I am running into a problem I have not been able to avoid. Redhat 6 (or most linux packages) comes with a default QT package installed with headers/etc in the /usr/lib and /usr/include folders.
Now, I am wanting to link against a newer version of QT without removing the older version. Unfortunately, since the headers are in the /include/ folder, gcc automatically finds them, and then uses the wrong include files (instead of those which I have elsewhere).
I cannot seem to stop the compiler from automatically doing this. I have gotten around it previously by simply manually removing the old libraries/headers but this is a terrible solution long term.
I do not think this problem is specific to QT either, it just happens to be my current instance of it.
Any suggestions?
Many thanks :)
If you give the include directories of the newer Qt installation through -I option, it should be searched before the standard include directories (i.e. /usr/include, etc.) Removing the standard include directories from the search path completely is likely not a good idea because standard headers will also be found there (note that the Qt headers themselves most likely include standard headers and will not work if those are not found).
However if you really don't want the standard include directories to be searched, the option -nostdinc should do what you want.
My issue turned out to be related to an incorrect version of qmake being used. It was finding a previous version of qmake, and even though it was from qt4, it was linking to the wrong includes.
Updating the qmake paths worked to fix this issue.
Related
I'm learning to use OpenCV (and C++) in Codeblocks. What confuses me, however, is that when I start to include header files from OpenCV in my main.cpp file, Codeblocks automatically suggests to me the files as shown in the image below.
I have not included any search paths to project build options, so how is this possible that Codeblocks can find the files? Is there some other variable working here that I'm unaware of?
Note that I'm a beginner with both Codeblocks and OpenCV and that I only have a little experience with C++.
Thank you
Of course when you install an IDE like code::blocks by default, it knows about standard path for library on your OS.
On my OS -> Ubuntu that is /usr/include
It only searches on a standard path, except you add one. If you install your library by command-line, it goes to the standard place, if you installed manually, then it depends on your option you added to installation. I can not see you screen-shot but it has access to /usr/include by default.
For more detail on Linux and OpenCV
And here is a screen-shot of codeblock on Ubuntu that I added some 3rd-party library
NOTE:
if you install any libraries by command-line, just use it.
But if you have installed them manually, you need to add 2 things to codeblock.
1. First is your path for header file
2. Second is your path for linker
And you see it in screen-shot that say: Search Directory
First is for header and second is for linker
I use 2 different GCC versions on the same CentOS machine (included in OS one and custom one), and I don't want to replace system GCC with my custom one, I use custom one to build some software only.
The problem is that Qt Creator adds /usr/include to include folders automatically, so custom GCC starts to use system C++ includes and crashes with strange error messages like error: '::memchr' has not been declared. I don't have /usr/include anywhere in my *.pro file, so it looks like Qt Creator adds them itself.
How to prohibit Qt Creator project to use some specific include patches to allow compilation on machine with 2 GCC versions? When I use Eclipse CDT on the same machine, it works excellently, because Eclipse doesn't add anything itself and only uses include directories specified by me.
You can use CXXFLAGS += -nostdinc.
This should do the following (excerpt from the manual):
Do not search the standard system directories for header files. Only the directories you have specified
with -I options (and the directory of the current file, if appropriate) are searched.
It is not elegant answer, if someone has better ideas, you are still welcome to post your answer and I'll accept it.
So, I added custom build step between qmake and make commands, and I use sed command in this custom build step to edit Makefile on the fly and remove extra includes. This solution works, however, it is ugly.
I have a project which is built using cmake.
This project is uses avr-gcc to compile the binaries and I use boost mpl for some parts of it.
As avr-gcc does not have /usr/include as a default include path but boost is installed there, I need to add it as an include path such that boost is found.
Unfortunately, adding -I/usr/include to the command line pulls in all other files and directories in /usr/include which seems to introduce collisions with the avr includes and thereby compiler errors.
My initial solution involved a softlink to /usr/include/boost in one of my user defined include directories to resolve the
#include <boost/mpl/*>
However, I thought this to be not very platform independent and decided for cmake to add the include path for boost. This again led to "-I/usr/include" being present on the compiler command.
How do I solve this in a platform agnostic manner?
A solution would be to let cmake create the link for me to get the right include directory.
However, I consider the whole symbolic link solution ugly.
