From 5926384bd9168ebb7fc6cbf6d58b22a909a89b89 Mon Sep 17 00:00:00 2001
From: Shulhi Sapli <shulhi@gmail.com>
Date: Sat, 31 May 2025 17:40:44 +0800
Subject: [PATCH 01/10] WIP

---
 compiler/syntax/src/res_core.ml | 30 ++++++++++++++++++++++++++----
 1 file changed, 26 insertions(+), 4 deletions(-)

diff --git a/compiler/syntax/src/res_core.ml b/compiler/syntax/src/res_core.ml
index aebd7bc62d..e42178b07f 100644
--- a/compiler/syntax/src/res_core.ml
+++ b/compiler/syntax/src/res_core.ml
@@ -4885,11 +4885,19 @@ and parse_constr_decl_args p =
  *  | constr-name const-args
  *  | attrs constr-name const-args *)
 and parse_type_constructor_declaration_with_bar p =
+  let doc_comment_attrs = match p.Parser.token with
+  | DocComment (loc, s) -> 
+      Parser.next p;
+      [doc_comment_to_attribute loc s]
+  | _ -> []
+  in
   match p.Parser.token with
   | Bar ->
     let start_pos = p.Parser.start_pos in
     Parser.next p;
-    Some (parse_type_constructor_declaration ~start_pos p)
+    let () = print_endline "3" in
+    let constr = parse_type_constructor_declaration ~start_pos p in
+    Some ({constr with Parsetree.pcd_attributes = doc_comment_attrs @ constr.Parsetree.pcd_attributes})
   | _ -> None
 
 and parse_type_constructor_declaration ~start_pos p =
@@ -4916,12 +4924,20 @@ and parse_type_constructor_declaration ~start_pos p =
 
 (* [|] constr-decl  { | constr-decl }   *)
 and parse_type_constructor_declarations ?first p =
+  let () = print_endline "2" in
   let first_constr_decl =
     match first with
     | None ->
+      let doc_comment_attrs = match p.Parser.token with
+      | DocComment (loc, s) -> 
+          Parser.next p;
+          [doc_comment_to_attribute loc s]
+      | _ -> []
+      in
       let start_pos = p.Parser.start_pos in
       ignore (Parser.optional p Token.Bar);
-      parse_type_constructor_declaration ~start_pos p
+      let constr = parse_type_constructor_declaration ~start_pos p in
+      {constr with  pcd_attributes = doc_comment_attrs @ constr.pcd_attributes}
     | Some first_constr_decl -> first_constr_decl
   in
   first_constr_decl
@@ -4947,7 +4963,8 @@ and parse_type_representation ?current_type_name_path ?inline_types_context p =
   in
   let kind =
     match p.Parser.token with
-    | Bar | Uident _ ->
+    | Bar | Uident _ | DocComment _ ->
+      let () = print_endline "1" in
       Parsetree.Ptype_variant (parse_type_constructor_declarations p)
     | Lbrace ->
       Parsetree.Ptype_record
@@ -5500,7 +5517,11 @@ and parse_type_equation_and_representation ?current_type_name_path
       parse_record_or_object_decl ?current_type_name_path ?inline_types_context
         p
     | Private -> parse_private_eq_or_repr p
-    | Bar | DotDot ->
+    | Bar | DotDot | DocComment _ ->
+      let () = print_endline "xxx" in
+      (* DOCCOMMENT: Reached here if the first variant starts with |. 
+         It is possible that the first variant may not have | (with multiple variants)
+       *)
       let priv, kind = parse_type_representation p in
       (None, priv, kind)
     | _ -> (
@@ -5606,6 +5627,7 @@ and parse_type_definitions ~current_type_name_path ~inline_types_context ~attrs
  * implemented for now. Needed to get a feel for the complexities of
  * this territory of the grammar *)
 and parse_type_definition_or_extension ~attrs p =
+  let () = print_endline "0" in
   let start_pos = p.Parser.start_pos in
   Parser.expect Token.Typ p;
   let rec_flag =

From 54ccb062d7e675378fb96d2d0a976b49db2b5083 Mon Sep 17 00:00:00 2001
From: Shulhi Sapli <shulhi@gmail.com>
Date: Sat, 31 May 2025 18:39:58 +0800
Subject: [PATCH 02/10] Format doc comment before bar

