From 066e0f93c4901e601d93e31fb700f8f66f95feb8 Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Tue, 14 Dec 2021 12:50:05 -0300
Subject: Fix debug information about finalizers

The flag CIST_FIN does not mark a finalizer, but the function that was
running when the finalizer was called. (So, the function did not call
the finalizer, but it looks that way in the stack.)
---
 ldebug.c | 54 +++++++++++++++++++++++++++++++-----------------------
 1 file changed, 31 insertions(+), 23 deletions(-)

(limited to 'ldebug.c')

diff --git a/ldebug.c b/ldebug.c
index dc5f78c6..a716d95e 100644
--- a/ldebug.c
+++ b/ldebug.c
@@ -34,8 +34,8 @@
 #define noLuaClosure(f)		((f) == NULL || (f)->c.tt == LUA_VCCL)
 
 
-static const char *funcnamefromcode (lua_State *L, CallInfo *ci,
-                                    const char **name);
+static const char *funcnamefromcall (lua_State *L, CallInfo *ci,
+                                                   const char **name);
 
 
 static int currentpc (CallInfo *ci) {
@@ -317,15 +317,9 @@ static void collectvalidlines (lua_State *L, Closure *f) {
 
 
 static const char *getfuncname (lua_State *L, CallInfo *ci, const char **name) {
-  if (ci == NULL)  /* no 'ci'? */
-    return NULL;  /* no info */
-  else if (ci->callstatus & CIST_FIN) {  /* is this a finalizer? */
-    *name = "__gc";
-    return "metamethod";  /* report it as such */
-  }
-  /* calling function is a known Lua function? */
-  else if (!(ci->callstatus & CIST_TAIL) && isLua(ci->previous))
-    return funcnamefromcode(L, ci->previous, name);
+  /* calling function is a known function? */
+  if (ci != NULL && !(ci->callstatus & CIST_TAIL))
+    return funcnamefromcall(L, ci->previous, name);
   else return NULL;  /* no way to find a name */
 }
 
@@ -597,16 +591,10 @@ static const char *getobjname (const Proto *p, int lastpc, int reg,
 ** Returns what the name is (e.g., "for iterator", "method",
 ** "metamethod") and sets '*name' to point to the name.
 */
-static const char *funcnamefromcode (lua_State *L, CallInfo *ci,
-                                     const char **name) {
+static const char *funcnamefromcode (lua_State *L, const Proto *p,
+                                     int pc, const char **name) {
   TMS tm = (TMS)0;  /* (initial value avoids warnings) */
-  const Proto *p = ci_func(ci)->p;  /* calling function */
-  int pc = currentpc(ci);  /* calling instruction index */
   Instruction i = p->code[pc];  /* calling instruction */
-  if (ci->callstatus & CIST_HOOKED) {  /* was it called inside a hook? */
-    *name = "?";
-    return "hook";
-  }
   switch (GET_OPCODE(i)) {
     case OP_CALL:
     case OP_TAILCALL:
@@ -643,6 +631,26 @@ static const char *funcnamefromcode (lua_State *L, CallInfo *ci,
   return "metamethod";
 }
 
+
+/*
+** Try to find a name for a function based on how it was called.
+*/
+static const char *funcnamefromcall (lua_State *L, CallInfo *ci,
+                                                   const char **name) {
+  if (ci->callstatus & CIST_HOOKED) {  /* was it called inside a hook? */
+    *name = "?";
+    return "hook";
+  }
+  else if (ci->callstatus & CIST_FIN) {  /* was it called as a finalizer? */
+    *name = "__gc";
+    return "metamethod";  /* report it as such */
+  }
+  else if (isLua(ci))
+    return funcnamefromcode(L, ci_func(ci)->p, currentpc(ci), name);
+  else
+    return NULL;
+}
+
 /* }====================================================== */
 
 
@@ -728,14 +736,14 @@ l_noret luaG_typeerror (lua_State *L, const TValue *o, const char *op) {
 
 
 /*
-** Raise an error for calling a non-callable object. Try to find
-** a name for the object based on the code that made the call
-** ('funcnamefromcode'); if it cannot get a name there, try 'varinfo'.
+** Raise an error for calling a non-callable object. Try to find a name
+** for the object based on how it was called ('funcnamefromcall'); if it
+** cannot get a name there, try 'varinfo'.
 */
 l_noret luaG_callerror (lua_State *L, const TValue *o) {
   CallInfo *ci = L->ci;
   const char *name = NULL;  /* to avoid warnings */
-  const char *kind = (isLua(ci)) ? funcnamefromcode(L, ci, &name) : NULL;
+  const char *kind = funcnamefromcall(L, ci, &name);
   const char *extra = kind ? formatvarinfo(L, kind, name) : varinfo(L, o);
   typeerror(L, o, "call", extra);
 }
-- 
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