I'm building a shared library and an application using that lib on Cygwin. With GCC CMake creates a .dll.a to use when linking. Switching to clang I get
[ 34%] Built target xxx_shared
make[2]: *** No rule to make target 'src/libxxx.dll.a', needed by 'xxx.exe'. Stop.
Is this a bug in the clang CMake extension?
I'm using cmake --version 3.3.2
Yes, it seems to be a bug in CMake. Running make VERBOSE=1 reveals that with GCC:
/usr/bin/c++.exe -g -shared -Wl,--enable-auto-import -o XXX -Wl,-Bstatic -lm -Wl,-Bdynamic -lstdc++ -lcygwin -ladvapi32 -lshell32 -luser32 -lkernel32
while with clang:
/usr/bin/clang++ -fPIC -g -shared -o XXX -Wl,-Bstatic -lm -Wl,-Bdynamic -lstdc++ -lcygwin -ladvapi32 -lshell32 -luser32 -lkernel32
So it seems that somehow clang++ does not get the -Wl,--enable-auto-import flag. Manually running the corrected clang++ command correctly creates the expected .dll.a allowing the rest of the build to proceed as expected.
Haven't figured out why this happens yet, though. At this point I can't decipher CMakes platform extensions, which seems to set this for GCC.
Update: I've reported this here.
Related
I have installed ROHC library (http://rohc-lib.org) using following commands during installation:
autoreconf -if
./configure --enable-static=yes --enable-shared=no --disable-shared --prefix=/usr
make
make install
It successfully installed static (and only static) libraries in /usr/lib directory. It contains librohc.a and librohc.la and no shared-library (i.e. librohc.so*).
I am trying to link this library with OpenVPN. I added following lines in configure.ac of OpenVPN:
AC_CHECK_HEADERS(
[rohc/rohc.h rohc/rohc_comp.h rohc/rohc_decomp.h],
,
[AC_MSG_ERROR([ROHC headers not found])]
)
AC_CHECK_LIB(
[rohc],
[rohc_compress4],
,
[AC_MSG_ERROR([ROHC library not found])]
)
But when I run make in OpenVPN source directory, I get the following error:
/bin/sh ../../libtool --tag=CC --mode=link gcc -DPLUGIN_LIBDIR=\"/usr/local/lib/openvpn/plugins\" -Wall -Wno-unused-parameter -Wno-unused-function -g -O2 -std=c99 -lrt -o openvpn argv.o base64.o buffer.o clinat.o comp.o compstub.o comp-lz4.o crypto.o crypto_openssl.o crypto_mbedtls.o dhcp.o error.o event.o fdmisc.o forward.o fragment.o gremlin.o helper.o httpdigest.o lladdr.o init.o interval.o list.o lzo.o manage.o mbuf.o misc.o platform.o console.o console_builtin.o console_systemd.o mroute.o mss.o mstats.o mtcp.o mtu.o mudp.o multi.o ntlm.o occ.o pkcs11.o pkcs11_openssl.o pkcs11_mbedtls.o openvpn.o options.o otime.o packet_id.o perf.o pf.o ping.o plugin.o pool.o proto.o proxy.o ps.o push.o reliable.o route.o schedule.o session_id.o shaper.o sig.o socket.o socks.o ssl.o ssl_openssl.o ssl_mbedtls.o ssl_verify.o ssl_verify_openssl.o ssl_verify_mbedtls.o status.o tls_crypt.o tun.o win32.o rohc.o trunk.o cryptoapi.o ../../src/compat/libcompat.la -lnsl -lresolv -llzo2 -llz4 -lssl -lcrypto -ldl -lrohc
libtool: link: gcc -DPLUGIN_LIBDIR=\"/usr/local/lib/openvpn/plugins\" -Wall -Wno-unused-parameter -Wno-unused-function -g -O2 -std=c99 -o openvpn argv.o base64.o buffer.o clinat.o comp.o compstub.o comp-lz4.o crypto.o crypto_openssl.o crypto_mbedtls.o dhcp.o error.o event.o fdmisc.o forward.o fragment.o gremlin.o helper.o httpdigest.o lladdr.o init.o interval.o list.o lzo.o manage.o mbuf.o misc.o platform.o console.o console_builtin.o console_systemd.o mroute.o mss.o mstats.o mtcp.o mtu.o mudp.o multi.o ntlm.o occ.o pkcs11.o pkcs11_openssl.o pkcs11_mbedtls.o openvpn.o options.o otime.o packet_id.o perf.o pf.o ping.o plugin.o pool.o proto.o proxy.o ps.o push.o reliable.o route.o schedule.o session_id.o shaper.o sig.o socket.o socks.o ssl.o ssl_openssl.o ssl_mbedtls.o ssl_verify.o ssl_verify_openssl.o ssl_verify_mbedtls.o status.o tls_crypt.o tun.o win32.o rohc.o trunk.o cryptoapi.o ../../src/compat/.libs/libcompat.a -lrt -lnsl -lresolv -llzo2 -llz4 -lssl -lcrypto -ldl /usr/lib/librohc.so
gcc: /usr/lib/librohc.so: No such file or directory
Yes, /usr/lib/librohc.so does not exist, but /usr/lib/librohc.a exists. Why is it not linking with the static library /usr/lib/librohc.a at absence of .so ?
