print message once

src/ast/ast.h

@@ -10,6 +10,8 @@
 namespace bpftrace {
 namespace ast {
 
+static bool PRINT_STACK_DEPRICATED = true;
+
 class Visitor;
 
 class Node {
@@ -59,8 +61,12 @@ class Builtin : public Expression {
 public:
   explicit Builtin(std::string ident) : ident(ident) {
     if (ident == "stack") {
-      std::cout << "\033[33mwarning: \033[0m";
-      std::cout << "stack is deprecated and will be removed in the future. Use kstack instead" << std::endl;
+      if (PRINT_STACK_DEPRICATED)
+      {
+        std::cerr << "warning: stack is deprecated and will be removed in the future. Use kstack instead" << std::endl;
+        PRINT_STACK_DEPRICATED = false;
+      }
+
       this->ident = "kstack";
     }
   }