Add construct, destroy to handler_alloc

fix #432

CHANGELOG.md

@@ -6,6 +6,7 @@ Version 51
 * Use BOOST_FALLTHROUGH
 * Use BOOST_STRINGIZE
 * DynamicBuffer benchmarks
+* Add construct, destroy to handler_alloc
 
 API Changes:
 

include/beast/core/handler_alloc.hpp

@@ -10,6 +10,7 @@
 
 #include <beast/config.hpp>
 #include <boost/asio/handler_alloc_hook.hpp>
+#include <boost/config.hpp>
 #include <cstddef>
 #include <cstdlib>
 #include <memory>
@@ -96,7 +97,7 @@ public:
     }
 
     value_type*
-    allocate(std::ptrdiff_t n)
+    allocate(size_type n)
     {
         auto const size = n * sizeof(T);
         using boost::asio::asio_handler_allocate;
@@ -105,21 +106,28 @@ public:
     }
 
     void
-    deallocate(value_type* p, std::ptrdiff_t n)
+    deallocate(value_type* p, size_type n)
     {
         auto const size = n * sizeof(T);
         using boost::asio::asio_handler_deallocate;
         asio_handler_deallocate(p, size, std::addressof(h_));
     }
 
-#ifdef _MSC_VER
-    // Work-around for MSVC not using allocator_traits
-    // in the implementation of shared_ptr
-    //
+//#if BOOST_WORKAROUND(BOOST_GCC, < 60000) // Works, but too coarse
+
+#if defined(BOOST_LIBSTDCXX_VERSION) && BOOST_LIBSTDCXX_VERSION < 60000
+    template<class U, class... Args>
     void
-    destroy(T* t)
+    construct(U* ptr, Args&&... args)
     {
-        t->~T();
+        ::new((void*)ptr) U(std::forward<Args>(args)...);
+    }
+
+    template<class U>
+    void
+    destroy(U* ptr)
+    {
+        ptr->~U();
     }
 #endif
 

test/core/handler_alloc.cpp

@@ -9,6 +9,7 @@
 #include <beast/core/handler_alloc.hpp>
 
 #include <beast/unit_test/suite.hpp>
+#include <list>
 #include <vector>
 
 namespace beast {
@@ -24,9 +25,23 @@ public:
         }
     };
 
+    // https://github.com/vinniefalco/Beast/issues/432
+    void
+    testRegression432()
+    {
+        handler h;
+        handler_alloc<int, handler> a{h};
+        std::list<int, handler_alloc<int, handler>> v{a};
+        v.push_back(1);
+        v.push_back(2);
+        v.push_back(3);
+    }
+
     void
     run() override
     {
+        testRegression432();
+
         handler h;
         handler h2;
         handler_alloc<char, handler> a1{h};