Implicit declaration of luaL_openlibs

Question

I'm writing a simple test of embedding Lua into a C program.

I have the same issue on Windows/Mingw and Linux. Here is the gcc command I use on Linux:

gcc -Wall -o test_lua lua_test.c -I/usr/include/lua5.1 -llua5.1

On Windows:

gcc -Wall -o test_lua.exe lua_test.c -llua5.1

In both case I have the following warning:

warning: implicit declaration of function 
              'luaL_openlibs' [-Wimplicit-function-declaration]

The program works but maybe I don't use any standard Lua libs in it ? Why do I get this warning ? I see luaL_openLibs definition in lauxlib.h !

Here is the C part:

#include <lua.h>
#include <lauxlib.h>
#include <stdlib.h>
#include <stdio.h>

int main(int argc, char *argv[]) {

  int status;
  lua_State *L;

  L = luaL_newstate();

  // Init lua
  luaL_openlibs(L);

  // Load script
  status = luaL_loadfile(L,"lua_test.lua");
  if (status) {
    fprintf(stderr,"Couldn't load file\n");
    exit(1);
  }

  // Push data
  lua_pushnumber(L, 5000);
  lua_setglobal(L, "clife");
  lua_pushnumber(L, 6000);
  lua_setglobal(L, "ttime");
  lua_pushnumber(L, 3000);
  lua_setglobal(L, "atime");

  // Run script
  int result = lua_pcall(L, 0, LUA_MULTRET, 0);
  if (result) {
    fprintf(stderr,"Failed to run script: %s\n", lua_tostring(L,-1));
    exit(1);
  }

  // Value at top of the stack is the result
  const char *schedule = lua_tostring(L,-1);

  fprintf(stdout,"Computed schedule is: %s\n", schedule);

  // Close lua
  lua_pop(L, 1);
  lua_close(L);

  return 0;

}

Here is the Lua part:

io.write("lua_test.lua -- will generate schedule\n")

io.write("Wizard life is " .. clife .. "\n")

schedule = ""
ctime = ttime - atime
if clife > 4500 then
   schedule = schedule .. "[" .. ctime .. ",p]"
   schedule = schedule .. "[" .. ctime+500 .. ",a]"
   schedule = schedule .. "[" .. ctime+1000 .. ",i]"
   schedule = schedule .. "[" .. ctime+1500 .. ",n]\n"
else
   schedule = schedule .. "[" .. ctime .. ",d]"
   schedule = schedule .. "[" .. ctime+500 .. ",r]"
   schedule = schedule .. "[" .. ctime+1000 .. ",a]"
   schedule = schedule .. "[" .. ctime+1500 .. ",i]"
   schedule = schedule .. "[" .. ctime+1500 .. ",n]\n"
end

io.write("Returning " .. schedule .. "\n");

return schedule

Answer 1

AFAIK & in my 5.1.4 installation the function resides in lualib.h, not lauxlib.h

Answer 2

May be luaL_openlibs defines in a ifdef block.

Use -E with gcc to get the source after preprocessing. Pipe. Grep.