Allow to opt-in to use the new Hermes on Android (#53580)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/53580

Changelog: [ANDROID][ADDED] Added opt-in to use the new Hermes

Reviewed By: cortinico

Differential Revision: D81035114

fbshipit-source-id: d01e44190941d161cf641ec4e03ed487aff18dd8

gradle.properties

@@ -12,3 +12,6 @@ reactNativeArchitectures=armeabi-v7a,arm64-v8a,x86,x86_64
 # Controls whether to use Hermes from nightly builds. This will speed up builds
 # but should NOT be turned on for CI or release builds.
 react.internal.useHermesNightly=false
+
+# Controls whether to use Hermes 1.0. Clean and rebuild when changing.
+hermesV1Enabled=false

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

@@ -28,6 +28,7 @@ import com.facebook.react.utils.DependencyUtils.readVersionAndGroupStrings
 import com.facebook.react.utils.JdkConfiguratorUtils.configureJavaToolChains
 import com.facebook.react.utils.JsonUtils
 import com.facebook.react.utils.NdkConfiguratorUtils.configureReactNativeNdk
+import com.facebook.react.utils.ProjectUtils.isHermesV1Enabled
 import com.facebook.react.utils.ProjectUtils.needsCodegenFromPackageJson
 import com.facebook.react.utils.findPackageJsonFile
 import java.io.File
@@ -54,6 +55,10 @@ class ReactPlugin : Plugin<Project> {
                 project,
             )
 
+    if (project.rootProject.isHermesV1Enabled != rootExtension.hermesV1Enabled.get()) {
+      rootExtension.hermesV1Enabled.set(project.rootProject.isHermesV1Enabled)
+    }
+
     // App Only Configuration
     project.pluginManager.withPlugin("com.android.application") {
       // We wire the root extension with the values coming from the app (either user populated or
@@ -67,9 +72,11 @@ class ReactPlugin : Plugin<Project> {
         val reactNativeDir = extension.reactNativeDir.get().asFile
         val propertiesFile = File(reactNativeDir, "ReactAndroid/gradle.properties")
         val versionAndGroupStrings = readVersionAndGroupStrings(propertiesFile)
-        val versionString = versionAndGroupStrings.first
-        val groupString = versionAndGroupStrings.second
-        configureDependencies(project, versionString, groupString)
+        val hermesV1Enabled =
+            if (project.rootProject.hasProperty("hermesV1Enabled"))
+                project.rootProject.findProperty("hermesV1Enabled") == "true"
+            else false
+        configureDependencies(project, versionAndGroupStrings, hermesV1Enabled)
         configureRepositories(project)
       }
 

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

@@ -11,6 +11,7 @@ import javax.inject.Inject
 import org.gradle.api.Project
 import org.gradle.api.file.DirectoryProperty
 import org.gradle.api.provider.ListProperty
+import org.gradle.api.provider.Property
 
 /**
  * A private extension we set on the rootProject to make easier to share values at execution time
@@ -57,4 +58,6 @@ 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)
 }

