fix shorthand fragment transformation

Author: mununki

jscomp/syntax/src/reactjs_jsx_v4.ml

@@ -1374,24 +1374,22 @@ let expr ~config mapper expression =
       let transformChildrenToProps childrenExpr =
         match childrenExpr with
         | {pexp_desc = Pexp_array children} -> (
-          match children with
-          | [] -> emptyRecord ~loc:Location.none
-          | [child] -> recordOfChildren child
-          | _ -> (
-            match config.mode with
-            | "automatic" -> recordOfChildren @@ applyReactArray childrenExpr
-            | "classic" | _ -> emptyRecord ~loc:Location.none))
-        | _ -> (
           match config.mode with
-          | "automatic" -> recordOfChildren @@ applyReactArray childrenExpr
-          | "classic" | _ -> emptyRecord ~loc:Location.none)
+          | "automatic" -> (
+            match children with
+            | [] -> emptyRecord ~loc:Location.none
+            | [child] -> recordOfChildren child
+            | _ -> recordOfChildren @@ applyReactArray childrenExpr)
+          | "classic" -> emptyRecord ~loc:Location.none
+          | _ -> recordOfChildren @@ applyReactArray childrenExpr)
+        | _ -> recordOfChildren @@ applyReactArray childrenExpr
       in
       let args =
         (nolabel, fragment)
         :: (nolabel, transformChildrenToProps childrenExpr)
         ::
         (match config.mode with
-        | "classic" when countOfChildren childrenExpr > 1 ->
+        | "classic" when countOfChildren childrenExpr > 0 ->
           [(nolabel, childrenExpr)]
         | _ -> [])
       in
@@ -1405,7 +1403,7 @@ let expr ~config mapper expression =
             Exp.ident ~loc {loc; txt = Ldot (Lident "React", "jsxs")}
           else Exp.ident ~loc {loc; txt = Ldot (Lident "React", "jsx")}
         | "classic" | _ ->
-          if countOfChildren childrenExpr > 1 then
+          if countOfChildren childrenExpr > 0 then
             Exp.ident ~loc
               {loc; txt = Ldot (Lident "React", "createElementVariadic")}
           else

jscomp/syntax/tests/ppx/react/expected/fragment.res.txt

@@ -1,16 +1,17 @@
 @@jsxConfig({version: 4, mode: "classic"})
 
 let _ = React.createElement(React.fragment, {})
-let _ = React.createElement(
+let _ = React.createElementVariadic(
   React.fragment,
-  {children: ReactDOM.createDOMElementVariadic("div", [])},
+  {},
+  [ReactDOM.createDOMElementVariadic("div", [])],
 )
 let _ = React.createElementVariadic(
   React.fragment,
   {},
   [ReactDOM.createDOMElementVariadic("div", []), ReactDOM.createDOMElementVariadic("div", [])],
 )
-let _ = React.createElement(React.fragment, {children: React.createElement(React.fragment, {})})
+let _ = React.createElementVariadic(React.fragment, {}, [React.createElement(React.fragment, {})])
 let _ = React.createElement(Z.make, {})
 let _ = React.createElement(Z.make, {children: ReactDOM.createDOMElementVariadic("div", [])})
 let _ = React.createElement(

jscomp/syntax/tests/ppx/react/expected/removedKeyProp.res.txt

@@ -14,7 +14,8 @@ module Foo = {
 module HasChildren = {
   type props<'children> = {children: 'children}
 
-  let make = ({children, _}: props<_>) => React.createElement(React.fragment, {children: children})
+  let make = ({children, _}: props<_>) =>
+    React.createElementVariadic(React.fragment, {}, [children])
   let make = {
     let \"RemovedKeyProp$HasChildren" = (props: props<_>) => make(props)