[RN][HermesV1] Use Hermes V1 as default engine

.github/workflows/prebuild-ios-core.yml

@@ -50,9 +50,11 @@ jobs:
         shell: bash
         run: |
           if [ "${{ inputs.use-hermes-nightly }}" == "true" ]; then
-            HERMES_VERSION="nightly"
+            # We are not publishing nightly versions of Hermes V1 yet.
+            # For now, we can use the latest version of Hermes V1 published on maven and npm.
+            HERMES_VERSION="latest-v1"
           else
-            HERMES_VERSION=$(sed -n 's/^HERMES_VERSION_NAME=//p' packages/react-native/sdks/hermes-engine/version.properties)
+            HERMES_VERSION=$(sed -n 's/^HERMES_V1_VERSION_NAME=//p' packages/react-native/sdks/hermes-engine/version.properties)
           fi
           echo "Using Hermes version: $HERMES_VERSION"
           echo "HERMES_VERSION=$HERMES_VERSION" >> $GITHUB_ENV

gradle.properties

@@ -26,4 +26,4 @@ react.internal.useHermesStable=false
 react.internal.useHermesNightly=true
 
 # Controls whether to use Hermes 1.0. Clean and rebuild when changing.
-hermesV1Enabled=false
+hermesV1Enabled=true

packages/gradle-plugin/react-native-gradle-plugin/src/main/kotlin/com/facebook/react/internal/PrivateReactExtension.kt

@@ -59,5 +59,5 @@ abstract class PrivateReactExtension @Inject constructor(project: Project) {
   val codegenDir: DirectoryProperty =
       objects.directoryProperty().convention(root.dir("node_modules/@react-native/codegen"))
 
-  val hermesV1Enabled: Property<Boolean> = objects.property(Boolean::class.java).convention(false)
+  val hermesV1Enabled: Property<Boolean> = objects.property(Boolean::class.java).convention(true)
 }

packages/gradle-plugin/react-native-gradle-plugin/src/main/kotlin/com/facebook/react/utils/DependencyUtils.kt

@@ -113,7 +113,7 @@ internal object DependencyUtils {
   fun configureDependencies(
       project: Project,
       coordinates: Coordinates,
-      hermesV1Enabled: Boolean = false,
+      hermesV1Enabled: Boolean = true,
   ) {
     if (
         coordinates.versionString.isBlank() ||
@@ -149,7 +149,7 @@ internal object DependencyUtils {
 
   internal fun getDependencySubstitutions(
       coordinates: Coordinates,
-      hermesV1Enabled: Boolean = false,
+      hermesV1Enabled: Boolean = true,
   ): List<Triple<String, String, String>> {
     val dependencySubstitution = mutableListOf<Triple<String, String, String>>()
     val hermesVersion =

packages/gradle-plugin/react-native-gradle-plugin/src/main/kotlin/com/facebook/react/utils/ProjectUtils.kt

@@ -29,6 +29,8 @@ internal object ProjectUtils {
 
   const val HERMES_FALLBACK = true
 
+  const val HERMES_V1_ENABLED_FALLBACK = true
+
   internal fun Project.isNewArchEnabled(): Boolean = true
 
   internal val Project.isHermesEnabled: Boolean
@@ -73,6 +75,9 @@ internal object ProjectUtils {
 
   internal val Project.isHermesV1Enabled: Boolean
     get() =
+        if (
+            project.hasProperty(HERMES_V1_ENABLED) || project.hasProperty(SCOPED_HERMES_V1_ENABLED)
+        ) {
         (project.hasProperty(HERMES_V1_ENABLED) &&
             project.property(HERMES_V1_ENABLED).toString().toBoolean()) ||
             (project.hasProperty(SCOPED_HERMES_V1_ENABLED) &&
@@ -81,6 +86,9 @@ internal object ProjectUtils {
                 project.extraProperties.get(HERMES_V1_ENABLED).toString().toBoolean()) ||
             (project.extraProperties.has(SCOPED_HERMES_V1_ENABLED) &&
                 project.extraProperties.get(SCOPED_HERMES_V1_ENABLED).toString().toBoolean())
+        } else {
+          HERMES_V1_ENABLED_FALLBACK
+        }
 
   internal fun Project.needsCodegenFromPackageJson(rootProperty: DirectoryProperty): Boolean {
     val parsedPackageJson = readPackageJsonFile(this, rootProperty)

packages/gradle-plugin/react-native-gradle-plugin/src/test/kotlin/com/facebook/react/utils/DependencyUtilsTest.kt

