In Lua 5.3, tables associated with functions in the C API accept and return lua_Integer .
void lua_rawgeti (lua_State *L, int idx, lua_Integer n); void lua_rawseti (lua_State *L, int idx, lua_Integer n); lua_Integer luaL_len (lua_State *L, int index);
But lua_createtable still gets int .
void lua_createtable (lua_State *L, int narr, int nrec);
In the sample function below, the length of the source table is used to create a copy with the same size.
static int copy_sequence(lua_State *L) { lua_Integer len, i; luaL_checktype(L, 1, LUA_TTABLE); len = luaL_len(L, 1); lua_createtable(L, (int)len, 0); for (i = 1; i <= len; i++) { lua_rawgeti(L, 1, i); lua_rawseti(L, -2, i); } return 1; }
But to turn off the warning, you need to throw:
warning: converting to 'int from' lua_Integer may change its value [-Wconversion]
Searching the Lua mailing list I found the following thread that applies to Lua 5.2 (also applies to earlier versions, which I also allow):
Quote: Roberto Ierusalimschy (August 7, 2012)
The size of the tables is already limited to 2147483647 elements. Lua internally uses 'int' to index all of its arrays (except strings / byte arrays). It is a pain to work with unsigned values (such as size_t) everywhere; ptrdiff_t has no warranty.
Is this still the case for Lua 5.3, which uses long long for lua_Integer ? Is listing int from lua_Integer as used in the above example safe in Lua 5.3?