Add more BOOST_CONTAINER_ATTRIBUTE_NODISCARD attributes and fix warnings triggered by this attribute

Author: igaztanaga

include/boost/container/adaptive_pool.hpp

@@ -150,11 +150,13 @@ class adaptive_pool
 
    //!Returns the number of elements that could be allocated.
    //!Never throws
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    size_type max_size() const BOOST_NOEXCEPT_OR_NOTHROW
    {  return size_type(-1)/(2u*sizeof(T));   }
 
    //!Allocate memory for an array of count elements.
    //!Throws bad_alloc if there is no enough memory
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    pointer allocate(size_type count, const void * = 0)
    {
       if(BOOST_UNLIKELY(count > size_type(-1)/(2u*sizeof(T))))
@@ -187,6 +189,7 @@ class adaptive_pool
       }
    }
 
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    pointer allocation_command(allocation_type command,
                          size_type limit_size,
                          size_type &prefer_in_recvd_out_size,
@@ -206,6 +209,7 @@ class adaptive_pool
    //!Allocates just one object. Memory allocated with this function
    //!must be deallocated only with deallocate_one().
    //!Throws bad_alloc if there is no enough memory
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    pointer allocate_one()
    {
       typedef dtl::shared_adaptive_node_pool
@@ -317,11 +321,13 @@ class adaptive_pool
 
    //!An allocator always compares to true, as memory allocated with one
    //!instance can be deallocated by another instance
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    friend bool operator==(const adaptive_pool &, const adaptive_pool &) BOOST_NOEXCEPT_OR_NOTHROW
    {  return true;   }
 
    //!An allocator always compares to false, as memory allocated with one
    //!instance can be deallocated by another instance
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    friend bool operator!=(const adaptive_pool &, const adaptive_pool &) BOOST_NOEXCEPT_OR_NOTHROW
    {  return false;   }
 
@@ -466,11 +472,13 @@ class private_adaptive_pool
 
    //!Returns the number of elements that could be allocated.
    //!Never throws
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    size_type max_size() const BOOST_NOEXCEPT_OR_NOTHROW
    {  return size_type(-1)/(2u*sizeof(T));   }
 
    //!Allocate memory for an array of count elements.
    //!Throws bad_alloc if there is no enough memory
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    pointer allocate(size_type count, const void * = 0)
    {
       if(BOOST_UNLIKELY(count > size_type(-1)/(2u*sizeof(T))))
@@ -497,6 +505,7 @@ class private_adaptive_pool
       }
    }
 
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    pointer allocation_command(allocation_type command,
                          size_type limit_size,
                          size_type &prefer_in_recvd_out_size,
@@ -516,6 +525,7 @@ class private_adaptive_pool
    //!Allocates just one object. Memory allocated with this function
    //!must be deallocated only with deallocate_one().
    //!Throws bad_alloc if there is no enough memory
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    pointer allocate_one()
    {
       return (pointer)m_pool.allocate_node();
@@ -583,11 +593,13 @@ class private_adaptive_pool
 
    //!An allocator always compares to true, as memory allocated with one
    //!instance can be deallocated by another instance
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    friend bool operator==(const private_adaptive_pool &, const private_adaptive_pool &) BOOST_NOEXCEPT_OR_NOTHROW
    {  return true;   }
 
    //!An allocator always compares to false, as memory allocated with one
    //!instance can be deallocated by another instance
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    friend bool operator!=(const private_adaptive_pool &, const private_adaptive_pool &) BOOST_NOEXCEPT_OR_NOTHROW
    {  return false;   }
 

include/boost/container/allocator.hpp

@@ -197,7 +197,7 @@ class allocator
 
    //!Returns the maximum number of elements that could be allocated.
    //!Never throws
-   inline size_type max_size() const BOOST_NOEXCEPT_OR_NOTHROW
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline size_type max_size() const BOOST_NOEXCEPT_OR_NOTHROW
    {  return size_type(-1)/(2u*sizeof(T));   }
 
