configure needs C++14 support but gcc -v = 4.9.3 - gcc

I am currently in the process of compiling graph-tool v1.13 from the Git version. I have managed to generate the configure file from autogen.sh but am now running into trouble.
Running ./configure I receive the message:
checking whether g++ supports C++14 features by default... no
checking whether g++ supports C++14 features with -std=gnu++14... no
checking whether g++ supports C++14 features with -std=gnu++0x... no
configure: error: *** A compiler with support for C++14 language features is required.
I have checked gcc -v and g++ -v and receive the response gcc version 4.9.3 (Ubuntu 4.9.3-8ubuntu2~14.04). To my knowledge this should support C++14 so where am I going wrong? I am running Ubuntu 14.04.

Try perhaps
./configure CXX='g++-5'
after having installed some GCC 5

gcc 4.9.3 supports C++14, but the correct compiler flag is '-std=c++14'

Related

setting g++ mode to C++11

I am trying to build cmake source, which requires C++11.
The build halts and apparently the complaint is that C++11 is not detected. The g++ mode is actually set to -std=gnu++17
This is part of the console log
---------------------------------------------
CMake 3.18.20200919, Copyright 2000-2020 Kitware, Inc. and Contributors
Found GNU toolchain
C compiler on this system is: gcc
C++ compiler on this system is: g++ -std=gnu++17
Makefile processor on this system is: make
g++ has setenv
g++ has unsetenv
g++ does not have environ in stdlib.h
g++ has stl wstring
g++ has <ext/stdio_filebuf.h>
---------------------------------------------
g++ -std=gnu++17 -DCMAKE_BOOTSTRAP -DCMake_HAVE_CXX_MAKE_UNIQUE=1 -c $HOME/Apps/CMake-master/Source/cmAddCustomCommandCommand.cxx -o cmAddCustomCommandCommand.o
This is part of the error in the log file...
In file included from /usr/include/c++/5/unordered_map:35:0,
from cmake_bootstrap_11920_test.cxx:4:
/usr/include/c++/5/bits/c++0x_warning.h:32:2: error: #error This file requires compiler and library support for the ISO C++ 2011 standard. This support must be enabled with the -std=c++11 or -std=gnu++11 compiler options.
#error This file requires compiler and library support \
^
cmake_bootstrap_11920_test.cxx:7:2: error: #error "Compiler is not in a mode aware of C++11."
#error "Compiler is not in a mode aware of C++11."
^
cmake_bootstrap_11920_test.cxx:70:16: warning: non-static data member initializers only available with -std=c++11 or -std=gnu++11
int Member = 1;
Looking around on the web, I noticed that C++11 is only available after gcc version 4.6.
I checked my version, and it seems to be above.
g++ --version
g++ (Ubuntu 5.4.0-6ubuntu1~16.04.12) 5.4.0 20160609
I understand the -std=c++11 flag is used to enable the C++11 features in g++, but I don't seem to know what I am doing in this case.
I tried editing the CompileFlags.cmake file, but no change occurs.
I came upon this page which points to the cmake source I am using.
It says...
bootstrap: Require compiler mode aware of C++11
Some compilers have enough features enabled in their default modes to
pass our simple C++11 unique_ptr check but do not enable enough to build
CMake. Poison this case so that we choose one of the explicit `-std=`
options for such compilers.
Not sure what that means exactly.
How exactly do I change the g++ mode, to C++11, so that on running the bootstrap command, C++11 is used?
Or, in other words, how do I change std to point to C++11 (-std=c++11)?
First of all, you have g++ version 5.4.0 in your host PC installed, which is good, cause it means this is also supports the C++11, which you want to use.
To set it up, you could define it in your CMakeList.txt file:
set (CMAKE_CXX_STANDARD 11)
that should do the trick.
Please also check the documentation:
https://cmake.org/cmake/help/v3.1/variable/CMAKE_CXX_STANDARD.html
Usually, I would suggest to use the latest standard that you compiler is supporting (https://gcc.gnu.org/projects/cxx-status.html), cause you'll get also the latest features introduced in that standard. Exception for this rather in case you are working with legacy codes.

