C++ 链接到Lua5.2.4时出现问题，即使在内联编译源代码时也是如此

我有一个文件configuration.cpp：

#include "configuration.hpp"

struct game_config* get_game_config(lua_State *L, char* script)
{
    debug("Attempting to load configuration from %s", script);
    // Execute the script
    luaL_dofile(L, script);

    // The environment should now be prepped, we can get the config variables
    struct game_config* game_config;

    lua_getglobal(L, "WINDOW_WIDTH");
    game_config->screen_width = lua_tointeger(L, -1);
    lua_getglobal(L, "WINDOW_HEIGHT");
    game_config->screen_height = lua_tointeger(L, -1);
    lua_getglobal(L, "GAME_TITLE");
    game_config->game_title = lua_tostring(L, -1);

    debug("Loaded config for %s, at %dx%d", game_config->game_title, game_config->screen_width, game_config->screen_height);

    return game_config;
};

其中包括configuration.hpp：

#ifndef CONFIGURATION_HPP_INCLUDED
#define CONFIGURATION_HPP_INCLUDED

#include "common.hpp"
#include "scripting.hpp"

// Data structures

struct game_config {
    int screen_width;
    int screen_height;

    const char *game_title;
};

/*
 * get_config
 * run a script and retrieve configuration data from it
 */

struct game_config *get_game_config(lua_State*, char *);

#endif // CONFIGURATION_HPP_INCLUDED

其中包括

scripting.hpp

，其中以下行导入Lua5.2：

#include "lua.h"
#include "lauxlib.h"
#include "lualib.h"

当我将这些行添加到configuration.cpp时，程序将编译并运行。但是，当它们位于任何其他文件（configuration.hpp、scripting.hpp）中时，它不会：

||=== Build: debug in rpfreedom (compiler: GNU GCC Compiler) ===|
src/configuration.cpp||In function ‘game_config* get_game_config(lua_State*, char*)’:|
src/configuration.cpp|13|warning: ‘game_config’ is used uninitialized in this function [-Wuninitialized]|
src/main.cpp||In function ‘int main()’:|
src/main.cpp|13|warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings]|
build/debug/configuration.o||In function `get_game_config(lua_State*, char*)':|
/home/leo/projects/rpfreedom/src/configuration.cpp|7|undefined reference to `luaL_loadfilex(lua_State*, char const*, char const*)'|
/home/leo/projects/rpfreedom/src/configuration.cpp|7|undefined reference to `lua_pcallk(lua_State*, int, int, int, int, int (*)(lua_State*))'|
/home/leo/projects/rpfreedom/src/configuration.cpp|12|undefined reference to `lua_getglobal(lua_State*, char const*)'|
/home/leo/projects/rpfreedom/src/configuration.cpp|13|undefined reference to `lua_tointegerx(lua_State*, int, int*)'|
/home/leo/projects/rpfreedom/src/configuration.cpp|14|undefined reference to `lua_getglobal(lua_State*, char const*)'|
/home/leo/projects/rpfreedom/src/configuration.cpp|15|undefined reference to `lua_tointegerx(lua_State*, int, int*)'|
/home/leo/projects/rpfreedom/src/configuration.cpp|16|undefined reference to `lua_getglobal(lua_State*, char const*)'|
/home/leo/projects/rpfreedom/src/configuration.cpp|17|undefined reference to `lua_tolstring(lua_State*, int, unsigned long*)'|
build/debug/scripting.o||In function `scripting_init()':|
/home/leo/projects/rpfreedom/src/scripting.cpp|7|undefined reference to `luaL_newstate()'|
/home/leo/projects/rpfreedom/src/scripting.cpp|20|undefined reference to `lua_settop(lua_State*, int)'|
build/debug/scripting.o||In function `scripting_report_errors(lua_State*, int)':|
/home/leo/projects/rpfreedom/src/scripting.cpp|30|undefined reference to `lua_tolstring(lua_State*, int, unsigned long*)'|
/home/leo/projects/rpfreedom/src/scripting.cpp|31|undefined reference to `lua_settop(lua_State*, int)'|
build/debug/scripting.o:(.rodata+0x88)||undefined reference to `luaopen_base(lua_State*)'|
Makefile|203|recipe for target 'bin/debug/rpfreedom' failed|
Makefile|160|recipe for target 'debug' failed|
||=== Build failed: 15 error(s), 2 warning(s) (0 minute(s), 1 second(s)) ===|

显然，包含configuration.hpp是有效的，因为这里定义的game_config struct没有错误；递归包含也一样，因为debug（）宏遵循路径

debug.hpp->common.hpp->configuration.hpp->configuration.cpp

。那么，为什么Lua头文件的#include没有以类似的方式工作呢

我决定调查；我运行了

g++-Iinclude-I/usr/include/lua5.2-esrc/configuration.cpp | grep lua_getglobal

来查看预处理器的输出，结果是。。。他们是。该命令及其在源代码中的使用将返回：

extern void (lua_getglobal) (lua_State *L, const char *var);

