I have installed gcc-plugin in my Ubuntu 16.10-32 bit and the installation have been done correctly:
>$ gcc -print-file-name=plugin
/usr/lib/gcc/i686-linux-gnu/6/plugin
However, when I try to compile the plugin, I get a huge amount of errors, warning, and exceptions ...
I can not understand what is the reason behind this.
Is it a mistake in the compiling command line? or the installation of the gcc-plugin was not the right way?
I have compiled the gcc-plugin file as follow:
gcc -g -I`gcc -print-file-name=plugin`/include -fpic -shared -o my_plugin.so my_plugin.c
any help?
You have to use the C++ compiler g++. The command line looks otherwise ok, but I don't know your source code, of course.
Related
I am trying to open my in-built camera in order to make a Face Detection program, but I notice that VideoCapture.open(0) does not work when I attempt to run through a cmake compilation, but DOES work when I compile and run through g++.
This program is part of a project, and compiling through CMake is necessary, but nothing seems to work...
(I'm using Ubuntu)
My code compiles and runs, opening the in-built camera (returning "true" on if(capture.isOpened())), when I use
g++ main.cpp FaceDetection.cpp `pkg-config --cflags --libs opencv4`
but returns false on if(capture.isOpened()) and does not open the in-built camera when I compile through cmake.
Any ideas on what I should do for this to run like it runs when I compile it with g++?
Edit: Removed my code, as it wasn't a problem with the code at all. Will answer my own question as I found a solution.
Ran make VERBOSE=1, cmake ../ --log-level=VERBOSE, and
g++ main.cpp FaceDetection.cpp `pkg-config --cflags --libs opencv4`
as Tsyvarev suggested, and found that g++ was including opencv from /usr/include while cmake was including opencv from /usr/local
I found this SOLUTION:
Ran cd /opt/opencv/build && make uninstall first and then ran make in my project folder, which actually solved the problem and opened the camera.
I'm not sure what caused this, but if this happens to anyone, hope this helps!
I'm trying to compile a project in C++ using cmake, and in the page of the project they tell me that it will crash if I don't add the standard 98. (I'm on a mac)
I've tried all I found on the internet and I could manage to make the cmake use the option -std=c++98 but it also adds -DNDEBUG -std=gnu++11. (I saw it using the make VERBOSE=1 option)
I would like to get rid of that. Using the --trace option I could see that the option is set in a file which is in the cellar folder, that is, is something that has to do with cmake itself and not in the CMakeList.txt file im using.
How can I solve this problem?
If it can help the code I'm trying to compile is this:
SAMoS
Thank you.
UPDATE:
with the --trace option I was able to see that the -std=gnu++11 option was selected in the file:
/usr/local/Cellar/cmake/3.9.4.1/share/cmake/Modules/Compiler/GNU-CXX.cmake
which can be seen here GNU-CXX.cmake
If I eddit that file in a way that every if sets the option to -std=c++98 then, the cmake complains giving me the next error:
CMake Error in src/CMakeLists.txt:
The compiler feature "cxx_nullptr" is not known to CXX compiler
"GNU"
version 7.2.0.
I don't know what else can I try...
You need to set the language standard:
set(CMAKE_CXX_STANDARD 98)
Depending on the compiler, it may enable extensions as well. To disable the GNU extensions also add:
set(CMAKE_CXX_EXTENSIONS OFF)
Note that setting this options does so only for the specified target and dependent targets.
Have take a look at this section of the CMake manual for more information on compiler features. Do note however, using this
The inclusion of VTK is polluting SAMoS's CMake scope with the C++11 requirement. You can test this by disabling VTK on your cmake command line.
$ cd ~SAMoS
$ mkdir build; cd build
$ cmake -DVTK_FOUND=FALSE ../
[...]
$ make VERBOSE=1
[...]
Scanning dependencies of target samos
/Applications/Xcode.app/Contents/Developer/usr/bin/make -f src/CMakeFiles/samos.dir/build.make src/CMakeFiles/samos.dir/build
[ 1%] Building CXX object src/CMakeFiles/samos.dir/samos.cpp.o
cd /Users/nega/SAMoS/build/src && /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++ -DCGAL_USE_GMP -DCGAL_USE_MPFR -DHAS_CGAL -isystem /usr/local/include -I/include -I/Users/nega/SAMoS/src/constraints -I/Users/nega/SAMoS/src/dump -I/Users/nega/SAMoS/src/log -I/Users/nega/SAMoS/src/integrators -I/Users/nega/SAMoS/src/messenger -I/Users/nega/SAMoS/src/parser -I/Users/nega/SAMoS/src/potentials -I/Users/nega/SAMoS/src/potentials/external -I/Users/nega/SAMoS/src/potentials/pair -I/Users/nega/SAMoS/src/potentials/bond -I/Users/nega/SAMoS/src/potentials/angle -I/Users/nega/SAMoS/src/system -I/Users/nega/SAMoS/src/utils -I/Users/nega/SAMoS/src/aligner -I/Users/nega/SAMoS/src/aligner/pair -I/Users/nega/SAMoS/src/aligner/external -I/Users/nega/SAMoS/src/population -I/Users/nega/SAMoS/src -I/Users/nega/SAMoS/build -DNDEBUG -o CMakeFiles/samos.dir/samos.cpp.o -c /Users/nega/SAMoS/src/samos.cpp
You'll notice there's no -std=gnu++11 flag anymore. Of course, since it looks like you're GCC version 7.2, you'll still want your set CMAKE_CXX_STANDARD to 98 since gcc-7.2 uses C++11 by default. (Or maybe it's C++14 now...) You can do this on your cmake command line.
