I'm trying to build some code. Here is the error I'm getting:
main.o: In function `__static_initialization_and_destruction_0':
/home/jmbeck/Downloads/boost_1_48_0/boost/system/error_code.hpp:214: undefined reference to `boost::system::generic_category()'
There is more, but I don't think it's relevant.
Here is the build command:
g++ -I/home/jmbeck/Downloads/boost_1_48_0
-L/home/jmbeck/Downloads/boost_1_48_0/stage/lib
-lm
-lboost_system
-lboost_thread
-lboost_regex
main.cpp
The /home/jmbeck/Downloads/boost_1_48_0/stage/lib directory contains the expected files:
libboost_system.a
libboost_system.so#
libboost_system.so.1.48.0*
libboost_thread.a
libboost_thread.so#
libboost_thread.so.1.48.0*
libboost_regex.a
libboost_regex.so#
libboost_regex.so.1.48.0*
... etc...
I've tried building a quick program that didn't use the pre-compiled libraries, and it compiled just fine. It finds the appropriate headers, but not the libraries.
What am I doing wrong?
Try putting the libraries after main.cpp.
I've experienced some weirdness in the past when GCC ignores libraries because it doesn't think they're used, before reaching my source files.
Often linkers require that libraries be ordered as most dependent to least dependent (I believe MS does not). In this case probably thread or regex depends on system, so you'd need to list the -lsystem after the other boost library that depends on it.
Related
I am trying to cross-compile apache-qpid for an arm system from a debian.
There is undefined reference to __dlopen error, but it seems that it is related to the previous warning:
using 'dlopen' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking ...
Here is the detail:
[ 86%] Linking CXX shared library libqpidcommon.so
CMakeFiles/qpidcommon.dir/qpid/sys/posix/Shlib.cpp.o: In function
`qpid::sys::Shlib::load(char const*)':
/home/mert/qpid-cpp-0.34/src/qpid/sys/posix/Shlib.cpp:32: warning: Using
'dlopen' in statically linked applications requires at runtime the shared
libraries from the glibc version used for linking
/home/mert/IDE/cVEND/00.00.14/bin/../arm-feig-linux-
gnueabi/sysroot/usr/lib/libdl.a(dlopen.o): In function `dlopen':
dlopen.c:(.text+0xc): undefined reference to `__dlopen'
I do not know what is happening exactly and how to solve it.
Here there is a similiar thing, I tried to add -static -ldl -lc C_FLAGS but made no difference.
Any help appreciated.
EDIT :
EDIT :
I am not sure exactly what is solved the problem, but I think that -ldl was looking exactly for libdl.so, but in arm directory, it was libdl-2.19.so, thus, probably it was then looking for and finding in another directory. I have linked libdl.so to libdl-2.19.so and now it is compiling.
The linker needs the options, not the compiler. See LDFLAGS.
https://www.gnu.org/software/make/manual/html_node/Implicit-Variables.html
Extra flags to give to compilers when they are supposed to invoke the
linker, ‘ld’, such as -L. Libraries (-lfoo) should be added to the
LDLIBS variable instead.
If this error occurs during the make step try doing
make LIBS=-ldl
And make sure the library path is present in LDFLAGS
export LDFLAGS=-L<path/to/ldl>
I'm trying to compile a program on Ubuntu 11.10 that uses the Boost libraries. I have the 1.46-dev Boost libraries from the Ubuntu Repository installed, but I get an error when compiling the program.
undefined reference to boost::system::system_category()
What is it that I do wrong?
The boost library you are using depends on the boost_system library. (Not all of them do.)
Assuming you use gcc, try adding -lboost_system to your compiler command line in order to link against that library.
Linking with a library that defines the missing symbol (-lboost_system) is the obvious solution, but in the particular case of Boost.System, a misfeature in the original design makes it use boost::system::generic_category() and boost::system::system_category() needlessly. Compiling with the flag -DBOOST_SYSTEM_NO_DEPRECATED disables that code and lets a number of programs compile without requiring -lboost_system (that link is of course still needed if you explicitly use some of the library's features).
Starting from Boost 1.66 and this commit, this behavior is now the default, so hopefully fewer and fewer users should need this answer.
