ah okay, I had problems with the ".a" suffix myself, so I though it was 
worth a shot.

I just know that this
>//#cgo LDFLAGS: $GOPATH/src/kflow/libcolor/lib/libCOLOR 

won't work, as the env variables won't be resolved by go afaik.

maybe test it with an absolute path instead

and/or use "go build -n" to see how go would invoke "link"

and maybe you need to link against "libboost_system" and "libxml2" as well, 
if "libCOLOR" really depends on it.


Am Mittwoch, 1. März 2017 20:04:50 UTC+1 schrieb Chun Zhang:
>
> Yes, I tried quite a few varieties, such as:
> //#cgo LDFLAGS: $GOPATH/src/kflow/libcolor/lib/libCOLOR with/without .a
> //#cgo LDFLAGS: ${SRCDIR}kflow/libcolor/lib/libCOLOR with/without .a
> //#cgo LDFLAGS: -L${SRCDIR}kflow/libcolor/lib -l:libCOLOR with/without .a
> //#cgo LDFLAGS: -L${SRCDIR}kflow/libcolor/lib -lCOLOR with/without .a
>
> None above works for me so far, they are simply ignored during the 
> building process. I even played with the empty spaces at various places, 
> still no luck :(
>
> Thanks,
> Chun
>
>
> On Wednesday, March 1, 2017 at 1:57:15 PM UTC-5, therecipe wrote:
>>
>> did you try it without the ".a" suffix in the LDFLAGS?
>>
>> Am Dienstag, 28. Februar 2017 20:06:20 UTC+1 schrieb Chun Zhang:
>>>
>>> Hi, All, 
>>>
>>> I have googled quite a bit about this issue, there are some tutorials 
>>> online. But most of them targeted either at older go releases or C instead 
>>> of C++. 
>>>
>>> Can somebody please help me to figure out how to solve the following 
>>> issues?
>>>
>>> I have to use a static library, wrote in C++ in a go project. I have the 
>>> libcolor.a and the COLOR.h header file, the libcolor.a relies on some other 
>>> libraries, such as libboost_system.a, libxml2.a etc to build. 
>>>
>>> I wrote a libcolor.swigcxx file as follows:
>>> ---------------------------
>>> %module libcoror
>>>
>>> %{
>>> #include "include/COLOR.h"
>>> #include <stddef.h>
>>> #include <vector>
>>>
>>> /* This is where we initialize any global parameters that are not 
>>> search-thread specific */
>>> extern void COLOR_init_global_config(int argc, char *argv[]);  // from 
>>> the COLOR.h file, which is one of the APIs I would like to use
>>>
>>> %}
>>>
>>> #include "include/COLOR.h"
>>> extern void COLOR_init_global_config(int argc, char *argv[]);
>>> ---------------------------
>>>
>>> An empty libcolor.go file with the following lines was manually created
>>>
>>> ---------------------------
>>> package libcolor
>>>
>>> // #cgo CFLAGS: -I .
>>> // #cgo CXXFLAGS: -std=c++11 <--- this does not seem to work
>>> // #cgo LDFLAGS: -L${SRCDIR}/lib/ -lCOLOR.a -lz <--- this is placed at 
>>> the correct place
>>> ---------------------------
>>>
>>> When I tried to build this using "go build -x" CLI, I hit the following 
>>> error:
>>>
>>> WORK=/tmp/go-build797493895
>>> mkdir -p $WORK/klow/libcolor/_obj/
>>> mkdir -p $WORK/klow/
>>> swig -version
>>> cd $WORK
>>> /usr/local/go/pkg/tool/linux_amd64/compile -o 
>>> ./klow/libcolor/_obj/_go_.o -trimpath . -p main -complete -buildid 
>>> 73a7f9534f74346db4b3e0f48875da9dbf8bc2fd -D _$WORK ./swig_intsize.go
>>> cd /home/chzhang/go/src/klow/libcolor
>>> swig -go -cgo -intgosize 64 -module libcolor -o 
>>> $WORK/klow/libcolor/_obj/libcolor_wrap.cxx -outdir 
>>> $WORK/klow/libcolor/_obj/ -c++ libcolor.swigcxx
>>> CGO_LDFLAGS="-g" "-O2" /usr/local/go/pkg/tool/linux_amd64/cgo -objdir 
>>> $WORK/klow/libcolor/_obj/ -importpath klow/libcolor -- -I 
>>> $WORK/klow/libcolor/_obj/ $WORK/klow/libcolor/_obj/libcolor.go
>>> cd $WORK
>>> gcc -fdebug-prefix-map=a=b -c trivial.c
>>> gcc -gno-record-gcc-switches -c trivial.c
>>> cd /home/chzhang/go/src/klow/libcolor
>>> gcc -I . -fPIC -m64 -pthread -fmessage-length=0 
>>> -fdebug-prefix-map=$WORK=/tmp/go-build -gno-record-gcc-switches -I 
