options: add automagic hack for handling sub-option deprecations

I decided that it's too much work to convert all the VO/AOs to the new
option system manually at once. So here's a shitty hack instead, which
achieves almost the same thing. (The only user-visible difference is
that e.g. --vo=name:help will list the sub-options normally, instead of
showing them as deprecation placeholders. Also, the sub-option parser
will verify each option normally, instead of deferring to the global
option parser.)

Another advantage is that once we drop the deprecated options,
converting the remaining things will be easier, because we obviously
don't need to add the compatibility hacks.

Using this mechanism is separate in the next commit to keep the diff
noise down.

1 files changed, 4 insertions, 0 deletions

diff --git a/options/m_option.h b/options/m_option.h
index 48afc23df7..024b62521a 100644
--- a/options/m_option.h
+++ b/options/m_option.h
@@ -132,6 +132,10 @@ struct m_obj_desc {
     const char *replaced_name;
     // For convenience: these are added as global command-line options.
     const struct m_sub_options *global_opts;
+    // Evil hack to essentially force-move .options to global_opts. All options
+    // will be added as global options with the given prefix, and using
+    // sub-options will be treated as deprecated and redirected.
+    const char *legacy_prefix;
 };
 
 // Extra definition needed for \ref m_option_type_obj_settings_list options.