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

@@ -7,12 +7,15 @@
 
 package com.facebook.react.utils
 
-import com.facebook.react.utils.PropertyUtils.DEFAULT_INTERNAL_PUBLISHING_GROUP
+import com.facebook.react.utils.PropertyUtils.DEFAULT_INTERNAL_HERMES_PUBLISHING_GROUP
+import com.facebook.react.utils.PropertyUtils.DEFAULT_INTERNAL_REACT_PUBLISHING_GROUP
 import com.facebook.react.utils.PropertyUtils.EXCLUSIVE_ENTEPRISE_REPOSITORY
 import com.facebook.react.utils.PropertyUtils.INCLUDE_JITPACK_REPOSITORY
 import com.facebook.react.utils.PropertyUtils.INCLUDE_JITPACK_REPOSITORY_DEFAULT
-import com.facebook.react.utils.PropertyUtils.INTERNAL_PUBLISHING_GROUP
+import com.facebook.react.utils.PropertyUtils.INTERNAL_HERMES_PUBLISHING_GROUP
+import com.facebook.react.utils.PropertyUtils.INTERNAL_HERMES_VERSION_NAME
 import com.facebook.react.utils.PropertyUtils.INTERNAL_REACT_NATIVE_MAVEN_LOCAL_REPO
+import com.facebook.react.utils.PropertyUtils.INTERNAL_REACT_PUBLISHING_GROUP
 import com.facebook.react.utils.PropertyUtils.INTERNAL_USE_HERMES_NIGHTLY
 import com.facebook.react.utils.PropertyUtils.INTERNAL_VERSION_NAME
 import com.facebook.react.utils.PropertyUtils.SCOPED_EXCLUSIVE_ENTEPRISE_REPOSITORY
@@ -25,6 +28,13 @@ import org.gradle.api.artifacts.repositories.MavenArtifactRepository
 
 internal object DependencyUtils {
 
+  internal data class Coordinates(
+      val versionString: String,
+      val hermesVersionString: String,
+      val reactGroupString: String = DEFAULT_INTERNAL_REACT_PUBLISHING_GROUP,
+      val hermesGroupString: String = DEFAULT_INTERNAL_HERMES_PUBLISHING_GROUP,
+  )
+
   /**
    * This method takes care of configuring the repositories{} block for both the app and all the 3rd
    * party libraries which are auto-linked.
@@ -95,14 +105,15 @@ internal object DependencyUtils {
    * This method takes care of configuring the resolution strategy for both the app and all the 3rd
    * party libraries which are auto-linked. Specifically it takes care of:
    * - Forcing the react-android/hermes-android version to the one specified in the package.json
-   * - Substituting `react-native` with `react-android` and `hermes-engine` with `hermes-android`.
+   * - Substituting `react-native` with `react-android` and `hermes-engine` with `hermes-android`
+   * - Selecting between the classic Hermes and Hermes V1
    */
   fun configureDependencies(
       project: Project,
-      versionString: String,
-      groupString: String = DEFAULT_INTERNAL_PUBLISHING_GROUP,
+      coordinates: Coordinates,
+      hermesV1Enabled: Boolean = false,
   ) {
-    if (versionString.isBlank()) return
+    if (coordinates.versionString.isBlank() || coordinates.hermesVersionString.isBlank()) return
     project.rootProject.allprojects { eachProject ->
       eachProject.configurations.all { configuration ->
         // Here we set a dependencySubstitution for both react-native and hermes-engine as those
@@ -110,53 +121,61 @@ internal object DependencyUtils {
         // This allows users to import libraries that are still using
         // implementation("com.facebook.react:react-native:+") and resolve the right dependency.
         configuration.resolutionStrategy.dependencySubstitution {
-          getDependencySubstitutions(versionString, groupString).forEach { (module, dest, reason) ->
+          getDependencySubstitutions(coordinates, hermesV1Enabled).forEach { (module, dest, reason)
+            ->
             it.substitute(it.module(module)).using(it.module(dest)).because(reason)
           }
         }
         configuration.resolutionStrategy.force(
-            "${groupString}:react-android:${versionString}",
+            "${coordinates.reactGroupString}:react-android:${coordinates.versionString}",
         )
         if (!(eachProject.findProperty(INTERNAL_USE_HERMES_NIGHTLY) as? String).toBoolean()) {
           // Contributors only: The hermes-engine version is forced only if the user has
           // not opted into using nightlies for local development.
-          configuration.resolutionStrategy.force("${groupString}:hermes-android:${versionString}")
+          configuration.resolutionStrategy.force(
+              "${coordinates.reactGroupString}:hermes-android:${coordinates.versionString}"
+          )
         }
       }
     }
   }
 
