4 files changed, 11 insertions, 7 deletions

diff --git a/lapi.c b/lapi.c
index 27bf23da..41e6b86d 100644
--- a/lapi.c
+++ b/lapi.c
@@ -39,7 +39,7 @@ const char lua_ident[] =
 
 
 /*
-** Test for a valid index.
+** Test for a valid index (one that is not the 'nilvalue').
 ** '!ttisnil(o)' implies 'o != &G(L)->nilvalue', so it is not needed.
 ** However, it covers the most common cases in a faster way.
 */
diff --git a/lmem.c b/lmem.c
index 43739bff..4822a0ea 100644
--- a/lmem.c
+++ b/lmem.c
@@ -29,7 +29,7 @@
 ** a full GC cycle at every allocation.)
 */
 static void *firsttry (global_State *g, void *block, size_t os, size_t ns) {
-  if (ttisnil(&g->nilvalue) && ns > os)
+  if (completestate(g) && ns > os)
     return NULL;  /* fail */
   else  /* normal allocation */
     return (*g->frealloc)(g->ud, block, os, ns);
@@ -146,7 +146,7 @@ void luaM_free_ (lua_State *L, void *block, size_t osize) {
 static void *tryagain (lua_State *L, void *block,
                        size_t osize, size_t nsize) {
   global_State *g = G(L);
-  if (ttisnil(&g->nilvalue)) {  /* is state fully build? */
+  if (completestate(g)) {  /* is state fully build? */
     luaC_fullgc(L, 1);  /* try to free some memory... */
     return (*g->frealloc)(g->ud, block, osize, nsize);  /* try again */
   }
diff --git a/lstate.c b/lstate.c
index c708a162..52336f44 100644
--- a/lstate.c
+++ b/lstate.c
@@ -226,8 +226,6 @@ static void init_registry (lua_State *L, global_State *g) {
 
 /*
 ** open parts of the state that may cause memory-allocation errors.
-** ('g->nilvalue' being a nil value flags that the state was completely
-** build.)
 */
 static void f_luaopen (lua_State *L, void *ud) {
   global_State *g = G(L);
@@ -238,7 +236,7 @@ static void f_luaopen (lua_State *L, void *ud) {
   luaT_init(L);
   luaX_init(L);
   g->gcrunning = 1;  /* allow gc */
-  setnilvalue(&g->nilvalue);
+  setnilvalue(&g->nilvalue);  /* now state is complete */
   luai_userstateopen(L);
 }
 
@@ -272,7 +270,7 @@ static void close_state (lua_State *L) {
   global_State *g = G(L);
   luaD_closeprotected(L, 0, LUA_OK);  /* close all upvalues */
   luaC_freeallobjects(L);  /* collect all objects */
-  if (ttisnil(&g->nilvalue))  /* closing a fully built state? */
+  if (completestate(g))  /* closing a fully built state? */
     luai_userstateclose(L);
   luaM_freearray(L, G(L)->strt.hash, G(L)->strt.size);
   freestack(L);
diff --git a/lstate.h b/lstate.h
index f3d791ab..5ef55355 100644
--- a/lstate.h
+++ b/lstate.h
@@ -324,6 +324,12 @@ struct lua_State {
 
 #define G(L)    (L->l_G)
 
+/*
+** 'g->nilvalue' being a nil value flags that the state was completely
+** build.
+*/
+#define completestate(g)        ttisnil(&g->nilvalue)
+
 
 /*
 ** Union of all collectable objects (only for conversions)