feat(api): pass 0 to nvim_get_chan_info for current channel (#27321)

Getting current channel info was kind of annoying via RPC. Two
functions had to be called:
1. `nvim_get_api_info` which returns `[channel_id, meta_data]`.
  - This results in `channel_id = api.nvim_get_api_info()[0]`.
  - Here the meta_data is sent but never used.
2. Finally call `nvim_get_chan_info(channel_id)`.

This commit reduces the need for `nvim_get_api_info` as passing 0
returns current channel info.

1 files changed, 7 insertions, 1 deletions

diff --git a/src/nvim/api/vim.c b/src/nvim/api/vim.c
index edee50f411..b1bfdd79e7 100644
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -1612,6 +1612,7 @@ void nvim_set_client_info(uint64_t channel_id, String name, Dictionary version,
 
 /// Gets information about a channel.
 ///
+/// @param chan channel_id, or 0 for current channel
 /// @returns Dictionary describing a channel, with these keys:
 ///    - "id"       Channel id.
 ///    - "argv"     (optional) Job arguments list.
@@ -1633,12 +1634,17 @@ void nvim_set_client_info(uint64_t channel_id, String name, Dictionary version,
 ///                 the RPC channel), if provided by it via
 ///                 |nvim_set_client_info()|.
 ///
-Dictionary nvim_get_chan_info(Integer chan, Error *err)
+Dictionary nvim_get_chan_info(uint64_t channel_id, Integer chan, Error *err)
   FUNC_API_SINCE(4)
 {
   if (chan < 0) {
     return (Dictionary)ARRAY_DICT_INIT;
   }
+
+  if (chan == 0 && !is_internal_call(channel_id)) {
+    assert(channel_id <= INT64_MAX);
+    chan = (Integer)channel_id;
+  }
   return channel_info((uint64_t)chan);
 }