---
 compiler/syntax/src/res_core.ml    | 28 ++++++++++++++------------
 compiler/syntax/src/res_printer.ml | 32 +++++++++++++++++++++++++-----
 2 files changed, 42 insertions(+), 18 deletions(-)

diff --git a/compiler/syntax/src/res_core.ml b/compiler/syntax/src/res_core.ml
index e42178b07f..fe8229f93c 100644
--- a/compiler/syntax/src/res_core.ml
+++ b/compiler/syntax/src/res_core.ml
@@ -4885,19 +4885,24 @@ and parse_constr_decl_args p =
  *  | constr-name const-args
  *  | attrs constr-name const-args *)
 and parse_type_constructor_declaration_with_bar p =
-  let doc_comment_attrs = match p.Parser.token with
-  | DocComment (loc, s) -> 
+  let doc_comment_attrs =
+    match p.Parser.token with
+    | DocComment (loc, s) ->
       Parser.next p;
       [doc_comment_to_attribute loc s]
-  | _ -> []
+    | _ -> []
   in
   match p.Parser.token with
   | Bar ->
     let start_pos = p.Parser.start_pos in
     Parser.next p;
-    let () = print_endline "3" in
     let constr = parse_type_constructor_declaration ~start_pos p in
-    Some ({constr with Parsetree.pcd_attributes = doc_comment_attrs @ constr.Parsetree.pcd_attributes})
+    Some
+      {
+        constr with
+        Parsetree.pcd_attributes =
+          doc_comment_attrs @ constr.Parsetree.pcd_attributes;
+      }
   | _ -> None
 
 and parse_type_constructor_declaration ~start_pos p =
@@ -4924,20 +4929,20 @@ and parse_type_constructor_declaration ~start_pos p =
 
 (* [|] constr-decl  { | constr-decl }   *)
 and parse_type_constructor_declarations ?first p =
-  let () = print_endline "2" in
   let first_constr_decl =
     match first with
     | None ->
-      let doc_comment_attrs = match p.Parser.token with
-      | DocComment (loc, s) -> 
+      let doc_comment_attrs =
+        match p.Parser.token with
+        | DocComment (loc, s) ->
           Parser.next p;
           [doc_comment_to_attribute loc s]
-      | _ -> []
+        | _ -> []
       in
       let start_pos = p.Parser.start_pos in
       ignore (Parser.optional p Token.Bar);
       let constr = parse_type_constructor_declaration ~start_pos p in
-      {constr with  pcd_attributes = doc_comment_attrs @ constr.pcd_attributes}
+      {constr with pcd_attributes = doc_comment_attrs @ constr.pcd_attributes}
     | Some first_constr_decl -> first_constr_decl
   in
   first_constr_decl
@@ -4964,7 +4969,6 @@ and parse_type_representation ?current_type_name_path ?inline_types_context p =
   let kind =
     match p.Parser.token with
     | Bar | Uident _ | DocComment _ ->
-      let () = print_endline "1" in
       Parsetree.Ptype_variant (parse_type_constructor_declarations p)
     | Lbrace ->
       Parsetree.Ptype_record
@@ -5518,7 +5522,6 @@ and parse_type_equation_and_representation ?current_type_name_path
         p
     | Private -> parse_private_eq_or_repr p
     | Bar | DotDot | DocComment _ ->
-      let () = print_endline "xxx" in
       (* DOCCOMMENT: Reached here if the first variant starts with |. 
          It is possible that the first variant may not have | (with multiple variants)
        *)
@@ -5627,7 +5630,6 @@ and parse_type_definitions ~current_type_name_path ~inline_types_context ~attrs
  * implemented for now. Needed to get a feel for the complexities of
  * this territory of the grammar *)
 and parse_type_definition_or_extension ~attrs p =
-  let () = print_endline "0" in
   let start_pos = p.Parser.start_pos in
   Parser.expect Token.Typ p;
   let rec_flag =
diff --git a/compiler/syntax/src/res_printer.ml b/compiler/syntax/src/res_printer.ml
index 4d00515e30..2a7dad3893 100644
--- a/compiler/syntax/src/res_printer.ml
+++ b/compiler/syntax/src/res_printer.ml
@@ -352,8 +352,7 @@ let print_listi ~get_loc ~nodes ~print ?(force_break = false) t =
         | Some comment -> (Comment.loc comment).loc_start
       in
       let sep =
-        if start_pos.pos_lnum - prev_loc.loc_end.pos_lnum > 1 then
-          Doc.concat [Doc.hard_line; Doc.hard_line]
+        if start_pos.pos_lnum - prev_loc.loc_end.pos_lnum > 1 then Doc.hard_line
         else Doc.line
       in
       let doc = print_comments (print node t i) t loc in
@@ -1550,12 +1549,35 @@ and print_constructor_declarations ~state ~private_flag
 and print_constructor_declaration2 ~state i
     (cd : Parsetree.constructor_declaration) cmt_tbl =
   let comment_attrs, attrs =
-    ParsetreeViewer.partition_doc_comment_attributes cd.pcd_attributes
+    List.partition
+      (fun ((id, payload) : Parsetree.attribute) ->
+        match (id, payload) with
+        | ( {txt = "res.doc"},
+            PStr
+              [
+                {
+                  pstr_desc =
+                    Pstr_eval
+                      ({pexp_desc = Pexp_constant (Pconst_string (_, _))}, _);
+                };
+              ] ) ->
+          true
+        | _ -> false)
+      cd.pcd_attributes
   in
   let comment_doc =
     match comment_attrs with
     | [] -> Doc.nil
-    | comment_attrs -> print_doc_comments ~state cmt_tbl comment_attrs
+    | comment_attrs ->
+      Doc.concat
+        [
+          Doc.group
+            (Doc.join_with_sep
+               (List.map
+                  (fun attr -> print_attribute ~state attr cmt_tbl)
+                  comment_attrs));
+          Doc.hard_line;
+        ]
   in
   let attrs = print_attributes ~state attrs cmt_tbl in
   let is_dot_dot_dot = cd.pcd_name.txt = "..." in
@@ -1579,8 +1601,8 @@ and print_constructor_declaration2 ~state i
   in
   Doc.concat
     [
-      bar;
       comment_doc;
+      bar;
       Doc.group
         (Doc.concat
            [

