fix(api): validation, documentation of hl_group #31195

Problem:  Documentation for "hl_group" in nvim_buf_set_extmark() is
          unclear. "hl_group" in nvim_echo() does not accept
          highlight group id.
Solution: Move documentation for highlight group name/id to first
          mention of hl_group. Update nvim_echo() to accept highlight
          group id.

3 files changed, 21 insertions, 30 deletions

diff --git a/src/nvim/api/extmark.c b/src/nvim/api/extmark.c
index 7786c30624..c94b8df9ea 100644
--- a/src/nvim/api/extmark.c
+++ b/src/nvim/api/extmark.c
@@ -381,8 +381,9 @@ Array nvim_buf_get_extmarks(Buffer buffer, Integer ns_id, Object start, Object e
 ///               - id : id of the extmark to edit.
 ///               - end_row : ending line of the mark, 0-based inclusive.
 ///               - end_col : ending col of the mark, 0-based exclusive.
-///               - hl_group : name of the highlight group used to highlight
-///                   this mark.
+///               - hl_group : highlight group used for the text range. This and below
+///                   highlight groups can be supplied either as a string or as an integer,
+///                   the latter of which can be obtained using |nvim_get_hl_id_by_name()|.
 ///               - hl_eol : when true, for a multiline highlight covering the
 ///                          EOL of a line, continue the highlight for the rest
 ///                          of the screen line (just like for diff and
@@ -392,9 +393,7 @@ Array nvim_buf_get_extmarks(Buffer buffer, Integer ns_id, Object start, Object e
 ///                   text chunk with specified highlight. `highlight` element
 ///                   can either be a single highlight group, or an array of
 ///                   multiple highlight groups that will be stacked
-///                   (highest priority last). A highlight group can be supplied
-///                   either as a string or as an integer, the latter which
-///                   can be obtained using |nvim_get_hl_id_by_name()|.
+///                   (highest priority last).
 ///               - virt_text_pos : position of virtual text. Possible values:
 ///                 - "eol": right after eol character (default).
 ///                 - "overlay": display over the specified column, without
@@ -465,15 +464,12 @@ Array nvim_buf_get_extmarks(Buffer buffer, Integer ns_id, Object start, Object e
 ///                   buffer or end of the line respectively. Defaults to true.
 ///               - sign_text: string of length 1-2 used to display in the
 ///                   sign column.
-///               - sign_hl_group: name of the highlight group used to
-///                   highlight the sign column text.
-///               - number_hl_group: name of the highlight group used to
-///                   highlight the number column.
-///               - line_hl_group: name of the highlight group used to
-///                   highlight the whole line.
-///               - cursorline_hl_group: name of the highlight group used to
-///                   highlight the sign column text when the cursor is on
-///                   the same line as the mark and 'cursorline' is enabled.
+///               - sign_hl_group: highlight group used for the sign column text.
+///               - number_hl_group: highlight group used for the number column.
+///               - line_hl_group: highlight group used for the whole line.
+///               - cursorline_hl_group: highlight group used for the sign
+///                   column text when the cursor is on the same line as the
+///                   mark and 'cursorline' is enabled.
 ///               - conceal: string which should be either empty or a single
 ///                   character. Enable concealing similar to |:syn-conceal|.
 ///                   When a character is supplied it is used as |:syn-cchar|.
diff --git a/src/nvim/api/private/helpers.c b/src/nvim/api/private/helpers.c
index d21caf7ed0..88e1664c04 100644
--- a/src/nvim/api/private/helpers.c
+++ b/src/nvim/api/private/helpers.c
@@ -771,7 +771,7 @@ int object_to_hl_id(Object obj, const char *what, Error *err)
     int id = (int)obj.data.integer;
     return (1 <= id && id <= highlight_num_groups()) ? id : 0;
   } else {
-    api_set_error(err, kErrorTypeValidation, "Invalid highlight: %s", what);
+    api_set_error(err, kErrorTypeValidation, "Invalid hl_group: %s", what);
     return 0;
   }
 }
@@ -809,27 +809,22 @@ HlMessage parse_hl_msg(Array chunks, Error *err)
 {
   HlMessage hl_msg = KV_INITIAL_VALUE;
   for (size_t i = 0; i < chunks.size; i++) {
-    if (chunks.items[i].type != kObjectTypeArray) {
-      api_set_error(err, kErrorTypeValidation, "Chunk is not an array");
+    VALIDATE_T("chunk", kObjectTypeArray, chunks.items[i].type, {
       goto free_exit;
-    }
+    });
     Array chunk = chunks.items[i].data.array;
-    if (chunk.size == 0 || chunk.size > 2
-        || chunk.items[0].type != kObjectTypeString
-        || (chunk.size == 2 && chunk.items[1].type != kObjectTypeString)) {
-      api_set_error(err, kErrorTypeValidation,
-                    "Chunk is not an array with one or two strings");
+    VALIDATE((chunk.size > 0 && chunk.size <= 2 && chunk.items[0].type == kObjectTypeString),
+             "%s", "Invalid chunk: expected Array with 1 or 2 Strings", {
       goto free_exit;
-    }
+    });
 
     String str = copy_string(chunk.items[0].data.string, NULL);
 
     int hl_id = 0;
     if (chunk.size == 2) {
-      String hl = chunk.items[1].data.string;
-      if (hl.size > 0) {
-        // TODO(bfredl): use object_to_hl_id and allow integer
-        hl_id = syn_check_group(hl.data, hl.size);
+      hl_id = object_to_hl_id(chunk.items[1], "text highlight", err);
+      if (ERROR_SET(err)) {
+        goto free_exit;
       }
     }
     kv_push(hl_msg, ((HlMessageChunk){ .text = str, .hl_id = hl_id }));
diff --git a/src/nvim/api/vim.c b/src/nvim/api/vim.c
index 199b9a9690..89e974c098 100644
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -779,8 +779,8 @@ void nvim_set_vvar(String name, Object value, Error *err)
 /// Echo a message.
 ///
 /// @param chunks  A list of `[text, hl_group]` arrays, each representing a
-///                text chunk with specified highlight. `hl_group` element
-///                can be omitted for no highlight.
+///                text chunk with specified highlight group name or ID.
+///                `hl_group` element can be omitted for no highlight.
 /// @param history  if true, add to |message-history|.
 /// @param opts  Optional parameters.
 ///          - verbose: Message is printed as a result of 'verbose' option.