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POWeird posix message queue linking issue - sometimes it doesn't link correctly
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copied!<p>When I build the following code, it builds fine. If I change the code to comment out the "while", using the same command line, it does not build (see below)</p> <pre><code>#include <stdio.h> #include <mqueue.h> int main(int argc, char *argv[]) { while (1) { } mq_open("/YouSUCK", O_RDWR | O_CREAT | O_EXCL, S_IRWXU | S_IRWXG, NULL); return 0; } </code></pre> <p>dada@thud:~/RaspberryPI$ gcc -g -Wall -lrt -o mqtest mqtest.c</p> <p>dada@thud:~/RaspberryPI$ </p> <pre><code>#include <stdio.h> #include <mqueue.h> int main(int argc, char *argv[]) { // while (1) { } mq_open("/YouSUCK", O_RDWR | O_CREAT | O_EXCL, S_IRWXU | S_IRWXG, NULL); return 0; } </code></pre> <p>dada@thud:~/RaspberryPI$ gcc -g -Wall -lrt -o mqtest mqtest.c</p> <p>/tmp/cccw376u.o: In function `main':</p> <p>/home/dada/RaspberryPI/mqtest.c:7: undefined reference to `mq_open'</p> <p>collect2: ld returned 1 exit status</p> <p>dada@thud:~/RaspberryPI$</p> <p>Any ideas ?</p> <p>dada@thud:~/RaspberryPI$ gcc -v Using built-in specs. COLLECT_GCC=gcc COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.6/lto-wrapper Target: x86_64-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro 4.6.3-1ubuntu5' --with-bugurl=file:///usr/share/doc/gcc-4.6/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.6 --enable-shared --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.6 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object --enable-plugin --enable-objc-gc --disable-werror --with-arch-32=i686 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu Thread model: posix gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5)</p> <p>Thanks ! Joe</p> <p>Update: Looks like a compiler verion issue, I built the same code on a different box, and it builds properly with either of the above files. So I guess I need a different compiler. </p> <p>dada@JoesPi ~ $ gcc -v</p> <p>Using built-in specs. COLLECT_GCC=gcc COLLECT_LTO_WRAPPER=/usr/lib/gcc/arm-linux-gnueabihf/4.6/lto-wrapper Target: arm-linux-gnueabihf Configured with: ../src/configure -v --with-pkgversion='Debian 4.6.3-14+rpi1' --with-bugurl=file:///usr/share/doc/gcc-4.6/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.6 --enable-shared --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.6 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object --enable-plugin --enable-objc-gc --disable-sjlj-exceptions --with-arch=armv6 --with-fpu=vfp --with-float=hard --enable-checking=release --build=arm-linux-gnueabihf --host=arm-linux-gnueabihf --target=arm-linux-gnueabihf Thread model: posix gcc version 4.6.3 (Debian 4.6.3-14+rpi1)</p>

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