let's just use ((void *)-1) as another invalid pointer result

src/backends/llk.c

@@ -276,8 +276,7 @@ typedef struct {
 // execute on their corresponding result.
 // also on the stack below the mark, we store the previously accumulated
 // value for the surrounding production.
-static int dummy;
-static void *MARK = &dummy;   // stack frame delimiter
+static void *MARK = (void *)-1; // stack frame delimiter
 
 static HLLkState *llk_parse_start_(HAllocator* mm__, const HParser* parser)
 {
@@ -329,7 +328,7 @@ static HCountedArray *llk_parse_chunk_(HLLkState *s, const HParser* parser,
       const HCFSequence *p = h_llk_lookup(table, x, stream);
       if(p == NULL)
         goto no_parse;
-      if(p == H_NEED_INPUT)
+      if(p == NEED_INPUT)
         goto need_input;
 
       // an infinite loop case that shouldn't happen

src/cfgrammar.c

@@ -349,7 +349,7 @@ void *h_stringmap_get(const HStringMap *m, const uint8_t *str, size_t n, bool en
   return m->epsilon_branch;
 }
 
-// A NULL result means no parse. H_NEED_INPUT means lookahead is too short.
+// A NULL result means no parse. NEED_INPUT means lookahead is too short.
 void *h_stringmap_get_lookahead(const HStringMap *m, HInputStream lookahead)
 {
   while(m) {
@@ -368,7 +368,7 @@ void *h_stringmap_get_lookahead(const HStringMap *m, HInputStream lookahead)
         // XXX assumption of byte-wise grammar and input
         return m->end_branch;
       } else {
-        return H_NEED_INPUT;
+        return NEED_INPUT;
       }
     }
 

src/cfgrammar.h

@@ -57,7 +57,7 @@ static inline HStringMap *h_stringmap_get_char(const HStringMap *m, const uint8_
  { return h_hashtable_get(m->char_branches, (void *)char_key(c)); }
 
 // dummy return value used by h_stringmap_get_lookahead when out of input
-#define H_NEED_INPUT ((void *)&h_stringmap_get_lookahead)
+#define NEED_INPUT ((void *)-1)
 
 
 /* Convert 'parser' into CFG representation by desugaring and compiling the set