How do I modify the install name of a .dylib at build time

Question

I am building the google-gflags commandline flags library for C++ on Mac OS X (10.7.1). The build process is as such:

$ ./configure --prefix=output
$ make
$ make install 

I'd like to change the install name of the generated shared library at build time and not use install_name_tool afterwards.

By default, the install name of the generated shared library, libgflags.dylib, is the output path:

$ otool -L ./output/libgflags.dylib
$ ./output/libgflags.dylib:
    /tmp/gflags-1.5/output/lib/libgflags.0.dylib (compatibility version 2.0.0, current version 2.0.0)
    /usr/lib/libstdc++.6.dylib (compatibility version 7.0.0, current version 52.0.0)
    /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 159.0.0) 

The man page for ld(1) has a -install_name option which can be used to change the install name of a dynamic library at link-time.

For example, with a dummy program:

$ g++ -dynamiclib temp.cc -install_name /tmp/temp.dylib -o temp.dylib
$ otool -L temp.dylib 
temp.dylib:
    /tmp/temp.dylib (compatibility version 0.0.0, current version 0.0.0)
    /usr/lib/libstdc++.6.dylib (compatibility version 7.0.0, current version 52.0.0)
    /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 159.0.0)

But, I am unable to use this command line option with the ./configure script. I've tried manually setting the CFLAGS variable, but that results in a error:

$ CFLAGS="-install_name /tmp/desired/location/libgflags.dylib" ./configure
checking for a BSD-compatible install... /opt/local/bin/ginstall -c
checking whether build environment is sane... yes
checking for gawk... no
checking for mawk... no
checking for nawk... no
checking for awk... awk
checking whether make sets $(MAKE)... yes
checking for gcc... gcc
checking whether the C compiler works... no
configure: error: in `/Users/vibhav/Code/install_name_test/gflags-1.5':
configure: error: C compiler cannot create executables

So, is it possible for me to change the install name of .dylib generated by configure and make without using install_name_tool?

Answer 1

Generally, passing linker arguments through g++ must be prefaced with -Wl and spaces must be replaced with commas. So, if you want to pass "-install_name /tmp/temp.dylib" to the linker you will need to call this:

g++ -Wl,-install_name,/tmp/temp.dylib ...

Answer 2

one possible approach would be editing the config.status manually. but before I try to do that, install_name_tool -id saved my life.