chore: Properly typecheck gatsby

packages/gatsby/package.json

@@ -118,7 +118,7 @@
     "opentracing": "^0.14.4",
     "p-defer": "^3.0.0",
     "parseurl": "^1.3.3",
-    "path-to-regexp": "0.1.7",
+    "path-to-regexp": "^6.2.0",
     "physical-cpu-count": "^2.0.0",
     "platform": "^1.3.6",
     "pnp-webpack-plugin": "^1.6.4",

packages/gatsby/src/bootstrap/schema-hot-reloader.ts

@@ -32,7 +32,7 @@ const maybeRebuildSchema = debounce(async (): Promise<void> => {
   const activity = report.activityTimer(`rebuild schema`)
   activity.start()
   await rebuild({ parentSpan: activity })
-  await updateStateAndRunQueries(false, { parentSpan: activity })
+  await updateStateAndRunQueries(false, { parentSpan: activity.span })
   activity.end()
 }, 1000)
 

packages/gatsby/src/cache/cache-fs.ts

@@ -54,7 +54,7 @@ exports.create = function (args): typeof DiskStore {
   return new DiskStore(args && args.options ? args.options : args)
 }
 
-function DiskStore(options): void {
+function DiskStore(this: any, options): void {
   options = options || {}
 
   this.options = {
@@ -91,7 +91,12 @@ function DiskStore(options): void {
  * @param {function} [cb]
  * @returns {Promise}
  */
-DiskStore.prototype.set = wrapCallback(async function (key, val, options) {
+DiskStore.prototype.set = wrapCallback(async function (
+  this: any,
+  key,
+  val,
+  options
+) {
   key = key + ``
   const filePath = this._getFilePathByKey(key)
 
@@ -128,7 +133,7 @@ DiskStore.prototype.set = wrapCallback(async function (key, val, options) {
  * @param {function} [cb]
  * @returns {Promise}
  */
-DiskStore.prototype.get = wrapCallback(async function (key) {
+DiskStore.prototype.get = wrapCallback(async function (this: any, key) {
   key = key + ``
   const filePath = this._getFilePathByKey(key)
 
@@ -172,7 +177,7 @@ DiskStore.prototype.get = wrapCallback(async function (key) {
 /**
  * delete entry from cache
  */
-DiskStore.prototype.del = wrapCallback(async function (key) {
+DiskStore.prototype.del = wrapCallback(async function (this: any, key) {
   const filePath = this._getFilePathByKey(key)
   try {
     if (this.options.subdirs) {
@@ -196,7 +201,9 @@ DiskStore.prototype.del = wrapCallback(async function (key) {
 /**
  * cleanup cache on disk -> delete all files from the cache
  */
-DiskStore.prototype.reset = wrapCallback(async function (): Promise<void> {
+DiskStore.prototype.reset = wrapCallback(async function (
+  this: any
+): Promise<void> {
   const readdir = promisify(fs.readdir)
   const stat = promisify(fs.stat)
   const unlink = promisify(fs.unlink)
@@ -265,10 +272,10 @@ function innerLock(resolve, reject, filePath): void {
  * unlocks a file path
  * @type {Function}
  * @param {string} filePath
- * @returns {Promise}
+ * @returns {void}
  * @private
  */
-DiskStore.prototype._unlock = function _unlock(filePath): Promise<void> {
+DiskStore.prototype._unlock = function _unlock(filePath): void {
   globalGatsbyCacheLock.delete(filePath)
 }
 

packages/gatsby/src/cache/json-file-store.ts

@@ -27,9 +27,14 @@ const promisify = require(`util`).promisify
 const fs = require(`fs`)
 const zlib = require(`zlib`)
 
+interface IExternalBuffer {
+  index: number
+  buffer: Buffer
+}
+
 exports.write = async function (path, data, options): Promise<void> {
-  const externalBuffers = []
-  let dataString = JSON.stringify(data, function replacerFunction(k, value) {
+  const externalBuffers: Array<IExternalBuffer> = []
+  let dataString = JSON.stringify(data, function replacerFunction(_k, value) {
     // Buffers searilize to {data: [...], type: "Buffer"}
     if (
       value &&
@@ -103,10 +108,10 @@ exports.read = async function (path, options): Promise<string> {
     )
   }
 
-  const externalBuffers = []
+  const externalBuffers: Array<IExternalBuffer> = []
   let data
   try {
-    data = JSON.parse(dataString, function bufferReceiver(k, value) {
+    data = JSON.parse(dataString, function bufferReceiver(_k, value) {
       if (value && value.type === `Buffer` && value.data) {
         return Buffer.from(value.data)
       } else if (

packages/gatsby/src/cache/wrap-callback.ts

@@ -37,8 +37,8 @@ module.exports = function wrapCallback<T>(
       cb = args.pop()
     }
 
