More of P0600; marking allocation routines as [[nodiscard]]

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@318992 91177308-0d34-0410-b5e6-96231b3b80d8

6 files changed, 147 insertions, 9 deletions

diff --git a/include/memory b/include/memory
index 913bc85c8..30cb79eb5 100644
--- a/include/memory
+++ b/include/memory
@@ -84,8 +84,8 @@ struct allocator_traits
     template <class T> using rebind_alloc  = Alloc::rebind<U>::other | Alloc<T, Args...>;
     template <class T> using rebind_traits = allocator_traits<rebind_alloc<T>>;
 
-    static pointer allocate(allocator_type& a, size_type n);
-    static pointer allocate(allocator_type& a, size_type n, const_void_pointer hint);
+    static pointer allocate(allocator_type& a, size_type n);                          // [[nodiscard]] in C++20
+    static pointer allocate(allocator_type& a, size_type n, const_void_pointer hint); // [[nodiscard]] in C++20
 
     static void deallocate(allocator_type& a, pointer p, size_type n) noexcept;
 
@@ -1536,10 +1536,10 @@ struct _LIBCPP_TEMPLATE_VIS allocator_traits
         {typedef allocator_traits<typename rebind_alloc<_Tp>::other> other;};
 #endif  // _LIBCPP_CXX03_LANG
 
-    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
     static pointer allocate(allocator_type& __a, size_type __n)
         {return __a.allocate(__n);}
-    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
     static pointer allocate(allocator_type& __a, size_type __n, const_void_pointer __hint)
         {return __allocate(__a, __n, __hint,
             __has_allocate_hint<allocator_type, size_type, const_void_pointer>());}
@@ -1778,7 +1778,8 @@ public:
         {return _VSTD::addressof(__x);}
     _LIBCPP_INLINE_VISIBILITY const_pointer address(const_reference __x) const _NOEXCEPT
         {return _VSTD::addressof(__x);}
-    _LIBCPP_INLINE_VISIBILITY pointer allocate(size_type __n, allocator<void>::const_pointer = 0)
+    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY 
+    pointer allocate(size_type __n, allocator<void>::const_pointer = 0)
         {
         if (__n > max_size())
             __throw_length_error("allocator<T>::allocate(size_t n)"
diff --git a/include/scoped_allocator b/include/scoped_allocator
index d60ae94f1..4760d946d 100644
--- a/include/scoped_allocator
+++ b/include/scoped_allocator
@@ -68,8 +68,8 @@ public:
     outer_allocator_type& outer_allocator() noexcept;
     const outer_allocator_type& outer_allocator() const noexcept;
 
-    pointer allocate(size_type n);
-    pointer allocate(size_type n, const_void_pointer hint);
+    pointer allocate(size_type n);                           // [[nodiscard]] in C++20
+    pointer allocate(size_type n, const_void_pointer hint);  // [[nodiscard]] in C++20
     void deallocate(pointer p, size_type n) noexcept;
 
     size_type max_size() const;
@@ -477,11 +477,11 @@ public:
     const outer_allocator_type& outer_allocator() const _NOEXCEPT
         {return base::outer_allocator();}
 
