I'm extremely new to using Makefiles and autoconf. I'm using the Camellia image library and trying to statically link my code against their libraries. When I run "make" on the Camellia image library, I get libCamellia.a, .so, .la, and .so.0.0.0 files inside my /usr/local/lib directory. This is the command I use to compile my code with their libraries:
gcc -L/usr/local/lib -lCamellia -o myprogram myprogram.c
This works fine, but when I try to statically link, this is what I get:
gcc -static -L/usr/local/lib -lCamellia -o myprogram myprogram.c
/tmp/cck0pw70.o: In function `main':
myprogram.c:(.text+0x23): undefined reference to `camLoadPGM'
myprogram.c:(.text+0x55): undefined reference to `camAllocateImage'
myprogram.c:(.text+0x97): undefined reference to `camZoom2x'
myprogram.c:(.text+0x104): undefined reference to `camSavePGM'
collect2: ld returned 1 exit status
I want to statically link because I'm trying to modify the Camellia source code and I want to compare my version against theirs. So after some googling, I tried adding AM_DISABLE_SHARED into the configure.in file. But after running ./configure, I still get the exact same Makefile. After I "make install", I still get the same results above.
What is an easy way to get two versions of my code, one with the original Camellia source code compiled and one with my modified version? I think static libraries should work. There is an easy way to get static libraries working or are there other simple solutions to my problem? I just don't want to re-"make" and re-"make install" everytime I want to compare my version against the original.
Did you re-run autoconf after adding AM_DISABLE_SHARED and before configure, make, make install? You also can just use configure --disable-dynamic to stop it building the shared libraries. Make sure you delete any previously installed ones - make uninstall should do that. I can't see anything else obviously wrong. Try being explicit:
gcc -static -o myprogram myprogram.c /usr/local/lib/libCamellia.a
or break it down into two steps and check the symbols in myprogram.o are what you expect with nm myprogram.o.
I am not skillful with autoconf and I don't know why your attempt to link statically fails, but if linking dynamically works I think using shared libraries would actually solve your problem a little better.
Just make two shared libraries, one with the original Camellia code and one with your modified version. Put them in two different directories, and when you run myprogram you can choose between them either by switching LD_LIBRARY_PATH (or whatever you're using to find libraries) or by keeping a symbolic link in /usr/local/lib and switching it between libraries. The advantage of this over static libraries (apart from the fact that this works) is that you can tinker with your modified code, rebuild the shared library and run without having to rebuild myprogram (as long as you don't modify the signatures).
P.S. An experiment: try removing the shared libraries from /usr/local/lib and rebuilding without the -static flag, just as if you were using the shared libraries. In theory this should cause gcc to use the static libraries instead. The results may give a clue to why the static link is failing.
Related
I have this strange issue where creating / using a static library works in my Ubuntu VM but not on macOS:
ld: warning: ignoring file ./dist/libXXXX.a, building for macOS-x86_64 but attempting to link with file built for macOS-x86_64
Command to create the static library is:
ar rcs libtest.a obj1.o obj2.o ...
Compiler invocation:
gcc -g -Wall -Wextra main.c -L./dist -lXXXX -o main
Searching on google didn't yield any usable results except for this (maybe) related question on SO:
Possible related question
I realize this is an old post and you found your fix, but let me post this here for anyone else who runs into this problem for whom these answers don't provide a solution.
You might be using two different toolchains unknowingly, one from Apple (installed via Xcode) and one from GNU (installed via Home-brew or MacPorts). If you type ranlib --version and see version info showing that ranlib is GNU, this is likely the case.
Make sure that /usr/bin comes in your $PATH before /usr/local/bin and /opt/local/bin. When you run which -a ranlib, the first result in the list should be /usr/bin/ranlib. Same for which -a ar-- the first result should be /usr/bin/ar. If it is not so, you need to fix your $PATH.
Once you fix your path and clean your project, try building again and things should work.