-    // eslint-disable-next-line @babel/no-invalid-this
-    const promise = fn.apply(this, args)
+    // @ts-ignore - unsure if fixing this introduces problems
+    const promise = fn.apply(this, args) // eslint-disable-line @babel/no-invalid-this
 
     if (typeof cb === `function`) {
       promise.then(

packages/gatsby/src/commands/build.ts

@@ -73,7 +73,9 @@ module.exports = async function build(program: IBuildArgs): Promise<void> {
 
   telemetry.trackCli(`BUILD_START`)
   signalExit(exitCode => {
-    telemetry.trackCli(`BUILD_END`, { exitCode })
+    telemetry.trackCli(`BUILD_END`, {
+      exitCode: exitCode as number | undefined,
+    })
   })
 
   const buildSpan = buildActivity.span
@@ -196,7 +198,7 @@ module.exports = async function build(program: IBuildArgs): Promise<void> {
     { parentSpan: buildSpan }
   )
   buildSSRBundleActivityProgress.start()
-  let pageRenderer: string
+  let pageRenderer = ``
   let waitForCompilerCloseBuildHtml
   try {
     const result = await buildRenderer(program, Stage.BuildHTML, buildSpan)

packages/gatsby/src/commands/develop.ts

@@ -295,7 +295,7 @@ module.exports = async (program: IProgram): Promise<void> => {
     null
   )
 
-  let unlocks: Array<UnlockFn> = []
+  let unlocks: Array<UnlockFn | null> = []
   if (!isCI()) {
     const statusUnlock = await createServiceLock(
       program.directory,
@@ -416,7 +416,7 @@ module.exports = async (program: IProgram): Promise<void> => {
   )
 
   const files = [rootFile(`gatsby-config.js`), rootFile(`gatsby-node.js`)]
-  let watcher: chokidar.FSWatcher = null
+  let watcher: chokidar.FSWatcher
 
   if (!isCI()) {
     watcher = chokidar.watch(files).on(`change`, filePath => {

packages/gatsby/src/commands/serve.ts

@@ -8,16 +8,16 @@ import { match as reachMatch } from "@gatsbyjs/reach-router/lib/utils"
 import onExit from "signal-exit"
 import report from "gatsby-cli/lib/reporter"
 import multer from "multer"
-import pathToRegexp from "path-to-regexp"
+import { pathToRegexp, Key } from "path-to-regexp"
 import cookie from "cookie"
-
 import telemetry from "gatsby-telemetry"
 
 import { detectPortInUseAndPrompt } from "../utils/detect-port-in-use-and-prompt"
 import { getConfigFile } from "../bootstrap/get-config-file"
 import { preferDefault } from "../bootstrap/prefer-default"
 import { IProgram } from "./types"
 import { IPreparedUrls, prepareUrls } from "../utils/prepare-urls"
+import { IGatsbyFunction } from "../redux/types"
 
 interface IMatchPath {
   path: string
@@ -120,10 +120,10 @@ module.exports = async (program: IServeProgram): Promise<void> => {
     `functions`
   )
 
-  let functions
+  let functions: Array<IGatsbyFunction> = []
   try {
     functions = JSON.parse(
-      fs.readFileSync(path.join(compiledFunctionsDir, `manifest.json`))
+      fs.readFileSync(path.join(compiledFunctionsDir, `manifest.json`), `utf-8`)
     )
   } catch (e) {
     // ignore
@@ -134,7 +134,7 @@ module.exports = async (program: IServeProgram): Promise<void> => {
       `/api/*`,
       multer().any(),
       express.urlencoded({ extended: true }),
-      (req, res, next) => {
+      (req, _, next) => {
         const cookies = req.headers.cookie
 
         if (!cookies) {
@@ -161,12 +161,13 @@ module.exports = async (program: IServeProgram): Promise<void> => {
           // We loop until we find the first match.
           functions.some(f => {
             let exp
-            const keys = []
+            const keys: Array<Key> = []
             if (f.matchPath) {
               exp = pathToRegexp(f.matchPath, keys)
             }
             if (exp && exp.exec(pathFragment) !== null) {
               functionObj = f
+              // @ts-ignore - TS bug? https://stackoverflow.com/questions/50234481/typescript-2-8-3-type-must-have-a-symbol-iterator-method-that-returns-an-iterato
               const matches = [...pathFragment.match(exp)].slice(1)
               const newParams = {}
               matches.forEach(