[Boost-build] Invoking compiler in user-config.jam even when toolset is different compiler

Subject: [Boost-build] Invoking compiler in user-config.jam even when toolset is different compiler
From: Edward Diener (eldiener_at_[hidden])
Date: 2014-08-12 22:40:15

I have a line in my user-config.jam of:

using clang : : 
C:/Programming/VersionControl/bninja_installed_clang/bin/clang++.exe ;

in order to use clang as a toolset in Windows. Yet if I invoke bjam with:

b2 toolset=gcc-4.8.1

in some modular-boost directory. Boost Build still ends up testing the 
clang++.exe executable in my user-config.jam for some reason.

Why is that and can this test of clang be eliminated in Boost Build 
since it is not clang I am invoking as my toolset ?