commit 4bd10b6fe81c0a56eb9e01e24fba10e655966870
parent 59e565d9555c07e82808d8c1db8f4f4d159b5e5c
Author: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Tue, 29 Dec 2020 13:15:27 -0300
Better error messages for calling non-callable objects
When available, use the calling code to find a suitable name for what
was being called; this is particularly useful for errors of non-callable
metamethods. This commit also improved the debug information for
order metamethods.
Diffstat:
6 files changed, 52 insertions(+), 11 deletions(-)
diff --git a/ldebug.c b/ldebug.c
@@ -629,12 +629,10 @@ static const char *funcnamefromcode (lua_State *L, CallInfo *ci,
case OP_LEN: tm = TM_LEN; break;
case OP_CONCAT: tm = TM_CONCAT; break;
case OP_EQ: tm = TM_EQ; break;
- case OP_LT: case OP_LE: case OP_LTI: case OP_LEI:
- *name = "order"; /* '<=' can call '__lt', etc. */
- return "metamethod";
- case OP_CLOSE: case OP_RETURN:
- *name = "close";
- return "metamethod";
+ /* no cases for OP_EQI and OP_EQK, as they don't call metamethods */
+ case OP_LT: case OP_LTI: case OP_GTI: tm = TM_LT; break;
+ case OP_LE: case OP_LEI: case OP_GEI: tm = TM_LE; break;
+ case OP_CLOSE: case OP_RETURN: tm = TM_CLOSE; break;
default:
return NULL; /* cannot find a reasonable name */
}
@@ -697,6 +695,19 @@ l_noret luaG_typeerror (lua_State *L, const TValue *o, const char *op) {
}
+l_noret luaG_callerror (lua_State *L, const TValue *o) {
+ CallInfo *ci = L->ci;
+ const char *name = NULL; /* to avoid warnings */
+ const char *what = (isLua(ci)) ? funcnamefromcode(L, ci, &name) : NULL;
+ if (what != NULL) {
+ const char *t = luaT_objtypename(L, o);
+ luaG_runerror(L, "%s '%s' is not callable (a %s value)", what, name, t);
+ }
+ else
+ luaG_typeerror(L, o, "call");
+}
+
+
l_noret luaG_forerror (lua_State *L, const TValue *o, const char *what) {
luaG_runerror(L, "bad 'for' %s (number expected, got %s)",
what, luaT_objtypename(L, o));
diff --git a/ldebug.h b/ldebug.h
@@ -31,6 +31,7 @@ LUAI_FUNC const char *luaG_findlocal (lua_State *L, CallInfo *ci, int n,
StkId *pos);
LUAI_FUNC l_noret luaG_typeerror (lua_State *L, const TValue *o,
const char *opname);
+LUAI_FUNC l_noret luaG_callerror (lua_State *L, const TValue *o);
LUAI_FUNC l_noret luaG_forerror (lua_State *L, const TValue *o,
const char *what);
LUAI_FUNC l_noret luaG_concaterror (lua_State *L, const TValue *p1,
diff --git a/ldo.c b/ldo.c
@@ -372,7 +372,7 @@ void luaD_tryfuncTM (lua_State *L, StkId func) {
const TValue *tm = luaT_gettmbyobj(L, s2v(func), TM_CALL);
StkId p;
if (unlikely(ttisnil(tm)))
- luaG_typeerror(L, s2v(func), "call"); /* nothing to call */
+ luaG_callerror(L, s2v(func)); /* nothing to call */
for (p = L->top; p > func; p--) /* open space for metamethod */
setobjs2s(L, p, p-1);
L->top++; /* stack space pre-allocated by the caller */
diff --git a/testes/db.lua b/testes/db.lua
@@ -823,8 +823,10 @@ assert(a + 30000 == "add" and a - 3.0 == "sub" and a * 3.0 == "mul" and
-a == "unm" and #a == "len" and a & 3 == "band")
assert(a|3 == "bor" and 3~a == "bxor" and a<<3 == "shl" and a>>1 == "shr")
assert (a==b and a.op == "eq")
-assert (a>=b and a.op == "order")
-assert (a>b and a.op == "order")
+assert (a>=b and a.op == "le")
+assert ("x">=a and a.op == "le")
+assert (a>b and a.op == "lt")
+assert (a>10 and a.op == "lt")
assert(~a == "bnot")
do -- testing for-iterator name
diff --git a/testes/errors.lua b/testes/errors.lua
@@ -24,8 +24,9 @@ local function doit (s)
end
-local function checkmessage (prog, msg)
+local function checkmessage (prog, msg, debug)
local m = doit(prog)
+ if debug then print(m) end
assert(string.find(m, msg, 1, true))
end
@@ -120,6 +121,17 @@ assert(not string.find(doit"a={13}; local bbbb=1; a[bbbb](3)", "'bbbb'"))
checkmessage("a={13}; local bbbb=1; a[bbbb](3)", "number")
checkmessage("a=(1)..{}", "a table value")
+-- calls
+checkmessage("local a; a(13)", "local 'a'")
+checkmessage([[
+ local a = setmetatable({}, {__add = 34})
+ a = a + 1
+]], "metamethod 'add'")
+checkmessage([[
+ local a = setmetatable({}, {__lt = {}})
+ a = a > a
+]], "metamethod 'lt'")
+
-- tail calls
checkmessage("local a={}; return a.bbbb(3)", "field 'bbbb'")
checkmessage("a={}; do local a=1 end; return a:bbbb(3)", "method 'bbbb'")
diff --git a/testes/locals.lua b/testes/locals.lua
@@ -459,7 +459,22 @@ do -- errors due to non-closable values
getmetatable(xyz).__close = nil -- remove metamethod
end
local stat, msg = pcall(foo)
- assert(not stat and string.find(msg, "attempt to call a nil value"))
+ assert(not stat and string.find(msg, "metamethod 'close'"))
+
+ local function foo ()
+ local a1 <close> = func2close(function (_, msg)
+ assert(string.find(msg, "number value"))
+ error(12)
+ end)
+ local a2 <close> = setmetatable({}, {__close = print})
+ local a3 <close> = func2close(function (_, msg)
+ assert(msg == nil)
+ error(123)
+ end)
+ getmetatable(a2).__close = 4 -- invalidate metamethod
+ end
+ local stat, msg = pcall(foo)
+ assert(not stat and msg == 12)
end