   internal fun getDependencySubstitutions(
-      versionString: String,
-      groupString: String = DEFAULT_INTERNAL_PUBLISHING_GROUP,
+      coordinates: Coordinates,
+      hermesV1Enabled: Boolean = false,
   ): List<Triple<String, String, String>> {
+    // TODO: T231755027 update coordinates and versioning
     val dependencySubstitution = mutableListOf<Triple<String, String, String>>()
+    val hermesVersionString =
+        if (hermesV1Enabled)
+            "${coordinates.hermesGroupString}:hermes-android:${coordinates.versionString}"
+        else "${coordinates.reactGroupString}:hermes-android:${coordinates.versionString}"
     dependencySubstitution.add(
         Triple(
             "com.facebook.react:react-native",
-            "${groupString}:react-android:${versionString}",
+            "${coordinates.reactGroupString}:react-android:${coordinates.versionString}",
             "The react-native artifact was deprecated in favor of react-android due to https://github.com/facebook/react-native/issues/35210.",
         )
     )
     dependencySubstitution.add(
         Triple(
             "com.facebook.react:hermes-engine",
-            "${groupString}:hermes-android:${versionString}",
+            hermesVersionString,
             "The hermes-engine artifact was deprecated in favor of hermes-android due to https://github.com/facebook/react-native/issues/35210.",
         )
     )
-    if (groupString != DEFAULT_INTERNAL_PUBLISHING_GROUP) {
+    if (coordinates.reactGroupString != DEFAULT_INTERNAL_REACT_PUBLISHING_GROUP) {
       dependencySubstitution.add(
           Triple(
               "com.facebook.react:react-android",
-              "${groupString}:react-android:${versionString}",
+              "${coordinates.reactGroupString}:react-android:${coordinates.versionString}",
               "The react-android dependency was modified to use the correct Maven group.",
           )
       )
       dependencySubstitution.add(
           Triple(
               "com.facebook.react:hermes-android",
-              "${groupString}:hermes-android:${versionString}",
+              hermesVersionString,
               "The hermes-android dependency was modified to use the correct Maven group.",
           )
       )
@@ -164,10 +183,14 @@ internal object DependencyUtils {
     return dependencySubstitution
   }
 
-  fun readVersionAndGroupStrings(propertiesFile: File): Pair<String, String> {
+  fun readVersionAndGroupStrings(propertiesFile: File): Coordinates {
     val reactAndroidProperties = Properties()
     propertiesFile.inputStream().use { reactAndroidProperties.load(it) }
     val versionStringFromFile = (reactAndroidProperties[INTERNAL_VERSION_NAME] as? String).orEmpty()
+    // TODO: T231755027 update HERMES_VERSION_NAME in gradle.properties to point to the correct
+    // hermes version
+    val hermesVersionStringFromFile =
+        (reactAndroidProperties[INTERNAL_HERMES_VERSION_NAME] as? String).orEmpty()
     // If on a nightly, we need to fetch the -SNAPSHOT artifact from Sonatype.
     val versionString =
         if (versionStringFromFile.startsWith("0.0.0") || "-nightly-" in versionStringFromFile) {
@@ -176,10 +199,18 @@ internal object DependencyUtils {
           versionStringFromFile
         }
     // Returns Maven group for repos using different group for Maven artifacts
-    val groupString =
-        reactAndroidProperties[INTERNAL_PUBLISHING_GROUP] as? String
-            ?: DEFAULT_INTERNAL_PUBLISHING_GROUP
-    return Pair(versionString, groupString)
+    val reactGroupString =
+        reactAndroidProperties[INTERNAL_REACT_PUBLISHING_GROUP] as? String
+            ?: DEFAULT_INTERNAL_REACT_PUBLISHING_GROUP
+    val hermesGroupString =
+        reactAndroidProperties[INTERNAL_HERMES_PUBLISHING_GROUP] as? String
+            ?: DEFAULT_INTERNAL_HERMES_PUBLISHING_GROUP
+    return Coordinates(
+        versionString,
+        hermesVersionStringFromFile,
+        reactGroupString,
+        hermesGroupString,
+    )
   }
 
