chore(requires-writer): use virtual modules instead of fs

packages/gatsby/cache-dir/__tests__/static-entry.js

@@ -18,7 +18,7 @@ jest.mock(`gatsby/package.json`, () => {
 })
 
 jest.mock(
-  `../sync-requires`,
+  `$virtual/sync-requires`,
   () => {
     return {
       components: {

packages/gatsby/cache-dir/app.js

@@ -8,9 +8,9 @@ import emitter from "./emitter"
 import { apiRunner, apiRunnerAsync } from "./api-runner-browser"
 import { setLoader, publicLoader } from "./loader"
 import DevLoader from "./dev-loader"
-import syncRequires from "./sync-requires"
+import syncRequires from "$virtual/sync-requires"
 // Generated during bootstrap
-import matchPaths from "./match-paths.json"
+import matchPaths from "$virtual/match-paths.json"
 
 window.___emitter = emitter
 

packages/gatsby/cache-dir/production-app.js

@@ -11,7 +11,7 @@ import {
 } from "./navigation"
 import emitter from "./emitter"
 import PageRenderer from "./page-renderer"
-import asyncRequires from "./async-requires"
+import asyncRequires from "$virtual/async-requires"
 import {
   setLoader,
   ProdLoader,
@@ -22,7 +22,7 @@ import EnsureResources from "./ensure-resources"
 import stripPrefix from "./strip-prefix"
 
 // Generated during bootstrap
-import matchPaths from "./match-paths.json"
+import matchPaths from "$virtual/match-paths.json"
 
 const loader = new ProdLoader(asyncRequires, matchPaths)
 setLoader(loader)

packages/gatsby/cache-dir/static-entry.js

@@ -17,7 +17,7 @@ const {
 
 const { RouteAnnouncerProps } = require(`./route-announcer-props`)
 const apiRunner = require(`./api-runner-ssr`)
-const syncRequires = require(`./sync-requires`)
+const syncRequires = require(`$virtual/sync-requires`)
 const { version: gatsbyVersion } = require(`gatsby/package.json`)
 
 const stats = JSON.parse(

packages/gatsby/src/bootstrap/requires-writer.ts

@@ -8,6 +8,7 @@ import { match } from "@reach/router/lib/utils"
 import { joinPath } from "gatsby-core-utils"
 import { store, emitter } from "../redux/"
 import { IGatsbyState, IGatsbyPage } from "../redux/types"
+import { writeModule } from "../utils/gatsby-webpack-virtual-modules"
 import { markWebpackStatusAsPending } from "../utils/webpack-status"
 
 interface IGatsbyPageComponent {
@@ -212,7 +213,7 @@ const preferDefault = m => m && m.default || m
     .map((c: IGatsbyPageComponent): string => {
       // we need a relative import path to keep contenthash the same if directory changes
       const relativeComponentPath = path.relative(
-        path.join(program.directory, `.cache`),
+        path.join(program.directory, `node_modules`, `$virtual`),
         c.component
       )
 
@@ -223,7 +224,16 @@ const preferDefault = m => m && m.default || m
     .join(`,\n`)}
 }\n\n`
 
-  const writeAndMove = (file: string, data: string): Promise<void> => {
+  const writeAndMove = (
+    virtualFilePath: string,
+    file: string,
+    data: string
+  ): Promise<void> => {
+    writeModule(virtualFilePath, data)
+
+    // files in .cache are not used anymore as part of webpack builds, but
+    // still can be used by other tools (for example `gatsby serve` reads
+    // `match-paths.json` to setup routing)
     const destination = joinPath(program.directory, `.cache`, file)
     const tmp = `${destination}.${Date.now()}`
     return fs
@@ -232,9 +242,17 @@ const preferDefault = m => m && m.default || m
   }
 
   await Promise.all([
-    writeAndMove(`sync-requires.js`, syncRequires),
-    writeAndMove(`async-requires.js`, asyncRequires),
-    writeAndMove(`match-paths.json`, JSON.stringify(matchPaths, null, 4)),
+    writeAndMove(`$virtual/sync-requires.js`, `sync-requires.js`, syncRequires),
+    writeAndMove(
+      `$virtual/async-requires.js`,
+      `async-requires.js`,
+      asyncRequires
+    ),
+    writeAndMove(
+      `$virtual/match-paths.json`,
+      `match-paths.json`,
+      JSON.stringify(matchPaths, null, 4)
+    ),
   ])
 
   return true