Installed boost and then tried example...
/usr/include/boost_1_73_0/build-develop/example/hello

Looking for input on...
How to solve this error after installing latest version boost (1.73.0)?

ERROR: rule "[[bbv2.builtin.features.warnings]]`warnings`::" unknown in module "warnings-feature".

If I remove the block comments in warnings-feature.jam the error simply propogates to next jam file with block comment.

Only thing I can find online is suggestion that may not be using latest version of boost.build as error suggestive that b2 does not understand block comments.

Here is link https://lists.boost.org/Archives/boost/2020/03/248336.php

Below is boost version and boost.build version after install...

$ cat /usr/include/boost_1_73_0/boost/version.hpp | grep "BOOST_LIB_VERSION"
//  BOOST_LIB_VERSION must be defined to be the same as BOOST_VERSION
#define BOOST_LIB_VERSION "1_73"

$ b2 -v
Boost.Jam  Version 2015.07. OS=LINUX.
   Copyright 1993-2002 Christopher Seiwald and Perforce Software, Inc.
   Copyright 2001 David Turner.
   Copyright 2001-2004 David Abrahams.
   Copyright 2002-2015 Rene Rivera.
   Copyright 2003-2015 Vladimir Prus.

Thanks in advance

Dennis