From 3debc0840b9a276053b3316e2a3428e6a4e67895 Mon Sep 17 00:00:00 2001
From: Shulhi Sapli <shulhi@gmail.com>
Date: Sat, 31 May 2025 19:27:28 +0800
Subject: [PATCH 03/10] Adjust loc

---
 compiler/syntax/src/res_core.ml    | 33 +++++++++++++++++++++++++++++-
 compiler/syntax/src/res_printer.ml |  3 ++-
 2 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/compiler/syntax/src/res_core.ml b/compiler/syntax/src/res_core.ml
index fe8229f93c..98ed32819b 100644
--- a/compiler/syntax/src/res_core.ml
+++ b/compiler/syntax/src/res_core.ml
@@ -4892,16 +4892,30 @@ and parse_type_constructor_declaration_with_bar p =
       [doc_comment_to_attribute loc s]
     | _ -> []
   in
+  let has_doc_comment = not (doc_comment_attrs = []) in
   match p.Parser.token with
   | Bar ->
     let start_pos = p.Parser.start_pos in
     Parser.next p;
     let constr = parse_type_constructor_declaration ~start_pos p in
+    let pcd_loc =
+      if has_doc_comment then
+        {
+          constr.Parsetree.pcd_loc with
+          loc_end =
+            {
+              constr.pcd_loc.loc_end with
+              pos_lnum = constr.pcd_loc.loc_end.pos_lnum + 1;
+            };
+        }
+      else constr.pcd_loc
+    in
     Some
       {
         constr with
         Parsetree.pcd_attributes =
           doc_comment_attrs @ constr.Parsetree.pcd_attributes;
+        pcd_loc;
       }
   | _ -> None
 
@@ -4939,10 +4953,27 @@ and parse_type_constructor_declarations ?first p =
           [doc_comment_to_attribute loc s]
         | _ -> []
       in
+      let has_doc_comment = not (doc_comment_attrs = []) in
       let start_pos = p.Parser.start_pos in
       ignore (Parser.optional p Token.Bar);
       let constr = parse_type_constructor_declaration ~start_pos p in
-      {constr with pcd_attributes = doc_comment_attrs @ constr.pcd_attributes}
+      let pcd_loc =
+        if has_doc_comment then
+          {
+            constr.Parsetree.pcd_loc with
+            loc_end =
+              {
+                constr.pcd_loc.loc_end with
+                pos_lnum = constr.pcd_loc.loc_end.pos_lnum + 1;
+              };
+          }
+        else constr.pcd_loc
+      in
+      {
+        constr with
+        pcd_attributes = doc_comment_attrs @ constr.pcd_attributes;
+        pcd_loc;
+      }
     | Some first_constr_decl -> first_constr_decl
   in
   first_constr_decl
diff --git a/compiler/syntax/src/res_printer.ml b/compiler/syntax/src/res_printer.ml
index 2a7dad3893..e0563fd969 100644
--- a/compiler/syntax/src/res_printer.ml
+++ b/compiler/syntax/src/res_printer.ml
@@ -352,7 +352,8 @@ let print_listi ~get_loc ~nodes ~print ?(force_break = false) t =
         | Some comment -> (Comment.loc comment).loc_start
       in
       let sep =
-        if start_pos.pos_lnum - prev_loc.loc_end.pos_lnum > 1 then Doc.hard_line
+        if start_pos.pos_lnum - prev_loc.loc_end.pos_lnum > 1 then
+          Doc.concat [Doc.hard_line; Doc.hard_line]
         else Doc.line
       in
       let doc = print_comments (print node t i) t loc in

