[Boost-build] What variables available in actions (was Re: actions bind doc slightly confusion and what variables available in actions?

From: Larry Evans (cppljevans_at_[hidden])
Date: 2007-08-04 09:01:35

On 08/03/2007 01:23 PM, Larry Evans wrote:
[snip]
> * question 2
> 
> The following is from gcc.jam:
> <-------- cut here ---------
> actions link bind LIBRARIES
> {
>      "$(CONFIG_COMMAND)" -L"$(LINKPATH)" 
> -Wl,$(RPATH_OPTION:E=-R)$(SPACE)-Wl,"$(RPATH)" 
> -Wl,-rpath-link$(SPACE)-Wl,"$(RPATH_LINK)" -o "$(<)" $(START-GROUP) 
> "$(>)" "$(LIBRARIES)" -l$(FINDLIBS-ST) -l$(FINDLIBS-SA) $(END-GROUP) 
> $(OPTIONS) $(USER_OPTIONS)
> #the above appears all on one line in my editor.
> }
> 
>  >-------- cut here ---------
> 
> What variable values are available in the actions body?  Was the
> 'bind LIBRARIES' needed because it wasn't among the set of
> variables passed to all actions or just actions for link commands
> or is there some other criteria for determining the variables
> passed to the actions body?

Part of the answer to this is, maybe, provided by:

http://www.boost.org/doc/html/bbv2/extender.html#bbv2.extending.features

which contains:

Then, the flags invocation says that whenever verbatin.inline-file 
action is run, the value of the verbatim-options feature will be added 
to the OPTIONS variable, and can be used inside the action body.

So, are RPATH_LINK, FINDLIBS-ST, FINDLIBS-SA, OPTIONS, and USER_OPTIONS
all declared as features of the gcc toolset (or more precisely,
the superclass of gcc, i.e. the unix toolset)?