Jsx ppx optimize object allocation (#6376)

Author: DZakh

CHANGELOG.md

@@ -19,6 +19,10 @@
 - Untagged variants: Support `promise`, RegExes, Dates, File and Blob. https://github.com/rescript-lang/rescript-compiler/pull/6383
 - Support aliased types as payloads to untagged variants. https://github.com/rescript-lang/rescript-compiler/pull/6394
 
+#### :nail_care: Polish
+
+- A little performance improvement for JSX V4 runtime helper by removing one object allocation for components with key prop. https://github.com/rescript-lang/rescript-compiler/pull/6376
+
 # 11.0.0-rc.3
 
 #### :bug: Bug Fix

jscomp/others/jsxPPXReactSupportC.res

@@ -26,12 +26,12 @@ module Jsx = JsxC
 
 %%private(
   @val
-  external propsWithKey: (@as(json`{}`) _, 'props, {"key": string}) => 'props = "Object.assign"
+  external propsWithKey: ({"key": string}, 'props) => 'props = "Object.assign"
 
   @inline
   let addKeyProp = (~key: option<string>=?, p: 'props): 'props =>
     switch key {
-    | Some(key) => propsWithKey(p, {"key": key})
+    | Some(key) => propsWithKey({"key": key}, p)
     | None => p
     }
 )

jscomp/others/jsxPPXReactSupportU.res

@@ -26,12 +26,12 @@ module Jsx = JsxU
 
 %%private(
   @val
-  external propsWithKey: (@as(json`{}`) _, 'props, {"key": string}) => 'props = "Object.assign"
+  external propsWithKey: ({"key": string}, 'props) => 'props = "Object.assign"
 
   @inline
   let addKeyProp = (~key: option<string>=?, p: 'props): 'props =>
     switch key {
-    | Some(key) => propsWithKey(p, {"key": key})
+    | Some(key) => propsWithKey({"key": key}, p)
     | None => p
     }
 )

lib/es6/jsxPPXReactSupportC.js

@@ -4,17 +4,17 @@ import * as React from "react";
 import * as Caml_splice_call from "./caml_splice_call.js";
 
 function createElementWithKey(key, component, props) {
-  return React.createElement(component, key !== undefined ? Object.assign({}, props, {
+  return React.createElement(component, key !== undefined ? Object.assign({
                     key: key
-                  }) : props);
+                  }, props) : props);
 }
 
 function createElementVariadicWithKey(key, component, props, elements) {
   return Caml_splice_call.spliceApply(React.createElement, [
               component,
-              key !== undefined ? Object.assign({}, props, {
+              key !== undefined ? Object.assign({
                       key: key
-                    }) : props,
+                    }, props) : props,
               elements
             ]);
 }

lib/es6/jsxPPXReactSupportU.js

@@ -4,17 +4,17 @@ import * as React from "react";
 import * as Caml_splice_call from "./caml_splice_call.js";
 
 function createElementWithKey(key, component, props) {
-  return React.createElement(component, key !== undefined ? Object.assign({}, props, {
+  return React.createElement(component, key !== undefined ? Object.assign({
                     key: key
-                  }) : props);
+                  }, props) : props);
 }
 
 function createElementVariadicWithKey(key, component, props, elements) {
   return Caml_splice_call.spliceApply(React.createElement, [
               component,
-              key !== undefined ? Object.assign({}, props, {
+              key !== undefined ? Object.assign({
                       key: key
-                    }) : props,
+                    }, props) : props,
               elements
             ]);
 }

lib/js/jsxPPXReactSupportC.js

@@ -4,17 +4,17 @@ var React = require("react");
 var Caml_splice_call = require("./caml_splice_call.js");
 
 function createElementWithKey(key, component, props) {
-  return React.createElement(component, key !== undefined ? Object.assign({}, props, {
+  return React.createElement(component, key !== undefined ? Object.assign({
                     key: key
-                  }) : props);
+                  }, props) : props);
 }
 
 function createElementVariadicWithKey(key, component, props, elements) {
   return Caml_splice_call.spliceApply(React.createElement, [
               component,
-              key !== undefined ? Object.assign({}, props, {
+              key !== undefined ? Object.assign({
                       key: key
-                    }) : props,
+                    }, props) : props,
               elements
             ]);
 }

lib/js/jsxPPXReactSupportU.js

@@ -4,17 +4,17 @@ var React = require("react");
 var Caml_splice_call = require("./caml_splice_call.js");
 
 function createElementWithKey(key, component, props) {
-  return React.createElement(component, key !== undefined ? Object.assign({}, props, {
+  return React.createElement(component, key !== undefined ? Object.assign({
                     key: key
-                  }) : props);
+                  }, props) : props);
 }
 
 function createElementVariadicWithKey(key, component, props, elements) {
   return Caml_splice_call.spliceApply(React.createElement, [
               component,
-              key !== undefined ? Object.assign({}, props, {
+              key !== undefined ? Object.assign({
                       key: key
-                    }) : props,
+                    }, props) : props,
               elements
             ]);
 }