Build LuaJIT w/ table.pack support (#1535)

It's unfortunately behind the Lua 5.2 extensions ifdef in a standard build (possibly because it's so common that it's usually implemented in Lua and monkey-patched over the table metatable?).

But it's trivial and doesn't actually poses an API issue, and it's helpful for a number of our use-cases.

.luacheckrc

@@ -6,6 +6,8 @@ self = false
 
 globals = {
     "G_defaults",
+    "table.pack",
+    "table.unpack",
 }
 
 exclude_files = {

ffi/util.lua

@@ -264,8 +264,8 @@ function util.execute(...)
     else
         local pid = C.fork()
         if pid == 0 then
-            local args = {...}
-            os.exit(C.execl(args[1], unpack(args, 1, #args+1)))
+            local args = table.pack(...)
+            os.exit(C.execl(args[1], unpack(args, 1, #args+1))) -- Last arg must be a NULL pointer
         end
         local status = ffi.new('int[1]')
         C.waitpid(pid, status, 0)
@@ -722,7 +722,7 @@ This function was inspired by Qt:
 <http://qt-project.org/doc/qt-4.8/internationalization.html#use-qstring-arg-for-dynamic-text>
 --]]
 function util.template(str, ...)
-    local params = {...}
+    local params = table.pack(...)
     -- shortcut:
     if #params == 0 then return str end
     local result = string.gsub(str, "%%([1-9][0-9]?)",

thirdparty/luajit/CMakeLists.txt

@@ -69,20 +69,22 @@ endif()
 
 set(BUILD_CMD sh -c "${BUILD_CMD_STR}")
 
-set(PATCH_CMD "${KO_PATCH} ${CMAKE_CURRENT_SOURCE_DIR}/koreader-luajit-makefile-tweaks.patch")
+set(PATCH_CMD1 "${KO_PATCH} ${CMAKE_CURRENT_SOURCE_DIR}/koreader-luajit-makefile-tweaks.patch")
+# Enable table.pack & table.unpack w/o the rest of the -DLUAJIT_ENABLE_LUA52COMPAT baggage...
+set(PATCH_CMD2 "${KO_PATCH} ${CMAKE_CURRENT_SOURCE_DIR}/koreader-luajit-enable-table_pack.patch")
 
 ko_write_gitclone_script(
     GIT_CLONE_SCRIPT_FILENAME
     https://github.com/LuaJIT/LuaJIT
-    dad04f1754723e76ba9dcf9f401f3134a0cd3972
+    6c4826f12c4d33b8b978004bc681eb1eef2be977
     ${SOURCE_DIR}
 )
 
 include(ExternalProject)
 ExternalProject_Add(
     ${PROJECT_NAME}
     DOWNLOAD_COMMAND ${CMAKE_COMMAND} -P ${GIT_CLONE_SCRIPT_FILENAME}
-    PATCH_COMMAND COMMAND ${PATCH_CMD}
+    PATCH_COMMAND COMMAND ${PATCH_CMD1} COMMAND ${PATCH_CMD2}
     BUILD_IN_SOURCE 1
     # skip configure
     CONFIGURE_COMMAND ""

thirdparty/luajit/koreader-luajit-enable-table_pack.patch

@@ -0,0 +1,31 @@
+diff --git a/src/lib_table.c b/src/lib_table.c
+index a723326a..28af227f 100644
+--- a/src/lib_table.c
++++ b/src/lib_table.c
+@@ -267,7 +267,6 @@ LJLIB_CF(table_sort)
+   return 0;
+ }
+
+-#if LJ_52
+ LJLIB_PUSH("n")
+ LJLIB_CF(table_pack)
+ {
+@@ -283,7 +282,6 @@ LJLIB_CF(table_pack)
+   lj_gc_check(L);
+   return 1;
+ }
+-#endif
+
+ LJLIB_NOREG LJLIB_CF(table_new)		LJLIB_REC(.)
+ {
+@@ -316,10 +314,8 @@ static int luaopen_table_clear(lua_State *L)
+ LUALIB_API int luaopen_table(lua_State *L)
+ {
+   LJ_LIB_REG(L, LUA_TABLIBNAME, table);
+-#if LJ_52
+   lua_getglobal(L, "unpack");
+   lua_setfield(L, -2, "unpack");
+-#endif
+   lj_lib_prereg(L, LUA_TABLIBNAME ".new", luaopen_table_new, tabV(L->top-1));
+   lj_lib_prereg(L, LUA_TABLIBNAME ".clear", luaopen_table_clear, tabV(L->top-1));
+   return 1;