   fun Project.mavenRepoFromUrl(

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

@@ -13,9 +13,11 @@ import com.facebook.react.utils.KotlinStdlibCompatUtils.lowercaseCompat
 import com.facebook.react.utils.KotlinStdlibCompatUtils.toBooleanStrictOrNullCompat
 import com.facebook.react.utils.PropertyUtils.EDGE_TO_EDGE_ENABLED
 import com.facebook.react.utils.PropertyUtils.HERMES_ENABLED
+import com.facebook.react.utils.PropertyUtils.HERMES_V1_ENABLED
 import com.facebook.react.utils.PropertyUtils.REACT_NATIVE_ARCHITECTURES
 import com.facebook.react.utils.PropertyUtils.SCOPED_EDGE_TO_EDGE_ENABLED
 import com.facebook.react.utils.PropertyUtils.SCOPED_HERMES_ENABLED
+import com.facebook.react.utils.PropertyUtils.SCOPED_HERMES_V1_ENABLED
 import com.facebook.react.utils.PropertyUtils.SCOPED_REACT_NATIVE_ARCHITECTURES
 import com.facebook.react.utils.PropertyUtils.SCOPED_USE_THIRD_PARTY_JSC
 import com.facebook.react.utils.PropertyUtils.USE_THIRD_PARTY_JSC
@@ -68,6 +70,13 @@ internal object ProjectUtils {
             (project.hasProperty(SCOPED_USE_THIRD_PARTY_JSC) &&
                 project.property(SCOPED_USE_THIRD_PARTY_JSC).toString().toBoolean())
 
+  internal val Project.isHermesV1Enabled: Boolean
+    get() =
+        (project.hasProperty(HERMES_V1_ENABLED) &&
+            project.property(HERMES_V1_ENABLED).toString().toBoolean()) ||
+            (project.hasProperty(SCOPED_HERMES_V1_ENABLED) &&
+                project.property(SCOPED_HERMES_V1_ENABLED).toString().toBoolean())
+
   internal fun Project.needsCodegenFromPackageJson(rootProperty: DirectoryProperty): Boolean {
     val parsedPackageJson = readPackageJsonFile(this, rootProperty)
     return needsCodegenFromPackageJson(parsedPackageJson)

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

@@ -18,6 +18,10 @@ object PropertyUtils {
   const val HERMES_ENABLED = "hermesEnabled"
   const val SCOPED_HERMES_ENABLED = "react.hermesEnabled"
 
+  /** Public property that toggles Hermes V1 */
+  const val HERMES_V1_ENABLED = "hermesV1Enabled"
+  const val SCOPED_HERMES_V1_ENABLED = "react.hermesV1Enabled"
+
   /** Public property that toggles edge-to-edge */
   const val EDGE_TO_EDGE_ENABLED = "edgeToEdgeEnabled"
   const val SCOPED_EDGE_TO_EDGE_ENABLED = "react.edgeToEdgeEnabled"
@@ -68,9 +72,13 @@ object PropertyUtils {
   const val INTERNAL_USE_HERMES_NIGHTLY = "react.internal.useHermesNightly"
 
   /** Internal property used to override the publishing group for the React Native artifacts. */
-  const val INTERNAL_PUBLISHING_GROUP = "react.internal.publishingGroup"
-  const val DEFAULT_INTERNAL_PUBLISHING_GROUP = "com.facebook.react"
+  const val INTERNAL_REACT_PUBLISHING_GROUP = "react.internal.publishingGroup"
+  const val INTERNAL_HERMES_PUBLISHING_GROUP = "react.internal.hermesPublishingGroup"
+  const val DEFAULT_INTERNAL_REACT_PUBLISHING_GROUP = "com.facebook.react"
+  const val DEFAULT_INTERNAL_HERMES_PUBLISHING_GROUP = "com.facebook.hermes"
 
