From 7f35404cce6e38196c00ab6820fb47da5da674c7 Mon Sep 17 00:00:00 2001
From: Shulhi Sapli <shulhi@gmail.com>
Date: Mon, 5 May 2025 19:17:31 +0800
Subject: [PATCH 1/3] WIP

---
 compiler/syntax/src/res_printer.ml | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/compiler/syntax/src/res_printer.ml b/compiler/syntax/src/res_printer.ml
index 8d23dabcf8..a6f039d031 100644
--- a/compiler/syntax/src/res_printer.ml
+++ b/compiler/syntax/src/res_printer.ml
@@ -4584,6 +4584,18 @@ and get_line_sep_for_jsx_children (children : Parsetree.jsx_children) =
 
 and print_jsx_children ~state (children : Parsetree.jsx_children) cmt_tbl =
   let open Parsetree in
+  let get_loc (expr : Parsetree.expression) =
+    let braces =
+      expr.pexp_attributes
+      |> List.find_map (fun (attr, _) ->
+             match attr with
+             | {Location.txt = "res.braces"; loc} -> Some loc
+             | _ -> None)
+    in
+    match braces with
+    | None -> expr.pexp_loc
+    | Some loc -> loc
+  in
   let sep = get_line_sep_for_jsx_children children in
   let print_expr (expr : Parsetree.expression) =
     let leading_line_comment_present =
@@ -4599,7 +4611,7 @@ and print_jsx_children ~state (children : Parsetree.jsx_children) cmt_tbl =
       else Doc.concat [Doc.lbrace; inner_doc; Doc.rbrace]
     in
     match Parens.jsx_child_expr expr with
-    | Nothing -> expr_doc
+    | Nothing -> print_comments expr_doc cmt_tbl (get_loc expr)
     | Parenthesized -> add_parens_or_braces expr_doc
     | Braced braces_loc ->
       print_comments (add_parens_or_braces expr_doc) cmt_tbl braces_loc
@@ -4608,19 +4620,6 @@ and print_jsx_children ~state (children : Parsetree.jsx_children) cmt_tbl =
   | JSXChildrenItems [] -> Doc.nil
   | JSXChildrenSpreading child -> Doc.concat [Doc.dotdotdot; print_expr child]
   | JSXChildrenItems children ->
-    let get_loc (expr : Parsetree.expression) =
-      let braces =
-        expr.pexp_attributes
-        |> List.find_map (fun (attr, _) ->
-               match attr with
-               | {Location.txt = "res.braces"; loc} -> Some loc
-               | _ -> None)
-      in
-      match braces with
-      | None -> expr.pexp_loc
-      | Some loc -> loc
-    in
-
     let rec visit acc children =
       match children with
       | [] -> acc

From 4782d78545eb1c73d231464b8d2d7857bbfae54d Mon Sep 17 00:00:00 2001
From: Shulhi Sapli <shulhi@gmail.com>
Date: Mon, 5 May 2025 20:13:14 +0800
Subject: [PATCH 2/3] Add test

---
 .../data/printer/comments/expected/jsx.res.txt           | 9 +++++++++
 tests/syntax_tests/data/printer/comments/jsx.res         | 8 ++++++++
 2 files changed, 17 insertions(+)

diff --git a/tests/syntax_tests/data/printer/comments/expected/jsx.res.txt b/tests/syntax_tests/data/printer/comments/expected/jsx.res.txt
index 98f1bf3ee3..664018ce3b 100644
--- a/tests/syntax_tests/data/printer/comments/expected/jsx.res.txt
+++ b/tests/syntax_tests/data/printer/comments/expected/jsx.res.txt
@@ -65,6 +65,15 @@ module Cite = {
   React.string("Hello, World!")}
 </div>
 
+<div>
+  // Outside comment
+  {
+    // But this one is inside
+    let x = 1
+    let y = 2
+  }
+</div>
+
 let x =
   <>
     // before a
diff --git a/tests/syntax_tests/data/printer/comments/jsx.res b/tests/syntax_tests/data/printer/comments/jsx.res
index d554e249af..40dd824745 100644
--- a/tests/syntax_tests/data/printer/comments/jsx.res
+++ b/tests/syntax_tests/data/printer/comments/jsx.res
@@ -67,6 +67,14 @@ value=""
     React.string("Hello, World!")}
 </div>
 
+<div>
+  // Outside comment
+  {// But this one is inside
+    let x = 1
+    let y = 2
+  }
+</div>
+
 let x = <>
   // before a
   {a} // after a

From 18a44418a27b4267f55d378eeaad935de53ade51 Mon Sep 17 00:00:00 2001
From: Shulhi Sapli <shulhi@gmail.com>
Date: Mon, 5 May 2025 20:29:50 +0800
Subject: [PATCH 3/3] Update CHANGELOG

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

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d1557a4e5e..0f667bae70 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -29,6 +29,7 @@
 
 - Fix broken `bstracing` CLI location. https://github.com/rescript-lang/rescript/pull/7398
 - Fix field flattening optimization to avoid creating unnecessary copies of allocating constants. https://github.com/rescript-lang/rescript-compiler/pull/7421
+- Fix leading comments removed when braces inside JSX contains `let` assignment. https://github.com/rescript-lang/rescript/pull/7424
 
 #### :house: Internal