From f98af5ac686f0a75d15985ece6474ed83ecf4b03 Mon Sep 17 00:00:00 2001
From: Shulhi Sapli <shulhi@gmail.com>
Date: Tue, 3 Jun 2025 18:55:24 +0800
Subject: [PATCH 04/10] Update test files

---
 tests/tests/src/arith_syntax.res              | 24 +++++++++----------
 tests/tests/src/mutual_non_recursive_type.res |  4 ++--
 tests/tools_tests/src/DocExtractionRes.res    | 18 +++++++-------
 3 files changed, 22 insertions(+), 24 deletions(-)

diff --git a/tests/tests/src/arith_syntax.res b/tests/tests/src/arith_syntax.res
index e4e2980ba7..14be6752f1 100644
--- a/tests/tests/src/arith_syntax.res
+++ b/tests/tests/src/arith_syntax.res
@@ -1,16 +1,16 @@
 type rec expression =
-  | /** non-negative integer constant */
-  Numeral(float)
-  | /** Addition [e1 + e2] */
-  Plus(expression, expression)
-  | /** Difference [e1 - e2] */
-  Minus(expression, expression)
-  | /** Product [e1 * e2] */
-  Times(expression, expression)
-  | /** Quotient [e1 / e2] */
-  Divide(expression, expression)
-  | /** Opposite value [-e] */
-  Negate(expression)
+  /** non-negative integer constant */
+  | Numeral(float)
+  /** Addition [e1 + e2] */
+  | Plus(expression, expression)
+  /** Difference [e1 - e2] */
+  | Minus(expression, expression)
+  /** Product [e1 * e2] */
+  | Times(expression, expression)
+  /** Quotient [e1 / e2] */
+  | Divide(expression, expression)
+  /** Opposite value [-e] */
+  | Negate(expression)
   | Variable(string)
 
 let rec str = e =>
diff --git a/tests/tests/src/mutual_non_recursive_type.res b/tests/tests/src/mutual_non_recursive_type.res
index 4b3a740bfb..e07c2a84b5 100644
--- a/tests/tests/src/mutual_non_recursive_type.res
+++ b/tests/tests/src/mutual_non_recursive_type.res
@@ -9,7 +9,7 @@ type t =
   | Ta(t) /* * u compilation error [nonrec applices to all] */
   | Tb(int)
 and u =
-  | /** one attribute nonrecursive will affect all */
-  H(t) /* refers to old t */
+  /** one attribute nonrecursive will affect all */
+  | H(t) /* refers to old t */
 
 let v: u = H(OT)
diff --git a/tests/tools_tests/src/DocExtractionRes.res b/tests/tools_tests/src/DocExtractionRes.res
index e86ab142e3..27ee44bc55 100644
--- a/tests/tools_tests/src/DocExtractionRes.res
+++ b/tests/tools_tests/src/DocExtractionRes.res
@@ -28,14 +28,12 @@ let \"SomeConstant" = 12
 module SomeInnerModule = {
   /*** Another module level docstring here.*/
   type status =
-    | /** If this is started or not */
-    Started(t)
-    | /** Stopped? */
-    Stopped
-    | /** Now idle.*/
-    Idle
-
-  /** These are all the valid inputs.*/
+    /** If this is started or not */
+    | Started(t)
+    /** Stopped? */
+    | Stopped
+    /** Now idle.*/
+    | Idle
   type validInputs = [#something | #"needs-escaping" | #withPayload(int) | #status(status)]
 
   type callback = (t, ~status: status) => unit
@@ -55,8 +53,8 @@ module AnotherModule = {
 
   /** Trying how it looks with an inline record in a variant. */
   type someVariantWithInlineRecords =
-    | /** This has inline records...*/
-    SomeStuff({
+    /** This has inline records...*/
+    | SomeStuff({
         offline: bool,
         /** Is the user online? */
         online?: bool,

