From daf09c476fe375d8a9a47bc1294a1cd430290226 Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Thu, 10 Aug 2000 16:50:47 -0300
Subject: still better error messages

---
 lcode.c  |  5 ++--
 ldebug.c | 84 +++++++++++++++++++++++++++++++---------------------------------
 ldebug.h |  6 ++---
 ldo.c    |  4 ++--
 lvm.c    | 34 +++++++++++++++-----------
 5 files changed, 67 insertions(+), 66 deletions(-)

diff --git a/lcode.c b/lcode.c
index 08068f01..33236931 100644
--- a/lcode.c
+++ b/lcode.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lcode.c,v 1.45 2000/08/09 14:49:13 roberto Exp roberto $
+** $Id: lcode.c,v 1.46 2000/08/09 19:16:57 roberto Exp roberto $
 ** Code generator for Lua
 ** See Copyright Notice in lua.h
 */
@@ -333,7 +333,6 @@ void luaK_tostack (LexState *ls, expdesc *v, int onlyone) {
           luaK_deltastack(fs, -1);  /* next PUSHes may be skipped */
         }
         p_nil = code_label(fs, OP_PUSHNILJMP, 0);
-        luaK_deltastack(fs, -1);  /* next PUSH is skipped */
         p_1 = code_label(fs, OP_PUSHINT, 1);
         luaK_patchlist(fs, j, luaK_getlabel(fs));
       }
@@ -690,7 +689,7 @@ const struct OpProperties luaK_opproperties[NUM_OPCODES] = {
   {iS, 0, 1},	/* OP_JMPONT */
   {iS, 0, 1},	/* OP_JMPONF */
   {iS, 0, 0},	/* OP_JMP */
-  {iO, 1, 0},	/* OP_PUSHNILJMP */
+  {iO, 0, 0},	/* OP_PUSHNILJMP */
   {iS, 0, 0},	/* OP_FORPREP */
   {iS, 0, 3},	/* OP_FORLOOP */
   {iS, 3, 0},	/* OP_LFORPREP */
diff --git a/ldebug.c b/ldebug.c
index 57d01b49..e81661e2 100644
--- a/ldebug.c
+++ b/ldebug.c
@@ -1,5 +1,5 @@
 /*
-** $Id: ldebug.c,v 1.30 2000/08/08 20:42:07 roberto Exp roberto $
+** $Id: ldebug.c,v 1.31 2000/08/09 19:16:57 roberto Exp roberto $
 ** Debug Interface
 ** See Copyright Notice in lua.h
 */
@@ -57,7 +57,7 @@ lua_Hook lua_setlinehook (lua_State *L, lua_Hook func) {
 
 static StkId aux_stackedfunction (lua_State *L, int level, StkId top) {
   int i;
-  for (i = (top-1)-L->stack; i>=0; i--) {
+  for (i = (top-1) - L->stack; i>=0; i--) {
     if (is_T_MARK(L->stack[i].ttype)) {
       if (level == 0)
         return L->stack+i;
@@ -214,7 +214,7 @@ static const char *travglobals (lua_State *L, const TObject *o) {
 }
 
 
-static void lua_getobjname (lua_State *L, StkId f, lua_Debug *ar) {
+static void lua_getname (lua_State *L, StkId f, lua_Debug *ar) {
   TObject o;
   setnormalized(&o, f);
   /* try to find a name for given function */
@@ -247,7 +247,7 @@ int lua_getinfo (lua_State *L, const char *what, lua_Debug *ar) {
         ar->nups = lua_nups(func);
         break;
       case 'n':
-        lua_getobjname(L, func, ar);
+        lua_getname(L, func, ar);
         break;
       case 'f':
         setnormalized(L->top, func);
@@ -267,8 +267,16 @@ int lua_getinfo (lua_State *L, const char *what, lua_Debug *ar) {
 ** =======================================================
 */
 