As noticed by #AndrewMarshall, an alternative is to define BOOST_ERROR_CODE_HEADER_ONLY which enables a header-only version of the code. This was discouraged by Boost as it can break some functionality. However, since 1.69, header-only seems to have become the default, supposedly making this question obsolete.
Another workaround for those who don't need the entire shebang: use the switch
-DBOOST_ERROR_CODE_HEADER_ONLY.
If you use CMake, it's add_definitions(-DBOOST_ERROR_CODE_HEADER_ONLY).
The above error is a linker error... the linker a program that takes one or more objects generated by a compiler and combines them into a single executable program.
You must add -lboost_system to you linker flags which indicates to the linker that it must look for symbols like boost::system::system_category() in the library libboost_system.so.
If you have main.cpp, either:
g++ main.cpp -o main -lboost_system
OR
g++ -c -o main.o main.cpp
g++ main.o -lboost_system
When using CMAKE and find_package, make sure it is :
find_package(Boost COMPONENTS system ...)
and not
find_package(boost COMPONENTS system ...)
Some people may have lost hours for that ...
I got the same Problem:
g++ -mconsole -Wl,--export-all-symbols -LC:/Programme/CPP-Entwicklung/MinGW-4.5.2/lib -LD:/bfs_ENTW_deb/lib -static-libgcc -static-libstdc++ -LC:/Programme/CPP-Entwicklung/boost_1_47_0/stage/lib \
D:/bfs_ENTW_deb/obj/test/main_filesystem.obj \
-o D:/bfs_ENTW_deb/bin/filesystem.exe -lboost_system-mgw45-mt-1_47 -lboost_filesystem-mgw45-mt-1_47
D:/bfs_ENTW_deb/obj/test/main_filesystem.obj:main_filesystem.cpp:(.text+0x54):
undefined reference to `boost::system::generic_category()
Solution was to use the debug-version of the system-lib:
g++ -mconsole -Wl,--export-all-symbols -LC:/Programme/CPP-Entwicklung/MinGW-4.5.2/lib -LD:/bfs_ENTW_deb/lib -static-libgcc -static-libstdc++ -LC:/Programme/CPP-Entwicklung/boost_1_47_0/stage/lib \
D:/bfs_ENTW_deb/obj/test/main_filesystem.obj \
-o D:/bfs_ENTW_deb/bin/filesystem.exe -lboost_system-mgw45-mt-d-1_47 -lboost_filesystem-mgw45-mt-1_47
But why?
When I had this, problem, the cause was the ordering of the libraries. To fix it, I put libboost_system last:
g++ mingw/timer1.o -o mingw/timer1.exe -L/usr/local/boost_1_61_0/stage/lib \
-lboost_timer-mgw53-mt-1_61 \
-lboost_chrono-mgw53-mt-1_61 \
-lboost_system-mgw53-mt-1_61
This was on mingw with gcc 5.3 and boost 1.61.0 with a simple timer example.
in my case, adding -lboost_system was not enough, it still could not find it in my custom build environment. I had to use the advice at Get rid of "gcc - /usr/bin/ld: warning lib not found" and change my ./configure command to:
./configure CXXFLAGS="-I$HOME/include" LDFLAGS="-L$HOME/lib -Wl,-rpath-link,$HOME/lib" --with-boost-libdir=$HOME/lib --prefix=$HOME
for more details see Boost 1.51 : "error: could not link against boost_thread !"
