refactor: add some dyn conversions to diff actions

src/dune_util/action.ml

@@ -3,6 +3,13 @@ module Diff = struct
     type t =
       | Binary
       | Text
+
+    let to_dyn =
+      let open Dyn in
+      function
+      | Binary -> variant "Binary" []
+      | Text -> variant "Text" []
+    ;;
   end
 
   type ('path, 'target) t =
@@ -12,6 +19,16 @@ module Diff = struct
     ; file2 : 'target
     }
 
+  let to_dyn path target { optional; mode; file1; file2 } =
+    let open Dyn in
+    record
+      [ "optional", bool optional
+      ; "mode", Mode.to_dyn mode
+      ; "file1", path file1
+      ; "file2", target file2
+      ]
+  ;;
+
   let map t ~path ~target = { t with file1 = path t.file1; file2 = target t.file2 }
 end
 

src/dune_util/action.mli

@@ -12,6 +12,7 @@ module Diff : sig
     ; file2 : 'target
     }
 
+  val to_dyn : ('path -> Dyn.t) -> ('target -> Dyn.t) -> ('path, 'target) t -> Dyn.t
   val map : ('p, 't) t -> path:('p -> 'a) -> target:('t -> 'b) -> ('a, 'b) t
 end