remove unneeded defer_spawn option from cpp-subprocess

For our use-case, there doesn't seem to be any need for this.

Author: theStack

src/util/subprocess.hpp

@@ -641,16 +641,6 @@ struct bufsize {
   int  bufsiz = 0;
 };
 
-/*!
- * Option to defer spawning of the child process
- * till `Popen::start_process` API is called.
- * Default value is false.
- */
-struct defer_spawn {
-  explicit defer_spawn(bool d): defer(d) {}
-  bool defer  = false;
-};
-
 /*!
  * Option to close all file descriptors
  * when the child process is spawned.
@@ -947,7 +937,6 @@ struct ArgumentDeducer
   void set_option(cwd&& cwdir);
   void set_option(bufsize&& bsiz);
   void set_option(environment&& env);
-  void set_option(defer_spawn&& defer);
   void set_option(input&& inp);
   void set_option(output&& out);
   void set_option(error&& err);
@@ -1153,8 +1142,6 @@ class Streams
                            in case of redirection. See piping examples.
  *12. error()            - Get the error channel/File pointer. Usually used
                            in case of redirection.
- *13. start_process()    - Start the child process. Only to be used when
- *                         `defer_spawn` option was provided in Popen constructor.
  */
 class Popen
 {
@@ -1172,7 +1159,7 @@ class Popen
     // Setup the communication channels of the Popen class
     stream_.setup_comm_channels();
 
-    if (!defer_process_start_) execute_process();
+    execute_process();
   }
 
   template <typename... Args>
@@ -1184,7 +1171,7 @@ class Popen
     // Setup the communication channels of the Popen class
     stream_.setup_comm_channels();
 
-    if (!defer_process_start_) execute_process();
+    execute_process();
   }
 
   template <typename... Args>
@@ -1195,7 +1182,7 @@ class Popen
     // Setup the communication channels of the Popen class
     stream_.setup_comm_channels();
 
-    if (!defer_process_start_) execute_process();
+    execute_process();
   }
 
 /*
@@ -1207,8 +1194,6 @@ class Popen
   }
 */
 
-  void start_process() noexcept(false);
-
   int pid() const noexcept { return child_pid_; }
 
   int retcode() const noexcept { return retcode_; }
@@ -1282,7 +1267,6 @@ class Popen
   std::future<void> cleanup_future_;
 #endif
 
-  bool defer_process_start_ = false;
   bool close_fds_ = false;
   bool session_leader_ = false;
 
@@ -1323,20 +1307,6 @@ inline void Popen::populate_c_argv()
   cargv_.push_back(nullptr);
 }
 
-inline void Popen::start_process() noexcept(false)
-{
-  // The process was started/tried to be started
-  // in the constructor itself.
-  // For explicitly calling this API to start the
-  // process, 'defer_spawn' argument must be set to
-  // true in the constructor.
-  if (!defer_process_start_) {
-    assert (0);
-    return;
-  }
-  execute_process();
-}
-
 inline int Popen::wait() noexcept(false)
 {
 #ifdef __USING_WINDOWS__
@@ -1594,10 +1564,6 @@ namespace detail {
     popen_->env_ = std::move(env.env_);
   }
 
-  inline void ArgumentDeducer::set_option(defer_spawn&& defer) {
-    popen_->defer_process_start_ = defer.defer;
-  }
-
   inline void ArgumentDeducer::set_option(session_leader&& sleader) {
     popen_->session_leader_ = sleader.leader_;
   }