help: link against rust std

main.c

#include <stdint.h>

extern void* create_vec();
extern void free_vec(void*);
extern void push_vec(void*, int64_t);
extern void print_vec(void*);

int main() {
  void* vec = create_vec();
  push_vec(vec, 3);
  push_vec(vec, 7);
  push_vec(vec, 7);
  push_vec(vec, 9);
  print_vec(vec);
  free_vec(vec);
  return 0;
}

Makefile

main: main.o vec.o
	# how to link against rust std ?
	# or can we compile rust std into staticlib ?
	gcc -o main main.o vec.o

main.o: main.c
	gcc -o main.o -c main.c

vec.o: vec.rs
	rustc --emit obj --crate-type staticlib -o vec.o vec.rs

clean:
	rm -f main *.o

.PHONY: clean

vec.rs

// NOTE: ignoring panic and not using catch_unwind for simplicity

use std::mem::{drop, forget};

#[no_mangle]
pub unsafe extern "C" fn create_vec() -> *mut Vec<i64> {
  let vec = Box::new(vec![]);
  Box::into_raw(vec)
}

#[no_mangle]
pub unsafe extern "C" fn free_vec(raw_vec: *mut Vec<i64>) {
  let vec = Box::from_raw(raw_vec);
  drop(vec)
}

#[no_mangle]
pub unsafe extern "C" fn push_vec(raw_vec: *mut Vec<i64>, data: i64) {
  let mut vec = Box::from_raw(raw_vec);
  vec.push(data);
  forget(vec)
}

#[no_mangle]
pub unsafe extern "C" fn print_vec(raw_vec: *mut Vec<i64>) {
  let vec = Box::from_raw(raw_vec);
  for v in vec.as_ref() {
    println!("{}", v);
  }
  forget(vec)
}

https://users.rust-lang.org/t/how-to-link-against-rust-std/29741