How do you statically link a c library in go using cgo?

Question

So there\'s a bunch of stuff on the group that suggests you can do this in go (although not on the cgo documentation):

package bridge

import \"fmt\"

// #cg         


        

Answer 1

You just have to link with -Ldirectory -lgb.

$ cat >toto.c
int x( int y ) { return y+1; }
$ cat >toto.h
int x(int);
$ gcc -O2 -c toto.c
$ ar q libgb.a toto.o
$ cat >test.go
package main

import "fmt"

// #cgo CFLAGS: -I.
// #cgo LDFLAGS: -L. -lgb 
// #include <toto.h>
import "C"

func main() {
  fmt.Printf("Invoking c library...\n")
  fmt.Println("Done ", C.x(10) )
}
$ go build test.go
$ ./test
Invoking c library...
Done  11

Answer 2

A straightforward Makefile to link Go code with a dynamic or static library:

static:
    gcc -c gb.c
    ar -rcs libgb.a gb.o
    go build -ldflags "-linkmode external -extldflags -static" bridge.go

dynamic:
    gcc -shared -o libgb.so gb.c
    go build bridge.go

Directives in bridge.go:

/*
#cgo CFLAGS: -I.
#cgo LDFLAGS: -L. -lgb
#include "gb.h"
*/
import "C"
...

Answer 3

Try:

// #cgo LDFLAGS: -l/Users/doug/projects/c/go-bridge/build/libgb.a

You missed the -l in the LDFLAGS directive.

Answer 4

Turns out my code is 100% fine; it was a copy of Go 1.0; under go 1.1 this works. Under go 1.0, it doesn't.

(it's a bit lame answering my own question, I know; but the 'use -L -l answers below aren't right either; it had nothing to do with that).

A working solution example is up on github here for anyone who find's this question later:

https://github.com/shadowmint/go-static-linking

in short that looks like:

CGO_ENABLED=0 go build -a -installsuffix cgo -ldflags '-s' src/myapp/myapp.go

see also: https://github.com/golang/go/issues/9344