Add throw_column to boost::exception, make get_throw_location work for it

test/throw_with_location_test4.cpp

@@ -0,0 +1,41 @@
+// Copyright 2022 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/throw_exception.hpp>
+#include <boost/core/lightweight_test.hpp>
+
+#if defined(_MSC_VER)
+# pragma warning(disable: 4702) // unreachable code
+#endif
+
+class my_exception: public std::exception
+{
+};
+
+int main()
+{
+    boost::source_location location = BOOST_CURRENT_LOCATION;
+
+    try
+    {
+        boost::throw_exception( my_exception(), location );
+
+        BOOST_ERROR( "boost::throw_exception failed to throw" );
+    }
+    catch( std::exception const & x )
+    {
+        boost::source_location loc = boost::get_throw_location( x );
+
+        BOOST_TEST_CSTR_EQ( loc.file_name(), location.file_name() );
+        BOOST_TEST_CSTR_EQ( loc.function_name(), location.function_name() );
+        BOOST_TEST_EQ( loc.line(), location.line() );
+        BOOST_TEST_EQ( loc.column(), location.column() );
+    }
+    catch( ... )
+    {
+        BOOST_ERROR( "boost::throw_exception failed to throw std::exception" );
+    }
+
+    return boost::report_errors();
+}