I am trying to compile a sample using gcc under MinGW in windows 7
Why does this work:
$ gcc -m32 -o cube.exe cube.o shader.o matrix.o window.o
/c/dev/mixed/SDKs/Extracted/OpenGLESEmulatorv1.3.0/examples/OpenGLES_20/cube/libEGL.lib
But this doesn't:
$ gcc -m32 -o cube.exe cube.o shader.o matrix.o window.o
-L/c/dev/mixed/SDKs/Extracted/OpenGLESEmulatorv1.3.0/examples/OpenGLES_20/cube
-llibEGL.lib
It fails with:
c:/mingw/bin/../lib/gcc/mingw32/4.7.0/../../../../mingw32/bin/ld.exe: cannot find -llibEGL.lib
collect2.exe: error: ld returned 1 exit status
Shouldn't the -L add the correct search path?
Per the MinGW documentation the -l argument adds lib to the front and .a to the end OR just adds .lib to the end. Removing the .lib from the end allows this to compile.
Related
I have the problem about linking libraries.
"見つかりません" means "Not found"
edit LD_LIBRARY_PATH
$ LD_LIBRARY_PATH="/home/myname/.local/boost/lib" g++ main.cc -lboost_serialization
/home/myname/.linuxbrew/bin/ld: -lboost_serialization が見つかりません
collect2: error: ld returned 1 exit status
edit LIBRARY_PATH
$ LIBRARY_PATH="/home/myname/.local/boost/lib" g++ main.cc -lboost_serialization
/home/myname/.linuxbrew/bin/ld: -lboost_serialization が見つかりません
collect2: error: ld returned 1 exit status
adding the -L option (successfully compiled)
$ g++ main.cc -lboost_serialization -L "/home/myname/.local/boost/lib"
$
Indeed I have successfully compiled my program with the -L option.
But I want to compile without this (like 1 or 2, not 3).
In this case, what do I have to check or modify in my environmental variables?
note: my gcc is 5.3.0 (Homebrew gcc 5.3.0).
I know this is something so simple I'm going to hate myself for having to ask it, but my head is aching from repeated hits on the desktop. I've read dozens of stackoverflow and google results which suggest that the following should work:
$ ls /usr/local/lib/libusb*
/usr/local/lib/libusb-1.0.a /usr/local/lib/libusb-1.0.so /usr/local/lib/libusb-1.0.so.0.1.0
/usr/local/lib/libusb-1.0.la /usr/local/lib/libusb-1.0.so.0
$ gcc -I ~/libusb-1.0.18/libusb -c test.c
$ gcc -L/usr/local/lib -o test test.o -llibusb
/usr/bin/ld: cannot find -llibusb
collect2: error: ld returned 1 exit status
$ gcc -L/usr/local/lib -o test test.o -llibusb-1.0
/usr/bin/ld: cannot find -llibusb-1.0
collect2: error: ld returned 1 exit status
Why is that not correct? One of those should have worked and I've tried many, many more variations.
For completeness I'm running Ubuntu 14.04 (fresh VM installation).
I built libusb from source (~/libusb-1.0.18) with:
./configure --disable-udev
make
sudo make install
The leading lib and trailing .so are automatically filled in by the linker, so you should not specify either on the command line. Your command should be:
gcc -L/usr/local/lib -o test test.o -lusb-1.0
my mingw compiler: http://sourceforge.net/projects/mingwbuilds/files/host-windows/releases/4.7.2/32-bit/threads-posix/sjlj/x32-4.7.2-release-posix-sjlj-rev6.7z
boost: http://sourceforge.net/projects/boost/files/boost/1.52.0/boost_1_52_0.7z
(both on D: drive)
code:
#include <boost\regex.hpp>
int main() {
boost::regex reg("[a-z]+");
}
command line:
SET PATH=%PATH%;D:\mingw\bin;D:\mingw\include
g++ -I "d:\mingw\include" -I "d:\boost" -Os -s -o test.exe test.cpp -std=c++11 -static -L "D:\boost\stage\lib" -lboost_regex
In the d:\boost\stage\lib directory there is libboost_regex-mgw47-mt-1_52.a.
