Avoid undefined behavior in calls like «fprintf("%s", NULL)».
('lua_writestringerror' is implemented as 'fprintf', and 'lua_tostring'
can return NULL if object is not a string.)
The parser were mixing compiler indices of variables with stack indices,
so that when a to-be-closed variable was used inside the scope of
compile-time constants (which may be optimized away), it might be closed
in the wrong place. (See new tests for examples.)
Besides fixing the bugs, this commit also changed comments and variable
names to avoid that kind of confusion and added tests.
- more consistent nomenclature for error handling
- more precise definition for dead objects
- added algorithm used by 'math.random'
- added luaL_pushfail
- some other minor changes
ISO C is silent about the return of 'system'. Windows sets 'errno' in
case of errors. Linux has several different error cases, with different
return values. ISO C allows 'system' to set 'errno' even if there are no
errors. Here we assume that a status==0 is success (which is the case
on several platforms), otherwise it is an error. If there is an error
number, gives the error based on it. (The worst a spurious 'errno'
can do is to generate a bad error message.) Otherwise uses the normal
results.
(Undoing part of commit f53eabeed8.) It is better to keep this encoding
stable, so that all Lua versions can read at least the version of a
binary file.
gcc now warns (with -Wextra) about casts between pointers to different
function types. The type 'void(*)(void)' works as a 'void*' for function
pointers, cleaning the warning.
The code should not compute an instruction address before checking that
it exists. (Virtually no machine complains of computing an invalid
address, as long as the address is not used, but for ISO C that is
undefined behavior.)
'simplesect' encloses the introductory text of sections with
subsections, so that each section either is all text or is all
subsections. (This commit also corrects a small brace error in the
manual and extra spaces/tabs in some other files.)
Collisions in short strings occurr just by their existence, when
internalizing them. (Collisions in long strings is caused/controlled
by the program, when adding them as keys to the same table.)
This function was computing invalid instruction addresses when the
expression was not a multi-return instruction. (Virtually all machines
don't raise errors when computing an invalid address, as long as the
address is not accessed, but this computation is undefined behavior in
ISO C.)
Instead of an explicit value (field 'b'), true and false use different
tag variants. This avoids reading an extra field and results in more
direct code. (Most code that uses booleans needs to distinguish between
true and false anyway.)
ISO C states that standard library functions should not be called
with NULL arguments, unless stated otherwise. 'sprintf' does not
state otherwise, and it doesn't hurt to be on the safe side.
Several "metamethods" are not required to be methods (functions),
so it seems clearer not to call them metamethods. The manual now
uses the word 'metavalue' for those values.
The file 'bugs' reports bugs in several different versions
(corresponding to different branches in the repository), without
a clear division of "this bugs belongs to this version". So, it
doesn't make sense to track it along with one (or many) versions.
The initial "\n\t" to properly indent a searcher message is being added
by 'findloader' when building the error message, instead of being
included in the original message by each searcher itself.
In 'str__dump', the call to 'lua_dump' assumes the function is on the
top of the stack, but the manual allows 'luaL_buffinit' to push stuff
on the stack (although the current implementation does not). So, the
call to 'luaL_buffinit' must come after the call to 'lua_dump'.
The old definition did one test for nil, but three tests for the all
too common booleans (and two tests for other values); this definition
does two tests for all values.
New threads were being created with very small C-stack limits.
This is not a problem for coroutines, because 'lua_resume' sets
a new limit, but not all threads are coroutines.
The performance of the Lua compiler is not critical for Lua
performance, but it is a big component in the source. So, it makes
sense to trade speed for size in this component.
- Several details in 'lcode.c'
- A few more tests for code generation
- Bug in assert in 'lcode.c' ("=" x "==")
- Comments in 'lopcodes.h' and 'ltable.c'
The difference in performance between immediate operands and K operands
does not seem to justify all those extra opcodes. We only keep OP_ADDI,
due to its ubiquity and because the difference is a little more relevant.
(Later, OP_SUBI will be implemented by OP_ADDI, negating the constant.)
In arithmetic/bitwise operators, the call to metamethods is made
in a separate opcode following the main one. (The main
opcode skips this next one when the operation succeeds.) This
change reduces slightly the size of the binary and the complexity
of the arithmetic/bitwise opcodes. It also simplfies the treatment
of errors and yeld/resume in these operations, as there are much
fewer cases to consider. (Only OP_MMBIN/OP_MMBINI/OP_MMBINK,
instead of all variants of all arithmetic/bitwise operators.)
The family of opcodes OP_ADDK (arithmetic operators with K constant)
were not being handled in 'luaV_finishOp', which completes their
task after an yield.
When using warn-mode '@store', from the test library, the tests ensure
not only that the expected warnings were issued, but also that there was
no extra warnings.
The macro 'luaL_pushfail' documents all places in the standard libraries
that return nil to signal some kind of failure. It is defined as
'lua_pushnil'. The manual also got a notation (@fail) to document those
returns. The tests were changed to be agnostic regarding whether 'fail'
is 'nil' or 'false'.
Added the concept of control messages to the warning system, plus the
implementation of the controls "@on"/"@off" to turn warnings on/off.
Moreover, the warning system in the test library adds some other
controls to ease the test of warnings.
When converging marks on ephemeron tables, change the direction the
tables are traversed at each iteration, to try to avoid bad-case
scenarios with linked lists of entries in a table.
The loop does not end on end of file, but when the iterator function
fails to read a value. (In particular, the format "a" never fails,
so a loop with 'io.lines(fname, "a")' never ends.)
When initializing a to-be-closed variable, check whether it has a
'__close' metamethod (or is a false value) and raise an error if
if it hasn't. This produces more accurate error messages. (The
check before closing still need to be done: in the C API, the value
is not constant; and the object may lose its '__close' metamethod
during the block.)
The test "to-be-closed variables in main chunk" was broken,
as it used the removed feature of functions as to-be-closed values.
The error was not detected because its expected result had no lines
to be checked (due to missing new lines).
Attributes changed to posfixed ('x <const>', instead of '<const> x'),
and "toclose" renamed to "close". Posfixed attributes seem to make it
clearer that it applies to only one variable when there are multiple
variables.
Instead of updating 'L->top' in every place that may call a
metamethod, the metamethod functions themselves (luaT_trybinTM and
luaT_callorderTM) correct the top. (When calling metamethods from
the C API, however, the callers must preserve 'L->top'.)
- OP_NEWTABLE can use 'ra + 1' to set top (instead of ci->top);
- OP_CLOSE doesn't need to set top ('Protect' already does that);
- OP_TFORCALL must use 'ProtectNT', to preserve the top already set.
(That was a small bug, because iterators could be called with
extra parameters besides the state and the control variable.)
- Comments and an extra test for the bug in previous item.
As an example, 'print(string.format("%.99f", 1e70))' may have a
lot of garbage after the number.
The old test to ensure that 'string.format("%.99f", n)' was not too
large, 'fabs(n) < 1e100', assumes that the number will fit in the 99
bytes; but the 99 is not the space for the number, it is the added
extra zeros. The option worked for smaller numbers because of the
extra space added to MAX_ITEM.
Open upvalues are kept alive together with their corresponding
stack. This change makes a simpler and safer fix to the issue in
commit 440a5ee78c, about upvalues in the list of open upvalues
being collected while others are being created. (That previous fix
may not be correct.)
