Introduce "static constructor" for mi_parse

Change the mi_parse function to be a static method of mi_parse.  This
lets us remove the 'set_args' setter function.

gdb/mi/mi-main.c

@@ -1919,7 +1919,7 @@ mi_execute_command (const char *cmd, int from_tty)
 
   try
     {
-      command = mi_parse (cmd, &token);
+      command = mi_parse::make (cmd, &token);
     }
   catch (const gdb_exception &exception)
     {

gdb/mi/mi-parse.c

@@ -109,7 +109,7 @@ mi_parse_escape (const char **string_ptr)
 void
 mi_parse::parse_argv ()
 {
-  const char *chp = m_args.get ();
+  const char *chp = m_args.c_str ();
   int argc = 0;
   char **argv = XNEWVEC (char *, argc + 1);
 
@@ -216,7 +216,7 @@ mi_parse::~mi_parse ()
 }
 
 std::unique_ptr<struct mi_parse>
-mi_parse (const char *cmd, char **token)
+mi_parse::make (const char *cmd, char **token)
 {
   const char *chp;
 
@@ -345,7 +345,7 @@ mi_parse (const char *cmd, char **token)
     }
 
   /* Save the rest of the arguments for the command.  */
-  parse->set_args (chp);
+  parse->m_args = chp;
 
   /* Fully parsed, flag as an MI command.  */
   parse->op = MI_COMMAND;

gdb/mi/mi-parse.h

@@ -41,7 +41,17 @@ enum mi_command_type
 
 struct mi_parse
   {
-    mi_parse () = default;
+    /* Attempts to parse CMD returning a ``struct mi_parse''.  If CMD is
+       invalid, an exception is thrown.  For an MI_COMMAND COMMAND, ARGS
+       and OP are initialized.  Un-initialized fields are zero.  *TOKEN is
+       set to the token, even if an exception is thrown.  It is allocated
+       with xmalloc; it must either be freed with xfree, or assigned to
+       the TOKEN field of the resultant mi_parse object, to be freed by
+       mi_parse_free.  */
+
+    static std::unique_ptr<struct mi_parse> make (const char *cmd,
+						  char **token);
+
     ~mi_parse ();
 
     DISABLE_COPY_AND_ASSIGN (mi_parse);
@@ -54,9 +64,6 @@ struct mi_parse
     const char *args () const
     { return m_args.c_str (); }
 
-    void set_args (const char *args)
-    { m_args = args; }
-
     enum mi_command_type op = MI_COMMAND;
     char *command = nullptr;
     char *token = nullptr;
@@ -75,20 +82,11 @@ struct mi_parse
 
   private:
 
+    mi_parse () = default;
+
     std::string m_args;
   };
 
-/* Attempts to parse CMD returning a ``struct mi_parse''.  If CMD is
-   invalid, an exception is thrown.  For an MI_COMMAND COMMAND, ARGS
-   and OP are initialized.  Un-initialized fields are zero.  *TOKEN is
-   set to the token, even if an exception is thrown.  It is allocated
-   with xmalloc; it must either be freed with xfree, or assigned to
-   the TOKEN field of the resultant mi_parse object, to be freed by
-   mi_parse_free.  */
-
-extern std::unique_ptr<struct mi_parse> mi_parse (const char *cmd,
-						  char **token);
-
 /* Parse a string argument into a print_values value.  */
 
 enum print_values mi_parse_print_values (const char *name);