Cannot run gcc with the -fopenmp flag on macOS

I have gcc 9.3 running on macOS, and I'm running a gcc command with -fopenmp flag, but I get the error: Unsupported optionerror: unsupported option '-fopenmp'```. How do I fix this?
OpenMP must be enabled when you run configure. Per default it is enabled, but when your target machine does not come with specific requirements like thread model then it is disabled.
For example, the top-level config.log for a gcc build that supports it reads:
...
target_configdirs=' libgcc libbacktrace libgomp libatomic libitm libstdc++-v3 libsanitizer libvtv libmpx libssp libquadmath libgfortran libobjc'
target_cpu='x86_64'
target_noncanonical='x86_64-linux-gnu'
target_os='linux-gnu'
target_subdir='x86_64-linux-gnu'
...
Notice the libgomp in target_configdirs. Use the config.log as a starting point to find out why your target does not support it.

How to accurately make configure script use the updated gcc version on CentOS?

I have followed instructions provided in other articles to fix the below issue but still doesn't appear to work for my system. I am trying to upgrade glibc to v2.27 on my CentOS 7.3 machine. I downloaded the package and running into the below compiler dependency during the configure script execution:
../configure --prefix=/opt/glibc-2.27
checking build system type... x86_64-pc-linux-gnu
checking host system type... x86_64-pc-linux-gnu
checking for gcc... gcc
...
...
checking if gcc is sufficient to build libc... no
checking for nm... nm
checking for python3... no
checking for python... python
configure: error:
*** These critical programs are missing or too old: compiler
*** Check the INSTALL file for required versions.
So I upgraded my gcc and verified the upgraded version:
gcc --version
gcc (GCC) 8.2.0
I also have the following environment variable set in my bashrc:
export CC=/usr/local/bin/gcc
For some reason, the configure script still throws the same error based on which it appears that the upgraded gcc version isn't being used.
What am I missing?

omp.h not found, OS X Yosemite not using newest gcc version

I am trying to build GraphChi on OS X Yosemite but get the following error:
fatal error: 'omp.h' file not found
From this question - How to include omp.h in OS X? - I learned that Yosemite uses Clang instead of gcc, which does not include omp.h.
$ which gcc
/usr/bin/gcc
$ gcc -v
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 6.0 (clang-600.0.56) (based on LLVM 3.5svn)
Target: x86_64-apple-darwin14.1.0
Thread model: posix
Next, I installed gcc via Homebrew
$ brew info gcc
gcc: stable 4.9.2 (bottled)
http://gcc.gnu.org
/usr/local/Cellar/gcc/4.9.2_1 (1092 files, 177M)
Built from source with: --without-multilib
and updated $PATH to include the path to the new gcc version
$ echo $PATH
/usr/local/Cellar/gcc/4.9.2_1:usr/local/bin:/opt/local/bin:/opt/local/sbin:/usr/bin:/bin:/usr/sbin:/sbin
however, gcc -v and which gcc still point to the old version, and building GraphChi still doesn't work due to the missing omp.h file
Does anyone know what else I need to do?
Update
locate omp.h returned:
/usr/local/Cellar/apple-gcc42/4.2.1-5666.3/lib/gcc/i686-apple-darwin11/4.2.1/include/omp.h
/usr/local/Cellar/gcc/4.9.2_1/lib/gcc/4.9/gcc/x86_64-apple-darwin14.1.0/4.9.2/include/omp.h
/usr/local/Cellar/gfortran/4.8.2/gfortran/lib/gcc/x86_64-apple-darwin13.0.0/4.8.2/include/omp.h
my ~/.profile:
export PATH=/usr/local/Cellar/gcc/4.9.2_1/lib/gcc/4.9/gcc/x86_64-apple-darwin14.1.0/4.9.2/include:/usr/local/Cellar/gcc/4.9.2_1/bin:usr/local/bin:/opt/local/bin:/opt/local/sbin:$PATH
I solved this with installing gcc with homebrew:
brew install gcc --without-multilib
and then building the source code with
CC=gcc-5 CXX=g++-5 cmake ..
CC=gcc-5 CXX=g++-5 make -j7
Once you have installed gcc-4.9 with homebrew, it will automatically be in your path. To use OpenMP, you just need to make sure you are using the newly installed gcc-4.9, and it will be able to find omp.h.
In the case of GraphChi, you will have to go change line 3 of the Makefile to be gcc-4.9. From there, running make should just work. They describe this in their README, but at least the version they describe is out of date https://github.com/GraphChi/graphchi-cpp#problems-compiling-on-mac.
clang does not support OpenMP yet. Also gcc by default links to Apple's LLVM clang compiler (not the GCC installed from brew).
Instead gcc-4.9 would link to GCC. I think if -fopenmp is specified omp.h is included automatically.
It is possible to manually build a version of clang with OpenMP support, see http://clang-omp.github.io
You shouldn't add the include path to PATH; instead, specify it as CFLAGS, including the -I option. You can export the CFLAGS variable, or set it on the fly.
Depending on how you compile things, you could do
CFLAGS=-I/usr/local/Cellar/gcc/4.9.2_1/lib/gcc/4.9/gcc/x86_64-apple-darwin14.1.0/4.9.2/include/omp.h gcc <whatever>
Of course, in this case you can specify it directly on the gcc command (as -I/usr/local/....), but the CFLAGS variable also works with configure (as configure often won't have an option to specify where it should look for specific include files); probably with make, or even for those installing a Python package: CFLAGS=-I... pip install <some-package>.
Other flags to consider are
CXXFLAGS: C++ specific pre-processor flags
LDFLAGS: linker specific flags (e.g. LDFLAGS=-L/some/path/... for linking with dynamic libraries).
CC: specify the C compiler to use. This is an easy way to avoid the built-in gcc alias for clang on OS X. Just use CC=/usr/local/bin/gcc-4 make or similar.
CXX: specify the C++ compiler to use.

