Fix regressions of list element comments (ocaml-ppx#1876)

Author: gpetiot

CHANGES.md

@@ -54,8 +54,7 @@
 
   + Set 'module-item-spacing=compact' in the default/conventional profile (#1848, @gpetiot)
 
-  + Preserve bracketed lists in the Parsetree (#1694, @gpetiot)
-    Comments are now wrapped around list elements instead of causing a break.
+  + Preserve bracketed lists in the Parsetree (#1694, #1876, @gpetiot)
 
   + Line directives now cause OCamlFormat to emit an error, they were previously silently ignored (#1845, @gpetiot)
 

lib/Fmt_ast.ml

@@ -1967,14 +1967,15 @@ and fmt_expression c ?(box = true) ?pro ?epi ?eol ?parens ?(indent_wrap = 0)
         $ fmt_atrs )
   | Pexp_list e1N ->
       let p = Params.get_list_expr c.conf in
+      let offset = if c.conf.dock_collection_brackets then 0 else 2 in
+      let cmt_break = break 1 offset in
       hvbox_if has_attr 0
         (Params.parens_if parens c.conf
            ( p.box
                (fmt_expressions c (expression_width c) (sub_exp ~ctx) e1N
                   (fun e ->
-                    let fmt_cmts = Cmts.fmt c ~eol:(break 1 0) e.pexp_loc in
-                    hvbox 0 @@ fmt_cmts
-                    @@ (sub_exp ~ctx >> fmt_expression c) e )
+                    let fmt_cmts = Cmts.fmt c ~eol:cmt_break e.pexp_loc in
+                    fmt_cmts @@ (sub_exp ~ctx >> fmt_expression c) e )
                   p )
            $ fmt_atrs ) )
   | Pexp_assert e0 ->

test/passing/tests/break_separators-after.ml.ref

@@ -167,7 +167,8 @@ let length =
 let length =
   [ 0;
     14;
-    (* foo *) 14;
+    (* foo *)
+    14;
     17 (* foo *);
     17;
     2777777777777777777777777777777777;
@@ -309,7 +310,8 @@ let length =
     14;
     14;
     14;
-    (* foo *) 14;
+    (* foo *)
+    14;
     15;
     15;
     15;

test/passing/tests/break_separators-after_docked.ml.err

@@ -1 +1 @@
-Warning: tests/break_separators.ml:571 exceeds the margin
+Warning: tests/break_separators.ml:573 exceeds the margin

test/passing/tests/break_separators-after_docked.ml.ref

@@ -189,7 +189,8 @@ let length =
   [
     0;
     14;
-    (* foo *) 14;
+    (* foo *)
+    14;
     17 (* foo *);
     17;
     2777777777777777777777777777777777;
@@ -337,7 +338,8 @@ let length =
     14;
     14;
     14;
-    (* foo *) 14;
+    (* foo *)
+    14;
     15;
     15;
     15;

test/passing/tests/break_separators-before_docked.ml.ref

@@ -189,7 +189,8 @@ let length =
   [
     0
   ; 14
-  ; (* foo *) 14
+  ; (* foo *)
+    14
   ; 17 (* foo *)
   ; 17
   ; 2777777777777777777777777777777777
@@ -337,7 +338,8 @@ let length =
   ; 14
   ; 14
   ; 14
-  ; (* foo *) 14
+  ; (* foo *)
+    14
   ; 15
   ; 15
   ; 15

test/passing/tests/break_separators.ml

@@ -167,7 +167,8 @@ let length =
 let length =
   [ 0
   ; 14
-  ; (* foo *) 14
+  ; (* foo *)
+    14
   ; 17 (* foo *)
   ; 17
   ; 2777777777777777777777777777777777
@@ -309,7 +310,8 @@ let length =
   ; 14
   ; 14
   ; 14
-  ; (* foo *) 14
+  ; (* foo *)
+    14
   ; 15
   ; 15
   ; 15