basic: CALL: fix yet another stack frame bug (with test)

We cannot modify the stack indices while evaluating arguments because
that would break references to local variables of the caller. That
means, however, that we also cannot push evaluated parameters on the
stack because they may be overwritten by functions called while evaluating
subsequent parameters.

We avoid this by storing parameters in temporary lists.

XXX: Probably not good for performance...

Author: Ulrich Hecht

tests/eb/fntest3.bas

@@ -0,0 +1,17 @@
+10 ' make sure CALL parameters that contain function evaluations
+20 ' do not overwrite previously evaluated parameters
+90 DIM cols(11,20)
+100 GOTO 900
+270 PROC setfield(of,v)
+272 cols((@of+1) MOD 40,@of/40)=@v
+276 RETURN 
+280 PROC getfield(of)
+282 RETURN cols((@of+1) MOD 40,@of/40)
+900 FOR x=0 TO 11:FOR y=0 TO 20
+910     cols(x,y)=x*1000+y
+920   NEXT:NEXT 
+1000 FOR x=0 TO 9:FOR yy=640 TO 40 STEP -40
+1010     CALL setfield(yy+x,FN getfield(yy+x-40))
+1020     IF FN getfield(yy+x-40)<>FN getfield(yy+x) THEN STOP 
+1030   NEXT:NEXT 
+1040 PRINT "we're fine"

tests/eb/fntest3.run

@@ -0,0 +1 @@
+we're fine

ttbasic/basic.cpp

@@ -5983,22 +5983,25 @@ void BASIC_FP icall() {
   }
   if (*cip == I_OPEN) {
     ++cip;
+    QList<BString> strargs;
+    QList<num_t> numargs;
+
     if (*cip != I_CLOSE) for(;;) {
       if (is_strexp()) {
         BString b = istrexp();
         if (err)
           return;
         if (new_astk_str_i >= SIZE_ASTK)
           goto overflow;
-        astk_str[new_astk_str_i++] = b;
+        strargs.push_back(b);
         ++str_args;
       } else {
         n = iexp();
         if (err)
           return;
         if (new_astk_num_i >= SIZE_ASTK)
           goto overflow;
-        astk_num[new_astk_num_i++] = n;
+        numargs.push_back(n);
         ++num_args;
       }
       if (*cip != I_COMMA)
@@ -6008,6 +6011,13 @@ void BASIC_FP icall() {
 
     if (checkClose())
       return;
+
+    for (int i = 0; i < strargs.size(); ++i) {
+      astk_str[new_astk_str_i++] = strargs[i];
+    }
+    for (int i = 0; i < numargs.size(); ++i) {
+      astk_num[new_astk_num_i++] = numargs[i];
+    }
   }
   astk_num_i = new_astk_num_i;
   astk_str_i = new_astk_str_i;