From 8d9cbbbcf259aa3743fd633ce82d6d804a8ab4ec Mon Sep 17 00:00:00 2001
From: Shulhi Sapli <shulhi@gmail.com>
Date: Tue, 3 Jun 2025 20:24:13 +0800
Subject: [PATCH 05/10] Lookahead if we are in variant

---
 compiler/syntax/src/res_core.ml            | 28 +++++++++++++++-------
 tests/tools_tests/src/DocExtractionRes.res |  2 ++
 2 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/compiler/syntax/src/res_core.ml b/compiler/syntax/src/res_core.ml
index 98ed32819b..f385772374 100644
--- a/compiler/syntax/src/res_core.ml
+++ b/compiler/syntax/src/res_core.ml
@@ -4885,16 +4885,27 @@ and parse_constr_decl_args p =
  *  | constr-name const-args
  *  | attrs constr-name const-args *)
 and parse_type_constructor_declaration_with_bar p =
-  let doc_comment_attrs =
-    match p.Parser.token with
-    | DocComment (loc, s) ->
-      Parser.next p;
-      [doc_comment_to_attribute loc s]
-    | _ -> []
+  let is_constructor_with_bar p =
+    Parser.lookahead p (fun state ->
+        match state.Parser.token with
+        | DocComment _ -> (
+          Parser.next state;
+          match state.token with
+          | Bar -> true
+          | _ -> false)
+        | Bar -> true
+        | _ -> false)
   in
-  let has_doc_comment = not (doc_comment_attrs = []) in
   match p.Parser.token with
-  | Bar ->
+  | _ when is_constructor_with_bar p ->
+    let doc_comment_attrs =
+      match p.Parser.token with
+      | DocComment (loc, s) ->
+        Parser.next p;
+        [doc_comment_to_attribute loc s]
+      | _ -> []
+    in
+    let has_doc_comment = not (doc_comment_attrs = []) in
     let start_pos = p.Parser.start_pos in
     Parser.next p;
     let constr = parse_type_constructor_declaration ~start_pos p in
@@ -4946,6 +4957,7 @@ and parse_type_constructor_declarations ?first p =
   let first_constr_decl =
     match first with
     | None ->
+      (* bar *)
       let doc_comment_attrs =
         match p.Parser.token with
         | DocComment (loc, s) ->
diff --git a/tests/tools_tests/src/DocExtractionRes.res b/tests/tools_tests/src/DocExtractionRes.res
index 27ee44bc55..444cb8e12c 100644
--- a/tests/tools_tests/src/DocExtractionRes.res
+++ b/tests/tools_tests/src/DocExtractionRes.res
@@ -34,6 +34,8 @@ module SomeInnerModule = {
     | Stopped
     /** Now idle.*/
     | Idle
+
+  /** These are all the valid inputs.*/
   type validInputs = [#something | #"needs-escaping" | #withPayload(int) | #status(status)]
 
   type callback = (t, ~status: status) => unit

From 85c053cd5bda9c1659bf19ffc0539dd265889099 Mon Sep 17 00:00:00 2001
From: Shulhi Sapli <shulhi@gmail.com>
Date: Tue, 3 Jun 2025 21:02:48 +0800
Subject: [PATCH 06/10] Cleanup

---
 compiler/syntax/src/res_core.ml    |  4 ----
 compiler/syntax/src/res_printer.ml | 30 ++----------------------------
 2 files changed, 2 insertions(+), 32 deletions(-)

diff --git a/compiler/syntax/src/res_core.ml b/compiler/syntax/src/res_core.ml
index f385772374..00219ae148 100644
--- a/compiler/syntax/src/res_core.ml
+++ b/compiler/syntax/src/res_core.ml
@@ -4957,7 +4957,6 @@ and parse_type_constructor_declarations ?first p =
   let first_constr_decl =
     match first with
     | None ->
-      (* bar *)
       let doc_comment_attrs =
         match p.Parser.token with
         | DocComment (loc, s) ->
@@ -5565,9 +5564,6 @@ and parse_type_equation_and_representation ?current_type_name_path
         p
     | Private -> parse_private_eq_or_repr p
     | Bar | DotDot | DocComment _ ->
-      (* DOCCOMMENT: Reached here if the first variant starts with |. 
-         It is possible that the first variant may not have | (with multiple variants)
-       *)
       let priv, kind = parse_type_representation p in
       (None, priv, kind)
     | _ -> (
diff --git a/compiler/syntax/src/res_printer.ml b/compiler/syntax/src/res_printer.ml
index e0563fd969..38b1281840 100644
--- a/compiler/syntax/src/res_printer.ml
+++ b/compiler/syntax/src/res_printer.ml
@@ -1549,37 +1549,11 @@ and print_constructor_declarations ~state ~private_flag
 
