Modifying the contents of a .cpp file - c++

UPDATE: I am now able to compile the .cpp file with make
(I can see the compilation output). However, the changes does not seem to take affect.
After i run make, i restart the computer, but still no changes.
As you probably understand, I have very limited experience with c++.
I am currently working on a project (OpenBTS) and have found an error in one of the .cpp files after the project has been built and installed.
My question is, how can I modify the contents (f.eks change the string of a JSON data reference) of a .cpp file and build it so I can see the changes afterwards?
I have currently tried the following:
1.
make 'filename.cpp'
make: Nothing to be done for 'filename.cpp'
2.
make 'filename'
g++ 'filename.cpp' -o 'filename'
In file included from 'filename.cpp:29:0:
'filname.h':26:21: fatal error: Timeval.h: No such file or directory
#include <Timeval.h>
compilation terminated.
3. Run make from root directory:
Nothing to be done for 'all.'
4. Run make clean and make from root. This rebuilds the project but the
changes are still not in effect (I can see that the JSON String is not
changed at the webserver).
5. Run ./build.sh script. Still no changes.
Regarding the 2. method, as the project was built and compiled successfully, how come when i try that with a single file, the compiler can't find the header files? The only thing i changed was a string from "ARFCN" to "ARFCNtest".
Since there are about 50 header files that depends on each other, changing the include from <> to "" and copy every single file into the same directory seems like a waste and unnecessary action?

The changes didn't take effect because the compilation failed. See the error message you quoted in the question. Fix that and rebuild.
Incidentally, restarting your computer shouldn't be necessary. Even the make clean shouldn't be necessary if the Makefile correctly expresses the dependencies. (It seems to do so in this case since it tried to recompile the source file you modified.)

Related

C++ Make asks for a file that doesn't exist

When I try to build/compile my code, I get this error:
make: *** No rule to make target '../../Source/GardenCounter.cpp', needed by 'build/intermediate/Debug/GardenCounter_15332182.o'. Stop.
The terminal process "/bin/bash '-c', 'make QUIET=0'" terminated with exit code: 2.
I don't have a file named GardenCounter.cpp anymore. I deleted it and yet it is still asking for it. I tried to delete the old .o and .d files and recompile everything from scratch but I'm still being asked for this.
Probably it would help to post your Makefile here. Without it, it's hard to know what the specific issue is. But here are some things to try off the top of my head:
-Look for the name of that source file in your Makefile. Did you remove it from all the build dependencies there?
-Is there a wildcard expression used somewhere in your Makefile that might be picking up that name from some other file? Possibly a header or an intermediate build file?

CMake+git: check file sha rather than timestamp

As far as I know, CMake checks the time stamp of a source file to detect if it is outdated and needs to be rebuild (and with it, all files including it). When switching branches in a large git repository, this can causes problems.
Let's say I have one source folder and two build directories (build1 and build2), which correspond to two different branches (branch1 and branch2)
project
+-- src
+-- branch1_build
+-- branch2_build
Say my two branches have few differences, in few files; mostly, they only differ for some configuration option, all encapsulated in a config.h file, generated by the CONFIGURE_FILE command in cmake. The source files for the two config.h files (the config.h.in, as it is often called) are different. For instance, one branch introduces a new subfolder, which can be activated with a config-time option, which gets put in config.h.in with something like #cmakedefine HAVE_NEW_FEATURE_FOLDER. In such a scenario, when switching branches in the source folder, this happens: cmake recognizes that something changed in the config.h.in file, so it runs again; by running again, it generates a new config.h file; since config.h has a new time stamp, all files that includes it (directly or indirectly) end up being recompiled.
Now, if I alternatively switch between branch1 and branch2 in the source folder (cause I'm working on both branches every day), two consecutive make commands issued in the same build folder (either branch1_build or branch2_build) will trigger a full recompilation, since, although config.h has not changed in content, its time stamp has changed, so cmake flags it has changed.
My question is: what options do I have to avoid this? Or, better phrased, how can I avoid recompiling a source-build tree pair that is in fact unchanged since the last build, while also minimizing the changes to the source code?
The only solution I can think of is to execute CONFIGURE_FILE on config.h.in, with output config.h.tmp; compare config.h.tmp with config.h, and, only if different, copy config.h.tmp to config.h. However, this seems clumsy, and overcomplicated. I hoped cmake already had a mechanism for this, perhaps hidden under some options/variations of CONFIGURE_FILE...
Assuming this is not yet possible, I was wondering how complicated it would be for cmake to check the sha (rather than the timestamp) of a particular file when deciding whether it is outdated or not, and comparing it with the sha of a previous build (yes, the word outdated has date in it, but let's not get into enlish vocabulary discussions here). I imagine this is more expensive, so I would think that, if possible at all, this behavior should not be the default, and the user should use sparingly this feature, by explicitly tagging a file as check_sha_not_time kind of file. In the example above, the user would tag config.h as check_sha_not_time, and avoid recompilation of pretty much the whole library.
Note 0: I know little of how cmake internally works, so my suggestion of using sha rather than timestamp could be completely crazy and/or impossible given cmake implementation. I apologize for that. But that's why one asks things here, cause he/she doesn't know, right?
Note 1: I also tried using ccache, but unsuccessfully. Perhaps I need to use some particular flag or configuration option in ccache to trigger this capability.
Note 2: I want to avoid duplicating the source folder.

