Static library issue on Mac OS X: Symbols (symbols) not found for x86_64 architecture
I am trying to create a static library and link it with an executable binary.
This is a library function:
#include <stdio.h>
int hello() {
return 10;
}
With these commands, I can get the static library.
gcc -c io.c
ar -crv libio.a io.o
Since lip -info
I checked it out as architecture x86_64
.
ar> lipo -info libio.a
input file libio.a is not a fat file
Non-fat file: libio.a is architecture: x86_64
This is the main function using the library.
#include <stdio.h>
extern int hello();
int main(int argc, char *argv[]) {
printf("%d", hello());
}
However, when I link an object with a static library, I have errors.
gcc main.c -lio -o main -L.
Error messages:
ld: warning: ignoring file ./libio.a, file was built for archive which is not the architecture being linked (x86_64): ./libio.a
Undefined symbols for architecture x86_64:
"_hello", referenced from:
_main in main-2c41a0.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
I am using ar
both in /bin/ar
and Mac OS X is 10.10.2 with clang-602.0.53.
ar> clang -v
Apple LLVM version 6.1.0 (clang-602.0.53) (based on LLVM 3.6.0svn)
Target: x86_64-apple-darwin14.3.0
Thread model: posix
What could be wrong?
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The library must be generated with libtool -static
.
gcc -c io.c
libtool -static -o libio.a io.o
gcc main.c -lio -o main -L.
main
Returns
10
ar> lipo -info libio.a
input file libio.a is not a fat file
Non-fat file: libio.a is architecture: x86_64
ar> file libio.a
libio.a: current ar archive
ar> nm libio.a
io.o:
0000000000000000 T _hello
Hints from this page .
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From a hack of the CMake metadata creation file (CMakeFiles / test.dir / link.txt) ar in /usr/local/ar
which is the default, it seems to be not working correctly.
This is the content link.txt
.
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ar qc libtest.a CMakeFiles/test.dir/test.c.o
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib libtest.a
From the script, /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ar
is the one I had to use.
smcho@macho ar> ls -alF /usr/bin/ar
-rwxr-xr-x 1 root wheel 18160 Oct 17 18:49 /usr/bin/ar*
smcho@macho ar> ls -alF /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ar
-rwxr-xr-x 1 root wheel 33472 Oct 29 16:36 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ar*
Likewise, the runlib to be used is /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib
not the default.
smcho@macho ar> ls -alF `which ar`
-rwxr-xr-x 1 root wheel 18160 Oct 17 18:49 /usr/bin/ar*
smcho@macho ar> ls -alF /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib
lrwxr-xr-x 1 root wheel 7 Nov 10 21:10 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib@ -> libtool
In addition, you should use the parameter -qc
(from the generated cmake script)
-c Whenever an archive is created, an informational message to that
effect is written to standard error. If the -c option is speci-
fied, ar creates the archive silently.
-q (Quickly) append the specified files to the archive. If the ar-
chive does not exist a new archive file is created. Much faster
than the -r option, when creating a large archive piece-by-piece,
as no checking is done to see if the files already exist in the
archive.
These are the commands to get the correct library file:
clang -c hellolib.cpp -o hellolib.o
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ar -qc libhello.a hellolib.o
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib libhello.a
Using:
clang usehello.cpp -lhello -L.
nm and lipo show the correct library file information:
smcho@macho ar> nm libhello.a
libhello.a(hellolib.o):
0000000000000000 T __Z3addii
smcho@macho ar> lipo -info libhello.a
input file libhello.a is not a fat file
Non-fat file: libhello.a is architecture: x86_64
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