[Bug bootstrap/44107] libstdc++ (dylib) is built with an erroneous dependency towards /usr/lib

["iains at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44107

Iain Sandoe <iains at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.6.1

--- Comment #8 from Iain Sandoe <iains at gcc dot gnu.org> 2011-03-20 09:27:15 UTC ---
(In reply to comment #7)
> 1) In no configuration the bootstrap fails (as long as you take care of PR45381
> and PR47016).

PR45381 has been fixed in trunk and on the branch - I guess it will be fixed in
the release (I think there's another RC coming).  As already commented in
PR47016, this is a tool problem, not  a gcc bug (but, since I doubt any tool
fixes will be forthcoming for darwin < 11, we will endeavor to solve it somehow
;-) - patches welcome... )

> 2) Indeed, the DYLD_LIBRARY_PATH that makes things to work properly is
> DYLD_LIBRARY_PATH=$(prefix)/lib

If everything is linked correctly with proper rpaths, and the products are
installed - there should be no need for a DYLD_LIBRARY_PATH - it should only be
necessary for uninstalled testing.

> 3) I have built with the patch attached in #4 (together with the addition
> included in #5), it seems
> to work properly now (see configuration 'y' below).
> 
> 4) I have now 3 configurations (all with 4.6.0 RC 20110314)
> - 4.6.x: built with my modification (the change in t-slibgcc-darwin)
> - 4.6.y: built with the 2 patches from yesterday
> - 4.6.z: no change from the distribution
> I have also built the Xerces-C library 3 times, xerces-c-3.1.1x,
> xerces-c-3.1.1y and
> xerces-c3.1.1.z.
> The libxerces-c-3.1.dylib contains (iaw otool -L) a dependency towards
> /usr/lib/libgcc_s.1.dylib
> in the cases 'y' and 'z'. The libxerces-c-3.1.dylib contains a dependency
> towards /usr/lib/libSystem.B.dylib in the three configurations. My C++ program
> links with this library.
> 
> The sets 'x' and 'y' work properly. 

Hm, configuration 'x' is actually generically incorrect - it will _only_  work
providing you don't link with any library that is already linked with the
unwinder in /usr/lib/libgcc_s.1.dylib.   This is because there can only be
_one_ unwinder - the whole program must use the same one.

Some stand-alone programs are unaffected (including the gcc test-suite), but -
anything that uses stuff from gcc together with system frameworks is almost
certainly doomed...

set 'y' is correct (IMO) - and if the products are installed should work
without a DYLD_LIBRARY_PATH - assuming that everything has its correct paths...

The set 'z' does not work (stuck between
> throw and  catch, CPU running).

that, to me, confirms that the bug is in our emitting unwind that is
incompatible with the darwin 9 unwinder (a known issue, but without a specific
bug - it has been treated as part of PR41991 to date). 

I don't know when (or if) the patch will make it into gcc - but surely not for
4.6.0 it's too intrusive and the time has gone - for now, a local patch is
required - although it might be that fink/macports would decide to apply this
too.

hint: 
"DYLD_PRINT_LIBRARIES=1 ./myexe " 
is really useful for making sure that the libraries you think should be used
actually are ;-)

thanks for  testing!!