@@ -290,6 +290,8 @@ class DependencyUtilsTest {
     assertThat(forcedModules.any { it.toString() == "com.facebook.react:react-android:1.2.3" })
         .isTrue()
     assertThat(forcedModules.any { it.toString() == "com.facebook.hermes:hermes-android:4.5.6" })
+        .isFalse()
+    assertThat(forcedModules.any { it.toString() == "com.facebook.hermes:hermes-android:7.8.9" })
         .isTrue()
   }
 
@@ -325,10 +327,14 @@ class DependencyUtilsTest {
     assertThat(appForcedModules.any { it.toString() == "com.facebook.react:react-android:1.2.3" })
         .isTrue()
     assertThat(appForcedModules.any { it.toString() == "com.facebook.hermes:hermes-android:4.5.6" })
+        .isFalse()
+    assertThat(appForcedModules.any { it.toString() == "com.facebook.hermes:hermes-android:7.8.9" })
         .isTrue()
     assertThat(libForcedModules.any { it.toString() == "com.facebook.react:react-android:1.2.3" })
         .isTrue()
     assertThat(libForcedModules.any { it.toString() == "com.facebook.hermes:hermes-android:4.5.6" })
+        .isFalse()
+    assertThat(libForcedModules.any { it.toString() == "com.facebook.hermes:hermes-android:7.8.9" })
         .isTrue()
   }
 
@@ -384,12 +390,20 @@ class DependencyUtilsTest {
     assertThat(
             appForcedModules.any { it.toString() == "io.github.test.hermes:hermes-android:4.5.6" }
         )
+        .isFalse()
+    assertThat(
+            appForcedModules.any { it.toString() == "io.github.test.hermes:hermes-android:7.8.9" }
+        )
         .isTrue()
     assertThat(libForcedModules.any { it.toString() == "io.github.test:react-android:1.2.3" })
         .isTrue()
     assertThat(
             libForcedModules.any { it.toString() == "io.github.test.hermes:hermes-android:4.5.6" }
         )
+        .isFalse()
+    assertThat(
+            libForcedModules.any { it.toString() == "io.github.test.hermes:hermes-android:7.8.9" }
+        )
         .isTrue()
   }
 
@@ -430,7 +444,7 @@ class DependencyUtilsTest {
   }
 
   @Test
-  fun getDependencySubstitutions_withDefaultGroup_substitutesCorrectly_withClassicHermes() {
+  fun getDependencySubstitutions_withDefaultGroup_substitutesCorrectly_withHermesV1() {
     val dependencySubstitutions =
         getDependencySubstitutions(DependencyUtils.Coordinates("0.42.0", "0.42.0", "0.43.0"))
 
@@ -442,7 +456,7 @@ class DependencyUtilsTest {
         )
         .isEqualTo(dependencySubstitutions[0].third)
     assertThat("com.facebook.react:hermes-engine").isEqualTo(dependencySubstitutions[1].first)
-    assertThat("com.facebook.hermes:hermes-android:0.42.0")
+    assertThat("com.facebook.hermes:hermes-android:0.43.0")
         .isEqualTo(dependencySubstitutions[1].second)
     assertThat(
             "The hermes-engine artifact was deprecated in favor of hermes-android due to https://github.com/facebook/react-native/issues/35210."
@@ -451,7 +465,7 @@ class DependencyUtilsTest {
   }
 
   @Test
-  fun getDependencySubstitutions_withDefaultGroup_substitutesCorrectly_withHermesV1() {
+  fun getDependencySubstitutions_withDefaultGroupAndFallback_substitutesCorrectly_withClassicHermes() {
     val dependencySubstitutions =
         getDependencySubstitutions(
             DependencyUtils.Coordinates("0.42.0", "0.42.0", "0.43.0"),
@@ -475,7 +489,7 @@ class DependencyUtilsTest {
   }
 
