I'm trying to build a 32-bit python on an x86_64 Linux box running Fedora Core 3.

Here's my configure command line:

CFLAGS=-m32 LDFLAGS=-m32 ../../../python/configure --prefix=/opt/python --enable-shared --enable-ipv6 --enable-profiling --enable-unicode=ucs4

When I try to do a make afterwards, the build immediately fails:

gcc -pthread -c -pg  -fno-strict-aliasing -DNDEBUG -g -O3 -Wall -Wstrict-prototypes -I. -I../../../python/Include -fPIC -DPy_BUILD_CORE -o Modules/python.o ../../../python/Modules/python.c
In file included from ../../../python/Include/Python.h:55,
                 from ../../../python/Modules/python.c:3:
../../../python/Include/pyport.h:612:2: #error "LONG_BIT definition appears wrong for platform (bad gcc/glibc config?)."
make: *** [Modules/python.o] Error 1

Notice the lack of "-m32" on the gcc command line. Sure enough, look in the Makefile and LDFLAGS is set correctly, with -m32, but CFLAGS makes no mention of it, nor does BASECFLAGS.

If I modify BASECFLAGS by hand, python itself builds OK, but then the shared libraries fail to link because LDSHARED is not having LDFLAGS passed in.

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The "correct" (i.e. works for me) way to work around this is to run configure with CC="gcc -32" CXX="g++ -m32" instead of setting CFLAGS and LDFLAGS.

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Try using LDSHARED instead. This works for compiling
extensions on x86_64 (using C shell):

setenv CCSHARED "-m32 -fPIC"
setenv LDSHARED "gcc -m32 -shared"

Here's a test case:

$ CFLAGS="--haflkhlaiuhfnafkghnaf" ./configure; make
[... configure does its thing... ]
[... make does its thing and completes successfully ...]

Expected result:  The build fails due to an unknown flag in CFLAGS.

Witnessed result:  CFLAGS is completely ignored.

Closing as a duplicate of issue 9189.