Problem compiling gcc 4.4.0 on OpenSolaris 2009.6

I am attempting to compile gcc 4.4.0 on opensolaris 2009.6
Currently in the box (which is a AMD 64bit machine), I have the gcc 3.4.6 installed.
I unpacked the gcc 4.4.0 tarball.
I set the following env variables:
export CXX=/usr/local/bin/g++
export CC=/usr/local/bin/gcc
Then I ran "configure && make" and this is the error message that I got:
checking for i386-pc-solaris2.11-gcc... /export/home/me/wd/gcc/gcc-4.4.0/host-i386-pc-solaris2.11/gcc/xgcc -B/export/home/me/wd/gcc/gcc-4.4.0/host-i386-pc-solaris2.11/gcc/ -B/usr/local/i386-pc-solaris2.11/bin/ -B/usr/local/i386-pc-solaris2.11/lib/ -isystem /usr/local/i386-pc-solaris2.11/include -isystem /usr/local/i386-pc-solaris2.11/sys-include -m64
checking for suffix of object files... configure: error: in `/export/home/me/wd/gcc/gcc-4.4.0/i386-pc-solaris2.11/amd64/libgcc':
configure: error: cannot compute suffix of object files: cannot compile
See `config.log' for more details.
Anyone has any suggestion as to how to work around this error message?
/Edit:
Content of the config.log is posted here: link text
Normally the GCC build is bootstrapped, i.e. first it uses the system compiler to build GCC C compiler, and then it uses the freshly built compiler to recompile GCC once again (and then even once more time again). The configure line shows that it is not the system compiler but the already-built GCC compiler which is used for configure test there.
Since it fails, the problem is that the freshly-built GCC is somehow "stillborn" here. If config.log will not help you, I'd suggest to ask at gcc-help#gcc.gnu.org.
EDIT: Ah-ha, I think it is the assembler. You are using GNU assembler, but the unsupported options look like they were meant for Sun assembler. This should be solved by adding --with-gnu-as configure option (and then possibly having to specify its path explicitly with --with-as=/usr/gnu/bin/as)
You can also take a look at Solaris-specific GCC build instructions.
There's a readily available build for gcc4, which you can try updating. Its current version is 4.3.3. To get started, install pkg-get from OpenCSW and check out the build from the subversion repository:
svn co https://gar.svn.sourceforge.net/svnroot/gar/csw/mgar/pkg/gcc4/trunk/ gcc4
cd gcc4
gmake package

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