...and in case you wanted to link your main statically, in your Jamfile add the following to requirements:
<link>static
<library>/boost/system//boost_system
and perhaps also:
<linkflags>-static-libgcc
<linkflags>-static-libstdc++
I have two simple files:
runner.cpp:
#define BOOST_TEST_DYN_LINK
#define BOOST_TEST_MODULE Main
#include <boost/test/unit_test.hpp>
and test1.cpp:
#define BOOST_TEST_DYN_LINK
#ifdef STAND_ALONE
# define BOOST_TEST_MODULE Main
#endif
#include <boost/test/unit_test.hpp>
BOOST_AUTO_TEST_SUITE( Foo)
BOOST_AUTO_TEST_CASE( TestSomething )
{
BOOST_CHECK( true );
}
BOOST_AUTO_TEST_SUITE_END()
To compile, I'm using:
$ g++ -I/e/code/boost_1_52_0 -o runner -lboost_unit_test_framework runner.cpp test1.cpp
I get the following error:
C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\ccU0cDSz.o:runner.cpp:(.text+0x8c): multiple definition of `main'
c:/pdev/mingw/bin/../lib/gcc/i686-pc-mingw32/4.7.2/../../../libboost_unit_test_framework.a(unit_test_main.o):unit_test_main.cpp:(.text.startup+0x0): first defined here
c:/pdev/mingw/bin/../lib/gcc/i686-pc-mingw32/4.7.2/../../../libboost_unit_test_framework.a(unit_test_main.o):unit_test_main.cpp:(.text.startup+0x14): undefined reference to `init_unit_test_suite(int, char**)'
C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\ccU0cDSz.o:runner.cpp:(.text+0x52): undefined reference to `_imp___ZN5boost9unit_test9framework17master_test_suiteEv'
C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\ccU0cDSz.o:runner.cpp:(.text+0xb0): undefined reference to `_imp___ZN5boost9unit_test14unit_test_mainEPFbvEiPPc'
C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\ccU0cDSz.o:runner.cpp:(.text$_ZN5boost9unit_test13test_observerD2Ev[__ZN5boost9unit_test13test_observerD2Ev]+0xe): undefined reference to `_imp___ZTVN5boost9unit_test13test_observerE'
C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\ccU0cDSz.o:runner.cpp:(.text$_ZN5boost9unit_test13test_observerC2Ev[__ZN5boost9unit_test13test_observerC2Ev]+0xe): undefined reference to `_imp___ZTVN5boost9unit_test13test_observerE'
C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\ccU0cDSz.o:runner.cpp:(.text$_ZN5boost9unit_test15unit_test_log_tC1Ev[__ZN5boost9unit_test15unit_test_log_tC1Ev]+0x22): undefined reference to `_imp___ZTVN5boost9unit_test15unit_test_log_tE'
C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\cciSdkmB.o:test1.cpp:(.text+0x88): undefined reference to `_imp___ZN5boost9unit_test15unit_test_log_t14set_checkpointENS0_13basic_cstringIKcEEjS4_'
C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\cciSdkmB.o:test1.cpp:(.text+0x136): undefined reference to `_imp___ZN5boost10test_tools9tt_detail10check_implERKNS0_16predicate_resultERKNS_9unit_test12lazy_ostreamENS5_13basic_cstringIKcEEjNS1_10tool_levelENS1_10check_typeEjz'
C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\cciSdkmB.o:test1.cpp:(.text+0x21d): undefined reference to `_imp___ZN5boost9unit_test9ut_detail24auto_test_unit_registrarC1ENS0_13basic_cstringIKcEE'
C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\cciSdkmB.o:test1.cpp:(.text+0x284): undefined reference to `_imp___ZN5boost9unit_test9ut_detail24auto_test_unit_registrarC1EPNS0_9test_caseEm'
C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\cciSdkmB.o:test1.cpp:(.text+0x2a4): undefined reference to `_imp___ZN5boost9unit_test9ut_detail24auto_test_unit_registrarC1Ei'
C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\cciSdkmB.o:test1.cpp:(.text$_ZN5boost9unit_test14make_test_caseERKNS0_9callback0INS0_9ut_detail6unusedEEENS0_13basic_cstringIKcEE[__ZN5boost9unit_test14make_test_caseERKNS0_9callback0INS0_9ut_detail6unusedEEENS0_13basic_cstringIKcEE]+0x1d): undefined reference to `_imp___ZN5boost9unit_test9ut_detail24normalize_test_case_nameENS0_13basic_cstringIKcEE'
C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\cciSdkmB.o:test1.cpp:(.text$_ZN5boost9unit_test14make_test_caseERKNS0_9callback0INS0_9ut_detail6unusedEEENS0_13basic_cstringIKcEE[__ZN5boost9unit_test14make_test_caseERKNS0_9callback0INS0_9ut_detail6unusedEEENS0_13basic_cstringIKcEE]+0x5b): undefined reference to `_imp___ZN5boost9unit_test9test_caseC1ENS0_13basic_cstringIKcEERKNS0_9callback0INS0_9ut_detail6unusedEEE'
collect2.exe: error: ld returned 1 exit status
I'm using g++ 4.7.2 on MinGW, with boost 1.52.0.
