support for LuaJIT -- Lua 5.1 compatibility

[fhoefling]

I was wondering whether the current development of luabind is still supporting LuaJIT? As of version 2.0.2, it provides Lua 5.1 headers and library.

The branch build_improvements has a file FindLua52.cmake which suggests that support for 5.1 has been dropped?

I have added LuaJIT to the CMake module (see https://github.com/fhoefling/luaponte/tree/build-improvements). It compiles with Clang 3.3, but all test except for one fail with a segfault.

[fhoefling]

With a patch from https://github.com/hishamhm/lua-compat-5.2 the SEGFAULTS have been fixed:
halmd-org@3a5d225

The following tests FAILED:
19 - free_functions (Failed)
30 - object (Failed)

[fhoefling]

The failing test "free_functions" has been fixed in halmd-org@707be05 . The reason was a typo (?) in the error message of Lua 5.1, which was fixed in LuaJIT.

The "object" test has the following output:

  30: Test command: /home/fluids/hoefling/build/luabind/test/test_object
  30: Test timeout computed to be: 1500
  30: .../luabind/test/test_object.cpp:465"TEST_CHECK failed: "boost::lexical_cast<std::string>(globals(L)["obj"]) == "custom __tostring"""
  1/1 Test #30: object ...........................***Failed    0.00 sec

with the following stack trace:

  #5  0x00007ffff7fcab22 in lua_rawset () from /local/modules/luajit-2.0.2/lib/libluajit-5.1.so.2
  #6  0x000000000042b052 in lua_rawsetp(lua_State*, int, void*) ()
  #7  0x0000000000439e7a in void* luabind::(anonymous namespace)::create_gc_udata<luabind::detail::class_registry>(lua_State*, void*) ()
  #8  0x0000000000439a21 in void luabind::(anonymous namespace)::push_gc_udata<luabind::detail::class_registry, lua_State*>(lua_State*, void*, lua_State*) ()
  #9  0x0000000000439912 in luabind::open(lua_State*) ()
  #10 0x00000000004226b2 in lua_state::lua_state() ()
  #11 0x0000000000422a22 in main ()

[the-nic]

This is due to the incorrect implementation of "luaL_tolstring" in lua_include.h. Further lua_[g,s]etuservalue seem to be wrong, too.
I'd suggest to use the implementations from https://github.com/hishamhm/lua-compat-5.2

[fhoefling]

lua-compat-5.2 could be included as a submodule, which is only needed if Lua 5.1 was found. Then, lua-include.h would include compat-5.2.hpp instead of lua.hpp. In addition, one has to link against a small library liblua-compat-5.2 (next to the Lua 5.1 library).

For the CMake build system, the following would be needed:

• FindLuaCompat.cmake
• add_library(lua-compat-5.2 compat-5.2.c)
• list(APPEND LUA_LIBRARIES "lua-compat-5.2")
• include_directories(LUA_COMPAT_INCLUDE_DIR) pointing to ".../lua-compat-5.2/c-api"

I'm not yet sure where to place it, and I don't know what to do for other build systems.

[decimad]

There are like how many calls in luabind that fail without a compatibility layer? 3 or so? If it were me to decide that would not be worth adding another external dependency. Of course it's a clean and modular solution in theory, but reality is always a tradeoff. So I'd go for simply copying the respective implementations from lua-compat with copyright info etc...

[fhoefling]

"luaL_tolstring" has been fixed in halmd-org@4ed73bc

The branch now fully supports Lua 5.1 and LuaJIT 2.0.