Add nodiscard to piped_processt::send

To avoid missing error handling.

Author: thomasspriggs

src/util/piped_process.cpp

@@ -335,6 +335,7 @@ piped_processt::~piped_processt()
 #  endif
 }
 
+NODISCARD
 piped_processt::send_responset piped_processt::send(const std::string &message)
 {
   if(process_state != statet::RUNNING)

src/util/piped_process.h

@@ -13,6 +13,7 @@ typedef struct _PROCESS_INFORMATION PROCESS_INFORMATION; // NOLINT
 typedef void *HANDLE;                                    // NOLINT
 #endif
 
+#include "nodiscard.h"
 #include "optional.h"
 #include <vector>
 
@@ -42,7 +43,7 @@ class piped_processt
   /// Send a string message (command) to the child process.
   /// \param message The string message to be sent.
   /// \return
-  send_responset send(const std::string &message);
+  NODISCARD send_responset send(const std::string &message);
   /// Read a string from the child process' output.
   /// \return a string containing data from the process, empty string if no data
   std::string receive();