docs(api): nvim_set_hl attributes #18558

src/nvim/api/vim.c

@@ -126,22 +126,43 @@ Dictionary nvim__get_hl_defs(Integer ns_id, Error *err)
 
 /// Sets a highlight group.
 ///
-/// Note: Unlike the `:highlight` command which can update a highlight group,
-/// this function completely replaces the definition. For example:
-/// ``nvim_set_hl(0, 'Visual', {})`` will clear the highlight group 'Visual'.
+/// @note Unlike the `:highlight` command which can update a highlight group,
+///       this function completely replaces the definition. For example:
+///       ``nvim_set_hl(0, 'Visual', {})`` will clear the highlight group
+///       'Visual'.
+///
+/// @note The fg and bg keys also accept the string values `"fg"` or `"bg"`
+///       which act as aliases to the corresponding foreground and background
+///       values of the Normal group. If the Normal group has not been defined,
+///       using these values results in an error.
 ///
 /// @param ns_id Namespace id for this highlight |nvim_create_namespace()|.
 ///              Use 0 to set a highlight group globally |:highlight|.
 /// @param name  Highlight group name, e.g. "ErrorMsg"
-/// @param val   Highlight definition map, like |synIDattr()|. In
-///              addition, the following keys are recognized:
+/// @param val   Highlight definition map, accepts the following keys:
+///                - fg (or foreground): color name or "#RRGGBB", see note.
+///                - bg (or background): color name or "#RRGGBB", see note.
+///                - sp (or special): color name or "#RRGGBB"
+///                - blend: integer between 0 and 100
+///                - bold: boolean
+///                - standout: boolean
+///                - underline: boolean
+///                - underlineline: boolean
+///                - undercurl: boolean
+///                - underdot: boolean
+///                - underdash: boolean
+///                - strikethrough: boolean
+///                - italic: boolean
+///                - reverse: boolean
+///                - nocombine: boolean
+///                - link: name of another highlight group to link to, see |:hi-link|.
+///              Additionally, the following keys are recognized:
 ///                - default: Don't override existing definition |:hi-default|
 ///                - ctermfg: Sets foreground of cterm color |highlight-ctermfg|
 ///                - ctermbg: Sets background of cterm color |highlight-ctermbg|
-///                - cterm: cterm attribute map, like
-///                  |highlight-args|.
-///                  Note: Attributes default to those set for `gui`
-///                        if not set.
+///                - cterm: cterm attribute map, like |highlight-args|. If not set,
+///                         cterm attributes will match those from the attribute map
+///                         documented above.
 /// @param[out] err Error details, if any
 ///
 // TODO(bfredl): val should take update vs reset flag