Remove support of children spread inside JSX (#7869)

* Initial plan

* Drop support of JSX children spread

Co-authored-by: tsnobip <2479216+tsnobip@users.noreply.github.com>

* remove JSXChildrenItems variant

* add error message when parsing children spread

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: tsnobip <2479216+tsnobip@users.noreply.github.com>

Author: Copilot

CHANGELOG.md

@@ -15,6 +15,7 @@
 #### :boom: Breaking Change
 
 - Fix return type of `String.charCodeAt`. https://github.com/rescript-lang/rescript/pull/7864
+- Remove support of JSX children spread. https://github.com/rescript-lang/rescript/pull/7869
 
 #### :eyeglasses: Spec Compliance
 

analysis/src/CompletionFrontEnd.ml

@@ -1353,7 +1353,7 @@ let completionWithParser1 ~currentFile ~debug ~offset ~path ~posCursor
                 (Jsx_container_element
                    {jsx_container_element_children = children}) ->
               children
-            | _ -> JSXChildrenItems []
+            | _ -> []
           in
           let compName_loc = compName.loc in
           let compName_lid =
@@ -1412,8 +1412,7 @@ let completionWithParser1 ~currentFile ~debug ~offset ~path ~posCursor
                   (Jsx_container_element
                      {
                        jsx_container_element_closing_tag = None;
-                       jsx_container_element_children =
-                         JSXChildrenSpreading _ | JSXChildrenItems (_ :: _);
+                       jsx_container_element_children = _ :: _;
                      }) ) ->
               None
             | Some jsxProps, _ ->

analysis/src/CompletionJsx.ml

@@ -460,8 +460,8 @@ let extractJsxProps ~(compName : Longident.t Location.loc) ~props ~children =
   let open Parsetree in
   let childrenStart =
     match children with
-    | JSXChildrenItems [] -> None
-    | JSXChildrenSpreading child | JSXChildrenItems (child :: _) ->
+    | [] -> None
+    | child :: _ ->
       if child.pexp_loc.loc_ghost then None else Some (Loc.start child.pexp_loc)
   in
   let props =

analysis/src/SemanticTokens.ml

@@ -311,10 +311,7 @@ let command ~debug ~emitter ~path =
            ~pos:(Pos.ofLexing posOfGreatherthanAfterProps);
 
       (* children *)
-      (match children with
-      | Parsetree.JSXChildrenSpreading child -> iterator.expr iterator child
-      | Parsetree.JSXChildrenItems children ->
-        List.iter (iterator.expr iterator) children);
+      List.iter (iterator.expr iterator) children;
 
       (* closing tag *)
       closing_tag_opt

compiler/frontend/bs_ast_mapper.ml

@@ -292,9 +292,7 @@ module M = struct
 end
 
 module E = struct
-  let map_jsx_children sub = function
-    | JSXChildrenSpreading e -> JSXChildrenSpreading (sub.expr sub e)
-    | JSXChildrenItems xs -> JSXChildrenItems (List.map (sub.expr sub) xs)
+  let map_jsx_children sub xs = List.map (sub.expr sub) xs
 
   let map_jsx_prop sub = function
     | JSXPropPunning (optional, name) ->

compiler/ml/ast_iterator.ml

@@ -267,9 +267,7 @@ module M = struct
 end
 
 module E = struct
-  let iter_jsx_children sub = function
-    | JSXChildrenSpreading e -> sub.expr sub e
-    | JSXChildrenItems xs -> List.iter (sub.expr sub) xs
+  let iter_jsx_children sub xs = List.iter (sub.expr sub) xs
 
   let iter_jsx_prop sub = function
     | JSXPropPunning (_, name) -> iter_loc sub name

compiler/ml/ast_mapper.ml

@@ -263,9 +263,7 @@ module M = struct
 end
 
 module E = struct
-  let map_jsx_children sub = function
-    | JSXChildrenSpreading e -> JSXChildrenSpreading (sub.expr sub e)
-    | JSXChildrenItems xs -> JSXChildrenItems (List.map (sub.expr sub) xs)
+  let map_jsx_children sub xs = List.map (sub.expr sub) xs
 
   let map_jsx_prop sub = function
     | JSXPropPunning (optional, name) ->

compiler/ml/ast_mapper_from0.ml

@@ -326,8 +326,8 @@ module E = struct
     match e.pexp_desc with
     | Pexp_construct ({txt = Longident.Lident "[]" | Longident.Lident "::"}, _)
       ->
-      JSXChildrenItems (visit e)
-    | _ -> JSXChildrenSpreading (sub.expr sub e)
+      visit e
+    | _ -> [sub.expr sub e]
 
   let try_map_jsx_prop (sub : mapper) (lbl : Asttypes.Noloc.arg_label)
       (e : expression) : Parsetree.jsx_prop option =

compiler/ml/ast_mapper_to0.ml

@@ -340,8 +340,7 @@ module E = struct
 
   let map_jsx_children sub loc children =
     match children with
-    | JSXChildrenSpreading e -> sub.expr sub e
-    | JSXChildrenItems xs ->
+    | xs ->
       let list_expr = Ast_helper.Exp.make_list_expression loc xs None in
       sub.expr sub list_expr
 

compiler/ml/depend.ml

@@ -312,9 +312,7 @@ let rec add_expr bv exp =
     and_jsx_props bv props;
     add_jsx_children bv children
 
-and add_jsx_children bv = function
-  | JSXChildrenSpreading e -> add_expr bv e
-  | JSXChildrenItems xs -> List.iter (add_expr bv) xs
+and add_jsx_children bv xs = List.iter (add_expr bv) xs
 
 and add_jsx_prop bv = function
   | JSXPropPunning (_, _) -> ()