+
+static int pushpc (int *stack, int pc, int top, int n) {
+  while (n--)
+    stack[top++] = pc-1;
+  return top;
+}
+
+
 static Instruction luaG_symbexec (const Proto *pt, int lastpc, int stackpos) {
-  int stack[MAXSTACK];  /* stores last instruction that changes each value */
+  int stack[MAXSTACK];  /* stores last instruction that changed a stack entry */
   const Instruction *code = pt->code;
   int top = pt->numparams;
   int pc = 0;
@@ -276,7 +284,7 @@ static Instruction luaG_symbexec (const Proto *pt, int lastpc, int stackpos) {
     top++;  /* `arg' */
   while (pc < lastpc) {
     const Instruction i = code[pc++];
-    LUA_ASSERT(top <= pt->maxstacksize, "wrong stack");
+    LUA_ASSERT(0 <= top && top <= pt->maxstacksize, "wrong stack");
     switch (GET_OPCODE(i)) {
       case OP_RETURN: {
         LUA_ASSERT(top >= GETARG_U(i), "wrong stack");
@@ -287,9 +295,7 @@ static Instruction luaG_symbexec (const Proto *pt, int lastpc, int stackpos) {
         int nresults = GETARG_B(i);
         if (nresults == MULT_RET) nresults = 1;
         LUA_ASSERT(top >= GETARG_A(i), "wrong stack");
-        top = GETARG_A(i);
-        while (nresults--)
-          stack[top++] = pc-1;
+        top = pushpc(stack, pc, GETARG_A(i), nresults);
         break;
       }
       case OP_TAILCALL: {
@@ -298,9 +304,7 @@ static Instruction luaG_symbexec (const Proto *pt, int lastpc, int stackpos) {
         break;
       }
       case OP_PUSHNIL: {
-        int n;
-        for (n=0; n<GETARG_U(i); n++)
-          stack[top++] = pc-1;
+        top = pushpc(stack, pc, top, GETARG_U(i));
         break;
       }
       case OP_POP: {
@@ -321,33 +325,27 @@ static Instruction luaG_symbexec (const Proto *pt, int lastpc, int stackpos) {
         stack[top++] = pc-1;
         break;
       }
-      case OP_JMPONT:
-      case OP_JMPONF: {
-        int newpc = pc + GETARG_S(i);
-        if (lastpc < newpc)
-          top--;  /* original code did not jump; condition was false */
-        else {
-          stack[top-1] = pc-1;  /* value generated by or-and */
-          pc = newpc;  /* do the jump */
-        }
-        break;
-      }
-      case OP_PUSHNILJMP: {
-        break;  /* do not `push', to compensate next instruction */
-      }
       case OP_CLOSURE: {
         top -= GETARG_B(i);
         stack[top++] = pc-1;
         break;
       }
       default: {
-        int n;
-        LUA_ASSERT(luaK_opproperties[GET_OPCODE(i)].push != VD,
+        OpCode op = GET_OPCODE(i);
+        LUA_ASSERT(luaK_opproperties[op].push != VD,
                    "invalid opcode for default");
-        top -= luaK_opproperties[GET_OPCODE(i)].pop;
+        top -= luaK_opproperties[op].pop;
         LUA_ASSERT(top >= 0, "wrong stack");
-        for (n=0; n<luaK_opproperties[GET_OPCODE(i)].push; n++)
-          stack[top++] = pc-1;
+        top = pushpc(stack, pc, top, luaK_opproperties[op].push);
+        if (ISJUMP(op)) {
+          int newpc = pc + GETARG_S(i);
+          /* jump is forward and do not skip `lastpc'? */
+          if (pc < newpc && newpc <= lastpc) {
+            if (op == OP_JMPONT || op == OP_JMPONF)
+              stack[top++] = pc-1;  /* do not pop when jumping */
+            pc = newpc;  /* do the jump */
+          }
+        }
       }
     }
   }
@@ -355,7 +353,7 @@ static Instruction luaG_symbexec (const Proto *pt, int lastpc, int stackpos) {
 }
 
 
-static const char *getname (lua_State *L, StkId obj, const char **name) {
+static const char *getobjname (lua_State *L, StkId obj, const char **name) {
   StkId func = aux_stackedfunction(L, 0, obj);
   if (func == NULL || ttype(func) != TAG_LMARK)
     return NULL;  /* not a Lua function */
@@ -389,23 +387,21 @@ static const char *getname (lua_State *L, StkId obj, const char **name) {
 /* }====================================================== */
 