You may ask me why I am not installing shared libs of ROHC; answer is that I want to force static linking with ROHC, and when it is done I will uninstall ROHC libs.
If someone could show me how to do this static linking without installing ROHC first (like adding dependency to configure.ac or Makefile.am of OpenVPN), it would be better for me.
Note that, both OpenVPN and ROHC library require autotools.
I specified --libdir=/usr/lib64 with ./configure of ROHC library and finally the build system used the static library librohc.a when linking with OpenVPN. I installed ROHC with:
autoreconf -if
./configure --enable-static --disable-shared --prefix=/usr --libdir=/usr/lib64
make
make install
Now it installs the library as /usr/lib64/librohc.a and Compilation of OpenVPN successfully finds and links to it.
And surely, it took place in a 64 bit machine (CentOS 6). In a 32 bit environment (OpenWrt in a 32-bit MIPS router) where there is nothing like /usr/lib64, the problem in the question does not take place.
I am trying to use address sanitizer with g++ and during the build it produces the following linker command, which produces the error g++: error: cannot specify -static with -fsanitize=address
I don't understand what this means, so any help is appreciated. The g++ version is g++ (GCC) 8.3.0 20190222 (Cray Inc.).
g++ -g -fsanitize=address CMakeFiles/pisa.dir/src/Alphabet.cpp.o {more .o files} -o pisa -L/global/homes/e/esaliya/sali/git/bitbucket/combinatorial-blas-2.0/CombBLAS/_install/lib -Wl,-rpath,/global/homes/e/esaliya/sali/git/bitbucket/combinatorial-blas-2.0/CombBLAS/_install/lib -lCombBLAS -lGraphGenlib -lUsortlib
From the research I have done, the problem seems to be with clang. If that is the case, how would I fix this on a Mac? Would switching to Ubuntu/Linux be a better option?
I'm not sure if it is relevant, but my professor is having us code using C syntax using g++ and saving our files as '.cpp' before we dive into C++.
Warning:
clang: warning: argument unused during compilation: '-ansi'
[-Wunused-command-line-argument]
Makefile:
CC = g++
calendar: main.o calendar.o appt.o day.o time.o
$(CC) main.o calendar.o appt.o day.o time.o -g -ansi -Wall -o calendar.out
%.o: %.cpp
$(CC) -Wall -c $<
You are correct in believing that this warning is issued by clang++ in these
circumstances and not by g++, and that you see it on your Mac because g++ is
really clang++.
The GCC option -ansi is meaningful for compilation and not meaningful
for linkage. Clang is warning you because you are passing it in your linkage recipe:
$(CC) main.o calendar.o appt.o day.o time.o -g -ansi -Wall -o calendar.out
where it is ineffective, and not passing it to your compilation recipe:
$(CC) -Wall -c $<
The wording of the diagnostic is misleading since it is provoked here
precisely by the absence of compilation. Nevertheless, it does
draw attention to a mistake on your part. Remove -ansi from your linkage recipe and add it to your compilation recipe.
