I've installed the newest LLVM toolchain from the official PPA, including clang, clang-tools-extra, lldb, lld, libc++ and libc++abi. I'm trying to use clangd with emacs + lsp.
All works fine except clangd cannot find default headers like memory, vector and so on. My code is fine, it is normally compiled using clang. My compile_commands.json also okay.
How to make clangd work?
Edit: removed mention about building llvm+clang from sources since it has been done incorrectly.
I didn't find any info on the internet, so posting the solution here.
Suppose the llvm toolchain is installed in /usr/lib/llvm-8.
The answer is:
sudo ln -s /usr/lib/llvm-8/include/c++/v1 /usr/include/c++/v1
That's it. Good luck.
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.
My system is macOS 12.3 21E230 arm64 and I have installed gcc and llvm from homebrew.
I use Neovim as editor and use nvim-lsp via clangd to complete my code, and it works well with clang.
Now I want to use clangd to find headers of gcc and compelete them in my code. I have tried to find answer from https://clangd.llvm.org/, but I haven't find any way to solve this problem.
I tried setting --query-driver, -include-dir, -isysroot, etc.
Using --query-driver seems to be the most promising approach.
If it's not working, please share more details in the form of clangd logs.
Some clangd issues reported my Mac users that might contain helpful discussion are:
https://github.com/clangd/clangd/issues/487
https://github.com/clangd/clangd/issues/1079
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.
Edit/Update/Note: Just let clang use libstdc++. Has been working really well for me so far.
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In the past I have been able to succeed by doing something with cmake, but just now I discovered a buildit script inside the lib directory of the http://llvm.org/svn/llvm-project/libcxx/trunk project tree.
This buildit script appears to not make use of libsupc++ which is what the cmake approach that I took earlier used. For instance, this guide shows one cmake incantation to produce a makefile for libc++, which will be able to take care of compiling and installation.
My question is what is the difference between these different ways to produce the LLVM-libc++ and which one should be used? Will they behave differently?
The buildit script does not appear to provide any help for installation. Are there directions anywhere for how to properly install the library? With my previous libc++ built with cmake, I had to always add -lc++ to the linker flags (and the path with -L), which is not necessary in my OS X makefiles.
The libc++ website has a nice overview of the possible ways to build libc++.
I suggest using CMake + libc++abi.
Also see the Arch Linux User Repository build script, which uses the buildit script. I installed libc++ from that and used it with the Arch Linux Clang package succesfully by using
clang++ -std=c++11 -stdlib=libc++ -lc++abi
Here's my problem: I want to use C++11 features provided by either gcc or clang. However, I have these requirements:
I'm using a mac
I'm dependent on a bunch of libraries provided by homebrew (and really don't want to compile them myself). Specifically OSG, which itself is dependent on a ton of other libraries. And boost, though I can always compile that myself.
Homebrew seems to only want to use gcc (please correct me if I'm wrong). I can't find any options to switch to LLVM instead. While I understand that this might be due to the fact that not all libraries are compatible with LLVM yet, this would still be a nice feature for those that are.
The version of gcc that comes pre-installed on a mac of gcc is 4.2. gcc 4.2 doesn't have the c++11 features required. I've installed 4.7 via homebrew, but searches for how to set homebrew to use it all say don't do it (gcc 4.2 on the mac is not the vanilla version, so the 4.7 version I got won't be able to compile some things).
My questions are: Does anyone have any suggestions or fixes they have implemented to get around this problem? Should I give up on Homebrew? Does anyone know if Homebrew has a plan to switch to LLVM in the future? Does anyone have any upgrade-plan for how to deal with these incompatibilities?
I don't see how homebrew can continue to depend on gcc 4.2 in the long run, but haven't found any real discussion on this matter.
The default GCC on Mac is not real GCC of GNU. It's LLVM-GCC in fact, which is a branch of GCC. Several years ago, LLVM-GCC was terminated, and replaced with DragonEgg, which is a GCC plugin to use LLVM as a GCC backend.
LLVM-GCC is just a compiler frontend, whose role is using GCC frontend to translate the source code into LLVM IR[Intro to LLVM 11.3]. Once IR generated, LLVM backend will use it to generate binary code. This step has nothing to do with GCC.
The above goal was fully achieved from 10.7, whose components were all compiled by clang, a frontend provided by LLVM.
But Apple still kept LLVM-GCC and GCC runtime libraries. I guess its purpose might be providing a opportunity to compile some code GCC ONLY.
Now let's answer your questions:
If you want to use C++11 features, use clang++ -stc=c++11 -stdlib=libc++ instead. And clang might have already supported all c++11 features.
If you want homebrew supporting LLVM, it has already supported, at least on backend.
If you want homebrew using clang as a compiler frontend, it depends on homebrew community schedule. For example, you can append --with-c++11 argument to use clang to compile boost.But you cannot use this argument when brew install autoconf. In fact, some components might not be compiled correctly by clang.
If you know it can be compiled by clang but homebrew hasn't supported yet, you have to hack the corresponding ruby script at $HOMEBREW_ROOT/Library/Formula directory. Fortunately, in most of cases, replacing ./configure blablabla with ./configure blablabla CXX=clang++ -stc=c++11 -stdlib=libc++ works well. And by the way, if your hack is successful, please make a pull request to homebrew.
So, try it and have a fun.
I have an OS X Mountain Lion environment and use C++11. In this answer I'll break your requirement for not compiling your own stuff.
I use Homebrew and, I must say, I advise you to give up on depending on it to provide you clang and libc++ and all its formulas built with them.
What I've done, and I like, is
clone llvm, clang and libc++ from repositories.
install to /opt/local and put /opt/local/bin at top on /etc/paths.
build my development stuff with my new clang.
let Homebrew for installing tools like git and things I'll not develop for, just use.
I've followed clang build instructions for installing it to /opt/local.
For libc++, one detail: after running the buildit script, I've symlinked the include directory to /opt/local/lib/c++/v1 (clang on /opt/local looks for this as default directory), and also symlinked the libs to /opt/local/lib/ (but look that binaries will not automatically link to libc++ on /opt/local/lib. You must use install_name_tool for that).
use
clang++ -std=c++11 -stdlib=libc++
you can also install latest gcc from homebrew-dups
brew install [flags] https://raw.github.com/Homebrew/homebrew-dupes/master/gcc.rb
For LLVM, brew install --HEAD llvm. To use clang or a brew-installed gcc, add --with-clang or --with-gcc=gcc-x.x where x.x is the version you want.