Behind a feature flag, update x64 macOS users to the arm64 build when possible

app/src/lib/feature-flag.ts

@@ -165,3 +165,8 @@ export function enableCherryPicking(): boolean {
 export function enableTextDiffExpansion(): boolean {
   return enableDevelopmentFeatures()
 }
+
+/** Should we allow apps running from Rosetta to auto-update to ARM64 builds? */
+export function enableUpdateFromRosettaToARM64(): boolean {
+  return false
+}

app/src/ui/lib/update-store.ts

@@ -14,6 +14,7 @@ import { parseError } from '../../lib/squirrel-error-parser'
 import { ReleaseSummary } from '../../models/release-notes'
 import { generateReleaseSummary } from '../../lib/release-notes'
 import { setNumber, getNumber } from '../../lib/local-storage'
+import { enableUpdateFromRosettaToARM64 } from '../../lib/feature-flag'
 
 /** The states the auto updater can be in. */
 export enum UpdateStatus {
@@ -160,10 +161,24 @@ class UpdateStore {
       return
     }
 
+    let updatesURL = __UPDATES_URL__
+
+    // If the app is running under Rosetta (i.e. it's a macOS x64 binary running
+    // on an arm64 machine), we need to tweak the update URL here to point at
+    // the arm64 binary.
+    if (
+      enableUpdateFromRosettaToARM64() &&
+      remote.app.runningUnderRosettaTranslation === true
+    ) {
+      const url = new URL(updatesURL)
+      url.searchParams.set('architecture', 'arm64')
+      updatesURL = url.toString()
+    }
+
     this.userInitiatedUpdate = !inBackground
 
     try {
-      autoUpdater.setFeedURL({ url: __UPDATES_URL__ })
+      autoUpdater.setFeedURL({ url: updatesURL })
       autoUpdater.checkForUpdates()
     } catch (e) {
       this.emitError(e)

script/dist-info.ts

@@ -152,13 +152,6 @@ export function getArchitecture(): 'arm64' | 'x64' {
     return 'arm64'
   }
 
-  // TODO: temporarily disable this to prevent upgrades from macOS users of the
-  // x64 version under Rosetta to the arm64 binary. This should be enabled again
-  // once we're confident about the arm64 build.
-  // if (remote.app.runningUnderRosettaTranslation === true) {
-  //   return 'arm64'
-  // }
-
   // TODO: Check if it's x64 running on an arm64 Windows with IsWow64Process2
   // More info: https://www.rudyhuyn.com/blog/2017/12/13/how-to-detect-that-your-x86-application-runs-on-windows-on-arm/
   // Right now (March 3, 2021) is not very important because support for x64