Embedding sqlite.c into Go code: ld complains about libdl while it should not

I'm absolutely new to CGo. I don't want to use mattn's go-sqlite package and would like to build my own minimal interface to SQLite.

I'm trying to get compiled the simplest program on my linux machine with go build, and it always returns the same error:

/usr/bin/ld: $WORK/b001/_x003.o: in function `unixDlError':
./sqlite3.c:42036: undefined reference to `dlerror'
/usr/bin/ld: $WORK/b001/_x003.o: in function `unixDlClose':
./sqlite3.c:42067: undefined reference to `dlclose'
/usr/bin/ld: $WORK/b001/_x003.o: in function `unixDlSym':
./sqlite3.c:42063: undefined reference to `dlsym'
/usr/bin/ld: $WORK/b001/_x003.o: in function `unixDlOpen':
./sqlite3.c:42022: undefined reference to `dlopen'
collect2: error: ld returned 1 exit status

The project layout is:

• go.mod
• main.go
• sqlite3.c
• sqlite3.h

The contents if main.go is:

//go:build cgo
// +build cgo

package main

/*
#cgo CFLAGS: -DSQLITE_OMIT_LOAD_EXTENSION
#cgo CFLAGS: -DSQLITE_THREADSAFE=1
#include "sqlite.h"
*/

import "C"

func main() {
}

I'm using Go 1.18.1.

Any help or nudge in the right direction is greatly appreciated!

To embed some C code inside a Go file, you write the C statements as something called preambles. There are certain strict rules regarding the formatting:

• import "C" is a standalone statement, and cannot be included in an import () group
• The C includes and other code (preambles) immediately precede the import "C" statement, without any blank lines in between

So in your case, what you need is something like:

package main

// #include "sqlite.h"
import "C"

import (
    "fmt"
    // normal imports here
)

As you have since verified: preambles can be multi-line comments, so use whichever you prefer. The main thing is that there is no blank lines between them and the import "C" statement.