The issue was solved when I directly put those object files rather than gathering them into a static library, i.e.,
gcc -g -Wall -Wextra main.c obj1.o obj2.o -o main
After that, I got many warnings like ld: warning: object file (obj1.o) was built for newer macOS version (11.0) than being linked (10.14), but it is a warning, and the object is linked, so the problem is solved.
The root cause is that some library passes -mmacosx-version-min=10.14 to gcc, so the object file is built for 10.14, but my macos is now 11.0.
If you want to make things work, try directly using object files rather than creating a static library.
If you want to resolve all the warnings, find ``-mmacosx-version-min` and comment it.
After looking at my script that automatically creates the static library I've found the culprit:
For some reason my tool created object files for header files (resulting in files like header.h.o).
Removing those fixed the issue.
I'm a student doing research involving extending the TM capabilities of gcc. My goal is to make changes to gcc source, build gcc from the modified source, and, use the new executable the same way I'd use my distro's vanilla gcc.
I built and installed gcc in a different location (not /usr/bin/gcc), specifically because the modified gcc will be unstable, and because our project goal is to compare transactional programs compiled with the two different versions.
Our changes to gcc source impact both /gcc and /libitm. This means we are making a change to libitm.so, one of the shared libraries that get built.
My expectation:
when compiling myprogram.cpp with /usr/bin/g++, the version of libitm.so that will get linked should be the one that came with my distro;
when compiling it with ~/project/install-dir/bin/g++, the version of libitm.so that will get linked should be the one that just got built when I built my modified gcc.
But in reality it seems both native gcc and mine are using the same libitm, /usr/lib/x86_64-linux-gnu/libitm.so.1.
I only have a rough grasp of gcc internals as they apply to our project, but this is my understanding:
Our changes tell one compiler pass to conditionally insert our own "function builtin" instead of one it would normally use, and this is / becomes a "symbol" which needs to link to libitm.
When I use the new gcc to compile my program, that pass detects those conditions and successfully inserts the symbol, but then at runtime my program gives a "relocation error" indicating the symbol is not defined in the file it is searching in: ./test: relocation error: ./test: symbol _ITM_S1RU4, version LIBITM_1.0 not defined in file libitm.so.1 with link time reference
readelf shows me that /usr/lib/x86_64-linux-gnu/libitm.so.1 does not contain our new symbols while ~/project/install-dir/lib64/libitm.so.1 does; if I re-run my program after simply copying the latter libitm over the former (backing it up first, of course), it does not produce the relocation error anymore. But naturally this is not a permanent solution.
So I want the gcc I built to use the shared libs that were built along with it when linking. And I don't want to have to tell it where they are every time - my feeling is that it should know where to look for them since I deliberately built it somewhere else to behave differently.
This sounds like the kind of problem any amateur gcc developer would have when trying to make a dev environment and still be able to use both versions of gcc, but I had difficulty finding similar questions. I am thinking this is a matter of lacking certain config options when I configure gcc before building it. What is the right configuration to do this?
My small understanding of the instructions for building and installing gcc led me to do the following:
cd ~/project/
mkdir objdir
cd objdir
../source-dir/configure --enable-languages=c,c++ --prefix=/home/myusername/project/install-dir
make -j2
make install
I only have those config options because they seemed like the ones closest related to "only building the parts I need" and "not overwriting native gcc", but I could be wrong. After the initial config step I just re-run make -j2 and make install every time I change the code. All these steps do complete without errors, and they produce the ~/project/install-dir/bin/ folder, containing the gcc and g++ which behave as described.
I use ~/project/install-dir/bin/g++ -fgnu-tm -o myprogram myprogram.cpp to compile a transactional program, possibly with other options for programs with threads.
(I am using Xubuntu 16.04.3 (64 bit), within VirtualBox on Windows. The installed /usr/bin/gcc is version 5.4.0. Our source at ~/project/source-dir/ is a modified version of 5.3.0.)
You’re running into build- versus run-time linking differences. When you build with -fgnu-tm, the compiler knows where the library it needs is found, and it tells the linker where to find it; you can see this by adding -v to your g++ command. However when you run the resulting program, the dynamic linker doesn’t know it should look somewhere special for the ITM library, so it uses the default library in /usr/lib/x86_64-linux-gnu.
