Fixed wrong error message in 'return math.seed(0)'

Bug introduced in commit 28d829c8: OP_TAILCALL might raise an
error without saving 'pc'. (This commit also fixes a detail in
'testes/uf8.lua'.)

lvm.c

@@ -1556,20 +1556,22 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
           L->top = ra + b;
         else  /* previous instruction set top */
           b = cast_int(L->top - ra);
+        savepc(ci);  /* some calls here can raise errors */
         if (TESTARG_k(i)) {
           int nparams1 = GETARG_C(i);
           if (nparams1)  /* vararg function? */
             delta = ci->u.l.nextraargs + nparams1;
-          /* close upvalues from current call */
+          /* close upvalues from current call; the compiler ensures
-          luaF_close(L, base, LUA_OK);
+             that there are no to-be-closed variables here */
-          updatestack(ci);
+          luaF_close(L, base, NOCLOSINGMETH);
         }
         if (!ttisfunction(s2v(ra))) {  /* not a function? */
           luaD_tryfuncTM(L, ra);  /* try '__call' metamethod */
           b++;  /* there is now one extra argument */
         }
         if (!ttisLclosure(s2v(ra))) {  /* C function? */
-          ProtectNT(luaD_call(L, ra, LUA_MULTRET));  /* call it */
+          luaD_call(L, ra, LUA_MULTRET);  /* call it */
+          updatetrap(ci);
           updatestack(ci);  /* stack may have been relocated */
           ci->func -= delta;
           luaD_poscall(L, ci, cast_int(L->top - ra));

testes/errors.lua

@@ -99,6 +99,10 @@ 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")
 
+-- tail calls
+checkmessage("local a={}; return a.bbbb(3)", "field 'bbbb'")
+checkmessage("a={}; do local a=1 end; return a:bbbb(3)", "method 'bbbb'")
+
 checkmessage("a = #print", "length of a function value")
 checkmessage("a = #3", "length of a number value")
 

testes/utf8.lua

@@ -66,7 +66,7 @@ local function check (s, t, nonstrict)
    assert(utf8.len(s, pi, pi1 - 1, nonstrict) == 1)
    assert(utf8.len(s, pi, -1, nonstrict) == l - i + 1)
    assert(utf8.len(s, pi1, -1, nonstrict) == l - i)
-   assert(utf8.len(s, 1, pi, -1, nonstrict) == i)
+   assert(utf8.len(s, 1, pi, nonstrict) == i)
   end
 
   local i = 0