Bug: yielding in '__close' mess up number of returns
Yielding in a __close metamethod called when returning vararg results
changes the top and so messes up the number of returned values.
diff --git a/lstate.h b/lstate.h
index c1283bb..44cf939 100644
--- a/lstate.h
+++ b/lstate.h
@@ -165,7 +165,7 @@
** - field 'nyield' is used only while a function is "doing" an
** yield (from the yield until the next resume);
** - field 'nres' is used only while closing tbc variables when
-** returning from a C function;
+** returning from a function;
** - field 'transferinfo' is used only during call/returnhooks,
** before the function starts or after it ends.
*/
diff --git a/lvm.c b/lvm.c
index 16e01d6..e4b1903 100644
--- a/lvm.c
+++ b/lvm.c
@@ -847,10 +847,19 @@
luaV_concat(L, total); /* concat them (may yield again) */
break;
}
- case OP_CLOSE: case OP_RETURN: { /* yielded closing variables */
+ case OP_CLOSE: { /* yielded closing variables */
ci->u.l.savedpc--; /* repeat instruction to close other vars. */
break;
}
+ case OP_RETURN: { /* yielded closing variables */
+ StkId ra = base + GETARG_A(inst);
+ /* adjust top to signal correct number of returns, in case the
+ return is "up to top" ('isIT') */
+ L->top = ra + ci->u2.nres;
+ /* repeat instruction to close other vars. and complete the return */
+ ci->u.l.savedpc--;
+ break;
+ }
default: {
/* only these other opcodes can yield */
lua_assert(op == OP_TFORCALL || op == OP_CALL ||
@@ -1672,6 +1681,7 @@
n = cast_int(L->top - ra); /* get what is available */
savepc(ci);
if (TESTARG_k(i)) { /* may there be open upvalues? */
+ ci->u2.nres = n; /* save number of returns */
if (L->top < ci->top)
L->top = ci->top;
luaF_close(L, base, CLOSEKTOP, 1);
diff --git a/testes/locals.lua b/testes/locals.lua
index 6aad5d2..6151f64 100644
--- a/testes/locals.lua
+++ b/testes/locals.lua
@@ -814,6 +814,65 @@
do
+ -- yielding inside closing metamethods while returning
+ -- (bug in 5.4.3)
+
+ local extrares -- result from extra yield (if any)
+
+ local function check (body, extra, ...)
+ local t = table.pack(...) -- expected returns
+ local co = coroutine.wrap(body)
+ if extra then
+ extrares = co() -- runs until first (extra) yield
+ end
+ local res = table.pack(co()) -- runs until yield inside '__close'
+ assert(res.n == 2 and res[2] == nil)
+ local res2 = table.pack(co()) -- runs until end of function
+ assert(res2.n == t.n)
+ for i = 1, #t do
+ if t[i] == "x" then
+ assert(res2[i] == res[1]) -- value that was closed
+ else
+ assert(res2[i] == t[i])
+ end
+ end
+ end
+
+ local function foo ()
+ local x <close> = func2close(coroutine.yield)
+ local extra <close> = func2close(function (self)
+ assert(self == extrares)
+ coroutine.yield(100)
+ end)
+ extrares = extra
+ return table.unpack{10, x, 30}
+ end
+ check(foo, true, 10, "x", 30)
+ assert(extrares == 100)
+
+ local function foo ()
+ local x <close> = func2close(coroutine.yield)
+ return
+ end
+ check(foo, false)
+
+ local function foo ()
+ local x <close> = func2close(coroutine.yield)
+ local y, z = 20, 30
+ return x
+ end
+ check(foo, false, "x")
+
+ local function foo ()
+ local x <close> = func2close(coroutine.yield)
+ local extra <close> = func2close(coroutine.yield)
+ return table.unpack({}, 1, 100) -- 100 nils
+ end
+ check(foo, true, table.unpack({}, 1, 100))
+
+end
+
+do
-- yielding inside closing metamethods after an error
local co = coroutine.wrap(function ()
