无法将 Lua 编译为 C++
Can't compile Lua as C++
我正在尝试使用以下 CMakeLists.txt(和 CMake 3.21)构建 Lua 5.4.3(撰写本文时的最新版本)(忽略目标被调用的事实lua_static
尽管它是共享库):
cmake_minimum_required(VERSION 3.16)
project(Lua LANGUAGES CXX)
# make cache variables for install destinations
include(GNUInstallDirs)
set(CMAKE_CXX_STANDARD 11)
set(CMAKE_CXX_STANDARD_REQUIRED True)
set(LUA_LIB_SRCS
"src/ldblib.c"
"src/ldebug.c"
"src/ldo.c"
"src/ldump.c"
"src/lfunc.c"
"src/lgc.c"
"src/linit.c"
"src/liolib.c"
"src/lopcodes.c"
"src/llex.c"
"src/lmathlib.c"
"src/lmem.c"
"src/loadlib.c"
"src/lobject.c"
"src/loslib.c"
"src/lparser.c"
"src/lstate.c"
"src/lstring.c"
"src/lstrlib.c"
"src/ltable.c"
"src/ltablib.c"
"src/ltm.c"
"src/lundump.c"
"src/lutf8lib.c"
"src/lvm.c"
"src/lzio.c"
"src/lapi.c"
"src/lauxlib.c"
"src/lbaselib.c"
"src/lcode.c"
"src/lcorolib.c"
"src/lctype.c"
)
set(LUA_HEADERS_INSTALL
"src/lua.h"
"src/luaconf.h"
"src/lualib.h"
"src/lauxlib.h"
"src/lua.hpp"
)
# Compile directly as C++.
set_source_files_properties(${LUA_LIB_SRCS} PROPERTIES LANGUAGE CXX )
add_library(lua_static SHARED ${LUA_LIB_SRCS})
set_target_properties(lua_static PROPERTIES LINKER_LANGUAGE CXX)
set_target_properties(lua_static PROPERTIES DEBUG_POSTFIX d)
# make sure __cplusplus is defined when using msvc
if (MSVC)
target_compile_options(lua_static PRIVATE /TP # /TP doesn't is somehow stripped or ignored?
/Zc:__cplusplus)
endif ()
target_include_directories(lua_static
PUBLIC
"$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>"
)
install(TARGETS lua_static
EXPORT lua_static_targets
LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
INCLUDES DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
)
install(FILES ${LUA_HEADERS_INSTALL} DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
install(EXPORT lua_static_targets
FILE LuaStaticTargets.cmake
NAMESPACE lua::
DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/lua
)
include(CMakePackageConfigHelpers)
configure_package_config_file(${CMAKE_CURRENT_SOURCE_DIR}/Config.cmake.in
"${CMAKE_CURRENT_BINARY_DIR}/LuaConfig.cmake"
INSTALL_DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/lua
)
install(FILES
"${CMAKE_CURRENT_BINARY_DIR}/LuaConfig.cmake"
DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/lua
)
当使用 MSVC 构建时,__cplusplus
被定义,因此我假设到目前为止的一切都按预期工作。然后在安装之后,我 link 像这样
对着库
cmake_minimum_required(VERSION 3.16)
project(TestProject)
add_executable(Test Main.cpp)
# Lua
find_package(lua REQUIRED PATHS ${CMAKE_CURRENT_LIST_DIR}/lua)
set_target_properties(lua::lua_static PROPERTIES LINKER_LANGUAGE CXX)
target_link_libraries(Test lua::lua_static)
之所以要编译Lua为C++是为了启用异常(而不是longjmp
)。所以为了测试是否会抛出异常,我尝试在这个测试程序中调用一个
#include <lua.h>
#include <lauxlib.h>
#include <lualib.h>
#include <iostream>
constexpr char* Test_Lua = R"(
function f (x, y)
unknown()
return 1/0
en
)";
lua_State* state;
int main(int argc, char* argv[])
{
state = luaL_newstate();
luaL_openlibs(state);
try
{
int error = luaL_loadbuffer(state, Test_Lua, strlen(Test_Lua), "Test");
lua_call(state, 0, LUA_MULTRET); // Should thow, because of the syntax error
}
catch (...)
