Function 'leaveblock' was generating "break" label before removing
variables from the closing block. If 'createlabel' created a 'close'
instruction (which it did when matching a goto/break that exited
the scope of an upvalue), that instruction would use the wrong level.
'luaD_growstack' already checks that. This commit also fixes an
internal bug in 'luaD_growstack': a large 'n' could cause an arithmetic
overflow when computing 'needed'.
The flag CIST_FIN does not mark a finalizer, but the function that was
running when the finalizer was called. (So, the function did not call
the finalizer, but it looks that way in the stack.)
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.
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).
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.)
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.
Instead of assuming that shrinking a block may be an emergency
collection, use an explicit field ('gcstopem') to stop emergency
collections while GC is working.
The function 'isinstack' tried to work around the undefined behavior
of subtracting two pointers that do not point to the same object,
but the compiler killed to trick. (It optimizes out the safety check,
because in a correct execution it will be always true.)
When, inside a coroutine, a C function with to-be-closed slots return,
the corresponding metamethods can yield. ('__close' metamethods called
through 'lua_closeslot' still cannot yield, as there is no continuation
to go when resuming.)
To-be-closed variables are linked in their own list, embedded into the
stack elements. (Due to alignment, this information does not change
the size of the stack elements in most architectures.) This new list
does not produce garbage and avoids memory errors when creating tbc
variables.
- 'L->top' is set once in 'luaD_hook', instead of being set in
'luaD_hookcall' and 'rethook';
- resume discard arguments when returning after an yield inside a hook
(arguments may interfere with the coroutine stack);
- yield inside a hook asserts it has no arguments.
The return hook should be called only after closing variables (which
are still part of the function). C functions were calling the hook
before the metamethods.
Completes commit b07fc10e91. '__close' metamethods can yield even
when they are being called due to an error. '__close' metamethods from
C functions are still not allowed to yield.
Initial implementation to allow yields inside '__close' metamethods.
This current version still does not allow a '__close' metamethod
to yield when called due to an error. '__close' metamethods from
C functions also are not allowed to yield.
Closing a to-be-closed variable with 'lua_settop' is too restrictive,
as it erases all slots above the variable. Moreover, it adds side
effects to 'lua_settop', which should be a fairly basic function.
When available, use the calling code to find a suitable name for what
was being called; this is particularly useful for errors of non-callable
metamethods. This commit also improved the debug information for
order metamethods.
A to-be-closed variable is constant and it must have a close metamethod
when it is created. A program has to go out of its way (e.g., by
changing the variable's metamethod) to invalidate that check. So,
it is not worth to test that again. If the program tampers with the
metamethod, Lua will raise a regular error when attempting to call it.
