Undefined references when linking with Lua compiled from source? - gcc

Question

Downloaded lua5_1_4_Sources.tar.gz and compiled liblua.a from source using TDM-GCC 4.5.1.
Everything compiled fine:
Linking ..
ar rcs liblua.a 5.1.4/src/lapi.o 5.1.4/src/lauxlib.o 5.1.4/src/lbaselib.o 5.1.4/src/lcode.o 5.1.4/src/ldblib.o 5.1.4/s rc/ldebug.o 5.1.4/src/ldo.o 5.1.4/src/ldump.o 5.1.4/src/lfunc.o 5.1.4/src/lgc.o 5.1.4/src/linit.o 5.1.4/src/liolib.o 5.1 .4/src/llex.o 5.1.4/src/lmathlib.o 5.1.4/src/lmem.o 5.1.4/src/loadlib.o 5.1.4/src/lobject.o 5.1.4/src/lopcodes.o 5.1.4/s rc/loslib.o 5.1.4/src/lparser.o 5.1.4/src/lstate.o 5.1.4/src/lstring.o 5.1.4/src/lstrlib.o 5.1.4/src/ltable.o 5.1.4/src/ ltablib.o 5.1.4/src/ltm.o 5.1.4/src/lua.o 5.1.4/src/luac.o 5.1.4/src/lundump.o 5.1.4/src/lvm.o 5.1.4/src/lzio.o 5.1.4/sr c/print.o 5.1.4/src/wmain.o
Compiled example source just fine:
http://pastebin.com/EGvMRjth
Tried to link:
Compiling..
g++ test.o -g -shared -Lshared/build/lua -llua -o libtest.so
test.o:test.cpp:(.text+0x15): undefined reference to `lua_tonumber(lua_State*, int)'
test.o:test.cpp:(.text+0x40): undefined reference to `lua_pushnumber(lua_State*, double)'
test.o:test.cpp:(.text+0x60): undefined reference to `lua_tonumber(lua_State*, int)'
test.o:test.cpp:(.text+0x8e): undefined reference to `lua_pushnumber(lua_State*, double)'
test.o:test.cpp:(.text+0xb6): undefined reference to `lua_pushcclosure(lua_State*, int (*)(lua_State*), int)'
test.o:test.cpp:(.text+0xd1): undefined reference to `lua_setfield(lua_State*, int, char const*)'
test.o:test.cpp:(.text+0xec): undefined reference to `lua_pushcclosure(lua_State*, int (*)(lua_State*), int)'
test.o:test.cpp:(.text+0x107): undefined reference to `lua_setfield(lua_State*, int, char const*)'
collect2: ld returned 1 exit status
I'm trying to follow the examples from here:
http://www.troubleshooters.com/codecorn/lua/lua_lua_calls_c.htm

Answer 1

As already discussed in the comments..
It seems you are compiling C++ and the Lua version you use is probably coded in C.
This means you need to include either the lua.hpp or if not available you need to include the libraries by using extern "C" like so:
extern "C" {
#include "lua.h"
#include "lualib.h"
#include "lauxlib.h"
};