{
std::cout << "Exception!" << std::endl;
goto end;
}
end:
lua_close(state);
return 0;
}
当使用调试器进入 lua_call
时,我有时会进入 ldo.c,其中 Visual Studio 表示 LUAI_THROW
不是通过 C++ 异常处理定义的。这是因为 __cplusplus
没有定义。跳转到我之前创建的 Lua 项目文件中的那个源文件,LUAI_THROW
是根据需要定义的。我可以包含 Lua headers 这一事实向我表明该库已被编译为 C++ 库。事实上,如果我尝试添加 extern "C" { ... }
,我会得到 linker 错误。
有人可以阐明问题的原因吗?
编辑:
在深入研究这个问题之后,我意识到所有编译都像 C++ 所做的那样,Lua 内部 处理 return 错误代码的函数(例如作为 luaL_loadbuffer
) 通过异常。这并不意味着我可以抓住并处理它们(我最初是这么想的)。像 lua_call
运行 这样的函数在无保护模式下调用 panic 函数(参见@bremen_matt 的 post)。
我对Lua一无所知。有了这个......
关于 Lua 的内部工作方式,我认为您遗漏了一些信息。如果我在第 57 行左右将 ldo.c
中的宏修改为:
#include <iostream>
#define LUAI_THROW(L,c) (fprintf(stderr, "THROWING\n"), throw(c))
#define LUAI_TRY(L,c,a) \
try { a } catch(...) { fprintf(stderr, "CAUGHT\n"); if ((c)->status == 0) (c)->status = -1; }
然后当我 运行 这个时,我看到输出:
THROWING
CAUGHT
PANIC: unprotected error in call to Lua API (attempt to call a string value)
这表明内部 Lua 正在尝试 运行 一段代码,捕获异常,然后退出而不抛出另一个异常。因此,作为用户的您无法捕获此异常。它正在 Lua.
内消耗
只要快速浏览一下代码,就会发现您可能想要使用 lua_pcall
。似乎 p
的意思是 protected
?你可以用它做一些错误处理吗?无论哪种方式,该功能似乎也不会将错误抛得更高。看来你必须传递一个错误处理函数。
我正在尝试使用以下 CMakeLists.txt(和 CMake 3.21)构建 Lua 5.4.3(撰写本文时的最新版本)(忽略目标被调用的事实lua_static
尽管它是共享库):
cmake_minimum_required(VERSION 3.16)
project(Lua LANGUAGES CXX)
# make cache variables for install destinations
include(GNUInstallDirs)
set(CMAKE_CXX_STANDARD 11)
set(CMAKE_CXX_STANDARD_REQUIRED True)
set(LUA_LIB_SRCS
"src/ldblib.c"
"src/ldebug.c"
"src/ldo.c"
"src/ldump.c"
"src/lfunc.c"
"src/lgc.c"
"src/linit.c"
"src/liolib.c"
"src/lopcodes.c"
"src/llex.c"
"src/lmathlib.c"
"src/lmem.c"
"src/loadlib.c"
"src/lobject.c"
"src/loslib.c"
"src/lparser.c"
"src/lstate.c"
"src/lstring.c"
"src/lstrlib.c"
"src/ltable.c"
"src/ltablib.c"
"src/ltm.c"
"src/lundump.c"
"src/lutf8lib.c"
"src/lvm.c"
"src/lzio.c"
"src/lapi.c"
"src/lauxlib.c"
"src/lbaselib.c"
"src/lcode.c"
"src/lcorolib.c"
"src/lctype.c"
)
set(LUA_HEADERS_INSTALL
"src/lua.h"
"src/luaconf.h"
"src/lualib.h"
"src/lauxlib.h"
"src/lua.hpp"
)
# Compile directly as C++.
set_source_files_properties(${LUA_LIB_SRCS} PROPERTIES LANGUAGE CXX )
add_library(lua_static SHARED ${LUA_LIB_SRCS})
set_target_properties(lua_static PROPERTIES LINKER_LANGUAGE CXX)
set_target_properties(lua_static PROPERTIES DEBUG_POSTFIX d)
# make sure __cplusplus is defined when using msvc
if (MSVC)
target_compile_options(lua_static PRIVATE /TP # /TP doesn't is somehow stripped or ignored?