>>> $WORK/klow/libcolor/_obj/ -g -O2 -o $WORK/klow/libcolor/_obj/_cgo_main.o -c 
>>> $WORK/klow/libcolor/_obj/_cgo_main.c
>>> gcc -I . -fPIC -m64 -pthread -fmessage-length=0 
>>> -fdebug-prefix-map=$WORK=/tmp/go-build -gno-record-gcc-switches -I 
>>> $WORK/klow/libcolor/_obj/ -g -O2 -o $WORK/klow/libcolor/_obj/_cgo_export.o 
>>> -c $WORK/klow/libcolor/_obj/_cgo_export.c
>>> gcc -I . -fPIC -m64 -pthread -fmessage-length=0 
>>> -fdebug-prefix-map=$WORK=/tmp/go-build -gno-record-gcc-switches -I 
>>> $WORK/klow/libcolor/_obj/ -g -O2 -o 
>>> $WORK/klow/libcolor/_obj/_tmp_go-build797493895_klow_libcolor__obj_libcolor.cgo2.o
>>>  
>>> -c 
>>> $WORK/klow/libcolor/_obj/_tmp_go-build797493895_klow_libcolor__obj_libcolor.cgo2.c
>>> g++ -I . -fPIC -m64 -pthread -fmessage-length=0 
>>> -fdebug-prefix-map=$WORK=/tmp/go-build -gno-record-gcc-switches -I 
>>> $WORK/klow/libcolor/_obj/ -g -O2 -o 
>>> $WORK/klow/libcolor/_obj/_tmp_go-build797493895_klow_libcolor__obj_libcolor_wrap.cxx.o
>>>  
>>> -c $WORK/klow/libcolor/_obj/libcolor_wrap.cxx
>>> # klow/libcolor
>>> In file included from $WORK/klow/libcolor/_obj/libcolor_wrap.cxx:243:0:
>>> ./include/COLOR.h:13:43: warning: defaulted and deleted functions only 
>>> available with -std=c++11 or -std=gnu++11
>>>    PerSessionData(const PerSessionData &d)=default;
>>>                                            ^
>>> ./include/COLOR.h:14:53: warning: defaulted and deleted functions only 
>>> available with -std=c++11 or -std=gnu++11
>>>    PerSessionData& operator=(const PerSessionData&d)=default;
>>>                                                      ^
>>> g++ -I . -fPIC -m64 -pthread -fmessage-length=0 
>>> -fdebug-prefix-map=$WORK=/tmp/go-build -gno-record-gcc-switches -o 
>>> $WORK/klow/libcolor/_obj/_cgo_.o $WORK/klow/libcolor/_obj/_cgo_main.o 
>>> $WORK/klow/libcolor/_obj/_cgo_export.o 
>>> $WORK/klow/libcolor/_obj/_tmp_go-build797493895_klow_libcolor__obj_libcolor.cgo2.o
>>>  
>>> $WORK/klow/libcolor/_obj/_tmp_go-build797493895_klow_libcolor__obj_libcolor_wrap.cxx.o
>>>  
>>> -g -O2
>>> # klow/libcolor
>>> /tmp/go-build797493895/klow/libcolor/_obj/_tmp_go-build797493895_klow_libcolor__obj_libcolor_wrap.cxx.o:
>>>  
>>> In function `_wrap_COLOR_init_global_config_libcolor_3cea422eb6211fe0':
>>> /tmp/go-build/klow/libcolor/_obj/libcolor_wrap.cxx:285: undefined 
>>> reference to `COLOR_init_global_config(int, char**)'
>>> collect2: error: ld returned 1 exit status
>>>
>>>
>>> Looks like there are two errors:
>>> 1, the C++11 warning
>>> 2, the linker can't find the function COLOR_init_global_config in the 
>>> static library. That means the compiler directives I defined in libcolor.go 
>>> was not successfully passed to the compiler. From the log, looks like 
>>> another libcolor.go was generated in the $WORK directory by swig. The one I 
>>> manually created was not used at all. 
>>>
>>> Can somebody please help me to figure out what I need to do to get this 
>>> compiled? The tutorial on swig.org does not seem to help. I tried to 
>>> manually build as in 
>>>
>>> http://zacg.github.io/blog/2013/06/06/calling-c-plus-plus-code-from-go-with-swig/
>>> But the 6c etc go tools does not exist anymore. 
>>>
>>>
>>> Thanks,
>>> Chun
>>>
>>> --------------------------------
>>>
>>> This is my setup
>>> go version go1.7.1 linux/amd64
>>> GOARCH="amd64"
>>> GOBIN=""
>>> GOEXE=""
>>> GOHOSTARCH="amd64"
>>> GOHOSTOS="linux"
>>> GOOS="linux"
>>> GOPATH="/home/chzhang/go"
>>> GORACE=""
>>> GOROOT="/usr/local/go"
>>> GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
>>> CC="gcc"
>>> GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 
>>> -fdebug-prefix-map=/tmp/go-build155119108=/tmp/go-build 
>>> -gno-record-gcc-switches"
>>> CXX="g++"
>>> CGO_ENABLED="1"
>>>
>>>
>>>

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