Things get even more confusing with ITM on Ubuntu because the library is installed system-wide, but the link script is installed in a GCC-private directory. This doesn’t happen with the default GCC build, so your own GCC build doesn’t do this, and you’ll see libitm.so in ~/project/install-dir/lib64.
To fix this at run-time, you need to tell the dynamic linker where to find the right library. You can do this either by setting LD_LIBRARY_PATH (to /home/.../project/install-dir/lib64), or by storing the path in the binary using -Wl,-rpath=/home/.../project/install-dir/lib64 when you build it.
I'm trying to compile CMake using a non-default GCC installed in /usr/local/gcc530, on Solaris 2.11.
I have LD_LIBRARY_PATH=/usr/local/gcc530/lib/sparcv9
Bootstrap proceeds fine, bootstrapped cmake successfully compiles various object files, but when it tries to link the real cmake (and other executables), I get pages of "undefined reference" errors to various standard library functions, because, as running the link command manually with -Wl,-verbose shows, the linker links with /usr/lib/64/libstdc++.so of the system default, much older GCC.
This is because apparently CMake tries to find curses/ncurses libraries (even if I tell it BUILD_CursesDialog:BOOL=OFF), finds them in /usr/lib/64, and adds -L/usr/lib/64 to build/Source/CMakeFiles/cmake.dir/link.txt, which causes the linker to use libstdc++.so from there, and not my actual GCC's own.
I found a workaround: I can get the path to proper libraries from $CC -m64 -print-file-name=libstdc++.so then put it with -L into LDFLAGS when running ./configure, and all works well then.
Is there a less hacky way? It's really weird that I can't tell GCC to prioritize its own libraries.
Also, is there some way to have CMake explain where different parts of a resulting command line came from?
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.)
I am trying to link a C++ module using GCC, essentially like this:
gcc -c hello.c
g++ -c world.cpp
gcc -ohello -lstdc++ hello.o world.o
Note that I use -lstdc++ to link the C++ module in, so that I can use gcc instead of g++. The problem is that I'm getting the error:
undefined reference to `operator new(unsigned long)'
(Assuming that world.cpp contains at least one call to new.)
This error is fixed if I put -lstdc++ at the end of the linker line, like this:
gcc -ohello hello.o world.o -lstdc++
I am aware that this question has been asked many times here, but I have a special requirement. I am not directly calling GCC. I am using a build system for a different programming language (Mercury) which is calling GCC on my behalf, and I can't easily modify the way it calls GCC (though I can specify additional libraries using the LDFLAGS environment variable). So I have two additional requirements:
I cannot use g++ to link (only gcc) -- that is why I am doing the -lstdc++ trick above rather than simply linking with g++).
I don't think that I can control the order of the linker commands -- Mercury will put the .o files on the command-line after any libraries.
I understand the basic reason why the order is important, but what is baffling me is why did this break now? I just updated to Ubuntu 11.10 / GCC 4.6.1. I have been successfully compiling this program for years using precisely the above technique (putting -lstdc++ first). Only now has this error come up. An unrelated program of mine links against OpenGL using -lgl and that too broke when I upgraded and I had to move -lgl to the end of the command-line. I'm probably going to discover that dozens of my programs no longer compile. Why did this change? Is there something wrong with my new system or is that the way it is now? Note that these are ordinary shared libraries, not statically linked.
Is there anything I can do to make GCC go back to the old way, where the order of libraries doesn't matter? Is there any other way I can convince GCC to link libstdc++ properly without moving it after the .o files on the command-line?
If Mercury puts object files after libraries, Mercury is broken. Libraries belong after object files - always. You may sometimes get away with the reverse order, but not reliably. (Static libraries must go after the object files that reference symbols in the static library. Sometimes, a linker will note the symbols defined by a shared library even when none of the symbols are used; sometimes, the linker will only note the shared library symbols if the shared library provides at least one symbol.)