 and print_constructor_declaration2 ~state i
     (cd : Parsetree.constructor_declaration) cmt_tbl =
-  let comment_attrs, attrs =
-    List.partition
-      (fun ((id, payload) : Parsetree.attribute) ->
-        match (id, payload) with
-        | ( {txt = "res.doc"},
-            PStr
-              [
-                {
-                  pstr_desc =
-                    Pstr_eval
-                      ({pexp_desc = Pexp_constant (Pconst_string (_, _))}, _);
-                };
-              ] ) ->
-          true
-        | _ -> false)
-      cd.pcd_attributes
-  in
+  let comment_attrs, attrs = ParsetreeViewer.partition_doc_comment_attributes cd.pcd_attributes in
   let comment_doc =
     match comment_attrs with
     | [] -> Doc.nil
-    | comment_attrs ->
-      Doc.concat
-        [
-          Doc.group
-            (Doc.join_with_sep
-               (List.map
-                  (fun attr -> print_attribute ~state attr cmt_tbl)
-                  comment_attrs));
-          Doc.hard_line;
-        ]
-  in
+    | comment_attrs -> print_doc_comments ~sep:Doc.hard_line ~state cmt_tbl comment_attrs in
   let attrs = print_attributes ~state attrs cmt_tbl in
   let is_dot_dot_dot = cd.pcd_name.txt = "..." in
   let bar =

From a41d014590f62460658580f2f17c88781ab0b457 Mon Sep 17 00:00:00 2001
From: Shulhi Sapli <shulhi@gmail.com>
Date: Wed, 4 Jun 2025 10:10:56 +0800
Subject: [PATCH 07/10] Remove loc adjustment hack

---
 compiler/syntax/src/res_core.ml    | 33 +-----------------------------
 compiler/syntax/src/res_printer.ml | 19 +++++++++++------
 2 files changed, 14 insertions(+), 38 deletions(-)

diff --git a/compiler/syntax/src/res_core.ml b/compiler/syntax/src/res_core.ml
index 00219ae148..fa303cb8a9 100644
--- a/compiler/syntax/src/res_core.ml
+++ b/compiler/syntax/src/res_core.ml
@@ -4905,28 +4905,14 @@ and parse_type_constructor_declaration_with_bar p =
         [doc_comment_to_attribute loc s]
       | _ -> []
     in
-    let has_doc_comment = not (doc_comment_attrs = []) in
     let start_pos = p.Parser.start_pos in
     Parser.next p;
     let constr = parse_type_constructor_declaration ~start_pos p in
-    let pcd_loc =
-      if has_doc_comment then
-        {
-          constr.Parsetree.pcd_loc with
-          loc_end =
-            {
-              constr.pcd_loc.loc_end with
-              pos_lnum = constr.pcd_loc.loc_end.pos_lnum + 1;
-            };
-        }
-      else constr.pcd_loc
-    in
     Some
       {
         constr with
         Parsetree.pcd_attributes =
           doc_comment_attrs @ constr.Parsetree.pcd_attributes;
-        pcd_loc;
       }
   | _ -> None
 
@@ -4964,27 +4950,10 @@ and parse_type_constructor_declarations ?first p =
           [doc_comment_to_attribute loc s]
         | _ -> []
       in
-      let has_doc_comment = not (doc_comment_attrs = []) in
       let start_pos = p.Parser.start_pos in
       ignore (Parser.optional p Token.Bar);
       let constr = parse_type_constructor_declaration ~start_pos p in
-      let pcd_loc =
-        if has_doc_comment then
-          {
-            constr.Parsetree.pcd_loc with
-            loc_end =
-              {
-                constr.pcd_loc.loc_end with
-                pos_lnum = constr.pcd_loc.loc_end.pos_lnum + 1;
-              };
-          }
-        else constr.pcd_loc
-      in
-      {
-        constr with
-        pcd_attributes = doc_comment_attrs @ constr.pcd_attributes;
-        pcd_loc;
-      }
+      {constr with pcd_attributes = doc_comment_attrs @ constr.pcd_attributes}
     | Some first_constr_decl -> first_constr_decl
   in
   first_constr_decl
diff --git a/compiler/syntax/src/res_printer.ml b/compiler/syntax/src/res_printer.ml
index 38b1281840..7e2c76a32b 100644
--- a/compiler/syntax/src/res_printer.ml
+++ b/compiler/syntax/src/res_printer.ml
@@ -340,7 +340,8 @@ let print_list ~get_loc ~nodes ~print ?(force_break = false) t =
     in
     Doc.breakable_group ~force_break docs
 
