[libc++] Disallow volatile types in std::allocator

LWG 2447 is marked as `Complete`, but there is no `static_assert` to
reject volatile types in `std::allocator`. See the discussion at
https://reviews.llvm.org/D108856.

Add `static_assert` in `std::allocator` to disallow volatile types. Since this
is an implementation choice, mark the binding test as `libc++` only.

Remove tests that use containers backed by `std::allocator` that test
the container when used with a volatile type.

Reviewed By: ldionne, #libc

Differential Revision: https://reviews.llvm.org/D109056

Author: JoeLoser

libcxx/TODO.TXT

@@ -21,4 +21,3 @@ Misc Tasks
 * Find all sequences of >2 underscores and eradicate them.
 * run clang-tidy on libc++
 * Document the "conditionally-supported" bits of libc++
-* Put a static_assert in std::allocator to deny const/volatile types (LWG 2447)

libcxx/include/__memory/allocator.h

@@ -80,6 +80,7 @@ template <class _Tp>
 class _LIBCPP_TEMPLATE_VIS allocator
     : private __non_trivial_if<!is_void<_Tp>::value, allocator<_Tp> >
 {
+    static_assert(!is_volatile<_Tp>::value, "std::allocator does not support volatile types");
 public:
     typedef size_t      size_type;
     typedef ptrdiff_t   difference_type;
@@ -162,6 +163,7 @@ template <class _Tp>
 class _LIBCPP_TEMPLATE_VIS allocator<const _Tp>
     : private __non_trivial_if<!is_void<_Tp>::value, allocator<const _Tp> >
 {
+    static_assert(!is_volatile<_Tp>::value, "std::allocator does not support volatile types");
 public:
     typedef size_t      size_type;
     typedef ptrdiff_t   difference_type;

libcxx/test/libcxx/memory/allocator_volatile.verify.cpp

@@ -0,0 +1,16 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: libc++
+
+// http://wg21.link/LWG2447 gives implementors freedom to reject volatile types in `std::allocator`.
+
+#include <memory>
+
+std::allocator<volatile int> A1; // expected-error@*:* {{std::allocator does not support volatile types}}
+std::allocator<const volatile int> A2; // expected-error@*:* {{std::allocator does not support volatile types}}

libcxx/test/std/concepts/concepts.lang/concept.default.init/default_initializable.compile.pass.cpp

@@ -204,8 +204,6 @@ void test()
     test_true     <std::deque<               int>>();
 #ifdef _LIBCPP_VERSION
     test_true     <std::deque<const          int>>();
-    test_true     <std::deque<      volatile int>>();
-    test_true     <std::deque<const volatile int>>();
 #endif // _LIBCPP_VERSION
     test_true     <std::forward_list<int>>();
     test_true     <std::list<int>>();
@@ -227,8 +225,6 @@ void test()
     test_true     <std::stack<               int>>();
 #ifdef _LIBCPP_VERSION
     test_true     <std::stack<const          int>>();
-    test_true     <std::stack<      volatile int>>();
-    test_true     <std::stack<const volatile int>>();
 #endif // _LIBCPP_VERSION
     test_true     <std::queue<int>>();
     test_true     <std::priority_queue<int>>();

libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.create/make_shared.pass.cpp

@@ -73,6 +73,26 @@ void test_pointer_to_function() {
 void test_pointer_to_function() {}
 #endif // _LIBCPP_VERSION
 
+template <typename T>
+void test(const T &t0)
+{
+    {
+      T t1 = t0;
+      std::shared_ptr<T> p0 = std::make_shared<T>(t0);
+      std::shared_ptr<T> p1 = std::make_shared<T>(t1);
+      assert(*p0 == t0);
+      assert(*p1 == t1);
+    }
+
+    {
+      const T t1 = t0;
+      std::shared_ptr<const T> p0 = std::make_shared<const T>(t0);
+      std::shared_ptr<const T> p1 = std::make_shared<const T>(t1);
+      assert(*p0 == t0);
+      assert(*p1 == t1);
+    }
+}
+
 int main(int, char**)
 {
     int nc = globalMemCounter.outstanding_new;
@@ -108,5 +128,9 @@ int main(int, char**)
 #endif
     assert(A::count == 0);
 
+    test<bool>(true);
+    test<int>(3);
+    test<double>(5.0);
+
   return 0;
 }