I installed CLang on CentOS using sudo yum install clang. Then tried using it by firing this command clang++ main.cpp -o main. This complained of missing ld.
Prior to this I had deleted the usr/bin/ld
I read that llvm has it's own linker; I am unable to find one. I also read that llvm lld was removed and the documentation says that one can make do with Clang only. Given that I have removed /usr/bin/ld, how do I get it back? Do I need to get it back? How do I make CLang use the linker that is supposed to be included with Clang?
I am debugging an issue and to one of the steps in trying to fix the issue was to reinstall the compiler, hence I resorted to deleting all the previously installed packaged and files, including ld.
Related
I am not sure if I should delete the X Code as it takes a lot of space on MacBook. I want to use g++ compiler for compiling my c++ program.
It is possible to install just the Xcode command line tools. Open Terminal and execute xcode-select --install. This will get you your compiler (clang, not g++. g++ is just an alias for clang++ on Macs), linker, make, etc.
To actually answer your question, yes. If you install something and then uninstall it, the stuff that got installed will get uninstalled.
If you want the actual g++ compiler, you will need to install it yourself, homebrew is the easiest way. The gcc package will create versioned symlinks for you (g++-9), and you can just use that, or create another symlink that redirects g++ to g++-9. If you did that, you'll have to remember to manually update that symlink when the major version changes. All this is found in usr/local/bin after installing homebrew and the gcc package.
I'm trying to compile a test openmp program on an Amazon AWS t2.micro instance. It seems to have trouble. Upon trying to compile this OpenMP hello world program, the compiler fails to find omp.h despite using gcc hello_world.c -fopenmp.
After that, I tried running locate omp.h and found it in /usr/lib/gcc/x86_64-amazon-linux/4.8.5/include. I next attempted to compile by including that directory with gcc -I. Then, the compiler still needed libgomp.spec, which has been encountered and solved in this stack overflow question.
Following the most upvoted answer on there by creating some symbolic links did nothing for me and still says error: libgomp.spec: No such file or directory, even though libgomp.spec is in my /usr/lib64 directory.
So, what can I do to fix this, and why won't -fopenmp work on amazon linux like expected? This is done on an instance which was created by CfnCluster, if that helps.
As usual, header files such as omp.h come with relevant version of gcc compiler. When the compiler can't find the header file, I guess you are using the different version compiler (other than 4.8.5 in this case).
You can find all gcc versions by typing:
sudo yum list installed | grep gcc
If there are other versions of gcc such as gcc72, you can erase them by:
sudo yum erase gcc72
After that, you will compile the code successfully.
Exactly, as told #S.Takezawa , currently only gcc 6.4 installation supports libgomp (fopenmp) and supports modern c++14 standard on Amazon AMI linux.
gcc4.7 is too old. So this helps for me:
sudo yum install gcc64-c++.x86_64 libgcc64.x86_64
I am currently running a debian Jessy whose g++'s version is 4.9. For some reason I need to compile a code in g++-4.7 or previous version.
I got the files of gcc-4.7 and g++-4.7 from a debian wheezy of a friend who has g++-4.7.
I tried to make the apt-get install, it seemed to have worked for the gcc but not for the g++. I put the files in the /bin, but he doesn't seem to locate the g++-4.7 package.
When I try to compile my code I specify g++-4.7 but get the error :
g++: error trying to exec 'cc1plus': execvp: No such file or directory
Any idea how to figure this out?
My advise is to add the wheezy repositories to /etc/apt/sources.list and then install g++-4.7 using apt-get. Using this method you will also get bugfixes etc.
I guess, currently you're just having dependency Problems. These will be solved when you use apt-get.
It is very easy to install gcc from sources. Remember that you have also to use a binutils version which maps to the gcc version. Mostly it is possible to run older gcc versions on actual binutils, but I have also seen a problem during install.
I have installed a long list of gcc versions in /opt/
Simply copy an older gcc version somewhere in the file system can result in problems with using the correct library versions.
If you install different gcc versions and also the related libraries e.g.libstdc++ , don't forget to update your library data base ( ldconfig/LD_LIBRARY_PATH/...) Maybe http://tldp.org/HOWTO/Program-Library-HOWTO/shared-libraries.html can help.
I had OpenMP compiling and executing in C/C++ on my Mac but then I formatted and reinstalled a fresh copy of OS X. I believe the only difference in the setup was that I had Xcode 5 before the format, and now I have Xcode 6.
Now I get fatal error: 'omp.h' file not found
I read this has something to do with clang and gcc, but, my confusion lies with why did it work before and now its not working?
After some research I seem to have found an answer.
GCC included in the latest version of Xcode (Xcode 6) is only a symbolic link to clang. Since clang does not support OpenMP at this time, you need to install a different version of GCC. The easiest way to do this would be to use Homebrew or MacPorts.
Keep in mind that even when you do this you will probably need to alter your $PATH to have /usr/local come before /usr/bin. This is because Homebrew will have placed your newly installed GCC in /usr/local. Also, some implementations may name the command gcc-49 instead of plain gcc.
Mac OSX uses clang.The gcc compiler in OS X does not support OpenMP. To use this feature a new gcc compiler needs to be installed.
Go to Terminal, if you have not installed Hombrew, install it:
/usr/bin/ruby -e "$(curl -fsSL https://`enter code here`raw.githubusercontent.com/Homebrew/install/master/install)"
then install new version of gcc
brew reinstall gcc --without-multilib
This will not make changes to the existing gcc compiler installed by Xcode as we are reinstalling it.
After running the command given below compile the files using the new version of gcc using the syntax : gcc-version -fopenmp filename.c
To find the version type gcc and then press tab. This will list out all the possible variants of gcc. The version number can be found out from this. For example : gcc-6, gcc-4.9,etc
I am receiving the following error when I try to compile a very basic C++ program.
$ g++ -fuse-linker-plugin test.cpp
g++: fatal error: -fuse-linker-plugin, but cyglto_plugin.dll not found
compilation terminated.
Code
int main() {
return 0;
}
This is using G++ installed straight out of a fresh Cygwin installation.
If I search for the file there, it does exist and is located at:
/usr/libexec/gcc/x86_64-pc-cygwin/4.8.2/cyglto_plugin.dll
How do I make Cygwin 64 look at this correctly?
I guess you only checked the gcc-g++ package at installation. Note that the version is 4.8.1-3 BUT on the next page you can see a lot of dependencies being installed, for example libgcc with version 4.8.2.
That mix of 4.8.1 and 4.8.2 seems to be the problem.
In the installer, copy all dependencies into an editor, search for 4.8.2 to find the problematic packages, go back in the installer and click those packages until 4.8.1-3 will be installed.
Double check you're not installing the latest version of those packages.
More recently using apt-cyg, g++ 4.9.2 was installed but gcc-core 4.8.2 remained.
Resolved by:
apt-cyg remove gcc-g++
apt-cyg remove gcc-core
apt-cyg install gcc-g++
Two version of gcc was causing proble, check folder /usr/libexec/gcc/x86_64-pc-cygwin/ there would be two version of gcc.
To solve remove one.
The above answer worked for me, but I got caught by the installer automatically upgrading packages back to 4.8.2. So, I initially thought this didn't work; it actually did. You just need to be aware of that when using the installer to add packages later, it may try to upgrade back to 4.8.2 again and break things.
There is the option to turn off LTO with -fno-use-linker-plugin, but that doesn't do me any good becuase CPAN is what is launching g++. It might serve as a workaround.
(I know this isn't much of an answer, but I was unable to comment)