Is there something better that I can do?
For example: Is there some option that adds an include path under an alias like:
-I/usr/include/boost:boost
Which would add only the boost subfolder under the name boost to be includable by the #include <boost/...> directive?
I see at least two options for you:
Where does avr-gcc include files from by default? Let's say it is /opt/avr-gcc/include for concreteness. Then what may work for you is -I/opt/avr-gcc/include -I/usr/include.
Another option is to install Boost in a different directory and use that instead of the Boost in /usr/include. For example, you might create /opt/boost and then use -I/opt/boost (or a sub-directory under that) on the command line.
Using OSX and vim...
Downloaded SDL2 from the website, then moved the SDL2.framework into /Library/Frameworks/
Using tutorial code, and Makefile... SDL.h is not found.
Makefile: g++sdl-config --cflags --libssdltest.cpp -o sdltest
I've read numerous things about pointing the compiler to the framework, but everything I've tried doesn't seem to work, and I thought /Library/Frameworks/ was the default area for the compiler to look
Got it to work.
Getting this to work took multiple tries, but the root of the issue for each try was that most of the Tutorials I was looking at were for SDL1.2 when I was using SDL2.
This changed flags in the make file, directories to search in and other things. Interestingly, I could never get the compiler to see SDL.h when it was in the /Library/Frameworks/ directory. However using Macports to install SDL2 allowed me to point the compiler to where Macports installed SDL2 header files - /opt/local/include/SDL2
That seems to have done it for me
Thank you for your question, because I was having similar difficulties! There seems to be a dearth of detailed and helpful tutorials on how to install SDL2 using Macports.
I got it working! Here are the steps:
Visit this link to find the Macports package appropriate for your version of Mac OS X. Install the version you need, and once that is done, proceed to step 2.
https://www.macports.org/install.php
After installation is done, visit this link to find the SDL2 port.
https://www.macports.org/ports.php?by=name&substr=libsdl
The one I needed was the third from the top, called libsdl2. I will be providing the name for you so feel free to visit the link simply for your own edification.
Open the Terminal, and type sudo port install libsdl2. If all goes to plan, you should see it installing and updating. Once it is complete, you should have a functional installation of the SDL2 Header files, (ending in .h), Static Library files (ending in .a) and Dynamic Library files (which contain dylib). You may have to do some poking around in Finder to locate where it installed.
The advantage of this workaround is the ability to use SDL with other IDE's besides Xcode, Eclipse for instance. Whereas Xcode requires you to assign a path of /Library/Frameworks, this technique should allow you to use the IDE of your choosing.
The final step is going into your IDE and assigning the build paths to these newly installed and compiled SDL files. For instance, the paths for mine are /opt/local/include and /opt/local/lib. Be mindful of the fact that your path may differ from these, but these examples should give you an idea of where to look.
Hopefully this is helpful for somebody!
I've downloaded, extracted, and compiled the Boost libraries (including the separately compiled libraries). I've used their install procedure a couple times now but I can't seem to get it to do exactly what I want. Right now, when I install Boost after compiling it goes to
C:\Boost
This is fine. The compiled libs go to
C:\Boost\lib
which is also fine. The problem I have is with the installation of the precompiled headers. They got put at
C:\Boost\include\boost-1_54\boost
Is there a way to use the Boost build system and install tools to set the precompiled headers to be installed to just
C:\Boost\include
and not have the Boost version number be a part of that folder hierarchy?
I don't plan on using multiple versions of Boost at the same time so I don't have a use for actually having that version number. I realize I could move them manually after the install is complete, but I wanted to see first if I've overlooked or misunderstood something about Boost's build system.
--layout=system removes the versioned subdirectory from the include path (as #IgorR. pointed out).
"Removing that second boost in the path" is a bad idea. In a respectable OS (cough...), the include files for various libraries are supposed to co-exist in one common include directory, hence the boost subdirectory to avoid clashes. Boost headers are therefore habitually referred to as e.g. #include <boost/any.hpp>, i.e. including that boost/ subdirectory.
This is done both by third-party software using Boost, and by Boost itself. If you remove the second boost from the path, you would end up with C:\Boost\include\any.hpp, and any Boost-using software won't compile as not even Boost could find its own includes.