所以，我不知道发生了什么

---

编辑：事实证明，我必须围绕我的

#include

s为Lua做

extern C{}

。但是，现在，仅在configuration.hpp中（不在scripting.hpp中，其中包含Lua头），我收到另一个错误：

include/configuration.hpp:21:37: error: ‘lua_State’ was not declared in this scope
 struct game_config *get_game_config(lua_State*, char *);

但是，scripting.cpp和scripting.hpp中lua_状态的使用不受影响

编辑2：显然，嵌入Lua5.2的推荐方法是在项目中编译它，因为它非常小，所以我这样做了。但是，即使我的Makefile生成的link命令将我的所有对象文件与Lua对象文件明确链接：

g++ build/release/configuration.o build/release/lua5.2.4/lparser.c.o build/release/lua5.2.4/lcode.c.o build/release/lua5.2.4/lundump.c.o build/release/lua5.2.4/lzio.c.o build/release/lua5.2.4/ldo.c.o build/release/lua5.2.4/lapi.c.o build/release/lua5.2.4/lgc.c.o build/release/lua5.2.4/lfunc.c.o build/release/lua5.2.4/ldump.c.o build/release/lua5.2.4/ltable.c.o build/release/lua5.2.4/lcorolib.c.o build/release/lua5.2.4/loslib.c.o build/release/lua5.2.4/liolib.c.o build/release/lua5.2.4/ltm.c.o build/release/lua5.2.4/lmem.c.o build/release/lua5.2.4/lctype.c.o build/release/lua5.2.4/lauxlib.c.o build/release/lua5.2.4/ldebug.c.o build/release/lua5.2.4/lobject.c.o build/release/lua5.2.4/loadlib.c.o build/release/lua5.2.4/linit.c.o build/release/lua5.2.4/lmathlib.c.o build/release/lua5.2.4/llex.c.o build/release/lua5.2.4/lstate.c.o build/release/lua5.2.4/lopcodes.c.o build/release/lua5.2.4/lstrlib.c.o build/release/lua5.2.4/lbaselib.c.o build/release/lua5.2.4/ltablib.c.o build/release/lua5.2.4/ldblib.c.o build/release/lua5.2.4/lbitlib.c.o build/release/lua5.2.4/lvm.c.o build/release/lua5.2.4/lstring.c.o build/release/scripting.o build/release/main.o  -L/usr/lib/x86_64-linux-gnu -Lm -Ldl -lsfml-graphics -lsfml-window -lsfml-audio -lsfml-network -lsfml-system   -o bin/release/rpfreedom

我得到的链接器错误与我之前得到的相同

---

链接器的参数顺序重要吗？

显示的错误消息似乎来自链接器，而不是编译器

一切都成功地包括在内。一切都顺利完成了。但是链接失败，因为某些必需的库没有链接到

请注意，错误消息引用：

build/debug/configuration.o
...
build/debug/scripting.o
...

。。。而不是您的源代码（错误中提到的cpp具有误导性，它们实际上是从.o文件中的调试信息中提取的）。错误消息通常是来自链接器的错误消息

---

你的源代码很好。您需要修复makefile。

嗯，您的第一个警告正是编译器告诉您的。您的代码如下：

// The environment should now be prepped, we can get the config variables
struct game_config* game_config;

lua_getglobal(L, "WINDOW_WIDTH");
game_config->screen_width = lua_tointeger(L, -1);

警告是：

‘game_config’ is used uninitialized in this function.

在访问

screen\u width

之前，您没有将指针

game\u config

设置为指向任何对象。也许您需要将其设置为

newgame\u config（）

。我更愿意在堆栈上创建一个，并按值返回：

game_config config;
lua_getglobal(L, "WINDOW_WIDTH");
config.screen_width = lua_tointeger(L, -1);
...
return config;

---

不管是哪种方式，让游戏标题成为一个

std:：string

可能比一个

const char*

更好。我最终自己编译了一个静态Lua（

liblua.a

），创建了一个lib/目录，并将

-Llib-llua

添加到我的链接器行，从而纠正了这个问题。这将需要额外的努力来实现跨平台，但目前还可以。

结果表明，我必须围绕我的

#include

s为Lua做

extern C{}

。但是，现在，只有在configuration.hpp中（不在scripting.hpp中，其中包含Lua头），我才收到另一个错误；我把它编辑成主要问题。非常感谢。您也可以使用

#include“lua.hpp”

，它可以为您做到这一点。当然，我打算在编译程序并与lua库链接后尽快解决这一问题。