Fix dropped comment in (function _ -> x (* cmt *)) (#2739)

Julow · web-flow · commit 96cc58c573f8 · 2025-10-27T14:48:02.000+01:00
diff --git a/CHANGES.md b/CHANGES.md
@@ -4,6 +4,12 @@ Items marked with an asterisk (\*) are changes that are likely to format
 existing code differently from the previous release when using the default
 profile. This started with version 0.26.0.
 
+## unreleased
+
+### Fixed
+
+- Fix dropped comment in `(function _ -> x (* cmt *))` (#2739, @Julow)
+
 ## 0.28.1
 
 ### Highlight
diff --git a/lib/Fmt_ast.ml b/lib/Fmt_ast.ml
@@ -1633,6 +1633,7 @@ and fmt_function ?force_closing_paren ~ctx ~ctx0 ?pro ~wrap_intro
           in
           fmt_infix_ext_attrs c ~pro:function_ infix_ext_attrs
         in
+        let cmt_after_cases = Cmts.fmt_after c function_loc in
         let box_cases ~pro cases =
           let pro_inner, pro_outer, indent =
             (* Formatting of if-then-else relies on the ~box argument. *)
@@ -1653,8 +1654,9 @@ and fmt_function ?force_closing_paren ~ctx ~ctx0 ?pro ~wrap_intro
                   ( fmt_pattern c ~pro:(if_newline "| ") (sub_pat ~ctx pc_lhs)
                   $ space_break $ str "->" )
                 $ space_break
-                $ cbox 0 (fmt_expression c (sub_exp ~ctx pc_rhs)) )
-          | _ -> (box, fmt_cases c ctx cs)
+                $ cbox 0 (fmt_expression c (sub_exp ~ctx pc_rhs))
+                $ cmt_after_cases )
+          | _ -> (box, fmt_cases c ctx cs $ cmt_after_cases)
         in
         (fun_ $ function_, box_cases cases, box, 0)
   in
diff --git a/test/passing/refs.ahrefs/fun_function.ml.ref b/test/passing/refs.ahrefs/fun_function.ml.ref
@@ -179,3 +179,9 @@ let f = function
         | ElementHole -> ElementHole
         | Element e -> Element (m#expression e)
         | ElementSpread e -> ElementSpread (m#expression e)))
+
+let _ =
+  f (function _ -> x
+    (* o::other reverses the list, in order to keep
+             Remote and other order-sensitive stanzas intact
+             we need to List.rev the [tl] list. *))
diff --git a/test/passing/refs.default/fun_function.ml.ref b/test/passing/refs.default/fun_function.ml.ref
@@ -146,3 +146,9 @@ let f = function
           | ElementHole -> ElementHole
           | Element e -> Element (m#expression e)
           | ElementSpread e -> ElementSpread (m#expression e)))
+
+let _ =
+  f (function _ -> x
+      (* o::other reverses the list, in order to keep
+             Remote and other order-sensitive stanzas intact
+             we need to List.rev the [tl] list. *))
diff --git a/test/passing/refs.janestreet/fun_function.ml.ref b/test/passing/refs.janestreet/fun_function.ml.ref
@@ -223,3 +223,10 @@ let f = function
          | Element e -> Element (m#expression e)
          | ElementSpread e -> ElementSpread (m#expression e)))
 ;;
+
+let _ =
+  f (function _ -> x
+      (* o::other reverses the list, in order to keep
+             Remote and other order-sensitive stanzas intact
+             we need to List.rev the [tl] list. *))
+;;
diff --git a/test/passing/refs.ocamlformat/fun_function.ml.ref b/test/passing/refs.ocamlformat/fun_function.ml.ref
@@ -167,3 +167,9 @@ let f = function
               Element (m#expression e)
           | ElementSpread e ->
               ElementSpread (m#expression e) ))
+
+let _ =
+  f (function _ -> x
+      (* o::other reverses the list, in order to keep
+             Remote and other order-sensitive stanzas intact
+             we need to List.rev the [tl] list. *) )
diff --git a/test/passing/tests/fun_function.ml b/test/passing/tests/fun_function.ml
@@ -86,3 +86,12 @@ let f = function
           | ElementHole -> ElementHole
           | Element e -> Element (m#expression e)
           | ElementSpread e -> ElementSpread (m#expression e)))
+
+let _ =
+  f
+    (function
+      | _ ->
+          x
+          (* o::other reverses the list, in order to keep
+             Remote and other order-sensitive stanzas intact
+             we need to List.rev the [tl] list. *))