And the process returns :
d:/mingw/bin/../lib/gcc/i686-w64-mingw32/4.7.2/../../../../i686-w64-mingw32/bin/ld.exe: cannot find -lboost_regex
collect2.exe: error: ld returned 1 exit status
If I put the exact name of the *.a file the result is cannot find -llibboost_regex-mgw47-mt-1_52.a
even whole path that is -ld:\boost\stage\lib\libboost_regex-mgw47-mt-1_52.a doesn't work. Whatever I put after the -l has the same effect.
As you can see here you must use either (-l followed by the named of the library removing the lib preffix and the extension .a):
g++ -I "d:\mingw\include" -I "d:\boost" -Os -s -o test.exe test.cpp -std=c++11 -static -L "D:\boost\stage\lib" -lboost_regex-mgw47-mt-1_52
or (full path of the library without using -l):
g++ -I "d:\mingw\include" -I "d:\boost" -Os -s -o test.exe test.cpp -std=c++11 -static D:/boost/stage/lib/libboost_regex-mgw47-mt-1_52.a
PS:One thing I personally do is build boost using --layout=tagged. This makes the name of the libraries a lot more manageable (in this case libboost_regex-mt.a).
Is this syntax incorrect?
C:\Users\Brett\Compilers>gcc -I MinGW\include -l MinGW\lib\libgdi32.a -o hello
world helloworld.c
The directory's are all fine, I mist be including and linking in the wrong order or something?
Here is the output:
c:/users/Brett/compilers/mingw/bin/../lib/gcc/mingw32/4.6.2/../../../../mingw
2/bin/ld.exe: cannot find -lMinGW\lib\libgdi32.a
collect2: ld returned 1 exit status
The syntax for -l switch is the library name without lib prefix and without the extension. If it cannot be found, it's directory should be given with -L option. So I would write:
gcc -I MinGW\include -L MinGW\lib -lgdi32 -o helloworld helloworld.c
Maybe -L is not needed, maybe you also need -mwindows to tell the linker you want windows app. To specify a library file explicitly, give it without any letter option, like this:
gcc -I MinGW\include MinGW\lib\libgdi32.a -o helloworld helloworld.c
Here is the gcc reference: linking options.
I'm trying to compile a program using a third party library, Omnet++ in my case. Apparently "make" does not find a library, but the path it uses is correct as you can see (in the sense that I can see the library under omnet++ source tree)
pv135168:basic Bob$ opp_makemake
Creating Makefile in /Users/Bob/Code/network_sim/basic... Makefile created, running "make depend" to add dependencies... opp_makedep -Y --objdirtree -I. -f Makefile -P\$O/ -- ./*.cc
pv135168:basic Bob$ make
g++ -c -g -Wall
-fno-stack-protector -m32 -DHAVE_PCAP -DXMLPARSER=libxml
-DWITH_PARSIM -DWITH_NETBUILDER -I.
-I/Users/Bob/Code/omnetpp-4.1/include -o out/gcc-debug//txc1.o txc1.cc g++ -m32 -Wl,-rpath,/Users/Bob/Code/omnetpp-4.1/lib -Wl,-rpath,. -o out/gcc-debug//basic out/gcc-debug//txc1.o -Wl,-all_load
-L"/Users/Bob/Code/omnetpp-4.1/lib/gcc"
-L"/Users/Bob/Code/omnetpp-4.1/lib" -u _tkenv_lib -lopptkenvd
-loppenvird -lopplayoutd -u _cmdenv_lib -loppcmdenvd -loppenvird
-loppsimd -lstdc++
ld: library not found for -lopptkenvd
collect2: ld returned 1 exit status make: *** [out/gcc-debug//basic]
Error 1 pv135168:basic Bob$
It's looking in the following directories for a file called libopptkenvd.dylib or libopptkenvd.a:
/Users/Bob/Code/omnetpp-4.1/lib/gcc
/Users/Bob/Code/omnetpp-4.1/lib
Is that file in one of those directories (or in the standard directories like /usr/lib)? I don't see an indication of that in your output.