I'm working on a c++ project which just implemented some of the shared pointer features from boost and/or TR1. Since the upgrade, my code no longer compiles with gcc 4.2.1 (provided by Xcode), I'm installing gcc 4.5.x which is suppose to provide the aforementioned features. I need to recompile mpich2 (and then my code) with the new compiler and I want to be sure macport is using the right one.
sudo port install gcc45
gcc_select mp-gcc45
should have gotten the job done, but I'd like port to tell me which compiler it is using.
Can anyone help me with this?
Thanks in advance,
Nick
MacPorts - Using the Right Compiler
Related
I am learning LLVMand C++, but I find it hard to import LLVM into my project.
The first problem is my system has already installed clang and clang++ in usr/bin, but the other LLVM which was installed by brew is in /opt/homebrew/opt/llvm, is ok to delete clang in usr/bin and add opt/homebrew/opt/llvm/bin to env variable?
The second problem is how to link LLVM to my VSCode project, I try link LLVM by
#include "/opt/homebrew/opt/llvm/include/llvm/IR/Constants.h"
but it can't work.
Thanks for any help !!!
Never delete system utilities. Of any kind. For any reason.
Read the information presented to you in brew info llvm. This information was shown to you when you installed it.
Don't #include absolute paths.
Learn how to use compiler/linker flags to tell your compiler where to find headers/libraries.
Read the libc++ documentation to learn how to specify a specific libc++.
Finally, use a tool like cmake to automate this for you.
A homespun makefile might be sufficient.
What you are attempting to do is highly non-trivial. As one of the comments suggests, I would also recommend getting familiar with what's baked in before you try switching to a custom version.
Im running Matlab on linux (Elementary OS)
The problem im facing is that Matlab isnt compatible with the gcc compiler higher than 4.9.
Same question as: https://www.mathworks.com/matlabcentral/answers/348906-downgrading-gcc-g-for-use-with-mex
When I use "sudo apt get install gcc" 5.4 is automatically installed. When I remove 5.4, Matlab will not recognize 4.9 which I've installed. How do I get Matlab to recognize gcc/g++ 4.9 as my compiler?
I've also followed this but it didnt resolve the problem:
https://www.mathworks.com/matlabcentral/answers/137228-setup-mex-compiler-for-r2014a-for-linux#answer_263109
Any help would be greatly appreciated.
When I remove 5.4, Matlab will not recognize 4.9 which I've installed. How do I get Matlab to recognize gcc/g++ 4.9 as my compiler?
I use Ubuntu (from which you OS is derived) and have had a similar issue. Basically, you can use update-alternative to switch between gcc versions on your choice. Here is a link that explains how to do it.
Here is the documentation on update-alternative, if you need more in-depth knowledge of its functionalities.
Note that uninstalling the default gcc for your distro (5.4 in your case) is no longer required with this solution: you can switch back to it for you development when not using Matlab. You can even install more than two versions of gcc if needed.
Hope this solves your issue.
There is no reason to downgrade GCC for MATLAB.
The reason you run into issues on Linux is because MATLAB installs its own copies of the GCC libraries. If your MEX-files expect newer libraries, they'll fail. You can delete the GCC libraries that come with MATLAB, and it will use the newer ones on your system.
The libraries are at $(MATLABROOT)/sys/os/glnx86 for 32-bit MATLAB, and $(MATLABROOT)/sys/os/glnxa64 for 64-bit MATLAB. $(MATLABROOT) is the installation root for MATLAB.
The files in question are libgcc_s.so*, libstdc++.so* and libg2c.so* (or at least they used to be called like this, I don't have a Linux MATLAB installation here to double-check).
This trick worked for MATLAB 7.0, and still worked a month ago when I suggested this to a colleague.
I do recommend that you rename or move the files, so you can replace them if things go sour.
You will need to restart MATLAB after this change, of course.
I have a project that uses cmake that I'm trying to compile (MapCrafter). I've already done cmake . to make the makefile. I've run brew install gcc47 to get GCC 4.7. It put it in /usr/local/Cellar/gcc47 for some reason.
Whenever I run make, it still uses GCC 4.2.1 at /usr/include/c++/4.2.1/ that cannot compile this code. I can't find any option for switching the compiler that works. make CC=/usr/local/Cellar/gcc47/4.7.3/bin/gcc-4.7 CXX=/usr/local/Cellar/gcc47/4.7.3/bin/c++-4.7 still uses 4.2.1. I almost never compile anything outside of Xcode or apt-get, so I'm really ignorant in this area. What step am I missing?
I do not know why this worked this time and not before, but I used cmake-gui and hit configure. Then I set my C compiler to /usr/local/Cellar/gcc47/4.7.3/bin/gcc-4.7 and my C++ compiler to /usr/local/Cellar/gcc47/4.7.3/bin/c++-4.7 and made the makefile. I've already tried this and don't remember changing anything… Now, make is using the correct GCC.
Someone might have a better answer than this, so I'm not going to mark my own answer as correct at all.
