My situation is very similar to what's discussed in this thread. The reason I want to do this is that I am using OpenCV with CUDA 6.0, but CUDA is currently linked against libstdc++. I followed the answer that suggested putting the flag -stdlib=libstdc++ as well as the other approach where we set CXX and CXXFLAGS but as it was being commented: Macports did not seem to acknowledge the flags and still built with libc++ instead of intended libstdc++.
I would like to comment on that thread to ask for a follow-up, but unfortunately I do not have enough reputation yet.
Does anyone know how to get Macports to install OpenCV with libstdc++?
Edited 1: I have not gone back to check whether or not one of the answers provided below works. Compiling OpenCV with libstdc++ will cause issues with a few other non-CUDA projects that use libc++ primarily, so it is unlikely I will try. I will, however, accept an answer if someone can try out an answer below and comment to me if it works.
Edited 2: This question no longer applies to my situation since CUDA 7.0 RC has libc++ support by default. I will still accept an answer per Edited 1.
In the case of boost, I was able to force MacPorts to link against libstdc++ like so:
sudo port -s install boost configure.cxx_stdlib="libstdc++" configure.compiler="macports-gcc-4.7"
And that was it! Apparently there's no need to pass "-stdlib=libstdc++" yourself. otool -L shows what I was hoping to see:
$ otool -L /opt/local/lib/libboost_date_time-mt.dylib
/opt/local/lib/libboost_date_time-mt.dylib:
/opt/local/lib/libboost_date_time-mt.dylib (compatibility version 0.0.0, current version 0.0.0)
/opt/local/lib/libgcc/libstdc++.6.dylib (compatibility version 7.0.0, current version 7.18.0)
/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1197.1.1)
/opt/local/lib/libgcc/libgcc_s.1.dylib (compatibility version 1.0.0, current version 1.0.0)
If CUDA is linked against /usr/lib/libsdtd++.6.dylib, then you cannot use the macports-gcc ports as indicated in the other answer as doing so would result in CUDA using a different C++ runtime than OpenCV which can result in issues.
If you have a fresh install of MacPorts, you can edit macports.conf and set up your install to use libstdc++ instead of libc++. Just edit /opt/local/etc/macports.conf to contain the line:
cxx_stdlib libstdc++
Note that doing so will mean that you won't have access to ports that require C++11 or newer functionality.
Also note, that libstdc++ is deprecated, and MacPorts does not support officially support its use in Mavericks and later.
Related
Is there a way to get clang/clang++ to use a gcc/g++ installation in a non-standard (i.e. not /usr) place?
I'm trying to get AMD's AOCC 4.0 compiler to work. They provide a pre-compiled version that you just unpack. The problem is that it seems to assume gcc is in /usr/lib/gcc/... In my case I'm on CentOS 7 so that's gcc 4.8.5. I want to use newer gcc's install in /sw/opt (and managed with environment modules) but even if the gcc is in my path, clang only finds that 4.8.5 version in /usr. This is also a problem in that I have a cluster that has no default gcc installed (but many gcc versions installed in /cluster/sw) and I can't get clang to see them.
When I want LLVM I usually just build from scratch and specify GCC_INSTALL_PREFIX but that only seems to be useful at build time and since AMD only provides executables I'm out of luck.
Ideally I'd like to get clang/clang++ to point to another gcc (en mass: include, libs, etc...) or not be dependent on gcc at all.
AOCC seems to be based on 14.0.6 if that matters:
AMD clang version 14.0.6 (CLANG: AOCC_4.0.0-Build#434 2022_10_28) (based on LLVM Mirror.Version.14.0.6)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /sw/opt/aocc-compiler-4.0.0/bin
After more poking around I've discovered that there is a clang option "--gcc-toolchain" that seems to address this. Some clang documentation also lists an option "--gcc-install-dir" but neither the 14.0.6 based version of AOCC nor the 16.0.0 based version of OneAPI (2023.0) seem to recognize it. I don't see it in the output of "clang --help" either so who knows.
Are there any special reasons why Cygwin Clang is so outdated (see here), version 8, while already version 13 exists?
For example Ubuntu (apt), MSYS2, MSVC all have version 12.
Also does anyone know (any links?) if there is any very simple way (like docker-based) to build recent Clang for Cygwin? Maybe Clang has no support for Cygwin anymore, that's why Cygwin has outdated version?
