Autoconf ignores compiler flags

I'm trying to build a C library with a non-native architecture. I'm running OSX 10.6 (which is x86_64) but I need the library compiled for i386. Normally, you can just add the compiler flag: -arch i386. But I'm using Autoconf开发者_JS百科 and it ignores this in the configure file and it also ignores it if I try running: ./configure CC="gcc -arch i386".

I know its building x86_64 object files because I've looked at the header using otool. The real kicker is that when autoconf writes out the configuration summary, it lists -arch i386 in the cc flags. What's going on here??

specs:

OSX 10.6.2

gcc 4.2.1

autoconf 2.64

make 3.81

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Assuming that "CFLAGS='-arch i386' is what you meant when you said "normally, you can just add the compiler flag", my best guess is that the maintainer of the code has done something wrong in the configure.ac and overwritten CFLAGS. Check through the configure.ac (or configure.in if the project is old) and see if they've explicitly assigned to CC or CFLAGS. Also check the Makefile.am for assignments. Chances are something is wrong. What you've done should work.

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You want to set it in the CFLAGS environmental variable, autoconf should append it to whatever it decides CFLAGS should be. If you type ./configure --help, you should get a list of all influential environmental variables.