   /** Internal property used to control the version name of React Native */
   const val INTERNAL_VERSION_NAME = "VERSION_NAME"
+  /** Internal property used to control the version name of Hermes Engine */
+  const val INTERNAL_HERMES_VERSION_NAME = "HERMES_VERSION_NAME"
 }

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

@@ -271,11 +271,13 @@ class DependencyUtilsTest {
         .isEqualTo(2)
   }
 
+  // TODO: T236767053
+
   @Test
   fun configureDependencies_withEmptyVersion_doesNothing() {
     val project = createProject()
 
-    configureDependencies(project, "")
+    configureDependencies(project, DependencyUtils.Coordinates("", ""))
 
     assertThat(project.configurations.first().resolutionStrategy.forcedModules.isEmpty()).isTrue()
   }
@@ -284,7 +286,7 @@ class DependencyUtilsTest {
   fun configureDependencies_withVersionString_appliesResolutionStrategy() {
     val project = createProject()
 
-    configureDependencies(project, "1.2.3")
+    configureDependencies(project, DependencyUtils.Coordinates("1.2.3", "1.2.3"))
 
     val forcedModules = project.configurations.first().resolutionStrategy.forcedModules
     assertThat(forcedModules.any { it.toString() == "com.facebook.react:react-android:1.2.3" })
@@ -301,7 +303,7 @@ class DependencyUtilsTest {
     appProject.plugins.apply("com.android.application")
     libProject.plugins.apply("com.android.library")
 
-    configureDependencies(appProject, "1.2.3")
+    configureDependencies(appProject, DependencyUtils.Coordinates("1.2.3", "1.2.3"))
 
     val appForcedModules = appProject.configurations.first().resolutionStrategy.forcedModules
     val libForcedModules = libProject.configurations.first().resolutionStrategy.forcedModules
@@ -323,7 +325,10 @@ class DependencyUtilsTest {
     appProject.plugins.apply("com.android.application")
     libProject.plugins.apply("com.android.library")
 
-    configureDependencies(appProject, "1.2.3", "io.github.test")
+    configureDependencies(
+        appProject,
+        DependencyUtils.Coordinates("1.2.3", "1.2.3", "io.github.test"),
+    )
 
     val appForcedModules = appProject.configurations.first().resolutionStrategy.forcedModules
     val libForcedModules = libProject.configurations.first().resolutionStrategy.forcedModules
@@ -339,7 +344,8 @@ class DependencyUtilsTest {
 
   @Test
   fun getDependencySubstitutions_withDefaultGroup_substitutesCorrectly() {
-    val dependencySubstitutions = getDependencySubstitutions("0.42.0")
+    val dependencySubstitutions =
+        getDependencySubstitutions(DependencyUtils.Coordinates("0.42.0", "0.42.0"))
 
     assertThat("com.facebook.react:react-native").isEqualTo(dependencySubstitutions[0].first)
     assertThat("com.facebook.react:react-android:0.42.0")
@@ -359,7 +365,10 @@ class DependencyUtilsTest {
 
   @Test
   fun getDependencySubstitutions_withCustomGroup_substitutesCorrectly() {
-    val dependencySubstitutions = getDependencySubstitutions("0.42.0", "io.github.test")
+    val dependencySubstitutions =
+        getDependencySubstitutions(
+            DependencyUtils.Coordinates("0.42.0", "0.42.0", "io.github.test")
+        )
 
     assertThat("com.facebook.react:react-native").isEqualTo(dependencySubstitutions[0].first)
     assertThat("io.github.test:react-android:0.42.0").isEqualTo(dependencySubstitutions[0].second)
@@ -396,7 +405,7 @@ class DependencyUtilsTest {
           )
         }
 
