[PATCH 2/2] [gdb/build] Return const reference in thread_info_to_thread_handle

[Pedro Alves]

On 2023-08-21 11:53, Tom de Vries via Gdb-patches wrote:
> In remote_target::thread_info_to_thread_handle we return a copy:
> ...
> gdb::byte_vector
> remote_target::thread_info_to_thread_handle (struct thread_info *tp)
> {
>   remote_thread_info *priv = get_remote_thread_info (tp);
>   return priv->thread_handle;
> }
> ...
> 
> Fix this by returning a const reference instead:
> ...
> const gdb::optional<gdb::byte_vector> &
> remote_target::thread_info_to_thread_handle (struct thread_info *tp)
> ...
> 
> Returning a gdb::optional allows us to return a nullptr, or std::nullopt in
> std::optional terms, something that is required by
> thread_db_target::thread_info_to_thread_handle.
> 
> In gdb we use gdb::optional instead std::optional, because std::optional is
> availabe starting c++17 and we support c++11 and c++14, but gdb::nullopt is
> currently not available, though a submission is available [1].
> 
> So we use a kludge gdb_optional_byte_vector_nullopt.
> 

IMHO making the function return gdb::array_view<const gdb_byte>
would be even better.  Then the byte_vector is completely an implementation 
detail, and, you wouldn't need to wrap with optional, as you could just
return an empty array_view, like currently we return an empty byte_vector.