The pointer to the metamethod can be invalidated by a finalizer that
can run during a GC in 'checkstackGCp'. (This commit also fixes a
detail in the manual.) Bug introduced in commit 91673a8ec.
When closing variables during 'coroutine.close' or 'lua_resetthread',
the status of a coroutine must be set to LUA_OK; a coroutine should
not run with any other status. (See assertion in 'lua_callk'.)
After the reset, the status should be kept as normal, as any error
was already reported.
'luaD_pretailcall' mimics 'luaD_precall', handling call metamethods
and calling C functions directly. That makes the code in the
interpreter loop simpler.
This commit also goes back to emulating the tail call in 'luaD_precall'
with a goto, as C compilers may not do proper tail calls and the C
stack can overflow much sooner than the Lua stack (which grows as the
metamethod is added to it).
Any C function can receive maxinteger as an integer argument, and
therefore cannot increment it without some care (e.g., doing unsigned
arithmetic as the core does).
The parameters 'nresults' and 'delta1', in 'luaD_precall', were never
meaningful simultaneously. So, they were combined in a single parameter
'retdel'.
In 'lcode.c', when adding constants to the list of constants of a
function, integers represent themselves in the cache and floats
with integral values get a small delta to avoid collision with
integers. (This change avoids creating artificial addresses; the old
implementation converted integers to pointers to index the cache.)
When integer keys do not form a sequence, it is better to use all their
bits to compute their hashes. (The previous implementation was quite bad
for integer keys with common lower bits, and disastrous for integer keys
changing only in their upper 32 bits.)
- Fixes a bug, by removing dummy nodes together with the node
itself. (The previous implementation could leave dummy nodes in frames
which otherwise had no tbc variables, and therefore would not close
variables; that could leave 'tbclist' pointing higher than 'top', which
could dangle if the stack shrank.)
- Computes MAXDELTA based on the type of delta, to ease changing its
type if needed.
- Instead of 'isdummy', uses 'delta==0' to signal dummy nodes. (Dummy
nodes always have MAXDELTA for their real delta.)
The use of 'l_likely' in auxlib macros 'luaL_argcheck' and
'luaL_argexpected' should not be restricted to Lua's own code.
For that, 'l_likely' was renamed to 'luai_likely' to be exported
to external code.
The existence of 'lua_closeslot' is no reason for lua_pop not to close
to-be-closed variables too. It is too error-prone for lua_pop not to
close tbc variables being popped from the stack.