$ cmake -DUSE_VTK=FALSE -DCMAKE_CXX_STANDARD=98 ..
CMake will then add -std=gnu++98 to its compile commands.
If you can't live without VTK, then you'll need to send a bug report upstream asking the SAMoS folks to clarify their documentation, or fix how they're including VTK.
I am trying to compile a program which uses GSL, in fact I am already able to compile it successfully on my local machine using
g++ -o program program.c prog0.o -L/usr/local/lib -lgsl -lgslcblas -lm
My problem is that I need to compile this program on a work machine in a shared system, but I know the program will not compile with an up to date version of GSL, so I need to install and use an older version.
I did this on my own system using the default installation, so the relevant files are located in /usr/local/lib on my local machine, and the compilation works for me with the above command.
But since the work machine is in a shared system, I cannot mess with the default directories, so I installed the correct GSL version on the work machine in my directory under /home/myname/gsl/.
So on the work machine the folder /home/myname/gsl/lib contains the same relevant files as the folder /usr/local/lib on my machine.
Now I did various attempts to try and tell g++ to use this custom installation folder, which I thought would come down to
g++ -o program program.c prog0.o -L/home/myname/gsl/lib -lgsl -lgslcblas -lm
but no success. No matter what I did g++ always used the GSL version installed on the shared system, even using just
g++ -o program program.c prog0.o
I only started programming C/C++ not long ago and only know the very basics of how to compile programs, so this linking thing is still always confusing me..
But as far as I can tell -L/dir/ should tell g++ to use the library in /dir/ and -lgsl -lgslcblas are the files which it should look for in that library... ?
But it seems g++ doesn't care what library I tell it here, it always seems to use whatever is in the PATH of the shared work system, which seems to include this up-to-date version of GSL that I cannot use. But I also cannot change the PATH since I only have access to my own subdirectories on the work system..
So how do I tell g++ to ignore the default version of GSL and use the one I installed manually at /home/myname/gsl/ ?
I figured out the answer, it is actually simple. The problem was just my lack of understanding proper usage of outside libraries and trying to fix the compilation command was the wrong approach.
In the code in program.c, gsl was included with
#include <gsl/gsl_blas.h>
and so on. Of course, the "<>" directly tell the compiler to look in known include directories, where the up-to-date GSL is installed on the shared system.. So the way to use a custom version was just to instead use
#include "/home/myname/gsl/lib/gsl_blas.h"
and so on, directly specifying that I want to use my custom installation.
I then compiled with
g++ -o program program.c prog0.o /home/myname/gsl/lib/libgsl.so /home/myname/gsl/lib/libgslcblas.so -lm
and it compiles successfully.
(This brought up some other unclarities for me, but at least this specific problem is solved.)
One of my users is getting an error message when trying to compile a C part of our mixed C/C++ codebase on ubuntu 12.04 with gcc 4.8.1
We have a library in C++ with some C-linkage functions in, and want to compile a C program linking to it. The library is compiled with g++ and builds fine. The c program fails like this:
> gcc -O3 -g -fPIC -I/media/Repo/lcdm/code/cosmosis/ -Wall -Wextra -pedantic -Werror -std=c99 -o c_datablock_t c_datablock_test.c -L . -lcosmosis
cc1plus: error: command line option ‘-std=c99’ is valid for C/ObjC but not for C++ [-Werror]
The program has a lower case .c file suffix, so why does gcc try to compile it as c++ ? We have not seen this on other OSes.
(I know we could kick the problem down the road by removing -Werror or handle this particular file with -x c but I'd like to solve the real problem.)
why does gcc try to compile it as c++
I can think of only two plausible explanations, and they both are end-user's fault.
It could be that the user transferred sources via Windows, and the file is really called C_DATABLOCK_TEST.C, and the user is misleading you.
It could also be that the user overwrote his gcc with g++ (surprisingly many people believe that gcc and g++ are the same thing, but they are not).
To disprove the first possibility, ask the user to execute his build commands under script, and send you resulting typescript.
To disprove the second, ask the user to add -v to the compile command.
This look like GCC Bug 54641, which has been fixed in a later release of GCC. It is only a warning, but your compile flags are causing GCC to treat all warnings as errors.
Following the guide over at http://www.scratchapixel.com/lessons/3d-basic-lessons/lesson-2-get-started/get-started/ and I got down to the part where you set up GLFW. Everything was going fine got CMake all installed properly and it went through the process just as shown on the images on the site. Everything installed fine to the /usr/local/include and /usr/local/lib folders. So the next thing to do is test that it installed fine and every time I try to do anything with whats in the glfw folder, gives me this error:
fatal error: 'GLFW/glfw3.h' file not found
These are the commands I've tried to run it with:
gcc boing.c -o boing
gcc -lglfw boing.c -o boing
gcc -lglfw3 boing.c -o boing
gcc -I/usr/local/include boing.c -o boing (different error)
The last one almost worked and gave several different errors, which I think may have been caused by something else. That's kind of besides the point though. What am I doing wrong here? To my knowledge gcc is meant to look in the /usr/local/include folder by default for libraries.