print prompt in client on platform without readline

deps/common/lang/defer.h

@@ -26,8 +26,10 @@ public:
 
   ~DeferHelper()
   {
+    if (defer_) {
       defer_();
     }
+  }
 
 private:
   const std::function<void()> defer_;
@@ -35,8 +37,5 @@ private:
 
 } // namespace common
 
-#define AA(B, C) B##C
-#define BB(B, C) AA(B,C)
-#define DEFER(callback) common::DeferHelper BB(defer_helper_, __LINE__)(callback)
-#undef AA
-#undef BB
+#define DERFER_NAME(suffix) defer_helper_##suffix
+#define DEFER(callback) common::DeferHelper DERFER_NAME(__LINE__)(callback)

src/obclient/client.cpp

@@ -51,6 +51,7 @@ char *my_readline(const char *prompt)
     fprintf(stderr, "failed to alloc line buffer");
     return nullptr;
   }
+  fprintf(stdout, prompt);
   char *s = fgets(buffer, MAX_MEM_BUFFER_SIZE, stdin);
   if (nullptr == s) {
     fprintf(stderr, "failed to read message from console");