I'm sorry, I don't know enough about shared libraries to build a small test case, but I don't think it should be hard to do for someone who does know.
It's simple to reproduce the problem. I installed Xcode 2.1 and built mainline and 4.0-branch with [descartes:~/programs] lucier% /pkgs/gcc-4.0-mainline/bin/gcc -v Using built-in specs. Target: powerpc-apple-darwin8.1.0 Configured with: ../configure --prefix=/pkgs/gcc-4.0-mainline --with-gmp=/pkgs/gmp-4.1.3 --with-mpfr=/pkgs/gmp-4.1.3 Thread model: posix gcc version 4.1.0 20050615 (experimental) [descartes:~/programs] lucier% /pkgs/gcc-4.0-branch/bin/gcc -v Using built-in specs. Target: powerpc-apple-darwin8.1.0 Configured with: ../configure --prefix=/pkgs/gcc-4.0-branch --with-gmp=/pkgs/gmp-4.1.3 --with-mpfr=/pkgs/gmp-4.1.3 Thread model: posix gcc version 4.0.1 20050615 (prerelease) Next I downloaded http://www.math.purdue.edu/~lucier/bugzilla/7/gambc40b13.tar.gz expanded it, cd'ed to gambc40b13, configured with [descartes:~/programs/gambc40b13] lucier% env CC='/pkgs/gcc-4.0-mainline/bin/gcc -mcpu=970 -m64 -force_cpusubtype_ALL' ./configure --enable-shared and ran "make" The library routines were compiled with, for example, /pkgs/gcc-4.0-mainline/bin/gcc -mcpu=970 -m64 -force_cpusubtype_ALL -I../include -I. -no-cpp-precomp -Wall -W -Wno-unused -O1 -fno-math-errno -fschedule-insns2 -fno-trapping-math -fno-strict-aliasing -fomit-frame-pointer -fPIC -fno-common -DHAVE_CONFIG_H -D___PRIMAL -D___LIBRARY -D___GAMBCDIR=\"/usr/local/Gambit-C\" -c _num.c and they were linked with /pkgs/gcc-4.0-mainline/bin/gcc -mcpu=970 -m64 -force_cpusubtype_ALL -flat_namespace -undefined suppress -o libgambc.dylib main.o setup.o mem.o c_intf.o os.o os_base.o os_time.o os_shell.o os_files.o os_dyn.o os_tty.o os_io.o _kernel.o _system.o _num.o _std.o _eval.o _io.o _nonstd.o _thread.o _repl.o _gambc.o making all in gsi /pkgs/gcc-4.0-mainline/bin/gcc -mcpu=970 -m64 -force_cpusubtype_ALL -I../include -no-cpp-precomp -Wall -W -Wno-unused -O1 -fno-math-errno -fschedule-insns2 -fno-trapping-math -fno-strict-aliasing -fomit-frame-pointer -fPIC -fno-common -DHAVE_CONFIG_H -c _gsi.c gcc: unrecognized option '-no-cpp-precomp' /pkgs/gcc-4.0-mainline/bin/gcc -mcpu=970 -m64 -force_cpusubtype_ALL -I../include -no-cpp-precomp -Wall -W -Wno-unused -O1 -fno-math-errno -fschedule-insns2 -fno-trapping-math -fno-strict-aliasing -fomit-frame-pointer -fPIC -fno-common -DHAVE_CONFIG_H -c _gsi_.c gcc: unrecognized option '-no-cpp-precomp' /pkgs/gcc-4.0-mainline/bin/gcc -mcpu=970 -m64 -force_cpusubtype_ALL _gsi.o _gsi_.o -L../lib -lgambc -o gsi ld64 failed: in ../lib/libgambc.dylib, unknown mach-o file type collect2: ld returned 1 exit status make[1]: *** [gsi] Error 1 make: *** [all-recursive] Error 1 [descartes:~/programs/gambc40b13] lucier% ld64 -v @(#)PROGRAM:ld64 PROJECT:ld64-26.0.80 DEVELOPER:root BUILT:May 26 2005 16:00:10 [descartes:~/programs/gambc40b13] lucier% ld -v Apple Computer, Inc. version cctools-590.obj~12 [descartes:~/programs/gambc40b13] lucier% as -v Apple Computer, Inc. version cctools-590.obj~12, GNU assembler version 1.38 The same thing happens with 4.0-branch, i.e., the 4.0.1 release candidate, which is more troubling. It doesn't happen with 4.0.0, so this is a regression from 4.0.0 to 4.0.1. Brad -- Summary: Can't link 64-bit shared libraries with Xcode 2.1 Product: gcc Version: 4.0.1 Status: UNCONFIRMED Severity: normal Priority: P2 Component: target AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: lucier at math dot purdue dot edu CC: gcc-bugs at gcc dot gnu dot org GCC build triplet: powerpc-apple-darwin8.1.0 GCC host triplet: powerpc-apple-darwin8.1.0 GCC target triplet: powerpc-apple-darwin8.1.0 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22082
