Cannot use $ORIGIN in <dll-path> when building boost

[Chris BeHanna <chris@…>]

Boost 1.40.0 has internal library dependencies (e.g., libboost_filesystem.so depends upon libboost_system.so) that I wanted to be able to automatically satisfy at run-time via RPATH. The most straightforward way to do this would be to embed an RPATH of $ORIGIN/../lib in the shared libraries (or even, more simply, $ORIGIN).

Unfortunately, there is no way that I could discern to modify project-config.jam to escape $ORIGIN so that it would get passed through to the linker. I attempted to change the gcc toolset line to

if ! gcc in [ feature.values <toolset> ] {

using gcc : : : <dll-path>\$ORIGIN/../lib <linkoptions>-z origin ;

}

but no matter what combination of single quotes, backslashes, etc., that I tried, $ORIGIN got evaluated as an empty shell variable, and I'd end up with /../lib as my RPATH.

In desperation, to move forward with my project, I hacked gcc.jam directly, and that produced the desired effect, but obviously, this is not a production-quality solution.

[Vladimir Prus]

(In [59765]) Special case processing of RPATH, so that '$ORIGIN' can be used

Fixes #3479