Auto-rpath revisited...

[Lee Iverson]

OK.  I have an implementation of a system for automatically generating
shared lib rpaths in collect2.  It carefully walks through
'-L'-specified paths and searches for shared libraries which will
actually resolve the link search.  This should deal with the
previously raised objections to automatic techniques which just map -L
to rpath, and definitely solves the problem of needing LD_LIBRARY_PATH
in order to even run a minimal C++ program on systems where
libstdc++.so is not installed in a standard place.

So, I have a sample implementation that I could submit today (modulo
assignment paperwork).  At this point we come to policy issues, what
exactly should it do?

Proposals:

1) Do an exhaustive walkthrough of -L/-l pairs, and add to the end of
   any user-supplied rpath an entry for any directory which resolves a
   shared lib link (this is what the implementation now does).

2) Restrict the auto-rpath generation to only checking against
   system-supplied -L directories (i.e. -L$(exec_prefix)/lib).

3) something else...

Suggestions?  Discussion?

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Lee Iverson     		SRI International
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