A to-be-closed variable must have a closable value (or be nil)

It is an error for a to-be-closed variable to have a non-closable
non-nil value when it is being closed. This situation does not seem to
be useful and often hints to an error. (Particularly in the C API, it is
easy to change a to-be-closed index by mistake.)

1 files changed, 3 insertions, 4 deletions

diff --git a/lvm.c b/lvm.c
index a6dcc9ff..50d967c6 100644
--- a/lvm.c
+++ b/lvm.c
@@ -1427,7 +1427,7 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
       }
       vmcase(OP_CLOSE) {
         L->top = ra + 1;  /* everything is free after this slot */
-        ProtectNT(luaF_close(L, ra, LUA_OK));
+        Protect(luaF_close(L, ra, LUA_OK));
         vmbreak;
       }
       vmcase(OP_TBC) {
@@ -1717,9 +1717,8 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
         vmbreak;
       }
       vmcase(OP_TFORPREP) {
-        /* is 'toclose' a function or has a '__close' metamethod? */
-        if (ttisfunction(s2v(ra + 3)) ||
-            !ttisnil(luaT_gettmbyobj(L, s2v(ra + 3), TM_CLOSE))) {
+        /* is 'toclose' not nil? */
+        if (!ttisnil(s2v(ra + 3))) {
           /* create to-be-closed upvalue for it */
           halfProtect(luaF_newtbcupval(L, ra + 3));
         }