https://svn.boost.org/trac10/ticket/10423 <p> The toolsets in user-config.jam and site-config.jam ( I will call them the 'global config jam files' ) are configured when a "using xxx ;" is encountered in these files, each time b2 is invoked. This occurs despite the fact that the toolset with which b2 is invoked may not be a particular toolset which is being configured in the global config jam files . </p> <p> This is extremely wasteful and unnecessarily time consuming. The global config jam files should be treated differently than the chain of jam files being invoked whenever b2 is run in some directory. Only the toolset(s) in the global config files which are needed for a particular b2 invocation should be configured when encountered there. </p> <p> It is very possible that the end-user has a 'using xxx ;' statement in one of the global config jam files which will only work when the appropriate toolset is actually being invoked, otherwise will fail. One example of this is if toolset A depends on a particular version of toolset B. If the end-user has switched to a different version of toolset B, and invoked b2 with that different version of toolset B, then b2 at the very least will issue error(s) when toolset A is configured. This is an actual situation in the relationship of clang to gcc, since a clang built with a particular version of gcc will depend on that particular versions headers/RTL. </p> <p> Forcing the end-user to comment out that toolset configuration statement until it is ready to be actually used would be tedious for the end-user and Boost Build unfriendly. </p> <p> Please consider changing Boost Build so that toolsets in the global config jam files are not configured until it can be determined that they actually need to be used. </p> en-us /htdocs/site/boost.png https://svn.boost.org/trac10/ticket/10423 Trac 1.4.3