See:
https://cygwin.com/packages/summary/clang.html
The reason is very simple, there is no current maintainer.
The previous one has no more available time to dedicate to the project.
I'm running Ubuntu 20.04 and I have installed libc++-dev (and ABI) package which is libc++-6.0-2.
However, now I have to use CLang 11, which requires a newer version of libc++ for better support to C++17, so I need to install libc++-11-dev, which is a different package and will replace my older.
My question is, how do I know if libc++ is backward compatible? I have hundreds of projects built and I don't want to rebuild all again.
I can't find a clear information about it in libcxx-11 documentation.
Yes. Newer versions of the libc++ dylib have new features, but it is intended that the dylib is compatible going forward.
I've been trying to build GCC 10.2 on my Intel MBP. As I've always done, I'm building from source and installing on /usr/local. Trouble is no matter what, the build fails on STAGE2 of bootstrapping. A careful search on all logs (including dependencies) could not point to a single fault. The only thing that stood out was the clang setup from Xcode Command Line Tools. When I run 'gcc -v' on a clean system (empty /usr/local), it outputs:
Configured with: --prefix=/Library/Developer/CommandLineTools/usr --with-gxx-include-dir=/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/c++/4.2.1
Apple clang version 12.0.0 (clang-1200.0.32.29)
Target: x86_64-apple-darwin20.2.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin
Trouble is that the target for --with-gxx-include-dir doesn't exist! There is no c++ subfolder, to begin with. Although there is one from the --prefix tree, instead of 4.2.1, there is just a v1 subfolder.
It would appear that there is something terribly wrong with Xcode Command Line Tools. But I can't be sure that this is the cause of my own troubles.
Please, don't answer this post pointing me to a package manager... there's a reason I abandoned those years ago. Also, it would be off-topic to the issue at hand.
I've finally managed to isolate the issue. GCC 10.2 depends on GMP, MPFR, MPC, and ISL libraries. I had them manually installed with the latest version available and fine tuned to my system. I didn't explore if it was a version conflict, or a fine tuning issue, but that broke the build. The solution was to let the script 'contrib/download_prerequisites' (within gcc tree) download the appropriate versions that were built along with GCC.
I also found out that the '--with-gxx-include-dir' target is a non-issue. It isn't supposed to point anywhere in my system. It is a reference to the system that built the "gcc" provided by Xcode Command Line Tools.
I am trying to build Clang following this: http://clang.llvm.org/get_started.html
At step 6 the command ../llvm/configure runs a series of checks and one tells me:
checking whether Clang will select a modern C++ standard library... no
configure: error:
We detected a missing feature in the standard C++ library that was known to be
missing in libstdc++4.6 and implemented in libstdc++4.7. There are numerous
C++11 problems with 4.6's library, and we don't support GCCs or libstdc++ older
than 4.7. You will need to update your system and ensure Clang uses the newer
standard library.
If this error is incorrect or you need to force things to work, you may pass
'--disable-compiler-version-checks' to configure to bypass this test.
I don't know how to resolve this and google searches for libstdc++4.7 did not produce anything useful to me or something I understand. How do I go about replacing / upgrading this? I am on a Mac (10.7.5)
I ran into the same problem. The easiest way to build Clang is to use libc++ instead of libstdc++. If you don't have libc++, you can obtain it by installing XCode 4.2 (or newer) or you can build it yourself by following the instructions here: http://libcxx.llvm.org/
After you have libc++ installed, you can use the --enable-libcpp=yes flag with the configure command.
Just this week, the LLVM & Clang project upped the minimal compiler version requirement to gcc 4.7, with its libstdc++. You'll need to install or build a newer gcc.
Here's a blog post I wrote earlier today about building gcc 4.8 on Ubuntu 12.04 and using that to compile trunk LLVM & Clang. Hope this helps!
i have the same error on mac 10.8.5 xcode 5.0
configure option --enable-libcpp resolve my problem
../llvm/configure --enable-cxx11 --enable-optimized --enable-libcpp
For me this happened because I had the old clang and clang++ that I'd previously built from source (the one I was attempting to build to replace) coming first in my PATH. These were too old. Removing those two files so that the build process would use the clang and clang++ that comes with XCode's Command Line Tools and then rebuilding worked fine.