    //!Swaps two allocators, does nothing

include/boost/container/allocator_traits.hpp

@@ -423,6 +423,7 @@ struct allocator_traits
 
    //! <b>Returns</b>: <code>a.allocate(n)</code>
    //!
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    inline static pointer allocate(Allocator &a, size_type n)
    {  return a.allocate(n);  }
 
@@ -434,6 +435,7 @@ struct allocator_traits
 
    //! <b>Effects</b>: calls <code>a.allocate(n, p)</code> if that call is well-formed;
    //! otherwise, invokes <code>a.allocate(n)</code>
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    inline static pointer allocate(Allocator &a, size_type n, const_void_pointer p)
    {
       const bool value = boost::container::dtl::
@@ -458,6 +460,7 @@ struct allocator_traits
 
    //! <b>Returns</b>: <code>a.max_size()</code> if that expression is well-formed; otherwise,
    //! <code>numeric_limits<size_type>::max()</code>.
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    inline static size_type max_size(const Allocator &a) BOOST_NOEXCEPT_OR_NOTHROW
    {
       const bool value = allocator_traits_detail::has_max_size<Allocator, size_type (Allocator::*)() const>::value;

include/boost/container/new_allocator.hpp

@@ -151,6 +151,7 @@ class new_allocator
 
    //!Allocates memory for an array of count elements.
    //!Throws bad_alloc if there is no enough memory
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    pointer allocate(size_type count)
    {
       return dtl::operator_new_allocate<T>(count);
@@ -165,6 +166,7 @@ class new_allocator
 
    //!Returns the maximum number of elements that could be allocated.
    //!Never throws
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    inline size_type max_size() const BOOST_NOEXCEPT_OR_NOTHROW
    {  return std::size_t(-1)/(2*sizeof(T));   }
 
@@ -175,11 +177,13 @@ class new_allocator
 
    //!An new_allocator always compares to true, as memory allocated with one
    //!instance can be deallocated by another instance
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    inline friend bool operator==(const new_allocator &, const new_allocator &) BOOST_NOEXCEPT_OR_NOTHROW
    {  return true;   }
 
    //!An new_allocator always compares to false, as memory allocated with one
    //!instance can be deallocated by another instance
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    inline friend bool operator!=(const new_allocator &, const new_allocator &) BOOST_NOEXCEPT_OR_NOTHROW
    {  return false;   }
 };

include/boost/container/node_allocator.hpp

@@ -137,11 +137,13 @@ class node_allocator
 
    //!Returns the number of elements that could be allocated.
    //!Never throws
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    size_type max_size() const
    {  return size_type(-1)/sizeof(T);   }
 
    //!Allocate memory for an array of count elements.
    //!Throws bad_alloc if there is no enough memory
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    pointer allocate(size_type count, const void * = 0)
    {
       if(BOOST_UNLIKELY(count > this->max_size()))
@@ -186,6 +188,7 @@ class node_allocator
       singleton_t::instance().deallocate_free_blocks();
    }
 
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    pointer allocation_command
       (allocation_type command, size_type limit_size, size_type &prefer_in_recvd_out_size, pointer &reuse)
    {
@@ -198,6 +201,7 @@ class node_allocator
 
    //!Returns maximum the number of objects the previously allocated memory
    //!pointed by p can hold.
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    size_type size(pointer p) const BOOST_NOEXCEPT_OR_NOTHROW
    {
       BOOST_CONTAINER_STATIC_ASSERT(( Version > 1 ));
@@ -207,6 +211,7 @@ class node_allocator
    //!Allocates just one object. Memory allocated with this function
    //!must be deallocated only with deallocate_one().
    //!Throws bad_alloc if there is no enough memory
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    pointer allocate_one()
    {
       BOOST_CONTAINER_STATIC_ASSERT(( Version > 1 ));
@@ -307,11 +312,13 @@ class node_allocator
 
