fix(apple): always enable Hermes from 0.80+ (#2444)

Author: tido64

ios/features.mjs

@@ -60,16 +60,24 @@ export function isBridgelessEnabled(reactNativeVersion, options) {
  * @returns {boolean | "from-source"}
  */
 export function isHermesEnabled(platform, reactNativeVersion, options) {
-  const useHermes = process.env["USE_HERMES"];
-  const enabled =
-    typeof useHermes === "string"
-      ? useHermes === "1"
-      : options["hermesEnabled"] === true;
+  if (reactNativeVersion < v(0, 80, 0)) {
+    const useHermes = process.env["USE_HERMES"];
+    const enabled =
+      typeof useHermes === "string"
+        ? useHermes === "1"
+        : options["hermesEnabled"] === true;
 
-  // Hermes prebuilds for visionOS was introduced in 0.76
-  if (enabled && platform === "visionos" && reactNativeVersion < v(0, 76, 0)) {
-    return "from-source";
+    // Hermes prebuilds for visionOS was introduced in 0.76
+    if (
+      enabled &&
+      platform === "visionos" &&
+      reactNativeVersion < v(0, 76, 0)
+    ) {
+      return "from-source";
+    }
+
+    return enabled;
   }
 
-  return enabled;
+  return true;
 }

test/ios/app.test.ts

@@ -268,7 +268,7 @@ const PROJECT_FILES = {
     testsBuildSettings: {},
     uitestsBuildSettings: {},
     useBridgeless: true,
-    useHermes: false,
+    useHermes: true,
     useNewArch: true,
     xcodeprojPath: "/~/node_modules/.generated/ios/ReactTestApp.xcodeproj",
   },
@@ -297,7 +297,7 @@ const PROJECT_FILES = {
         testsBuildSettings: {},
         uitestsBuildSettings: {},
         useBridgeless: true,
-        useHermes: false,
+        useHermes: true,
         useNewArch: true,
         xcodeprojPath: "/~/node_modules/.generated/ios/ReactTestApp.xcodeproj",
       },
@@ -362,7 +362,7 @@ const PROJECT_FILES = {
         testsBuildSettings: {},
         uitestsBuildSettings: {},
         useBridgeless: true,
-        useHermes: false,
+        useHermes: true,
         useNewArch: true,
         xcodeprojPath:
           "/~/node_modules/.generated/macos/ReactTestApp.xcodeproj",
@@ -428,7 +428,7 @@ const PROJECT_FILES = {
         testsBuildSettings: {},
         uitestsBuildSettings: {},
         useBridgeless: true,
-        useHermes: false,
+        useHermes: true,
         useNewArch: true,
         xcodeprojPath:
           "/~/node_modules/.generated/visionos/ReactTestApp.xcodeproj",
@@ -490,7 +490,7 @@ const PROJECT_FILES = {
         testsBuildSettings: {},
         uitestsBuildSettings: {},
         useBridgeless: false,
-        useHermes: false,
+        useHermes: true,
         useNewArch: false,
         xcodeprojPath: "/~/node_modules/.generated/ios/ReactTestApp.xcodeproj",
       },
@@ -549,7 +549,7 @@ const PROJECT_FILES = {
         testsBuildSettings: {},
         uitestsBuildSettings: {},
         useBridgeless: false,
-        useHermes: false,
+        useHermes: true,
         useNewArch: false,
         xcodeprojPath:
           "/~/node_modules/.generated/macos/ReactTestApp.xcodeproj",
@@ -609,7 +609,7 @@ const PROJECT_FILES = {
         testsBuildSettings: {},
         uitestsBuildSettings: {},
         useBridgeless: false,
-        useHermes: false,
+        useHermes: true,
         useNewArch: false,
         xcodeprojPath:
           "/~/node_modules/.generated/visionos/ReactTestApp.xcodeproj",

test/ios/features.test.ts

@@ -55,31 +55,39 @@ describe("isBridgelessEnabled()", () => {
 });
 
 describe("isHermesEnabled()", () => {
-  before(() => {
+  function resetEnvironmentVariables() {
     delete process.env["USE_HERMES"];
-  });
+  }
 
-  afterEach(() => {
-    delete process.env["USE_HERMES"];
-  });
+  before(resetEnvironmentVariables);
+
+  afterEach(resetEnvironmentVariables);
 
   for (const platform of ["ios", "macos", "visionos"] as const) {
     it(`[${platform}] is disabled by default`, () => {
-      ok(!isHermesEnabled(platform, v(1, 0, 0), {}));
+      ok(!isHermesEnabled(platform, v(0, 79, 0), {}));
     });
 
     it(`[${platform}] returns true when enabled`, () => {
-      ok(isHermesEnabled(platform, v(1, 0, 0), { hermesEnabled: true }));
+      ok(isHermesEnabled(platform, v(0, 79, 0), { hermesEnabled: true }));
     });
 
     it(`[${platform}] returns true if 'USE_HERMES=1'`, () => {
       process.env["USE_HERMES"] = "1";
-      ok(isHermesEnabled(platform, v(1, 0, 0), {}));
+      ok(isHermesEnabled(platform, v(0, 79, 0), {}));
     });
 
     it(`[${platform}] returns false if 'USE_HERMES=0'`, () => {
       process.env["USE_HERMES"] = "0";
-      ok(!isHermesEnabled(platform, v(1, 0, 0), { hermesEnabled: true }));
+      ok(!isHermesEnabled(platform, v(0, 79, 0), { hermesEnabled: true }));
+    });
+
+    it(`[${platform}] always returns true from 0.80 on`, () => {
+      ok(isHermesEnabled(platform, v(0, 80, 0), {}));
+
+      process.env["USE_HERMES"] = "0";
+
+      ok(isHermesEnabled(platform, v(0, 80, 0), {}));
     });
   }