cmd/cgo: cgo fails to find static library when in Go package on linux/amd64 #6454
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The difference here between windows/amd64 and linux/amd64 is that the latter is using the new external linking mode, in which the final link and LDFLAGS happen once per final binary. At that point the link is no longer in any particular package directory, and in particular it is not in the package directory where libwrapper.a sits. You need to use an absolute path to libwrapper.a or else install it somewhere standard and use -lwrapper. Since there is only one link but many packages, we can't support this behavior. Note that you can put your code into a wrapper_linux_amd64.syso file and that will be passed to the final linker command automatically. Status changed to Unfortunate. |
Russ, I previously avoided the syso approach because I need to statically link against several libraries (in my case libfreetype, libpng, libz, and libbz2), if I rename them all to .syso files, they aren't linked in the correct order it seems (because libfreetype depends on libpng, etc). I found I can use GCC's ar tool to extract the .o files and re-link all the .o files into a single .syso file, like so: ld -r *.o -o freetype_windows_amd64.syso I have only tried this on windows/amd64 thus far, and I receive some errors during the final link: __mingw_vfprintf(0): not defined modf(0): not defined floor(0): not defined pow(0): not defined close(0): not defined open(0): not defined __ms_vsnprintf(0): not defined ___chkstk_ms(0): not defined write(0): not defined read(0): not defined Perhaps I should link against the static .a files on windows/amd64, but on linux/amd64 I should use .syso files? (I haven't tried yet to see if the above errors also occur on Linux, but I would guess that they probably don't). I apologize if this is the wrong place for this discussion; but I feel it is related somewhat. |
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What steps will reproduce the problem? If possible, include a link to a program on play.golang.org. 1. Create simple static library in C. libwrapper.a 2. Create Go package 'wrapper': $GOPATH/src/wrapper 3. Tell CGO to statically link against lib: #cgo LDFLAGS: libwrapper.a 4. Create exported Go function to call the export C function in static library. 5. Create Go program 'test' that imports 'wrapper' package, and invokes Go function. $GOPATH/wrapper/test 6. go install wrapper Compiles OK. 7. go install wrapper/test Fails to compile; "libwrapper.a: No such file or directory" Note: attached is zip of sources needed to reproduce What is the expected output? The program should compile / find libwrapper.a inside package directory. I suspect this is a bug because the program compiles on windows/amd64 fine. What do you see instead? go install -x wrapper/test WORK=/tmp/go-build592762736 mkdir -p $WORK/wrapper/test/_obj/ mkdir -p $WORK/wrapper/test/_obj/exe/ cd /home/stephen/Desktop/godev/src/wrapper/test /home/stephen/go/pkg/tool/linux_amd64/6g -o $WORK/wrapper/test/_obj/_go_.6 -p wrapper/test -complete -D _/home/stephen/Desktop/godev/src/wrapper/test -I $WORK -I /home/stephen/Desktop/godev/pkg/linux_amd64 ./test.go /home/stephen/go/pkg/tool/linux_amd64/pack grcP $WORK $WORK/wrapper/test.a $WORK/wrapper/test/_obj/_go_.6 cd . /home/stephen/go/pkg/tool/linux_amd64/6l -o $WORK/wrapper/test/_obj/exe/a.out -L $WORK -L /home/stephen/Desktop/godev/pkg/linux_amd64 $WORK/wrapper/test.a # wrapper/test gcc: error: libwrapper.a: No such file or directory /home/stephen/go/pkg/tool/linux_amd64/6l: running gcc failed: unsuccessful exit status 0x100 Which compiler are you using (5g, 6g, 8g, gccgo)? 6g Which operating system are you using? linux/amd64 Which version are you using? (run 'go version') tip go version devel +bc30dedffb3d Sun Sep 22 22:31:08 2013 -0700 linux/amd64Attachments:
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