    //!An allocator always compares to true, as memory allocated with one
    //!instance can be deallocated by another instance
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD   
    friend bool operator==(const node_allocator &, const node_allocator &) BOOST_NOEXCEPT_OR_NOTHROW
    {  return true;   }
 
    //!An allocator always compares to false, as memory allocated with one
    //!instance can be deallocated by another instance
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    friend bool operator!=(const node_allocator &, const node_allocator &) BOOST_NOEXCEPT_OR_NOTHROW
    {  return false;   }
 

include/boost/container/pmr/memory_resource.hpp

@@ -62,11 +62,13 @@ class BOOST_CONTAINER_NOVTABLE memory_resource
 
    //! <b>Returns</b>:
    //!   `&a == &b || a.is_equal(b)`.
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD   
    friend bool operator==(const memory_resource& a, const memory_resource& b) BOOST_NOEXCEPT
    {  return &a == &b || a.is_equal(b);   }
 
    //! <b>Returns</b>:
    //!   !(a == b).
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    friend bool operator!=(const memory_resource& a, const memory_resource& b) BOOST_NOEXCEPT
    {  return !(a == b); }
 

include/boost/container/pmr/monotonic_buffer_resource.hpp

@@ -112,6 +112,7 @@ class BOOST_CONTAINER_DECL monotonic_buffer_resource
    ~monotonic_buffer_resource() BOOST_OVERRIDE;
 
    //! <b>Effects</b>: `upstream_resource()->deallocate()` as necessary to release all allocated memory.
+   //!   Resets *this to its initial state at construction.
    //!   [Note: memory is released back to `upstream_resource()` even if some blocks that were allocated
    //!   from this have not been deallocated from this. - end note]
    void release() BOOST_NOEXCEPT;

include/boost/container/pmr/polymorphic_allocator.hpp

@@ -78,7 +78,7 @@ class polymorphic_allocator
 
    //! <b>Returns</b>: Equivalent to
    //!   `static_cast<T*>(m_resource->allocate(n * sizeof(T), alignof(T)))`.
-   T* allocate(size_t n)
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD T* allocate(size_t n)
    {  return static_cast<T*>(m_resource->allocate(n*sizeof(T), ::boost::move_detail::alignment_of<T>::value));  }
 
    //! <b>Requires</b>: p was allocated from a memory resource, x, equal to *m_resource,

include/boost/container/scoped_allocator.hpp

@@ -734,6 +734,7 @@ class scoped_allocator_adaptor
 
    //! <b>Returns</b>:
    //!   <code>allocator_traits<OuterAlloc>:: max_size(outer_allocator())</code>.
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    inline size_type max_size() const BOOST_NOEXCEPT_OR_NOTHROW
    {  return outer_traits_type::max_size(this->outer_allocator());   }
 
@@ -748,11 +749,13 @@ class scoped_allocator_adaptor
 
    //! <b>Returns</b>:
    //! <code>allocator_traits<OuterAlloc>::allocate(outer_allocator(), n)</code>.
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    inline pointer allocate(size_type n)
    {  return outer_traits_type::allocate(this->outer_allocator(), n);   }
 
    //! <b>Returns</b>:
    //! <code>allocator_traits<OuterAlloc>::allocate(outer_allocator(), n, hint)</code>.
+   BOOST_CONTAINER_ATTRIBUTE_NODISCARD
    inline pointer allocate(size_type n, const_void_pointer hint)
    {  return outer_traits_type::allocate(this->outer_allocator(), n, hint);   }
 
