Statically linking Nim code to Go

Question

I'm trying in Linux to statically link some code created in Nim into a Go application. I've followed the Nim Backend Integration docs and some articles for linking C in Go but haven't gotten it working.

Here's where I'm at so far...

---

Nim code target.nim:

proc testnim* {.exportc.} =
  echo "In Nim!"

I compile it with:

nim c --app:staticLib --noMain --header target.nim

---

Go code app.go:

package main

/*
#cgo CFLAGS: -I/my/path/to/target/nimcache
#cgo CFLAGS: -I/my/path/to/Nim/lib
#cgo LDFLAGS: /my/path/to/target/libtarget.a
#include "/my/path/to/target/nimcache/target.h"
*/
import "C"
import "fmt"

func main() {
  fmt.Println("In Go!")
  C.NimMain()
  C.testnim()
}

---

I tried building it both of these:

go build

go build --ldflags '-extldflags "-static"' app.go

Here's what I get:

# command-line-arguments
/my/path/to/target/libtarget.a(stdlib_system.o): In function `nimUnloadLibrary':
stdlib_system.c:(.text+0xe6f0): undefined reference to `dlclose'
/my/path/to/target/libtarget.a(stdlib_system.o): In function `nimLoadLibrary':
stdlib_system.c:(.text+0xe71b): undefined reference to `dlopen'
/my/path/to/target/libtarget.a(stdlib_system.o): In function `nimGetProcAddr':
stdlib_system.c:(.text+0xe750): undefined reference to `dlsym'
collect2: error: ld returned 1 exit status

---

So I'm missing something(s). I'm using Go 1.5 and Nim 0.11.3 (devel branch). Any advice or hints would be much appreciated.

Answer 1

You're missing the libdl library. Add -ldl to your LDFLAGS