From 5894ca7b95d7fb05f1e93ee77e849a8d816d1c6d Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Mon, 30 Dec 2024 16:53:51 -0300
Subject: [PATCH] Scanner doesn't need to anchor reserved words

---
 llex.c    | 30 +++++++++++++++++++-----------
 lstring.h |  2 +-
 2 files changed, 20 insertions(+), 12 deletions(-)

diff --git a/llex.c b/llex.c
index d913db17..3518f0da 100644
--- a/llex.c
+++ b/llex.c
@@ -127,21 +127,20 @@ l_noret luaX_syntaxerror (LexState *ls, const char *msg) {
 
 
 /*
-** Creates a new string and anchors it in scanner's table so that it
-** will not be collected until the end of the compilation; by that time
-** it should be anchored somewhere. It also internalizes long strings,
-** ensuring there is only one copy of each unique string.
+** Anchors a string in scanner's table so that it will not be collected
+** until the end of the compilation; by that time it should be anchored
+** somewhere. It also internalizes long strings, ensuring there is only
+** one copy of each unique string.
 */
-TString *luaX_newstring (LexState *ls, const char *str, size_t l) {
+static TString *anchorstr (LexState *ls, TString *ts) {
   lua_State *L = ls->L;
-  TString *ts = luaS_newlstr(L, str, l);  /* create new string */
   TValue oldts;
   int tag = luaH_getstr(ls->h, ts, &oldts);
   if (!tagisempty(tag))  /* string already present? */
     return tsvalue(&oldts);  /* use stored value */
   else {  /* create a new entry */
     TValue *stv = s2v(L->top.p++);  /* reserve stack space for string */
-    setsvalue(L, stv, ts);  /* temporarily anchor the string */
+    setsvalue(L, stv, ts);  /* push (anchor) the string on the stack */
     luaH_set(L, ls->h, stv, stv);  /* t[string] = string */
     /* table is not a metatable, so it does not need to invalidate cache */
     luaC_checkGC(L);
@@ -151,6 +150,14 @@ TString *luaX_newstring (LexState *ls, const char *str, size_t l) {
 }
 
 
+/*
+** Creates a new string and anchors it in scanner's table.
+*/
+TString *luaX_newstring (LexState *ls, const char *str, size_t l) {
+  return anchorstr(ls, luaS_newlstr(ls->L, str, l));
+}
+
+
 /*
 ** increment line number and skips newline sequence (any of
 ** \n, \r, \n\r, or \r\n)
@@ -544,12 +551,13 @@ static int llex (LexState *ls, SemInfo *seminfo) {
           do {
             save_and_next(ls);
           } while (lislalnum(ls->current));
-          ts = luaX_newstring(ls, luaZ_buffer(ls->buff),
-                                  luaZ_bufflen(ls->buff));
-          seminfo->ts = ts;
-          if (isreserved(ts))  /* reserved word? */
+          /* find or create string */
+          ts = luaS_newlstr(ls->L, luaZ_buffer(ls->buff),
+                                   luaZ_bufflen(ls->buff));
+          if (isreserved(ts))   /* reserved word? */
             return ts->extra - 1 + FIRST_RESERVED;
           else {
+            seminfo->ts = anchorstr(ls, ts);
             return TK_NAME;
           }
         }
diff --git a/lstring.h b/lstring.h
index 26f4b8e1..1751e043 100644
--- a/lstring.h
+++ b/lstring.h
@@ -45,7 +45,7 @@
 /*
 ** test whether a string is a reserved word
 */
-#define isreserved(s)	((s)->tt == LUA_VSHRSTR && (s)->extra > 0)
+#define isreserved(s)	(strisshr(s) && (s)->extra > 0)
 
 
 /*