-    val versionString = readVersionAndGroupStrings(propertiesFile).first
+    val versionString = readVersionAndGroupStrings(propertiesFile).versionString
 
     assertThat(versionString).isEqualTo("1000.0.0")
   }
@@ -414,7 +423,7 @@ class DependencyUtilsTest {
           )
         }
 
-    val versionString = readVersionAndGroupStrings(propertiesFile).first
+    val versionString = readVersionAndGroupStrings(propertiesFile).versionString
 
     assertThat(versionString).isEqualTo("0.0.0-20221101-2019-cfe811ab1-SNAPSHOT")
   }
@@ -431,7 +440,7 @@ class DependencyUtilsTest {
           )
         }
 
-    val versionString = readVersionAndGroupStrings(propertiesFile).first
+    val versionString = readVersionAndGroupStrings(propertiesFile).versionString
     assertThat(versionString).isEqualTo("")
   }
 
@@ -448,7 +457,7 @@ class DependencyUtilsTest {
           )
         }
 
-    val versionString = readVersionAndGroupStrings(propertiesFile).first
+    val versionString = readVersionAndGroupStrings(propertiesFile).versionString
     assertThat(versionString).isEqualTo("")
   }
 
@@ -465,7 +474,7 @@ class DependencyUtilsTest {
           )
         }
 
-    val groupString = readVersionAndGroupStrings(propertiesFile).second
+    val groupString = readVersionAndGroupStrings(propertiesFile).reactGroupString
 
     assertThat(groupString).isEqualTo("io.github.test")
   }
@@ -482,7 +491,7 @@ class DependencyUtilsTest {
           )
         }
 
-    val groupString = readVersionAndGroupStrings(propertiesFile).second
+    val groupString = readVersionAndGroupStrings(propertiesFile).reactGroupString
 
     assertThat(groupString).isEqualTo("com.facebook.react")
   }

packages/react-native/ReactAndroid/build.gradle.kts

@@ -39,6 +39,9 @@ val downloadsDir =
 val thirdPartyNdkDir = File("$buildDir/third-party-ndk")
 val reactNativeRootDir = projectDir.parent
 
+val hermesV1Enabled =
+    rootProject.extensions.getByType(PrivateReactExtension::class.java).hermesV1Enabled.get()
+
 // We put the publishing version from gradle.properties inside ext. so other
 // subprojects can access it as well.
 extra["publishing_version"] = project.findProperty("VERSION_NAME")?.toString()!!
@@ -565,6 +568,10 @@ android {
             "-DCMAKE_POLICY_DEFAULT_CMP0069=NEW",
         )
 
+        if (hermesV1Enabled) {
+          arguments("-DHERMES_V1_ENABLED=1")
+        }
+
         targets(
             "reactnative",
             "jsi",

packages/react-native/ReactAndroid/gradle.properties

@@ -1,5 +1,7 @@
 VERSION_NAME=1000.0.0
+HERMES_VERSION_NAME=1000.0.0
 react.internal.publishingGroup=com.facebook.react
+react.internal.hermesPublishingGroup=com.facebook.hermes
 
 android.useAndroidX=true
 

packages/react-native/ReactAndroid/hermes-engine/build.gradle.kts

@@ -5,6 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
+import com.facebook.react.internal.PrivateReactExtension
 import com.facebook.react.tasks.internal.*
 import de.undercouch.gradle.tasks.download.Download
 import org.apache.tools.ant.taskdefs.condition.Os
@@ -50,6 +51,8 @@ fun getSDKManagerPath(): String {
   }
 }
 
+val hermesV1Enabled =
+    rootProject.extensions.getByType(PrivateReactExtension::class.java).hermesV1Enabled.get()
 val reactNativeRootDir = project(":packages:react-native:ReactAndroid").projectDir.parent
 val customDownloadDir = System.getenv("REACT_NATIVE_DOWNLOADS_DIR")
 val downloadsDir =
@@ -79,12 +82,21 @@ val hermesBuildOutputFileTree =
     fileTree(hermesBuildDir.toString())
         .include("**/*.cmake", "**/*.marks", "**/compiler_depends.ts", "**/Makefile", "**/link.txt")
 
