Fixed GitHub #74 ("vector assignment not using memcpy")

doc/container.qbk

@@ -1252,6 +1252,7 @@ use [*Boost.Container]? There are several reasons for that:
 * Fixed bugs:
    * [@https://svn.boost.org/trac/boost/ticket/13533 Trac #13533:  ['"Boost vector resize causes assert(false)"]].
    * [@https://github.com/boostorg/container/issues/73 GitHub #73: ['"triviality of pair"]].
+   * [@https://github.com/boostorg/container/issues/74 GitHub #74: ['"vector assignment not using memcpy"]].
    * Fixed race condition bug in [classref boost::container::pmr::unsynchronized_pool_resource unsynchronized_pool_resource]
      found by Arthur O'Dowyer in his blog post
      [@https://quuxplusone.github.io/blog/2018/06/05/libcpp-memory-resource/ <memory_resource> for libc++]

include/boost/container/vector.hpp

@@ -1192,6 +1192,7 @@ class vector
    //! <b>Complexity</b>: Linear to n.
    template <class InIt>
    void assign(InIt first, InIt last
+      //Input iterators or version 0 allocator
       BOOST_CONTAINER_DOCIGN(BOOST_MOVE_I typename dtl::disable_if_or
          < void
          BOOST_MOVE_I dtl::is_convertible<InIt BOOST_MOVE_I size_type>
@@ -1241,6 +1242,7 @@ class vector
    //! <b>Complexity</b>: Linear to n.
    template <class FwdIt>
    void assign(FwdIt first, FwdIt last
+      //Forward iterators and version > 0 allocator
       BOOST_CONTAINER_DOCIGN(BOOST_MOVE_I typename dtl::disable_if_or
          < void
          BOOST_MOVE_I dtl::is_same<alloc_version BOOST_MOVE_I version_0>
@@ -1280,21 +1282,9 @@ class vector
             //Forward expansion, use assignment + back deletion/construction that comes later
          }
       }
-      //Overwrite all elements we can from [first, last)
-      iterator cur = this->begin();
-      const iterator end_it = this->end();
-      for ( ; first != last && cur != end_it; ++cur, ++first){
-         *cur = *first;
-      }
 
-      if (first == last){
+      boost::container::copy_assign_range_alloc_n(this->m_holder.alloc(), first, input_sz, this->priv_raw_begin(), this->size());
-         //There are no more elements in the sequence, erase remaining
+      this->m_holder.m_size = input_sz;
-         this->priv_destroy_last_n(this->size() - input_sz);
-      }
-      else{
-         //Uninitialized construct at end the remaining range
-         this->priv_uninitialized_construct_at_end(first, last);
-      }
    }
 
    //! <b>Effects</b>: Assigns the n copies of val to *this.

test/vector_test.hpp

@@ -203,6 +203,45 @@ bool vector_copyable_only(MyBoostVector &boostvector, MyStdVector &stdvector, bo
       boostvectorp->resize(100, IntType(9));
       if(!test::CheckEqualContainers(*boostvectorp, *stdvectorp)) return 1;
    }
+   //operator=
+   {
+      //Copy constructor test
+      MyBoostVector bcopy((const MyBoostVector&) boostvector);
+      MyStdVector   scopy((const MyStdVector&)   stdvector);
+      MyBoostVector bcopy2(boostvector);
+      MyStdVector   scopy2(stdvector);
+
+      if(!test::CheckEqualContainers(bcopy, scopy)) return false;
+      if(!test::CheckEqualContainers(bcopy2, scopy2)) return false;
+
+      //Assignment from a smaller vector
+      bcopy2.erase(bcopy2.begin() + bcopy2.size()/2, bcopy2.end());
+      scopy2.erase(scopy2.begin() + scopy2.size()/2, scopy2.end());
+      bcopy = bcopy2;
+      scopy = scopy2;
+      if(!test::CheckEqualContainers(bcopy, scopy)) return false;
+
+      //Assignment from a bigger vector with capacity
+      bcopy2  = boostvector;
+      scopy2  = stdvector;
+      if(!test::CheckEqualContainers(bcopy2, scopy2)) return false;
+
+      //Assignment from bigger vector with no capacity
+      bcopy2.erase(bcopy2.begin() + bcopy2.size()/2, bcopy2.end());
+      scopy2.erase(scopy2.begin() + scopy2.size()/2, scopy2.end());
+      bcopy2.shrink_to_fit();
+      MyStdVector(scopy2).swap(scopy2);
+
+      bcopy2 = boostvector;
+      scopy2 = stdvector;
+      if(!test::CheckEqualContainers(bcopy, scopy)) return false;
+
+      //Assignment with equal capacity
+      bcopy2 = boostvector;
+      scopy2 = stdvector;
+      if(!test::CheckEqualContainers(bcopy2, scopy2)) return false;
+   }
+
    return true;
 }