I get the same errors when only trying to compile test1.cpp - except the "multiple main definition" one.
I perused the official documentation for quite a while, but its scarce on details regarding linking options. When I compiled the boost libs, besides unit_test_framework, I also got prg_exec_monitor and test_exec_monitor; perhaps I should link these somehow ? I tried many combinations, but all resulted in some kind of undefined reference linker error.
Complete list of boost generated libraries - I have them all in the project root:
libboost_prg_exec_monitor-mgw47-mt-1_52.a
libboost_prg_exec_monitor-mgw47-mt-1_52.dll
libboost_prg_exec_monitor-mgw47-mt-1_52.dll.a
libboost_prg_exec_monitor-mgw47-mt-d-1_52.a
libboost_prg_exec_monitor-mgw47-mt-d-1_52.dll
libboost_prg_exec_monitor-mgw47-mt-d-1_52.dll.a
libboost_test_exec_monitor-mgw47-mt-1_52.a
libboost_test_exec_monitor-mgw47-mt-d-1_52.a
libboost_unit_test_framework-mgw47-mt-1_52.a
libboost_unit_test_framework-mgw47-mt-1_52.dll
libboost_unit_test_framework-mgw47-mt-1_52.dll.a
libboost_unit_test_framework-mgw47-mt-d-1_52.a
libboost_unit_test_framework-mgw47-mt-d-1_52.dll
libboost_unit_test_framework-mgw47-mt-d-1_52.dll.a
With help from #llonesmiz, a number of issues were identified.
1. Libraries need to be specified after objects and sources which use them.
As described here:
The traditional behavior of linkers is to search for external functions from
left to right in the libraries specified on the command line. This means that a
library containing the definition of a function should appear after any source
files or object files which use it. This includes libraries specified with the
short-cut -l option, as shown in the following command:
$ gcc -Wall calc.c -lm -o calc (correct order)
With some linkers the opposite ordering (placing the -lm option before the file
which uses it) would result in an error,
$ cc -Wall -lm calc.c -o calc (incorrect order)
main.o: In function 'main':
main.o(.text+0xf): undefined reference to 'sqrt'
because there is no library or object file containing sqrt after ‘calc.c’. The
option -lm should appear after the file ‘calc.c’
2. Library paths should be explicitly specified.
If no lib paths are specified, the linker might look for the libs in a series
of default folders, thus loading a different library then intended. This is what
happened in my case - I wanted to link boost_unit_test_framework, but did not
specify a path because I assumed the linker would look in the current folder.
That's what happens at runtime, after all - if the dll is in the same folder
with the exe, it will find it.
I found it a little bit strange the linker would find the lib, since it was
named ibboost_unit_test_framework-mgw47-mt-1_52.dll. When I tried to link to
a non-existing lib, the linker complained though, so I assumed this isn't an
issue, and MinGW 's linker ignores those suffixes.
After some more research, I found this article about MinGW library paths.
The folders MinGW searches for libs can be found in the output of gcc -print-search-dirs.
The article also contains some bash magic to make sense of that output:
gcc -print-search-dirs | sed '/^lib/b 1;d;:1;s,/[^/.][^/]*/\.\./,/,;t 1;s,:[^=]*=,:;,;s,;,; ,g' | tr \; \\012 | grep -v '^ */'
This will print a nice list of those folders. gcc will not, by default,
look in the current directory for libs. I looked in each of them, and found the
lib that was being loaded - libboost_unit_test_framework.a, a static lib.
This brings into light another issue worth mentioning:
3. Static versus dynamic linking
I did not specify whether I want boost_unit_test_framework linked statically or dynamically.
In this case, gcc prefers dynamic linking:
Because of these advantages gcc compiles programs to use shared libraries by
default on most systems, if they are available. Whenever a static library
‘libNAME.a’ would be used for linking with the option -lNAME the compiler
first checks for an alternative shared library with the same name and a ‘.so’
extension.
(so is the extension for dynamic libraries on Unix - on Windows, the equivalent is dll.)
So, what happened is that gcc looked for libboost_unit_test_framework.dll
in all it's default folders, but couldn't find it. Then it looked for
libboost_unit_test_framework.a, and statically linked that. This resulted in
linking errors because the sources have #define BOOST_TEST_DYN_LINK, and
therefore expect to have the lib dynamically linked.
