1469 - warn when calling macros with spliced args

Author: akkartik

008eval.cc

@@ -155,6 +155,7 @@ Cell* reorderKeywordArgs(Cell* params, Cell* args) {
                                         addCons(curr, arg);
                                         continue;
                                       }
+                                      RAISE << "calling macros with splice can have subtle effects (http://arclanguage.org/item?id=15659)" << endl;
                                       Cell* newLimb = unsplice(arg);
                                       setCdr(curr, newLimb);
                                       rmref(newLimb);
@@ -167,6 +168,8 @@ Cell* reorderKeywordArgs(Cell* params, Cell* args) {
                                     Cell* result = unsplice(car(args));
                                     if (result == nil)
                                       return evalArgs(params, cdr(args));
+                                    if (isCons(params) ? isQuoted(car(params)) : isQuoted(params))
+                                      RAISE << "calling macros with splice can have subtle effects (http://arclanguage.org/item?id=15659)" << endl;
                                     Cell* curr = result;
                                     for (; cdr(curr) != nil; curr=cdr(curr))
                                       params=cdr(params); // don't eval spliced args again, even if param is unquoted

008eval.test.cc

@@ -88,7 +88,24 @@ void test_evalArgs_handles_quoted_rest_param() {
   endDynamicScope("a");
 }
 
-void test_evalArgs_handles_spliced_vararg_arg() {
+void test_evalArgs_handles_spliced_arg_for_vararg_param() {
+  newDynamicScope("a", newNum(3));
+  newDynamicScope("b", newCons(newNum(4), newCons(newNum(5), nil)));
+  Cell* params = read(stream("x"));
+  Cell* args = read(stream("(a @b)"));
+  Cell* evaldArgs = evalArgs(params, args);
+  checkEq(car(evaldArgs), newNum(3));
+  checkEq(car(cdr(evaldArgs)), newNum(4));
+  checkEq(car(cdr(cdr(evaldArgs))), newNum(5));
+  checkEq(cdr(cdr(cdr(evaldArgs))), nil);
+  rmref(evaldArgs);
+  rmref(args);
+  rmref(params);
+  endDynamicScope("b");
+  endDynamicScope("a");
+}
+
+void test_evalArgs_handles_spliced_arg_for_quoted_vararg_param() {
   newDynamicScope("a", newNum(3));
   newDynamicScope("b", newCons(newNum(4), newCons(newNum(5), nil)));
   Cell* params = read(stream("'x"));
@@ -103,6 +120,8 @@ void test_evalArgs_handles_spliced_vararg_arg() {
   rmref(params);
   endDynamicScope("b");
   endDynamicScope("a");
+  checkEq(errorCount, 1); // raised warning
+  errorCount = 0;
 }
 
 void test_evalArgs_handles_spliced_arg() {