 
-static void call_index_error (lua_State *L, StkId o, const char *op,
-                              const char *tp) {
+void luaG_typeerror (lua_State *L, StkId o, const char *op) {
   const char *name;
-  const char *kind = getname(L, o, &name);
+  const char *kind = getobjname(L, o, &name);
+  const char *t = lua_type(L, o);
   if (kind)
-    luaL_verror(L, "%s `%s' is not a %s", kind, name, tp);
+    luaL_verror(L, "attempt to %.30s %.20s `%.40s' (a %.10s value)",
+                op, kind, name, t);
   else
-    luaL_verror(L, "attempt to %.10s a %.10s value", op, lua_type(L, o));
-}
-
-
-void luaG_callerror (lua_State *L, StkId func) {
-  call_index_error(L, func, "call", "function");
+    luaL_verror(L, "attempt to %.30s a %.10s value", op, t);
 }
 
 
-void luaG_indexerror (lua_State *L, StkId t) {
-  call_index_error(L, t, "index", "table");
+void luaG_binerror (lua_State *L, StkId p1, lua_Type t, const char *op) {
+  if (ttype(p1) == t) p1++;
+  LUA_ASSERT(ttype(p1) != t, "must be an error");
+  luaG_typeerror(L, p1, op);
 }
 
diff --git a/ldebug.h b/ldebug.h
index 15be1eb4..3db8976f 100644
--- a/ldebug.h
+++ b/ldebug.h
@@ -1,5 +1,5 @@
 /*
-** $Id: ldebug.h,v 1.2 2000/06/28 20:20:36 roberto Exp roberto $
+** $Id: ldebug.h,v 1.3 2000/08/08 18:26:05 roberto Exp roberto $
 ** Auxiliary functions from Debug Interface module
 ** See Copyright Notice in lua.h
 */
@@ -12,8 +12,8 @@
 #include "luadebug.h"
 
 
-void luaG_callerror (lua_State *L, StkId func);
-void luaG_indexerror (lua_State *L, StkId t);
+void luaG_typeerror (lua_State *L, StkId o, const char *op);
+void luaG_binerror (lua_State *L, StkId p1, lua_Type t, const char *op);
 int luaG_getline (int *lineinfo, int pc, int refline, int *refi);
 
 
diff --git a/ldo.c b/ldo.c
index a18dadd9..06eb0d2d 100644
--- a/ldo.c
+++ b/ldo.c
@@ -1,5 +1,5 @@
 /*
-** $Id: ldo.c,v 1.83 2000/08/08 20:42:07 roberto Exp roberto $
+** $Id: ldo.c,v 1.84 2000/08/09 19:16:57 roberto Exp roberto $
 ** Stack and Call structure of Lua
 ** See Copyright Notice in lua.h
 */
@@ -202,7 +202,7 @@ void luaD_call (lua_State *L, StkId func, int nResults) {
     default: { /* `func' is not a function; check the `function' tag method */
       const TObject *im = luaT_getimbyObj(L, func, IM_FUNCTION);
       if (ttype(im) == TAG_NIL)
-        luaG_callerror(L, func);
+        luaG_typeerror(L, func, "call");
       luaD_openstack(L, func);
       *func = *im;  /* tag method is the new function to be called */
       goto retry;   /* retry the call */
diff --git a/lvm.c b/lvm.c
index 86047f44..3152a74c 100644
--- a/lvm.c
+++ b/lvm.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lvm.c,v 1.123 2000/08/09 14:49:41 roberto Exp roberto $
+** $Id: lvm.c,v 1.124 2000/08/09 19:16:57 roberto Exp roberto $
 ** Lua virtual machine
 ** See Copyright Notice in lua.h
 */
@@ -121,7 +121,7 @@ void luaV_gettable (lua_State *L, StkId top) {
     im = luaT_getimbyObj(L, table, IM_GETTABLE);
     if (ttype(im) == TAG_NIL) {
       L->top = top;
-      luaG_indexerror(L, table);
+      luaG_typeerror(L, table, "index");
     }
   }
   else {  /* object is a table... */
@@ -156,7 +156,7 @@ void luaV_settable (lua_State *L, StkId t, StkId top) {
     L->top = top;
     im = luaT_getimbyObj(L, t, IM_SETTABLE);
     if (ttype(im) == TAG_NIL)
-      luaG_indexerror(L, t);
+      luaG_typeerror(L, t, "index");
   }
   else {  /* object is a table... */
     im = luaT_getim(L, hvalue(t)->htag, IM_SETTABLE);
@@ -223,7 +223,7 @@ void luaV_setglobal (lua_State *L, TString *s, StkId top) {
 }
 