To enforce static or dynamic linking, the -Wl,-Bstatic and -Wl,-Bdynamic
linker options come into play, described here.
If I tell the linker that I want dynamic linking:
$ g++ -I/e/code/boost_1_52_0 runner.cpp test1.cpp -o runner -Wl,Bdynamic -lboost_unit_test_framework
This will fail, because the linker will not be able to find the dll.
4.Summary
The issues were:
libraries where specified before the sources which used them
the lib path wasn't specified
the type of linking wasn't specified
the name of the library was not correct
Final, working command:
$ g++ -I/e/code/boost_1_52_0 -o runner runner.cpp test1.cpp -L. -Wl,-Bdynamic -lboost_unit_test_framework-mgw47-mt-1_52
I'm trying to compile a program on Ubuntu 11.10 that uses the Boost libraries. I have the 1.46-dev Boost libraries from the Ubuntu Repository installed, but I get an error when compiling the program.
undefined reference to boost::system::system_category()
What is it that I do wrong?
The boost library you are using depends on the boost_system library. (Not all of them do.)
Assuming you use gcc, try adding -lboost_system to your compiler command line in order to link against that library.
Linking with a library that defines the missing symbol (-lboost_system) is the obvious solution, but in the particular case of Boost.System, a misfeature in the original design makes it use boost::system::generic_category() and boost::system::system_category() needlessly. Compiling with the flag -DBOOST_SYSTEM_NO_DEPRECATED disables that code and lets a number of programs compile without requiring -lboost_system (that link is of course still needed if you explicitly use some of the library's features).
Starting from Boost 1.66 and this commit, this behavior is now the default, so hopefully fewer and fewer users should need this answer.
As noticed by #AndrewMarshall, an alternative is to define BOOST_ERROR_CODE_HEADER_ONLY which enables a header-only version of the code. This was discouraged by Boost as it can break some functionality. However, since 1.69, header-only seems to have become the default, supposedly making this question obsolete.
Another workaround for those who don't need the entire shebang: use the switch
-DBOOST_ERROR_CODE_HEADER_ONLY.
If you use CMake, it's add_definitions(-DBOOST_ERROR_CODE_HEADER_ONLY).
The above error is a linker error... the linker a program that takes one or more objects generated by a compiler and combines them into a single executable program.
You must add -lboost_system to you linker flags which indicates to the linker that it must look for symbols like boost::system::system_category() in the library libboost_system.so.
If you have main.cpp, either:
g++ main.cpp -o main -lboost_system
OR
g++ -c -o main.o main.cpp
g++ main.o -lboost_system
When using CMAKE and find_package, make sure it is :
find_package(Boost COMPONENTS system ...)
and not
find_package(boost COMPONENTS system ...)
Some people may have lost hours for that ...
I got the same Problem:
g++ -mconsole -Wl,--export-all-symbols -LC:/Programme/CPP-Entwicklung/MinGW-4.5.2/lib -LD:/bfs_ENTW_deb/lib -static-libgcc -static-libstdc++ -LC:/Programme/CPP-Entwicklung/boost_1_47_0/stage/lib \
D:/bfs_ENTW_deb/obj/test/main_filesystem.obj \
-o D:/bfs_ENTW_deb/bin/filesystem.exe -lboost_system-mgw45-mt-1_47 -lboost_filesystem-mgw45-mt-1_47
D:/bfs_ENTW_deb/obj/test/main_filesystem.obj:main_filesystem.cpp:(.text+0x54):
undefined reference to `boost::system::generic_category()
Solution was to use the debug-version of the system-lib:
g++ -mconsole -Wl,--export-all-symbols -LC:/Programme/CPP-Entwicklung/MinGW-4.5.2/lib -LD:/bfs_ENTW_deb/lib -static-libgcc -static-libstdc++ -LC:/Programme/CPP-Entwicklung/boost_1_47_0/stage/lib \
D:/bfs_ENTW_deb/obj/test/main_filesystem.obj \
-o D:/bfs_ENTW_deb/bin/filesystem.exe -lboost_system-mgw45-mt-d-1_47 -lboost_filesystem-mgw45-mt-1_47
But why?