   @Test
-  fun getDependencySubstitutions_withCustomGroup_substitutesCorrectly_withClassicHermes() {
+  fun getDependencySubstitutions_withCustomGroup_substitutesCorrectly_withHermesV1() {
     val dependencySubstitutions =
         getDependencySubstitutions(
             DependencyUtils.Coordinates(
@@ -494,14 +508,14 @@ class DependencyUtilsTest {
         )
         .isEqualTo(dependencySubstitutions[0].third)
     assertThat("com.facebook.react:hermes-engine").isEqualTo(dependencySubstitutions[1].first)
-    assertThat("io.github.test.hermes:hermes-android:0.42.0")
+    assertThat("io.github.test.hermes:hermes-android:0.43.0")
         .isEqualTo(dependencySubstitutions[1].second)
     assertThat(
             "The hermes-engine artifact was deprecated in favor of hermes-android due to https://github.com/facebook/react-native/issues/35210."
         )
         .isEqualTo(dependencySubstitutions[1].third)
     assertThat("com.facebook.react:hermes-android").isEqualTo(dependencySubstitutions[2].first)
-    assertThat("io.github.test.hermes:hermes-android:0.42.0")
+    assertThat("io.github.test.hermes:hermes-android:0.43.0")
         .isEqualTo(dependencySubstitutions[2].second)
     assertThat("The hermes-android artifact was moved to com.facebook.hermes publishing group.")
         .isEqualTo(dependencySubstitutions[2].third)
@@ -510,14 +524,14 @@ class DependencyUtilsTest {
     assertThat("The react-android dependency was modified to use the correct Maven group.")
         .isEqualTo(dependencySubstitutions[3].third)
     assertThat("com.facebook.react:hermes-android").isEqualTo(dependencySubstitutions[4].first)
-    assertThat("io.github.test.hermes:hermes-android:0.42.0")
+    assertThat("io.github.test.hermes:hermes-android:0.43.0")
         .isEqualTo(dependencySubstitutions[4].second)
     assertThat("The hermes-android dependency was modified to use the correct Maven group.")
         .isEqualTo(dependencySubstitutions[4].third)
   }
 
   @Test
-  fun getDependencySubstitutions_withCustomGroup_substitutesCorrectly_withHermesV1() {
+  fun getDependencySubstitutions_withCustomGroupAndFallbackToClassicHermes_substitutesCorrectly_withClassicHermes() {
     val dependencySubstitutions =
         getDependencySubstitutions(
             DependencyUtils.Coordinates(
@@ -527,7 +541,7 @@ class DependencyUtilsTest {
                 "io.github.test",
                 "io.github.test.hermes",
             ),
-            hermesV1Enabled = true,
+            hermesV1Enabled = false,
         )
 
     assertThat("com.facebook.react:react-native").isEqualTo(dependencySubstitutions[0].first)
@@ -537,14 +551,14 @@ class DependencyUtilsTest {
         )
         .isEqualTo(dependencySubstitutions[0].third)
     assertThat("com.facebook.react:hermes-engine").isEqualTo(dependencySubstitutions[1].first)
-    assertThat("io.github.test.hermes:hermes-android:0.43.0")
+    assertThat("io.github.test.hermes:hermes-android:0.42.0")
         .isEqualTo(dependencySubstitutions[1].second)
     assertThat(
             "The hermes-engine artifact was deprecated in favor of hermes-android due to https://github.com/facebook/react-native/issues/35210."
         )
         .isEqualTo(dependencySubstitutions[1].third)
     assertThat("com.facebook.react:hermes-android").isEqualTo(dependencySubstitutions[2].first)
-    assertThat("io.github.test.hermes:hermes-android:0.43.0")
+    assertThat("io.github.test.hermes:hermes-android:0.42.0")
         .isEqualTo(dependencySubstitutions[2].second)
     assertThat("The hermes-android artifact was moved to com.facebook.hermes publishing group.")
         .isEqualTo(dependencySubstitutions[2].third)
@@ -553,7 +567,7 @@ class DependencyUtilsTest {
     assertThat("The react-android dependency was modified to use the correct Maven group.")
         .isEqualTo(dependencySubstitutions[3].third)
     assertThat("com.facebook.react:hermes-android").isEqualTo(dependencySubstitutions[4].first)
-    assertThat("io.github.test.hermes:hermes-android:0.43.0")
+    assertThat("io.github.test.hermes:hermes-android:0.42.0")
         .isEqualTo(dependencySubstitutions[4].second)
     assertThat("The hermes-android dependency was modified to use the correct Maven group.")
         .isEqualTo(dependencySubstitutions[4].third)

packages/gradle-plugin/react-native-gradle-plugin/src/test/kotlin/com/facebook/react/utils/ProjectUtilsTest.kt

