[Boost-build] Help deciphering gcc.jam, please

From: Steve M. Robbins (steve_at_[hidden])
Date: 2008-03-08 13:32:56

Hi,

I'm trying to decipher the following bit of tools/gcc.jam from the
Boost 1.34.1 distribution, directory tools/build/v2:

actions link.dll bind LIBRARIES
{
    "$(CONFIG_COMMAND)" -L"$(LINKPATH)" -Wl,$(RPATH_OPTION:E=-R)$(SPACE)-Wl,"$(RPATH)" "$(.IMPLIB-COMMAND)$(<[1])" -o "$(<[-1])"
 $(HAVE_SONAME)-Wl,$(SONAME_OPTION)$(SPACE)-Wl,$(<[-1]:D=) -shared $(START-GROUP) "$(>)" "$(LIBRARIES)" -l$(FINDLIBS-ST) -l$(FIN
DLIBS-SA) $(END-GROUP) $(OPTIONS) $(USER_OPTIONS)
}

In particular, I'd like to know:

(a) what does $(<[-1]:D=) expand to, and
(b) where is that computed.

I've searched doc/userman.pdf without success.  Did I miss it?  Where
should I be looking?

If you've read this far: my goal is to remove the compiler-name
decoration from the SONAME of the shared libraries.  This decoration
causes grief building packages for distributions like Debian.  I do
know about --layout=system, but that causes even more grief because
the resulting libraries have *no* SONAME at all.  Distributions need a
SONAME that doesn't include the compiler version.

Thanks,
-Steve