When I had this, problem, the cause was the ordering of the libraries. To fix it, I put libboost_system last:
g++ mingw/timer1.o -o mingw/timer1.exe -L/usr/local/boost_1_61_0/stage/lib \
-lboost_timer-mgw53-mt-1_61 \
-lboost_chrono-mgw53-mt-1_61 \
-lboost_system-mgw53-mt-1_61
This was on mingw with gcc 5.3 and boost 1.61.0 with a simple timer example.
in my case, adding -lboost_system was not enough, it still could not find it in my custom build environment. I had to use the advice at Get rid of "gcc - /usr/bin/ld: warning lib not found" and change my ./configure command to:
./configure CXXFLAGS="-I$HOME/include" LDFLAGS="-L$HOME/lib -Wl,-rpath-link,$HOME/lib" --with-boost-libdir=$HOME/lib --prefix=$HOME
for more details see Boost 1.51 : "error: could not link against boost_thread !"
...and in case you wanted to link your main statically, in your Jamfile add the following to requirements:
<link>static
<library>/boost/system//boost_system
and perhaps also:
<linkflags>-static-libgcc
<linkflags>-static-libstdc++
I have this assignment due that requires the usage of FLTK. The code is given to us and it should compile straight off of the bat, but I am having linking errors and do not know which other libraries I need to include.
I currently have "opengl32", "fltk_gl", "glu32", and "fltk" included (-l), each of which seem to reduce the number of errors. I compiled FLTK using make with no specified options. Including all of the produced library files doesn't fix the problem, and I'm convinced that it's just some Windows specific problem.
Compile log:
**** Build of configuration Debug for project CG5 ****
make all
Building target: CG5.exe
Invoking: Cygwin C++ Linker
g++ -o"CG5.exe" ./src/draw_routines.o ./src/gl_window.o ./src/my_shapes.o ./src/shape.o ./src/shapes_ui.o ./src/tesselation.o -lopengl32 -lfltk_z -lfltk_gl -lglu32 -lfltk
/usr/lib/gcc/i686-pc-cygwin/3.4.4/../../../libfltk_gl.a(Fl_Gl_Window.o):Fl_Gl_Window.cxx:(.text+0x197): undefined reference to `_SelectPalette#12'
/usr/lib/gcc/i686-pc-cygwin/3.4.4/../../../libfltk_gl.a(Fl_Gl_Window.o):Fl_Gl_Window.cxx:(.text+0x1a7): undefined reference to `_RealizePalette#4'
/usr/lib/gcc/i686-pc-cygwin/3.4.4/../../../libfltk_gl.a(Fl_Gl_Window.o):Fl_Gl_Window.cxx:(.text+0x1fe): undefined reference to `_glDrawBuffer#4'
/usr/lib/gcc/i686-pc-cygwin/3.4.4/../../../libfltk_gl.a(Fl_Gl_Window.o):Fl_Gl_Window.cxx:(.text+0x20d): undefined reference to `_glReadBuffer#4'
/usr/lib/gcc/i686-pc-cygwin/3.4.4/../../../libfltk_gl.a(Fl_Gl_Window.o):Fl_Gl_Window.cxx:(.text+0x23a): undefined reference to `_glGetIntegerv#8'
/usr/lib/gcc/i686-pc-cygwin/3.4.4/../../../libfltk_gl.a(Fl_Gl_Window.o):Fl_Gl_Window.cxx:(.text+0x2c3): undefined reference to `_glOrtho#48'
/usr/lib/gcc/i686-pc-cygwin/3.4.4/../../../libfltk_gl.a(Fl_Gl_Window.o):Fl_Gl_Window.cxx:(.text+0x2f3): undefined reference to `_SwapBuffers#4'
...and lots more
Thanks a ton for the help.
EDIT: These first few lines are obviously OpenGL related, although I'm still not sure what additional libraries need to be included.
Just a guess: your makefile was written for Linux, and on Cygwin some libraries are either missing or in a different place. You're going to have to examine the makefile, locate the missing libraries, and either move the libs to where the makefile expects them or change the makefile to look in the right place.
The libraries it needs are listed on the line starting g++ (prepend 'lib' to the names after the -l flags)
Sorry for the lack of closure, but I just booted into my Linux netbook and got it working.
-lfltk -lfltk_gl -lGLU -lGL -lXext -lX11 -lm