API: nvim_get_commands(): always return keys

- Always return all keys, with at least NIL value.
- Require `opts` param to be {"builtin":false}
- Validate `opts` param

src/nvim/api/buffer.c

@@ -479,12 +479,11 @@ ArrayOf(Dictionary) nvim_buf_get_keymap(Buffer buffer, String mode, Error *err)
   return keymap_array(mode, buf);
 }
 
-/// Gets a list of dictionaries describing buffer-local commands.
-/// The "buffer" key in the returned dictionary reflects the buffer
-/// handle where the command is present.
+/// Gets a list of maps describing buffer-local |user-commands|.
 ///
-/// @param  buffer     Buffer handle.
-/// @param  opts       Optional parameters, currently always 
+/// @param  buffer  Buffer handle.
+/// @param  opts  Optional parameters. Currently only supports
+///               {"builtin":false}
 /// @param[out]  err   Error details, if any.
 ///
 /// @returns Array of dictionaries describing commands.
@@ -492,6 +491,25 @@ ArrayOf(Dictionary) nvim_buf_get_commands(Buffer buffer, Dictionary opts,
                                           Error *err)
     FUNC_API_SINCE(4)
 {
+  for (size_t i = 0; i < opts.size; i++) {
+    String k = opts.items[i].key;
+    Object v = opts.items[i].value;
+    if (!strequal("builtin", k.data)) {
+      api_set_error(err, kErrorTypeValidation, "unexpected key: %s",
+                    k.data);
+      return (Array)ARRAY_DICT_INIT;
+    }
+    if (v.type != kObjectTypeBoolean || v.data.boolean != false) {
+      api_set_error(err, kErrorTypeValidation,
+                    "builtin commands not supported yet");
+      return (Array)ARRAY_DICT_INIT;
+    }
+  }
+
+  if (buffer == -1) {
+    return commands_array(NULL);
+  }
+
   buf_T *buf = find_buffer_by_handle(buffer, err);
   if (!buf) {
     return (Array)ARRAY_DICT_INIT;

src/nvim/api/private/helpers.c

@@ -685,7 +685,7 @@ tabpage_T *find_tab_by_handle(Tabpage tabpage, Error *err)
 String cchar_to_string(char c)
 {
   char buf[] = { c, NUL };
-  return (String) {
+  return (String){
     .data = xmemdupz(buf, 1),
     .size = (c != NUL) ? 1 : 0
   };
@@ -701,13 +701,13 @@ String cchar_to_string(char c)
 String cstr_to_string(const char *str)
 {
     if (str == NULL) {
-      return (String) STRING_INIT;
+      return (String)STRING_INIT;
     }
 
     size_t len = strlen(str);
-    return (String) {
-        .data = xmemdupz(str, len),
-        .size = len
+    return (String){
+      .data = xmemdupz(str, len),
+      .size = len,
     };
 }
 
@@ -722,7 +722,7 @@ String cstr_to_string(const char *str)
 String cbuf_to_string(const char *buf, size_t size)
   FUNC_ATTR_NONNULL_ALL
 {
-  return (String) {
+  return (String){
     .data = xmemdupz(buf, size),
     .size = size
   };
@@ -737,9 +737,9 @@ String cbuf_to_string(const char *buf, size_t size)
 String cstr_as_string(char *str) FUNC_ATTR_PURE
 {
   if (str == NULL) {
-    return (String) STRING_INIT;
+    return (String)STRING_INIT;
   }
-  return (String) { .data = str, .size = strlen(str) };
+  return (String){ .data = str, .size = strlen(str) };
 }
 
 /// Converts from type Object to a VimL value.

src/nvim/api/vim.c

@@ -959,17 +959,17 @@ ArrayOf(Dictionary) nvim_get_keymap(String mode)
   return keymap_array(mode, NULL);
 }
 
-/// Gets a list of dictionaries describing global(non-buffer) commands.
+/// Gets a list of maps describing global |user-commands|.
 ///
-/// @param  opts       Holds the API Metadata describing what type of commands
-///                    are needed.
+/// @param  opts  Optional parameters. Currently only supports
+///               {"builtin":false}
 /// @param[out]  err   Error details, if any.
 ///
 /// @returns Array of dictionaries describing commands.
 ArrayOf(Dictionary) nvim_get_commands(Dictionary opts, Error *err)
     FUNC_API_SINCE(4)
 {
-  return commands_array(NULL);
+  return nvim_buf_get_commands(-1, opts, err);
 }
 
 /// Returns a 2-tuple (Array), where item 0 is the current channel id and item