@@ -117,8 +117,8 @@ class ProjectUtilsTest {
   }
 
   @Test
-  fun isHermesV1Enabled_returnsFalseByDefault() {
-    assertThat(createProject().isHermesV1Enabled).isFalse()
+  fun isHermesV1Enabled_returnsTrueByDefault() {
+    assertThat(createProject().isHermesV1Enabled).isTrue()
   }
 
   @Test

packages/react-native/Package.swift

@@ -924,6 +924,7 @@ extension Target {
         .define("NDEBUG", .when(configuration: .release)),
         .define("USE_HERMES", to: "1"),
         .define("RCT_REMOVE_LEGACY_ARCH", to: "1"),
+        .define("HERMES_V1_ENABLED", to: "1"),
       ] + defines + cxxCommonHeaderPaths
 
     return .target(

packages/react-native/ReactCommon/hermes/executor/HermesExecutorFactory.cpp

@@ -13,6 +13,8 @@
 #include <jsi/decorator.h>
 #include <jsinspector-modern/InspectorFlags.h>
 
+#include <thread>
+
 #include <hermes/inspector-modern/chrome/HermesRuntimeTargetDelegate.h>
 
 #if defined(HERMES_ENABLE_DEBUGGER) && !defined(HERMES_V1_ENABLED)

packages/react-native/scripts/ios-prebuild/hermes.js

@@ -54,9 +54,13 @@ async function prepareHermesArtifactsAsync(
   // Only check if the artifacts folder exists if we are not using a local tarball
   if (!localPath) {
     // Resolve the version from the environment variable or use the default version
-    let resolvedVersion = process.env.HERMES_VERSION ?? 'nightly';
+    let resolvedVersion = process.env.HERMES_VERSION ?? 'latest-v1';
 
-    if (resolvedVersion === 'nightly') {
+    if (resolvedVersion === 'latest-v1') {
+      hermesLog('Using latest-v1 tarball');
+      const hermesVersion = await getLatestV1VersionFromNPM();
+      resolvedVersion = hermesVersion;
+    } else if (resolvedVersion === 'nightly') {
       hermesLog('Using latest nightly tarball');
       const hermesVersion = await getNightlyVersionFromNPM();
       resolvedVersion = hermesVersion;
@@ -102,14 +106,31 @@ async function prepareHermesArtifactsAsync(
   return artifactsPath;
 }
 
+async function getLatestV1VersionFromNPM() /*: Promise<string> */ {
+  const npmResponse /*: Response */ = await fetch(
+    'https://registry.npmjs.org/hermes-compiler/latest-v1',
+  );
+
+  if (!npmResponse.ok) {
+    throw new Error(
+      `Couldn't get a response from NPM: ${npmResponse.status} ${npmResponse.statusText}`,
+    );
+  }
+
+  const json = await npmResponse.json();
+  const latestV1 = json.version;
+  hermesLog(`Using version ${latestV1}`);
+  return latestV1;
+}
+
 async function getNightlyVersionFromNPM() /*: Promise<string> */ {
   const npmResponse /*: Response */ = await fetch(
     'https://registry.npmjs.org/hermes-compiler/nightly',
   );
 
   if (!npmResponse.ok) {
     throw new Error(
-      `Couldn't get an answer from NPM: ${npmResponse.status} ${npmResponse.statusText}`,
+      `Couldn't get a response from NPM: ${npmResponse.status} ${npmResponse.statusText}`,
     );
   }
 

packages/react-native/scripts/react_native_pods.rb

@@ -92,6 +92,11 @@ def use_react_native! (
   # excluding the legacy arch unless the user turns this flag off explicitly.
   ENV['RCT_REMOVE_LEGACY_ARCH'] = ENV['RCT_REMOVE_LEGACY_ARCH'] == '0' ? '0' : '1'
 
+  # Enable Hermes V1 by default.
+  # Users can still turn it off and use legacy hermes by setting the RCT_HERMES_V1_ENABLED
+  # environment variable to '0'.
+  ENV['RCT_HERMES_V1_ENABLED']= ENV['RCT_HERMES_V1_ENABLED'] == '0' ? '0' : '1'
+
   ReactNativePodsUtils.check_minimum_required_xcode()
 