-var hermesVersion = "main"
-val hermesVersionFile = File(reactNativeRootDir, "sdks/.hermesversion")
+val hermesVersionProvider: Provider<String> =
+    providers.provider {
+      var hermesVersion = if (hermesV1Enabled) "250829098.0.0-stable" else "main"
+      val hermesVersionFile =
+          File(
+              reactNativeRootDir,
+              if (hermesV1Enabled) "sdks/.hermesv1version" else "\"sdks/.hermesversion\"",
+          )
 
-if (hermesVersionFile.exists()) {
-  hermesVersion = hermesVersionFile.readText()
-}
+      if (hermesVersionFile.exists()) {
+        hermesVersion = hermesVersionFile.readText()
+      }
+
+      hermesVersion
+    }
 
 val ndkBuildJobs = Runtime.getRuntime().availableProcessors().toString()
 val prefabHeadersDir = File("$buildDir/prefab-headers")
@@ -95,7 +107,11 @@ val jsiDir = File(reactNativeRootDir, "ReactCommon/jsi")
 val downloadHermesDest = File(downloadsDir, "hermes.tar.gz")
 val downloadHermes by
     tasks.registering(Download::class) {
-      src("https://github.com/facebook/hermes/tarball/${hermesVersion}")
+      src(
+          providers.provider {
+            "https://github.com/facebook/hermes/tarball/${hermesVersionProvider.get()}"
+          }
+      )
       onlyIfModified(true)
       overwrite(true)
       quiet(true)
@@ -151,6 +167,7 @@ val configureBuildForHermes by
               "-B",
               hermesBuildDir.toString(),
               "-DJSI_DIR=" + jsiDir.absolutePath,
+              "-DCMAKE_BUILD_TYPE=Release",
           )
       if (Os.isFamily(Os.FAMILY_WINDOWS)) {
         cmakeCommandLine = cmakeCommandLine + "-GNMake Makefiles"
@@ -295,7 +312,11 @@ android {
           // Therefore we're passing as build type Release, to provide a faster build.
           // This has the (unlucky) side effect of letting AGP call the build
           // tasks `configureCMakeRelease` while is actually building the debug flavor.
-          arguments("-DCMAKE_BUILD_TYPE=Release")
+          arguments(
+              "-DCMAKE_BUILD_TYPE=Release",
+              // For debug builds, explicitly enable the Hermes Debugger.
+              "-DHERMES_ENABLE_DEBUGGER=True",
+          )
         }
       }
     }

packages/react-native/ReactAndroid/src/main/jni/CMakeLists.txt

@@ -22,6 +22,8 @@ file(TO_CMAKE_PATH "${REACT_ANDROID_DIR}" REACT_ANDROID_DIR)
 file(TO_CMAKE_PATH "${REACT_BUILD_DIR}" REACT_BUILD_DIR)
 file(TO_CMAKE_PATH "${REACT_COMMON_DIR}" REACT_COMMON_DIR)
 
+set(HERMES_V1_ENABLED OFF CACHE BOOL "Build with support for Hermes v1")
+
 # If you have ccache installed, we're going to honor it.
 find_program(CCACHE_FOUND ccache)
 if(CCACHE_FOUND)

scripts/releases/set-rn-artifacts-version.js

@@ -155,6 +155,8 @@ function updateTestFiles(
 async function updateGradleFile(version /*: string */) /*: Promise<void> */ {
   const contents = await fs.readFile(GRADLE_FILE_PATH, 'utf-8');
 
+  // TODO: T231755027 set HERMES_VERSION_NAME
+
   return fs.writeFile(
     GRADLE_FILE_PATH,
     contents.replace(/^VERSION_NAME=.*/, `VERSION_NAME=${version}`),