Normalise shared field prefixes at underscore boundaries

record.ml

@@ -52,3 +52,20 @@ let () =
   assert (view focus changed = 8 && Swatch.label changed = "grey");
   assert (set focus (view focus original) original = original);
   assert (set Box._contents "grey" Box.{ contents = 9 } = Box.{ contents = "grey" })
+
+module Prefixed = struct
+  type t = { paint_colour_red : int; paint_colour_green : int } [@@fieldglass generate]
+end
+
+module Unprefixed = struct
+  type t = { yes : bool; yellow : bool } [@@fieldglass generate]
+end
+
+module Single = struct
+  type t = { paint_red : int } [@@fieldglass generate]
+end
+
+let () =
+  assert (Prefixed.red Prefixed.{ paint_colour_red = 3; paint_colour_green = 4 } = 3);
+  assert (Unprefixed.yes Unprefixed.{ yes = true; yellow = false });
+  assert (Single.paint_red Single.{ paint_red = 3 } = 3)