Add source to an existing automake program

I would like to edit an existing software to add a new source file (Source.cpp).
But, I can't manage the compilation process (it seems to be automake and it looks very complicated).
The software (iperf 2: https://sourceforge.net/projects/iperf2/files/?source=navbar) is compiled using a classical ./configure make then make install.
If I just add the file to the corresponding source and include directory, I got this error message:
Settings.cpp:(.text+0x969) : undefined reference to ...
It looks like the makefile isn't able to produce the output file associated with my new source file (Source.cpp). So, I probably need to indicate it manually somewhere.
I searched a bit in the project files and it seemed that the file to edit was: "Makefile.am".
I added my source to the variable iperf_SOURCES in that file but it didn't workded.
Could you help me to find the file where I need to indicate my new source file (it seems a pretty standard compilation scheme but I never used automake softwares and this one seems very complicated).
Thank you in advance
This project is built with the autotools, as you already figured out.
The makefiles are built by automake. It takes its input in files that usually have a am file name extension.
The iperf program is built by the makefile generated from src/Makefile.am. This is indicated by:
bin_PROGRAMS = iperf
All (actually this is a simplification, but which holds in this case) source files of a to be built binary are in the corresponding name_SOURCES variable, thus in this case iperf_SOURCES. Just add your source file to the end of that list, like so (keeping their formatting):
iperf_SOURCES = \
Client.cpp \
# lines omitted
tcp_window_size.c \
my_new_file.c
Now, to reflect this change in any future generated src/Makefile you need to run automake. This will modify src/Makefile.in, which is a template that is used by config.sub at the end of configure to generate the actual makefile.
Running automake can happen in various ways:
If you already have makefiles that were generated after an configure these should take care of rebuilding themselves. This seems to fail sometimes though!
You could run automake (in the top level directory) by hand. I've never done this, as there is the better solution to...
Run autoreconf --install (possibly add --force to the arguments) in the top level directory. This will regenerate the entire build system, calling all needed programs such as autoheader, autoconf and of course automake. This is my favorite solution.
The later two options require calling configure again, IMO ideally doing an out of source built:
# in top level dir
mkdir build
cd build
../configure # arguments
make # should now also compile and link your new source file

Changing name of application file (.C file)

I changed the name of an modified application to seperate it from the basic application. Lets say the .C file of the old application is "OldApplication.C" and of the new modified one is "NewApplication.C" Unfortunately, when trying to start the new modified application in terminal by typing "NewApplication" I get:
NewApplication: command not found
Two Question:
How can I make my new application executeable?
Can someone give me a brief overview about the files of a project/application and their functions?
greetings, streight
The mistake of this kind
make: * No rule to make target OldApplication.dep', needed byMake/linuxGccDPOpt/dependencies'. Stop.
often occurs in situation when the Makefile ceases to comply with the structure of the whole project.
In your case make script obviously trying to find the file that was renamed by you and therefore it fails with en error. I think that you should explore the structure of your Makefile and replace all the changed file names with its new versions.
Also you say the you are refused to launch your new executable, but what else could be expected since the project was not compiled?

Change in source code

I have two question
I have done some changes in C-backend of LLVM-2.9 source code. Now what I wanna is how can I reflect these changes in build folder?
What does make update do ? When I run this command this is what happen in my terminal.
arpit#arpit-HP-dx2480-MT-KL969AV:~/llvm1/build$ sudo make update
svn update /home/arpit/llvm1/llvm
Skipped '/home/arpit/llvm1/llvm'
svn: warning: '/home/arpit/llvm1/llvm' is not a working copy
Skipped '.'
make update updates LLVM and Clang and other sub-projects, so it's not what you need. What you do need is just make in the build folder. If any of the source files changed, make is supposed to pick it up and re-build the relevant files.
Maybe the specific changes you made are not picked up by make, have you added a new file? You can always try to build everything anew (e.g. make -B) and see if the change is included.