@@ -880,6 +883,7 @@ struct scoped_allocator_operator_equal<true>
 /// @endcond
 
 template <typename OuterA1, typename OuterA2, BOOST_CONTAINER_SCOPEDALLOC_ALLINNERCLASS>
+BOOST_CONTAINER_ATTRIBUTE_NODISCARD
 inline bool operator==(const scoped_allocator_adaptor<OuterA1, BOOST_CONTAINER_SCOPEDALLOC_ALLINNER>& a
                       ,const scoped_allocator_adaptor<OuterA2, BOOST_CONTAINER_SCOPEDALLOC_ALLINNER>& b)
 {
@@ -894,6 +898,7 @@ inline bool operator==(const scoped_allocator_adaptor<OuterA1, BOOST_CONTAINER_S
 }
 
 template <typename OuterA1, typename OuterA2, BOOST_CONTAINER_SCOPEDALLOC_ALLINNERCLASS>
+BOOST_CONTAINER_ATTRIBUTE_NODISCARD
 inline bool operator!=(const scoped_allocator_adaptor<OuterA1, BOOST_CONTAINER_SCOPEDALLOC_ALLINNER>& a
                       ,const scoped_allocator_adaptor<OuterA2, BOOST_CONTAINER_SCOPEDALLOC_ALLINNER>& b)
 {  return !(a == b);   }

test/allocator_traits_test.cpp

@@ -320,27 +320,36 @@ int main()
    CAlloc c_alloc;
    SAlloc s_alloc;
 
-   //allocate
-   CAllocTraits::allocate(c_alloc, 1);
-   BOOST_TEST(c_alloc.allocate_called());
-
-   SAllocTraits::allocate(s_alloc, 1);
-   BOOST_TEST(s_alloc.allocate_called());
+   //allocate/deallocate
+   {
+      CAllocTraits::pointer p = CAllocTraits::allocate(c_alloc, 1);
+      BOOST_TEST(c_alloc.allocate_called());
 
-   //deallocate
-   CAllocTraits::deallocate(c_alloc, CAllocTraits::pointer(), 1);
-   BOOST_TEST(c_alloc.deallocate_called());
+      CAllocTraits::deallocate(c_alloc, p, 1);
+      BOOST_TEST(c_alloc.deallocate_called());
+   }
+   {
+      SAllocTraits::pointer p = SAllocTraits::allocate(s_alloc, 1);
+      BOOST_TEST(s_alloc.allocate_called());
 
-   SAllocTraits::deallocate(s_alloc, SAllocTraits::pointer(), 1);
-   BOOST_TEST(s_alloc.deallocate_called());
+      SAllocTraits::deallocate(s_alloc, p, 1);
+      BOOST_TEST(s_alloc.deallocate_called());
+   }
 
    //allocate with hint
-   CAllocTraits::allocate(c_alloc, 1, CAllocTraits::const_void_pointer());
-   BOOST_TEST(c_alloc.allocate_hint_called());
-
-   s_alloc.allocate_called_ = false;
-   SAllocTraits::allocate(s_alloc, 1, SAllocTraits::const_void_pointer());
-   BOOST_TEST(s_alloc.allocate_called());
+   {
+      CAllocTraits::pointer p = CAllocTraits::allocate(c_alloc, 1, CAllocTraits::const_void_pointer());
+      BOOST_TEST(c_alloc.allocate_hint_called());
+      CAllocTraits::deallocate(c_alloc, p, 1);
+      BOOST_TEST(c_alloc.deallocate_called());
+   }
+   {      
+      s_alloc.allocate_called_ = false;
+      SAllocTraits::pointer p = SAllocTraits::allocate(s_alloc, 1, SAllocTraits::const_void_pointer());
+      BOOST_TEST(s_alloc.allocate_called());
+      SAllocTraits::deallocate(s_alloc, p, 1);
+      BOOST_TEST(s_alloc.deallocate_called());
+   }
 
    //destroy
    float dummy;
@@ -350,7 +359,7 @@ int main()
    SAllocTraits::destroy(s_alloc, &dummy);
 
    //max_size
-   CAllocTraits::max_size(c_alloc);
+   BOOST_TEST(0 != CAllocTraits::max_size(c_alloc));
    BOOST_TEST(c_alloc.max_size_called());
 
    BOOST_TEST(SAllocTraits::size_type(-1)/sizeof(SAllocTraits::value_type) == SAllocTraits::max_size(s_alloc));