I'm trying to link a really simple GLES2 & EGL program using g++ 4.9.1, on a Ubuntu Trusty system. I'm using the mesa libraries.
I'm getting linker errors for EGL functions:
test.cpp:(.text+0x342): undefined reference to `eglGetDisplay'
test.cpp:(.text+0x389): undefined reference to `eglInitialize'
test.cpp:(.text+0x40f): undefined reference to `eglCreateContext'
test.cpp:(.text+0x458): undefined reference to `eglCreatePbufferSurface'
test.cpp:(.text+0x49e): undefined reference to `eglMakeCurrent'
I am compiling test.cpp with
g++ -std=c++0x -Wall -Werror -lEGL -lGLESv2 -o test test.cpp
I've tried switching the order of libraries, which sometimes matters, but I get the same problem. Is there a library I'm missing here?
I've run readelf -Ws /usr/lib/x86_64-linux-gnu/mesa-egl/libEGL.so and all of the required functions are defined.
You should put libraries to the end of a command line
g++ -std=c++0x -Wall -Werror -o test test.cpp -lEGL -lGLESv2
I managed to fix this by compiling the C++ file to an object file, and then linking as a separate step. I'm not sure why this works, when the one-line compilation doesn't.
g++ -std=c++0x -Wall -Werror -c -o test.o test.cpp
g++ -o test test.o -lGLESv2 -lEGL
I've put the question to the community to try to figure out why: Single-command compile and link fails, separate steps work
I have a GNU build system with autoconf-2.69, automake-1.14.1, libtool-2.4.2. I've configured with --host=i686-linux on a x86_64 RHEL6 host OS to build a 32-bit program. The libtool command seems to be:
/bin/sh ../libtool --tag=CXX --mode=link g++ -I/home/STools/RLX/boost/include/boost-1_44 -m32 -g3 -Wall -static -o engine engine-main.o ../components/librlxvm.la /home/STools/RLX/boost/include/boost-1_44/../../lib/libboost_program_options-gcc42-mt-1_44.a -lz -lpthread -ldl -lrt -ldl -lz -lm
But the real command is to search the 64-bit libraries not the 32-bit libraries as shown below:
libtool: link: g++ -I/home/STools/RLX/boost/include/boost-1_44 -m32 -g3 -Wall -o engine engine-main.o -L/home/robert_bu/src/gcc/gcc-4.2.2/build-x86_64/x86_64-unknown-linux-gnu/libstdc++-v3/src -L/home/robert_bu/src/gcc/gcc-4.2.2/build-x86_64/x86_64-unknown-linux-gnu/libstdc++-v3/src/.libs -L/home/robert_bu/src/gcc/gcc-4.2.2/build-x86_64/./gcc ../components/.libs/librlxvm.a /home/STools/RLX/boost/include/boost-1_44/../../lib/libboost_program_options-gcc42-mt-1_44.a /home/STools/RLX/gcc-4.2.2-x86_64/lib/../lib64/libstdc++.so -L/lib/../lib64 -L/usr/lib/../lib64 -lc -lgcc_s -lrt -ldl -lz -lm -pthread -Wl,-rpath -Wl,/home/STools/RLX/gcc-4.2.2-x86_64/lib/../lib64 -Wl,-rpath -Wl,/home/STools/RLX/gcc-4.2.2-x86_64/lib/../lib64
The --host config seems to have no effect. Is there anyway to tell libtool that 32-bit libraries are what we want?
It seems that libtool uses "CC", "CXX" to check the library search path. After I set CC to "gcc -m32", and CXX to "g++ -m32", it works. So libtool does not add "-m32" automatically even if I try to build a 32-bit program on a 64-bit system.
You're being hit by the problem of libtool .la files expansion. In particular libstdc++.la is being expanded for you to a full path rather than a simple -lstdc++.
My suggestion is to remove .la file from the SDK you're using (/home/STools). This way libtool can't assume things for you. Usually the ones you have in the system are fine, because the libraries are already in the search path, so it does not need to use -rpath or the full path to the .so file.
Depending on how well the SDK was crafted, this might or might not work correctly, so take it with a grain of salt.