 
-static void call_binTM (lua_State *L, StkId top, IMS event, const char *msg) {
+static int call_binTM (lua_State *L, StkId top, IMS event) {
   /* try first operand */
   const TObject *im = luaT_getimbyObj(L, top-2, event);
   L->top = top;
@@ -232,16 +232,18 @@ static void call_binTM (lua_State *L, StkId top, IMS event, const char *msg) {
     if (ttype(im) == TAG_NIL) {
       im = luaT_getim(L, 0, event);  /* try a `global' method */
       if (ttype(im) == TAG_NIL)
-        lua_error(L, msg);
+        return 0;  /* error */
     }
   }
   lua_pushstring(L, luaT_eventname[event]);
   luaD_callTM(L, im, 3, 1);
+  return 1;
 }
 
 
 static void call_arith (lua_State *L, StkId top, IMS event) {
-  call_binTM(L, top, event, "unexpected type in arithmetic operation");
+  if (!call_binTM(L, top, event))
+    luaG_binerror(L, top-2, TAG_NUMBER, "perform arithmetic on");
 }
 
 
@@ -276,7 +278,8 @@ int luaV_lessthan (lua_State *L, const TObject *l, const TObject *r, StkId top)
     luaD_checkstack(L, 2);
     *top++ = *l;
     *top++ = *r;
-    call_binTM(L, top, IM_LT, "unexpected type in comparison");
+    if (!call_binTM(L, top, IM_LT))
+      lua_error(L, "unexpected type in comparison");
     L->top--;
     return (ttype(L->top) != TAG_NIL);
   }
@@ -286,8 +289,10 @@ int luaV_lessthan (lua_State *L, const TObject *l, const TObject *r, StkId top)
 static void strconc (lua_State *L, int total, StkId top) {
   do {
     int n = 2;  /* number of elements handled in this pass (at least 2) */
-    if (tostring(L, top-2) || tostring(L, top-1))
-      call_binTM(L, top, IM_CONCAT, "unexpected type for concatenation");
+    if (tostring(L, top-2) || tostring(L, top-1)) {
+      if (!call_binTM(L, top, IM_CONCAT))
+        luaG_binerror(L, top-2, TAG_STRING, "concat");
+    }
     else if (tsvalue(top-1)->u.s.len > 0) {  /* if len=0, do nothing */
       /* at least two string values; get as many as possible */
       lint32 tl = (lint32)tsvalue(top-1)->u.s.len + 
@@ -508,7 +513,7 @@ StkId luaV_execute (lua_State *L, const Closure *cl, StkId base) {
       }
 
       case OP_ADD:
-        if (tonumber(top-1) || tonumber(top-2))
+        if (tonumber(top-2) || tonumber(top-1))
           call_arith(L, top, IM_ADD);
         else
           nvalue(top-2) += nvalue(top-1);
@@ -526,7 +531,7 @@ StkId luaV_execute (lua_State *L, const Closure *cl, StkId base) {
         break;
 
       case OP_SUB:
-        if (tonumber(top-1) || tonumber(top-2))
+        if (tonumber(top-2) || tonumber(top-1))
           call_arith(L, top, IM_SUB);
         else
           nvalue(top-2) -= nvalue(top-1);
@@ -534,7 +539,7 @@ StkId luaV_execute (lua_State *L, const Closure *cl, StkId base) {
         break;
 
       case OP_MULT:
-        if (tonumber(top-1) || tonumber(top-2))
+        if (tonumber(top-2) || tonumber(top-1))
           call_arith(L, top, IM_MUL);
         else
           nvalue(top-2) *= nvalue(top-1);
@@ -542,7 +547,7 @@ StkId luaV_execute (lua_State *L, const Closure *cl, StkId base) {
         break;
 
       case OP_DIV:
-        if (tonumber(top-1) || tonumber(top-2))
+        if (tonumber(top-2) || tonumber(top-1))
           call_arith(L, top, IM_DIV);
         else
           nvalue(top-2) /= nvalue(top-1);
@@ -550,7 +555,8 @@ StkId luaV_execute (lua_State *L, const Closure *cl, StkId base) {
         break;
 
       case OP_POW:
-        call_binTM(L, top, IM_POW, "undefined operation");
+        if (!call_binTM(L, top, IM_POW))
+          lua_error(L, "undefined operation");
         top--;
         break;
 
-- 
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