Checking for calls to nonexistent functions.

eval_apply.cpp

@@ -6,7 +6,7 @@
 namespace Sass {
   using std::cerr; using std::endl;
   
-  void eval_error(string message, size_t line_number, const char* file_name)
+  static void eval_error(string message, size_t line_number, const char* file_name)
   {
     string fn;
     if (file_name) {
@@ -212,6 +212,11 @@ namespace Sass {
       case Node::function_call: {
         // TO DO: default-constructed Function should be a generic callback
         pair<string, size_t> sig(expr[0].content.token.to_string(), expr[1].size());
+        if (!f_env.count(sig)) {
+          stringstream ss;
+          ss << "no function named " << expr[0].content.token.to_string() << " taking " << expr[1].size() << " arguments has been defined";
+          eval_error(ss.str(), expr.line_number, expr.file_name);
+        }
         return apply_function(f_env[sig], expr[1], env, f_env);
       } break;