-    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
     pointer allocate(size_type __n)
         {return allocator_traits<outer_allocator_type>::
             allocate(outer_allocator(), __n);}
-    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
     pointer allocate(size_type __n, const_void_pointer __hint)
         {return allocator_traits<outer_allocator_type>::
             allocate(outer_allocator(), __n, __hint);}
diff --git a/test/std/utilities/allocator.adaptor/allocator.adaptor.members/allocate_size.fail.cpp b/test/std/utilities/allocator.adaptor/allocator.adaptor.members/allocate_size.fail.cpp
new file mode 100644
index 000000000..c5244a0d1
--- /dev/null
+++ b/test/std/utilities/allocator.adaptor/allocator.adaptor.members/allocate_size.fail.cpp
@@ -0,0 +1,29 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
+// UNSUPPORTED: clang-3.3, clang-3.4, clang-3.5, clang-3.6, clang-3.7, clang-3.8
+
+// <memory>
+
+// template <class OuterAlloc, class... InnerAllocs>
+//   class scoped_allocator_adaptor
+
+// pointer allocate(size_type n);
+
+#include <scoped_allocator>
+#include <cassert>
+
+#include "allocators.h"
+
+int main()
+{
+    std::scoped_allocator_adaptor<A1<int>> a;
+    a.allocate(10);  // expected-error {{ignoring return value of function declared with 'nodiscard' attribute}}
+}
diff --git a/test/std/utilities/allocator.adaptor/allocator.adaptor.members/allocate_size_hint.fail.cpp b/test/std/utilities/allocator.adaptor/allocator.adaptor.members/allocate_size_hint.fail.cpp
new file mode 100644
index 000000000..622147c9c
--- /dev/null
+++ b/test/std/utilities/allocator.adaptor/allocator.adaptor.members/allocate_size_hint.fail.cpp
@@ -0,0 +1,29 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
+// UNSUPPORTED: clang-3.3, clang-3.4, clang-3.5, clang-3.6, clang-3.7, clang-3.8
+
+// <memory>
+
+// template <class OuterAlloc, class... InnerAllocs>
+//   class scoped_allocator_adaptor
+
+// pointer allocate(size_type n, const_void_pointer hint);
+
+#include <scoped_allocator>
+#include <cassert>
+
+#include "allocators.h"
+
+int main()
+{
+    std::scoped_allocator_adaptor<A1<int>> a;
+    a.allocate(10, (const void*)0); // expected-error {{ignoring return value of function declared with 'nodiscard' attribute}}
+}
diff --git a/test/std/utilities/memory/allocator.traits/allocator.traits.members/allocate.fail.cpp b/test/std/utilities/memory/allocator.traits/allocator.traits.members/allocate.fail.cpp
new file mode 100644
index 000000000..71201f0ef
--- /dev/null
+++ b/test/std/utilities/memory/allocator.traits/allocator.traits.members/allocate.fail.cpp
@@ -0,0 +1,51 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <memory>
+
+// template <class Alloc>
+// struct allocator_traits
+// {
+//     static pointer allocate(allocator_type& a, size_type n);
+//     ...
+// };
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
+// UNSUPPORTED: clang-3.3, clang-3.4, clang-3.5, clang-3.6, clang-3.7, clang-3.8
+
+#include <memory>
+#include <cstdint>
+#include <cassert>
+
+#include "test_macros.h"
+
+template <class T>
+struct A
+{
+    typedef T value_type;
+
+    value_type* allocate(std::size_t n)
+    {
+        assert(n == 12);
+        return reinterpret_cast<value_type*>(static_cast<std::uintptr_t>(0xEEADBEEF));
+    }
+    value_type* allocate(std::size_t n, const void* p)
+    {
+        assert(n == 11);
+        assert(p == 0);
+        return reinterpret_cast<value_type*>(static_cast<std::uintptr_t>(0xFEADBEEF));
+    }
+};
+
+int main()
+{
+    A<int> a;
+    std::allocator_traits<A<int> >::allocate(a, 10);          // expected-error {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::allocator_traits<A<int> >::allocate(a, 10, nullptr); // expected-error {{ignoring return value of function declared with 'nodiscard' attribute}}
+}
diff --git a/test/std/utilities/memory/default.allocator/allocator.members/allocate.fail.cpp b/test/std/utilities/memory/default.allocator/allocator.members/allocate.fail.cpp
new file mode 100644
index 000000000..490309edd
--- /dev/null
+++ b/test/std/utilities/memory/default.allocator/allocator.members/allocate.fail.cpp
@@ -0,0 +1,28 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <memory>
+
+// allocator:
+// pointer allocate(size_type n, allocator<void>::const_pointer hint=0);
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
+// UNSUPPORTED: clang-3.3, clang-3.4, clang-3.5, clang-3.6, clang-3.7, clang-3.8
+
+#include <memory>
+#include <cassert>
+
+#include "test_macros.h"
+
+int main()
+{
+    std::allocator<int> a;
+    a.allocate(3);          // expected-error {{ignoring return value of function declared with 'nodiscard' attribute}}
+    a.allocate(3, nullptr); // expected-error {{ignoring return value of function declared with 'nodiscard' attribute}}
+}