Upgrade react-hot-loader to 4.6 (gatsbyjs#10455)

Fixes gatsbyjs#9489 

~~The docs also [recommend](https://github.com/gaearon/react-hot-loader#react--dom) (but don't require) using a patched `react-dom`, but as I understand it that would override the user's `react-dom` version we have as a peer dependency so I left it out.~~ ➡️ gatsbyjs@3894f0a

/cc @wKovacs64

packages/gatsby/cache-dir/app.js

@@ -1,7 +1,6 @@
 import React from "react"
 import ReactDOM from "react-dom"
 import domReady from "domready"
-import { hot, setConfig } from "react-hot-loader"
 
 import socketIo from "./socketIo"
 import emitter from "./emitter"
@@ -13,12 +12,6 @@ import pages from "./pages.json"
 window.___emitter = emitter
 setApiRunnerForLoader(apiRunner)
 
-// necessary for hot-reloading of react hooks
-setConfig({
-  ignoreSFC: true,
-  pureRender: true,
-})
-
 // Let the site/plugins run code very early.
 apiRunnerAsync(`onClientEntry`).then(() => {
   // Hook up the client to socket.io on server
@@ -57,7 +50,8 @@ apiRunnerAsync(`onClientEntry`).then(() => {
   loader.addDevRequires(syncRequires)
 
   loader.getResourcesForPathname(window.location.pathname).then(() => {
-    let Root = hot(module)(preferDefault(require(`./root`)))
+    const preferDefault = m => (m && m.default) || m
+    let Root = preferDefault(require(`./root`))
     domReady(() => {
       renderer(<Root />, rootElement, () => {
         apiRunner(`onInitialClientRender`)
@@ -66,8 +60,6 @@ apiRunnerAsync(`onClientEntry`).then(() => {
   })
 })
 
-const preferDefault = m => (m && m.default) || m
-
 function supportsServiceWorkers(location, navigator) {
   if (location.hostname === `localhost` || location.protocol === `https:`) {
     return `serviceWorker` in navigator

packages/gatsby/cache-dir/root.js

@@ -1,6 +1,7 @@
 import React, { createElement } from "react"
 import { Router } from "@reach/router"
 import { ScrollContext } from "gatsby-react-router-scroll"
+
 import {
   shouldUpdateScroll,
   init as navigationInit,

packages/gatsby/package.json

@@ -102,7 +102,7 @@
     "raw-loader": "^0.5.1",
     "react-dev-utils": "^4.2.1",
     "react-error-overlay": "^3.0.0",
-    "react-hot-loader": "^4.5.1",
+    "react-hot-loader": "^4.6.0",
     "redux": "^4.0.0",
     "relay-compiler": "1.5.0",
     "request": "^2.85.0",

packages/gatsby/src/internal-plugins/query-runner/pages-writer.js

@@ -72,15 +72,17 @@ const writePages = async () => {
   components = _.uniqBy(components, c => c.componentChunkName)
 
   // Create file with sync requires of components/json files.
-  let syncRequires = `// prefer default export if available
+  let syncRequires = `const { hot } = require("react-hot-loader/root")
+
+// prefer default export if available
 const preferDefault = m => m && m.default || m
 \n\n`
   syncRequires += `exports.components = {\n${components
     .map(
       c =>
-        `  "${c.componentChunkName}": preferDefault(require("${joinPath(
+        `  "${c.componentChunkName}": hot(preferDefault(require("${joinPath(
           c.component
-        )}"))`
+        )}")))`
     )
     .join(`,\n`)}
 }\n\n`

yarn.lock

@@ -15641,10 +15641,10 @@ react-error-overlay@^3.0.0:
   resolved "https://registry.yarnpkg.com/react-error-overlay/-/react-error-overlay-3.0.0.tgz#c2bc8f4d91f1375b3dad6d75265d51cd5eeaf655"
   integrity sha512-XzgvowFrwDo6TWcpJ/WTiarb9UI6lhA4PMzS7n1joK3sHfBBBOQHUc0U4u57D6DWO9vHv6lVSWx2Q/Ymfyv4hw==
 
-react-hot-loader@^4.5.1:
-  version "4.5.1"
-  resolved "https://registry.yarnpkg.com/react-hot-loader/-/react-hot-loader-4.5.1.tgz#4a9cf136542b1db4f948ac74b31fa16a411ceebb"
-  integrity sha512-aqw8F0ZTCakfTXTj1n3F9vXfEKWWHEpQ3Mq9YmYvrNdHvey5RfkSGv7rz4r9TXjqVLt2mpItqydJQdhboZ/acQ==
+react-hot-loader@4.6:
+  version "4.6.0"
+  resolved "https://registry.yarnpkg.com/react-hot-loader/-/react-hot-loader-4.6.0.tgz#7a556efea51a3c79e8bffdb094fbe17883a79432"
+  integrity sha512-ytmtbJB0RlTUqa9HnpVsoZiZ6iRsTzu+O2WovKT++f+tDYOTNZYa7OesVAE+R90e/1w/OJO4G/tw4rNSMYCjFw==
   dependencies:
     fast-levenshtein "^2.0.6"
     global "^4.3.0"