I would like to upgrade my old GCC compiler to v. 4.8.1.
Currently I'm using Code::Blocks IDE (nightly build, svn 8982), and my compiler is GCC 4.4.1.
I downloaded fresh GCC from their site - gcc.gnu.org
From what I've read in documentation, they say that I should first build compiler by myself. Afterwards, they throw something like this:
% mkdir objdir
% cd objdir
% srcdir/configure [options] [target]
However, I completly have no idea what to do with these lines.
And even if I did, afterwards come maaany lines with some additional options, where I am even more lost then before.
I don't know if there is any easy way of installing it, but from what I've read here, I can download MSYS from MinGW and it will do everything(I hope?) for me. However, from what I see there, it says that MinGW comes with already built version of GCC, meaning I won't be able to use mine anyway. Am I right? If yes, what should I do to build and use GCC? If not, then will I be able to easily install GCC after downloading MSYS?
Thanks in advance.
I can download MSYS from MinGW
YOu can.
and it will do everything(I hope?) for me.
It won't. MSys provides environment for building software that requires unix-like environment. To be more precise - autotools. If you aren't familiar with *nix build process (configure script), Mingw won't really help you.
However, from what I see there, it says that MinGW comes with already built version of GCC,
Yes, version 4.7.2 at the moment.
meaning I won't be able to use mine anyway. Am I right?
No. If you don't add Mingw/MSys to your PATH, you can keep multiple different installations on the same machine. It also SHOULD be possible to use multiple different versions of gcc within the same installation of mingw, but things can get messy here. (gcc3 and gcc4 should be able to exist, not sure about 4.7.2 and 4.8.1)
If yes, what should I do to build and use GCC?
You should search for precompiled binaries provided by somebody else. Compiling gcc yourself is possible, but for you (i.e. if you aren't arleady familiar with msys) it might not be worth the effort.
Either you could try http://mingw-w64.sourceforge.net/ or mingw-nuwen. Mingw provided by nuwen is 32bit only, but is very easy to install. The problem is that standard mingw distribution includes update tool (with "mingw uppdate" and "mingw upgrade" you can upgrade installed packages to their latest version), bug "mingw-nuwen" doesn't have such tool.
Because you say
However, I completly have no idea what to do with these lines.
You should either use precompiled mingw provded by somebody else, or use another compiler. If you don't really need bleeding-edge C++11 support ON WINDOWS, use visual studio express.
I am new to programming, so have never experienced a language update. With the release of C++11, I want to make use of all the new features such as lambda expressions and threads. I know I can do this with external libraries but using native language features would be more convenient.
I am using gcc 4.2.1 on Mac OS X Snowleopard in Xcode 3.2.6
What all do I need to do and update to start using C++11 features?
You can update to Xcode 4.1 (or whatever the most recent version you can get for Snow Leopard is) and get a new compiler with a few more C++11 features. There are some posts here on Stack Overflow about getting better support for C++11 in Xcode 4.1 on Snow Leopard.
But even the latest compiler available through Xcode does not support some C++11 features like lambdas. To get the best C++11 support you'll want to install a newer compiler, gcc 4.6 or 4.7, or Clang.
I frequently build the latest version of clang from source. It's not difficult to do if you're familiar with building other open source software. I use the git repos for clang and llvm, http://llvm.org/git/llvm.git and http://llvm.org/git/clang.git. You can also find instructions on their website for getting started: http://clang.llvm.org/get_started.html. Once you have the source for clang and llvm it's just ./configure && make && sudo make install. (you might want to run the tests before installing, since this is directly out of the repository. After make do make check in the llvm directory, and once that passes cd down to tools/clang and run make test. If everything is okay then sudo make install)
I don't remember if Snow Leopard included libc++ or not, so you may need to get that as well. http://libcxx.llvm.org/
Once everything is built and installed you can do:
clang++ -std=c++11 -stdlib=libc++ main.cpp && ./a.out
and you should have just about the best C++11 support around.
Recent patches in clang have really improved support for the last features you're likely to notice as a new C++ programmer. There are still a few bits and pieces left, but as of 3.1, and as far as I'm aware, clang has every C++11 feature that either gcc 4.7 or VC++11 has and more besides. libc++ also has the fewest gaps in terms of C++11 standard library features IME (though I think VC++'s standard library will also be pretty complete once they catch up on language features, e.g. char32_t and char16_t as native types so that the standard's mandated specializations for those types can be used).
Basically you only need to get a toolchain that has support for the new features. In macosx that would be either GCC or clang++. You might need to download/compile a particular version if needed (i.e. if the feature that you want to try is not in a prepacked compiler bundle but is available in the repository).
I downloaded and compiled the latest trunk of clang++ from subversion to do some testing, and installed g++ 4.6 with macports in Snow Leopard. I remember that I had some issues with the setup of the environment, but don't quite remember which of the compilers gave me problems or how I solved them. Google is your friend there :)
If you have homebrew installed, from this article, just two steps:
brew tap homebrew/dupes
brew install gcc --enable-cxx --enable-fortran --use-llvm