   # Current target definition is provided by Cocoapods and it refers to the target

packages/react-native/sdks/hermes-engine/hermes-engine.podspec

@@ -22,14 +22,15 @@ end
 package = JSON.parse(File.read(File.join(react_native_path, "package.json")))
 versionProperties = Hash[*File.read("version.properties").split(/[=\n]+/)]
 
-if ENV['RCT_HERMES_V1_ENABLED'] == "1"
-  version = versionProperties['HERMES_V1_VERSION_NAME']
-else
+if ENV['RCT_HERMES_V1_ENABLED'] == "0"
   version = versionProperties['HERMES_VERSION_NAME']
+else
+  version = versionProperties['HERMES_V1_VERSION_NAME']
 end
 
 # Local monorepo build
-if package['version'] == "1000.0.0" then
+# We don't want to build Hermes V1 from source
+if ENV['RCT_HERMES_V1_ENABLED'] == "0" && package['version'] == "1000.0.0" then
   hermesCompilerVersion = package['dependencies']['hermes-compiler']
   if hermesCompilerVersion != "0.0.0" then
     version = hermesCompilerVersion
@@ -68,7 +69,15 @@ Pod::Spec.new do |spec|
 
     spec.subspec 'Pre-built' do |ss|
       ss.preserve_paths = ["destroot/bin/*"].concat(["**/*.{h,c,cpp}"])
-      ss.source_files = "destroot/include/hermes/**/*.h"
+      if ENV["RCT_HERMES_V1_ENABLED"] == "0"
+        ss.source_files = "destroot/include/hermes/**/*.h"
+      else
+        # Hermes v1 is shipping a jsi/hermes.h header which is imported by the hermes.h header
+        # and that file is not present in React Native's JSI
+        # (see https://github.com/facebook/react-native/tree/main/packages/react-native/ReactCommon/jsi/jsi/ where there is
+        # hermes-interface.h but not hermes.h)
+        ss.source_files = ["destroot/include/hermes/**/*.h", "destroot/include/jsi/hermes.h"]
+      end
       ss.header_mappings_dir = "destroot/include"
       ss.ios.vendored_frameworks = "destroot/Library/Frameworks/universal/hermesvm.xcframework"
       ss.visionos.vendored_frameworks = "destroot/Library/Frameworks/universal/hermesvm.xcframework"
@@ -131,7 +140,7 @@ Pod::Spec.new do |spec|
       ss.header_dir = 'hermes/Public'
     end
 
-    if ENV['RCT_HERMES_V1_ENABLED'] != "1"
+    if ENV['RCT_HERMES_V1_ENABLED'] == "0"
       spec.subspec 'inspector' do |ss|
         ss.source_files = ''
         ss.public_header_files = 'API/hermes/inspector/*.h'

packages/react-native/sdks/hermes-engine/hermes-utils.rb

@@ -86,7 +86,7 @@ def hermes_commit_envvar_defined()
 end
 
 def hermes_v1_enabled()
-    return ENV['RCT_HERMES_V1_ENABLED'] == "1"
+    return ENV['RCT_HERMES_V1_ENABLED'] != "0"
 end
 
 def force_build_from_tag(react_native_path)

scripts/releases/utils/hermes-utils.js

@@ -27,6 +27,7 @@ const MAVEN_VERSIONS_FILE_PATH = path.join(
 
 async function getLatestHermesNightlyVersion() /*: Promise<{
   compilerVersion: string,
+  compilerV1Version: string,
   runtimeVersion: string,
   runtimeV1Version: string,
 }> */ {
@@ -43,6 +44,7 @@ async function getLatestHermesNightlyVersion() /*: Promise<{
 
   return {
     compilerVersion,
+    compilerV1Version,
     // runtime version should match the compiler version
     runtimeVersion: compilerVersion,
     runtimeV1Version: compilerV1Version,
@@ -84,7 +86,7 @@ async function updateHermesRuntimeDependenciesVersions(
 async function updateHermesVersionsToNightly() {
   const hermesVersions = await getLatestHermesNightlyVersion();
   await updateHermesCompilerVersionInDependencies(
-    hermesVersions.compilerVersion,
+    hermesVersions.compilerV1Version,
   );
   await updateHermesRuntimeDependenciesVersions(
     hermesVersions.runtimeVersion,