[boost] [build] clang-win help needed

Subject: [boost] [build] clang-win help needed
From: Edward Diener (eldiener_at_[hidden])
Date: 2013-11-27 22:21:45

The clang-win.jam file, which was provided by 'tr1gun' as an attachment 
to another thread in Boost Build, inherits its generators, flags, and 
rules from msvc.jam. The lines in clang-win.jam are:

toolset.inherit-generators clang-win <toolset>clang 
<toolset-clang:platform>win : msvc ;
toolset.inherit-flags clang-win : msvc : 
<debug-symbols>on/<debug-store>object  : YLOPTION ;
toolset.inherit-rules clang-win : msvc ;

In order to eliminate the VC++ /EH(x) option, which clang using VC++ RTL 
does not use, I added into the file a rule:

rule compile.c++ ( targets * : sources * : properties * )
{
     C++FLAGS on $(targets) = [ set.difference
         [ on $(targets[1]) return $(C++FLAGS) ] :
         /EHs ] ;
}

suggested by Steve Watanabe. This effectively eliminates the /EHs option 
when compiling with clang. However when a 'run' action is done, with 
clang as the compiler, the compile step is never called. If I remove the 
'rule compile.c++' from the clang-win.jam file the compile step is 
called before the link and execute steps of the 'run' action, but of 
course the compile step then issues the /EHs warning which the insertion 
of the above rule eliminated.

Does anybody know why adding the above rule causes the 'run' action to 
not compile the appropriate fle before attempting the link and execute ?