-let print_listi ~get_loc ~nodes ~print ?(force_break = false) t =
+let print_listi ~get_loc ~nodes ~print ?(ignore_empty_lines = false)
+    ?(force_break = false) t =
   let rec loop i (prev_loc : Location.t) acc nodes =
     match nodes with
     | [] -> (prev_loc, Doc.concat (List.rev acc))
@@ -352,8 +353,10 @@ let print_listi ~get_loc ~nodes ~print ?(force_break = false) t =
         | Some comment -> (Comment.loc comment).loc_start
       in
       let sep =
-        if start_pos.pos_lnum - prev_loc.loc_end.pos_lnum > 1 then
-          Doc.concat [Doc.hard_line; Doc.hard_line]
+        if
+          start_pos.pos_lnum - prev_loc.loc_end.pos_lnum > 1
+          && not ignore_empty_lines
+        then Doc.concat [Doc.hard_line; Doc.hard_line]
         else Doc.line
       in
       let doc = print_comments (print node t i) t loc in
@@ -1542,18 +1545,22 @@ and print_constructor_declarations ~state ~private_flag
       ~print:(fun cd cmt_tbl i ->
         let doc = print_constructor_declaration2 ~state i cd cmt_tbl in
         print_comments doc cmt_tbl cd.Parsetree.pcd_loc)
-      ~force_break cmt_tbl
+      ~force_break cmt_tbl ~ignore_empty_lines:true
   in
   Doc.breakable_group ~force_break
     (Doc.indent (Doc.concat [Doc.line; private_flag; rows]))
 
 and print_constructor_declaration2 ~state i
     (cd : Parsetree.constructor_declaration) cmt_tbl =
-  let comment_attrs, attrs = ParsetreeViewer.partition_doc_comment_attributes cd.pcd_attributes in
+  let comment_attrs, attrs =
+    ParsetreeViewer.partition_doc_comment_attributes cd.pcd_attributes
+  in
   let comment_doc =
     match comment_attrs with
     | [] -> Doc.nil
-    | comment_attrs -> print_doc_comments ~sep:Doc.hard_line ~state cmt_tbl comment_attrs in
+    | comment_attrs ->
+      print_doc_comments ~sep:Doc.hard_line ~state cmt_tbl comment_attrs
+  in
   let attrs = print_attributes ~state attrs cmt_tbl in
   let is_dot_dot_dot = cd.pcd_name.txt = "..." in
   let bar =

From 739bbc5f577f2a1507a7d9b72d35a36c9503f411 Mon Sep 17 00:00:00 2001
From: Shulhi Sapli <shulhi@gmail.com>
Date: Wed, 4 Jun 2025 12:39:54 +0800
Subject: [PATCH 08/10] Update test files

---
 tests/tests/src/condition_compilation_test.mjs | 4 ++--
 tests/tests/src/condition_compilation_test.res | 3 ---
 tests/tests/src/gpr_1822_test.mjs              | 2 +-
 tests/tests/src/gpr_1822_test.res              | 1 -
 tests/tests/src/test_seq.res                   | 1 -
 5 files changed, 3 insertions(+), 8 deletions(-)

diff --git a/tests/tests/src/condition_compilation_test.mjs b/tests/tests/src/condition_compilation_test.mjs
index 533679e9e7..9ac6ac50a1 100644
--- a/tests/tests/src/condition_compilation_test.mjs
+++ b/tests/tests/src/condition_compilation_test.mjs
@@ -33,9 +33,9 @@ function eq(loc, x, y) {
   };
 }
 
-eq("File \"condition_compilation_test.res\", line 63, characters 5-12", 3, 3);
+eq("File \"condition_compilation_test.res\", line 60, characters 5-12", 3, 3);
 
-eq("File \"condition_compilation_test.res\", line 64, characters 5-12", v.contents, 2);
+eq("File \"condition_compilation_test.res\", line 61, characters 5-12", v.contents, 2);
 
