Change del.p_=0 to del.p_=nullptr (#22)

* Change del.p_=0 to del.p_=nullptr

A simple change (I hope) that cleans up compiler warnings and errors.

* Support older compilers

* Update throw_exception.hpp

* Update throw_exception.hpp

doc/description.adoc

@@ -44,3 +44,7 @@ enable `boost::exception_ptr` support.
 The source location of the exception thrown by `boost::throw_with_location`
 can be retrieved, after `catch(std::exception const & x)`, by using
 `boost::get_throw_location(x)`.
+
+`boost::get_throw_location` also works for exceptions thrown by the two argument
+overload of `boost::throw_exception`, or by `BOOST_THROW_EXCEPTION`; in this case
+it returns the source location stored in the `boost::exception` base class.

doc/examples.adoc

@@ -59,7 +59,7 @@ logical throw point, instead of always pointing into the helper.
 ----
 #include <boost/throw_exception.hpp>
 #include <boost/lexical_cast.hpp>
-#include <boost/exception/diagnostic_information.hpp>
+#include <boost/core/verbose_terminate_handler.hpp>
 #include <stdexcept>
 #include <cstddef>
 #include <iostream>
@@ -93,24 +93,21 @@ void f2( std::size_t i, std::size_t n )
 
 int main()
 {
-    try
-    {
-        f1( 0, 3 );
-        f2( 4, 3 );
-    }
-    catch( std::exception const & x )
-    {
-        std::cerr << boost::diagnostic_information( x ) << std::endl;
-    }
+    std::set_terminate( boost::core::verbose_terminate_handler );
+
+    f1( 0, 3 );
+    f2( 4, 3 );
 }
 ----
 
 Sample output:
 
 ```none
-example.cpp(31): Throw in function void f2(std::size_t, std::size_t)
-Dynamic exception type: boost::wrapexcept<std::out_of_range>
-std::exception::what: Index out of range: 4 >= 3
+std::terminate called after throwing an exception:
+
+      type: boost::wrapexcept<std::out_of_range>
+    what(): Index out of range: 4 >= 3
+  location: <source>:31:34 in function 'f2'
 ```
 
 ## Using boost::throw_with_location

doc/reference.adoc

@@ -130,7 +130,8 @@ template<class E> boost::source_location get_throw_location( E const & e );
 ```
 
 Requires: :: `E` must be polymorphic.
-Effects: :: If `e` is a subobject of the object thrown by
-  `boost::throw_with_location( x, loc )`, returns `loc`. Otherwise, returns
-  a default constructed source location.
+Effects: ::
+* If `e` is a subobject of the object thrown by `boost::throw_with_location( x, loc )`, returns `loc`.
+* If `dynamic_cast<boost::exception const*>( e )` returns a nonzero value, returns the source location stored in that `boost::exception` subobject, if any.
+* Otherwise, returns a default constructed source location.
 

include/boost/throw_exception.hpp

@@ -116,7 +116,7 @@ public:
 
         boost::exception_detail::copy_boost_exception( p, this );
 
-        del.p_ = 0;
+        del.p_ = BOOST_NULLPTR;
         return p;
     }