feature: italicise "Hint" in User_message (#6685)

We also add italic to ansi_color.

Signed-off-by: Ali Caglayan <[email protected]>

otherlibs/stdune/ansi_color.ml

@@ -113,6 +113,8 @@ module Style = struct
 
   let dim = "2"
 
+  let italic = "3"
+
   let underlined = "4"
 
   let escape_sequence l =

otherlibs/stdune/ansi_color.mli

@@ -75,6 +75,8 @@ module Style : sig
 
   val dim : t
 
+  val italic : t
+
   val underlined : t
 
   (** Ansi escape sequence that set the terminal style to exactly these styles *)

otherlibs/stdune/user_message.ml

@@ -6,6 +6,7 @@ module Style = struct
     | Kwd
     | Id
     | Prompt
+    | Hint
     | Details
     | Ok
     | Debug
@@ -34,6 +35,7 @@ module Print_config = struct
     | Kwd -> [ bold; fg_blue ]
     | Id -> [ bold; fg_yellow ]
     | Prompt -> [ bold; fg_green ]
+    | Hint -> [ italic; fg_white ]
     | Details -> [ dim; fg_white ]
     | Ok -> [ dim; fg_green ]
     | Debug -> [ underlined; fg_bright_cyan ]
@@ -73,7 +75,8 @@ let pp { loc; paragraphs; hints; annots = _ } =
     | [] -> paragraphs
     | _ ->
       List.append paragraphs
-        (List.map hints ~f:(fun hint -> Pp.verbatim "Hint:" ++ Pp.space ++ hint))
+        (List.map hints ~f:(fun hint ->
+             Pp.tag Style.Hint (Pp.verbatim "Hint:") ++ Pp.space ++ hint))
   in
   let paragraphs = List.map paragraphs ~f:Pp.box in
   let paragraphs =

otherlibs/stdune/user_message.mli

@@ -15,6 +15,7 @@ module Style : sig
     | Kwd
     | Id
     | Prompt
+    | Hint
     | Details
     | Ok
     | Debug