 Mt.from_pair_suites("Condition_compilation_test", suites.contents);
 
diff --git a/tests/tests/src/condition_compilation_test.res b/tests/tests/src/condition_compilation_test.res
index 5bf56bed1b..8c7a8629ac 100644
--- a/tests/tests/src/condition_compilation_test.res
+++ b/tests/tests/src/condition_compilation_test.res
@@ -15,11 +15,8 @@ type open_flag =
   | O_DSYNC
   | O_SYNC
   | O_RSYNC
-
   | O_SHARE_DELETE
-
   | O_CLOEXEC
-
   | O_KEEPEXEC
 
 let vv = 3
diff --git a/tests/tests/src/gpr_1822_test.mjs b/tests/tests/src/gpr_1822_test.mjs
index 053f75f08a..c6a595a565 100644
--- a/tests/tests/src/gpr_1822_test.mjs
+++ b/tests/tests/src/gpr_1822_test.mjs
@@ -34,7 +34,7 @@ let area;
 
 area = myShape.TAG === "Circle" ? 100 * 3.14 : 10 * myShape._1 | 0;
 
-eq("File \"gpr_1822_test.res\", line 23, characters 3-10", area, 314);
+eq("File \"gpr_1822_test.res\", line 22, characters 3-10", area, 314);
 
 Mt.from_pair_suites("Gpr_1822_test", suites.contents);
 
diff --git a/tests/tests/src/gpr_1822_test.res b/tests/tests/src/gpr_1822_test.res
index 0d9006280f..a83c2a036c 100644
--- a/tests/tests/src/gpr_1822_test.res
+++ b/tests/tests/src/gpr_1822_test.res
@@ -11,7 +11,6 @@ let eq = (loc, x, y) => {
 
 type shape =
   | Circle(int)
-
   | Rectangle(int, int)
 
 let myShape = Circle(10)
diff --git a/tests/tests/src/test_seq.res b/tests/tests/src/test_seq.res
index 8927d6119a..fd9bead672 100644
--- a/tests/tests/src/test_seq.res
+++ b/tests/tests/src/test_seq.res
@@ -29,7 +29,6 @@ type rec spec =
   | Set_float(ref<float>) /* Set the reference to the float argument */
   | Tuple(list<spec>) /* Take several arguments according to the
    spec list */
-
   | Symbol(list<string>, string => unit)
   /* Take one of the symbols as argument and
    call the function with the symbol. */

From f7497fec1bb9d8572d1b94ae1a6f05e380d8c0e5 Mon Sep 17 00:00:00 2001
From: Shulhi Sapli <shulhi@gmail.com>
Date: Wed, 4 Jun 2025 13:16:01 +0800
Subject: [PATCH 09/10] Update CHANGELOG

---
 CHANGELOG.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 86fab3a77e..f8142b4302 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -36,6 +36,7 @@
 - Fix `index out of bounds` exception thrown in rare cases by `rescript-editor-analysis.exe codeAction` command. https://github.com/rescript-lang/rescript/pull/7523
 - Don't produce duplicate type definitions for recursive types on hover. https://github.com/rescript-lang/rescript/pull/7524
 - Prop punning when types don't match results in I/O error: _none_: No such file or directory. https://github.com/rescript-lang/rescript/pull/7533
+- Fix doc comment before variant throwing syntax error. https://github.com/rescript-lang/rescript/pull/7535
 
 #### :nail_care: Polish
 

From aec4bc74efcedf27dfc683f894dcb727666e8ee0 Mon Sep 17 00:00:00 2001
From: Shulhi Sapli <shulhi@gmail.com>
Date: Wed, 4 Jun 2025 15:17:20 +0800
Subject: [PATCH 10/10] Resolve review feedback

---
 compiler/syntax/src/res_core.ml | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/compiler/syntax/src/res_core.ml b/compiler/syntax/src/res_core.ml
index fa303cb8a9..154969e2c2 100644
--- a/compiler/syntax/src/res_core.ml
+++ b/compiler/syntax/src/res_core.ml
@@ -4896,8 +4896,7 @@ and parse_type_constructor_declaration_with_bar p =
         | Bar -> true
         | _ -> false)
   in
-  match p.Parser.token with
-  | _ when is_constructor_with_bar p ->
+  if is_constructor_with_bar p then (
     let doc_comment_attrs =
       match p.Parser.token with
       | DocComment (loc, s) ->
@@ -4913,8 +4912,8 @@ and parse_type_constructor_declaration_with_bar p =
         constr with
         Parsetree.pcd_attributes =
           doc_comment_attrs @ constr.Parsetree.pcd_attributes;
-      }
-  | _ -> None
+      })
+  else None
 
 and parse_type_constructor_declaration ~start_pos p =
   Parser.leave_breadcrumb p Grammar.ConstructorDeclaration;