gdb: add string_file::release method

A common pattern for string_file is to want to move out the internal
string buffer, because it is the result of the computation that we want
to return.  It is the reason why string_file::string returns a non-const
reference, as explained in the comment.  I think it would make sense to
have a dedicated method for that instead and make string_file::string
return a const reference.

This allows removing the explicit std::move in the typical case.  Note
that compile_program::compute was missing a move, meaning that the
resulting string was copied.  With the new version, it's not possible to
forget to move.

Change-Id: Ieaefa35b73daa7930b2f3a26988b6e3b4121bb79

1 files changed, 5 insertions, 3 deletions

diff --git a/gdb/tui/tui-stack.c b/gdb/tui/tui-stack.c
index 0489a5f..be8ffbd 100644
--- a/gdb/tui/tui-stack.c
+++ b/gdb/tui/tui-stack.c
@@ -181,12 +181,14 @@ tui_locator_window::make_status_line () const
       string.puts (pc_buf);
     }
 
+  std::string string_val = string.release ();
+
   if (string.size () < status_size)
-    string.puts (n_spaces (status_size - string.size ()));
+    string_val.append (status_size - string.size (), ' ');
   else if (string.size () > status_size)
-    string.string ().erase (status_size, string.size ());
+    string_val.erase (status_size, string.size ());
 
-  return std::move (string.string ());
+  return string_val;
 }
 
 /* Get a printable name for the function at the address.  The symbol