23 && defined(__cpp_lib_concepts)
 
-    _CONSTEXPR20 vector(vector&& _Right) noexcept(is_nothrow_move_constructible_v<_Mybase>) // strengthened
-        : _Mybase(_STD move(_Right)) {
+    _CONSTEXPR20 vector(vector&& _Right) noexcept : _Mybase(_STD move(_Right)) {
         this->_Swap_proxy_and_iterators(_Right);
     }
 
     _CONSTEXPR20 vector(vector&& _Right, const _Identity_t<_Alloc>& _Al) noexcept(
-        is_nothrow_constructible_v<_Mybase, _Mybase, const _Alloc&>)
+        is_nothrow_constructible_v<_Mybase, _Mybase, const _Alloc&>) // strengthened
         : _Mybase(_STD move(_Right), _Al) {
         if constexpr (!_Alvbase_traits::is_always_equal::value) {
             if (this->_Getal() != _Right._Getal()) {
@@ -2932,7 +2927,8 @@ public:
         this->_Swap_proxy_and_iterators(_Right);
     }
 
-    _CONSTEXPR20 vector& operator=(vector&& _Right) noexcept(is_nothrow_move_assignable_v<_Mybase>) {
+    _CONSTEXPR20 vector& operator=(vector&& _Right) noexcept(
+        _Choose_pocma_v<_Alvbase> != _Pocma_values::_No_propagate_allocators) {
         if (this == _STD addressof(_Right)) {
             return *this;
         }

diff --git a/tests/std/tests/Dev11_0437519_container_requirements/test.compile.pass.cpp b/tests/std/tests/Dev11_0437519_container_requirements/test.compile.pass.cpp
@@ -3006,6 +3006,33 @@ DEFINE_TEST_SPECIALIZATION(
 //
 //
 
+// Adhoc tests for exception specifications of std::vector<bool, Alloc> (LWG-3778)
+template <class Alloc>
+void assert_vector_bool_noexcept_impl() {
+    using vec_bool = std::vector<bool, Alloc>;
+
+    constexpr bool nothrow_on_pocma = std::allocator_traits<Alloc>::propagate_on_container_move_assignment::value
+                                   || std::allocator_traits<Alloc>::is_always_equal::value;
+
+    STATIC_ASSERT(std::is_nothrow_default_constructible_v<vec_bool> == std::is_nothrow_default_constructible_v<Alloc>);
+    STATIC_ASSERT(std::is_nothrow_constructible_v<vec_bool, const Alloc&>);
+    STATIC_ASSERT(std::is_nothrow_move_constructible_v<vec_bool>);
+    STATIC_ASSERT(std::is_nothrow_move_assignable_v<vec_bool> == nothrow_on_pocma);
+    STATIC_ASSERT(std::is_nothrow_destructible_v<vec_bool>);
+
+    STATIC_ASSERT(noexcept(std::declval<vec_bool&>().swap(std::declval<vec_bool&>()))); // strengthened
+    STATIC_ASSERT(noexcept(std::swap(std::declval<vec_bool&>(), std::declval<vec_bool&>()))); // strengthened
+#if _HAS_CXX17
+    STATIC_ASSERT(std::is_nothrow_swappable_v<vec_bool>); // strengthened
+#endif // _HAS_CXX17
+}
+
+void assert_vector_bool_noexcept() {
+    assert_vector_bool_noexcept_impl<std::allocator<bool>>();
+    assert_vector_bool_noexcept_impl<pocma_allocator<bool>>();
+    assert_vector_bool_noexcept_impl<non_pocma_allocator<bool>>();
+}
+
 template <container_tag Tag>
 void assert_container() {
     check_all_container_requirements<Tag>();

diff --git a/tests/std/tests/P1004R2_constexpr_vector_bool/test.cpp b/tests/std/tests/P1004R2_constexpr_vector_bool/test.cpp
@@ -274,7 +274,7 @@ constexpr bool test_interface() {
         vec default_constructed;
         const auto alloc = default_constructed.get_allocator();
         static_assert(is_same_v<remove_const_t<decltype(alloc)>, soccc_allocator<bool>>);
-        assert(alloc.id == 1);
+        assert(alloc.id == 2);
         assert(alloc.soccc_generation == 0);
     }