Keep the color palette, iterator entry points and Mod.mk as live

The first commit removed what no code used today, including parts of
general APIs that new code is likely to need. These come back, marked
[@@LiVe] with a comment so the dead-code check accepts them:

- Misc.Color: the full ANSI palette (Black, Green, Blue, White) and
  background colors (BG), exported again so OCaml's unused-constructor
  warning does not fire.
- Typedtree_iter.Make_iterator: iter_structure, iter_signature,
  iter_signature_item, iter_module_type and iter_pattern.
- Ast_helper.Mod.mk: the builder the other Mod builders specialize.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Kbf3gLDo8mBJKpNE25WAwT
Signed-off-by: Christoph Knittel <ck@cca.io>

Author: cknitt

compiler/ext/misc.ml

@@ -229,23 +229,31 @@ end)
 (* Color handling *)
 module Color = struct
   (* use ANSI color codes, see https://en.wikipedia.org/wiki/ANSI_escape_code *)
-  type color = Red | Yellow | Magenta | Cyan
+  (* The full ANSI palette, also the colors no message uses yet. *)
+  type color = Black | Red | Green | Yellow | Blue | Magenta | Cyan | White
+  [@@live]
 
   type style =
-    | FG of color
-    (* foreground *)
+    | FG of color (* foreground *)
+    | BG of color (* background *)
     | Bold
     | Reset
     | Dim
+  [@@live]
 
   let ansi_of_color = function
+    | Black -> "0"
     | Red -> "1"
+    | Green -> "2"
     | Yellow -> "3"
+    | Blue -> "4"
     | Magenta -> "5"
     | Cyan -> "6"
+    | White -> "7"
 
   let code_of_style = function
     | FG c -> "3" ^ ansi_of_color c
+    | BG c -> "4" ^ ansi_of_color c
     | Bold -> "1"
     | Reset -> "0"
     | Dim -> "2"

compiler/ext/misc.mli

@@ -95,6 +95,18 @@ module String_map : Map.S with type key = string
 
 (* Color handling *)
 module Color : sig
+  (* The full ANSI palette, also the colors no message uses yet. *)
+  type color = Black | Red | Green | Yellow | Blue | Magenta | Cyan | White
+  [@@live]
+
+  type style =
+    | FG of color (* foreground *)
+    | BG of color (* background *)
+    | Bold
+    | Reset
+    | Dim
+  [@@live]
+
   type setting = Auto | Always | Never
 
   val setup : setting option -> unit

compiler/ml/ast_helper.mli

@@ -411,6 +411,10 @@ end
 
 (** Module expressions *)
 module Mod : sig
+  val mk : ?loc:loc -> ?attrs:attrs -> module_expr_desc -> module_expr
+  [@@live]
+  (** The builder the others specialize, as in every module of this file. *)
+
   val ident : ?loc:loc -> ?attrs:attrs -> lid -> module_expr
   val structure : ?loc:loc -> ?attrs:attrs -> structure -> module_expr
   val functor_ :

compiler/ml/typedtree_iter.ml

@@ -73,9 +73,15 @@ module type IteratorArgument = sig
   val enter_expression : expression -> unit
 end
 
+(* The iterator's whole interface, also the entry points no pass uses yet. *)
 module Make_iterator (Iter : IteratorArgument) : sig
+  val iter_structure : structure -> unit [@@live]
+  val iter_signature : signature -> unit [@@live]
   val iter_structure_item : structure_item -> unit
+  val iter_signature_item : signature_item -> unit [@@live]
   val iter_expression : expression -> unit
+  val iter_module_type : module_type -> unit [@@live]
+  val iter_pattern : pattern -> unit [@@live]
 end = struct
   let may_iter f v =
     match v with

compiler/ml/typedtree_iter.mli

@@ -65,9 +65,15 @@ module type IteratorArgument = sig
   val enter_expression : expression -> unit
 end
 
+(* The iterator's whole interface, also the entry points no pass uses yet. *)
 module Make_iterator : functor (_ : IteratorArgument) -> sig
+  val iter_structure : structure -> unit [@@live]
+  val iter_signature : signature -> unit [@@live]
   val iter_structure_item : structure_item -> unit
+  val iter_signature_item : signature_item -> unit [@@live]
   val iter_expression : expression -> unit
+  val iter_module_type : module_type -> unit [@@live]
+  val iter_pattern : pattern -> unit [@@live]
 end
 
 module Default_iterator_argument : IteratorArgumentDefaults