updated main()

git-svn-id: svn://anubis/misc/llvm@74 bd8a9e45-a331-0410-811e-c64571078777

jlc/jlc.yy

@@ -1,6 +1,8 @@
 
 %{
 #include <stdio.h>
+#include <iostream>
+using namespace std;
 
 extern "C" {
     int yylex(void);
@@ -153,6 +155,11 @@ int main(int argc, char * argv[])
     if (argc > 0)
     {
         yyin = fopen(argv[1], "r");
+        if (yyin == NULL)
+        {
+            cerr << "Failed to open file '" << argv[1] << "'" << endl;
+            return -1;
+        }
     }
     yyparse();
 }