/Zc:__cplusplus)
endif ()
target_include_directories(lua_static
PUBLIC
"$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>"
)
install(TARGETS lua_static
EXPORT lua_static_targets
LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
INCLUDES DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
)
install(FILES ${LUA_HEADERS_INSTALL} DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
install(EXPORT lua_static_targets
FILE LuaStaticTargets.cmake
NAMESPACE lua::
DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/lua
)
include(CMakePackageConfigHelpers)
configure_package_config_file(${CMAKE_CURRENT_SOURCE_DIR}/Config.cmake.in
"${CMAKE_CURRENT_BINARY_DIR}/LuaConfig.cmake"
INSTALL_DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/lua
)
install(FILES
"${CMAKE_CURRENT_BINARY_DIR}/LuaConfig.cmake"
DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/lua
)
当使用 MSVC 构建时,__cplusplus
被定义,因此我假设到目前为止的一切都按预期工作。然后在安装之后,我 link 像这样
cmake_minimum_required(VERSION 3.16)
project(TestProject)
add_executable(Test Main.cpp)
# Lua
find_package(lua REQUIRED PATHS ${CMAKE_CURRENT_LIST_DIR}/lua)
set_target_properties(lua::lua_static PROPERTIES LINKER_LANGUAGE CXX)
target_link_libraries(Test lua::lua_static)
之所以要编译Lua为C++是为了启用异常(而不是longjmp
)。所以为了测试是否会抛出异常,我尝试在这个测试程序中调用一个
#include <lua.h>
#include <lauxlib.h>
#include <lualib.h>
#include <iostream>
constexpr char* Test_Lua = R"(
function f (x, y)
unknown()
return 1/0
en
)";
lua_State* state;
int main(int argc, char* argv[])
{
state = luaL_newstate();
luaL_openlibs(state);
try
{
int error = luaL_loadbuffer(state, Test_Lua, strlen(Test_Lua), "Test");
lua_call(state, 0, LUA_MULTRET); // Should thow, because of the syntax error
}
catch (...)
{
std::cout << "Exception!" << std::endl;
goto end;
}
end:
lua_close(state);
return 0;
}
当使用调试器进入 lua_call
时,我有时会进入 ldo.c,其中 Visual Studio 表示 LUAI_THROW
不是通过 C++ 异常处理定义的。这是因为 __cplusplus
没有定义。跳转到我之前创建的 Lua 项目文件中的那个源文件,LUAI_THROW
是根据需要定义的。我可以包含 Lua headers 这一事实向我表明该库已被编译为 C++ 库。事实上,如果我尝试添加 extern "C" { ... }
,我会得到 linker 错误。
有人可以阐明问题的原因吗?
编辑:
在深入研究这个问题之后,我意识到所有编译都像 C++ 所做的那样,Lua 内部 处理 return 错误代码的函数(例如作为 luaL_loadbuffer
) 通过异常。这并不意味着我可以抓住并处理它们(我最初是这么想的)。像 lua_call
运行 这样的函数在无保护模式下调用 panic 函数(参见@bremen_matt 的 post)。
我对Lua一无所知。有了这个......
关于 Lua 的内部工作方式,我认为您遗漏了一些信息。如果我在第 57 行左右将 ldo.c
中的宏修改为:
#include <iostream>
#define LUAI_THROW(L,c) (fprintf(stderr, "THROWING\n"), throw(c))
#define LUAI_TRY(L,c,a) \
try { a } catch(...) { fprintf(stderr, "CAUGHT\n"); if ((c)->status == 0) (c)->status = -1; }
然后当我 运行 这个时,我看到输出:
THROWING
CAUGHT
PANIC: unprotected error in call to Lua API (attempt to call a string value)
这表明内部 Lua 正在尝试 运行 一段代码,捕获异常,然后退出而不抛出另一个异常。因此,作为用户的您无法捕获此异常。它正在 Lua.
内消耗只要快速浏览一下代码,就会发现您可能想要使用 lua_pcall
。似乎 p
的意思是 protected
?你可以用它做一些错误处理吗?无论哪种方式,该功能似乎也不会将错误抛得更高。看来你必须传递一个错误处理函数。