Use nightly Hermes by default when building in OSS

.github/actions/build-android/action.yml

@@ -45,16 +45,19 @@ runs:
         if [[ "${{ inputs.release-type }}" == "dry-run" ]]; then
           # dry-run: we only build ARM64 to save time/resources. For release/nightlies the default is to build all archs.
           export ORG_GRADLE_PROJECT_reactNativeArchitectures="arm64-v8a,x86" # x86 is required for E2E testing
+          export HERMES_PREBUILT_FLAG="ORG_GRADLE_PROJECT_react.internal.useHermesNightly=true"
           TASKS="publishAllToMavenTempLocal build"
         elif [[ "${{ inputs.release-type }}" == "nightly" ]]; then
           # nightly: we set isSnapshot to true so artifacts are sent to the right repository on Maven Central.
           export ORG_GRADLE_PROJECT_isSnapshot="true"
+          export HERMES_PREBUILT_FLAG="ORG_GRADLE_PROJECT_react.internal.useHermesNightly=true"
           TASKS="publishAllToMavenTempLocal publishAndroidToSonatype build"
         else
           # release: we want to build all archs (default)
+          export HERMES_PREBUILT_FLAG="ORG_GRADLE_PROJECT_react.internal.useHermesStable=true"
           TASKS="publishAllToMavenTempLocal publishAndroidToSonatype build"
         fi
-        ./gradlew $TASKS -PenableWarningsAsErrors=true
+        env "$HERMES_PREBUILT_FLAG" ./gradlew $TASKS -PenableWarningsAsErrors=true
     - name: Save Android ccache
       if: ${{ github.ref == 'refs/heads/main' || contains(github.ref, '-stable') }}
       uses: actions/cache/save@v5

build.gradle.kts

@@ -109,16 +109,43 @@ tasks.register("publishAllToMavenTempLocal") {
 tasks.register("publishAndroidToSonatype") {
   description = "Publish the Android artifacts to Sonatype (Maven Central or Snapshot repository)"
   dependsOn(":packages:react-native:ReactAndroid:publishToSonatype")
-  dependsOn(":packages:react-native:ReactAndroid:hermes-engine:publishToSonatype")
 }
 
-if (project.findProperty("react.internal.useHermesNightly")?.toString()?.toBoolean() == true) {
+var hermesSubstitution: Pair<String, String>? = null
+
+if (project.findProperty("react.internal.useHermesStable")?.toString()?.toBoolean() == true) {
+  val hermesVersions = java.util.Properties()
+  val hermesVersionPropertiesFile =
+      File("./packages/react-native/sdks/hermes-engine/version.properties")
+  hermesVersionPropertiesFile.inputStream().use { hermesVersions.load(it) }
+  val selectedHermesVersion = hermesVersions["HERMES_VERSION_NAME"] as String
+
+  hermesSubstitution = selectedHermesVersion to "Users opted to use stable hermes release"
+} else if (
+    project.findProperty("react.internal.useHermesNightly")?.toString()?.toBoolean() == true
+) {
+  val reactNativePackageJson = File("./packages/react-native/package.json")
+  val reactNativePackageJsonContent = reactNativePackageJson.readText()
+  val packageJson = groovy.json.JsonSlurper().parseText(reactNativePackageJsonContent) as Map<*, *>
+
+  val hermesCompilerVersion =
+      (packageJson["dependencies"] as Map<*, *>)["hermes-compiler"] as String
+
+  if (hermesCompilerVersion == "0.0.0") {
+    throw RuntimeException(
+        "Trying to use Hermes Nightly but hermes-compiler version is not specified"
+    )
+  }
+
+  hermesSubstitution = "$hermesCompilerVersion-SNAPSHOT" to "Users opted to use hermes nightly"
+} else {
   logger.warn(
       """
       ********************************************************************************
-      INFO: You're using Hermes from nightly as you set
+      INFO: You're building Hermes from source as you set
 
-      react.internal.useHermesNightly=true
+      react.internal.useHermesStable=false
+      react.internal.useHermesNightly=false
 
       in the ./gradle.properties file.
 
@@ -127,12 +154,20 @@ if (project.findProperty("react.internal.useHermesNightly")?.toString()?.toBoole
       """
           .trimIndent()
   )
+}
+
+if (hermesSubstitution != null) {
+  val (hermesVersion, reason) = hermesSubstitution!!
+  project(":packages:react-native:ReactAndroid:hermes-engine") {
+    tasks.configureEach { enabled = false }
+  }
+
   allprojects {
     configurations.all {
       resolutionStrategy.dependencySubstitution {
         substitute(project(":packages:react-native:ReactAndroid:hermes-engine"))
-            .using(module("com.facebook.hermes:hermes-android:0.+"))
-            .because("Users opted to use hermes from nightly")
+            .using(module("com.facebook.hermes:hermes-android:$hermesVersion"))
+            .because(reason)
       }
     }
   }

gradle.properties

@@ -16,9 +16,14 @@ android.newDsl=false
 # ./gradlew <task> -PreactNativeArchitectures=x86_64
 reactNativeArchitectures=armeabi-v7a,arm64-v8a,x86,x86_64
 
+# Controls whether to use Hermes from stable builds. This will force hermes version
+# set in the sdks/hermes-engine/version.properties file to be used. This has a higher
+# priority than react.internal.useHermesNightly.
+react.internal.useHermesStable=false
+
 # 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
+react.internal.useHermesNightly=true
 
 # Controls whether to use Hermes 1.0. Clean and rebuild when changing.
 hermesV1Enabled=false

package.json

@@ -23,6 +23,7 @@
     "lint-kotlin": "./gradlew ktfmtFormat",
     "lint-markdown": "markdownlint-cli2 2>&1",
     "lint": "eslint --max-warnings 0 .",
+    "preinstall": "node ./scripts/try-set-nightly-hermes-compiler.js",
     "prettier": "prettier --write \"./**/*.{js,md,yml,ts,tsx}\"",
     "print-packages": "node ./scripts/monorepo/print",
     "shellcheck": "./.github/workflow-scripts/analyze_scripts.sh",

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

@@ -65,6 +65,13 @@ object PropertyUtils {
    */
   const val INTERNAL_REACT_WINDOWS_BASH = "react.internal.windowsBashPath"
 
+  /**
+   * Controls whether to use Hermes from stable builds. This will force hermes version set in the
+   * sdks/hermes-engine/version.properties file to be used. This has a higher priority than
+   * react.internal.useHermesNightly.
+   */
+  const val INTERNAL_USE_HERMES_STABLE = "react.internal.useHermesStable"
+
   /**
    * Internal property to force the build to use Hermes from the latest nightly. This speeds up the
    * build at the cost of not testing the latest integration against Hermes.

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

@@ -11,7 +11,6 @@ import de.undercouch.gradle.tasks.download.Download
 import org.apache.tools.ant.taskdefs.condition.Os
 
 plugins {
-  id("maven-publish")
   id("signing")
   alias(libs.plugins.android.library)
   alias(libs.plugins.download)
@@ -348,10 +347,7 @@ android {
     java.srcDirs("$hermesDir/lib/Platform/Intl/java", "$hermesDir/lib/Platform/Unicode/java")
   }
 
-  buildFeatures {
-    prefab = true
-    prefabPublishing = true
-  }
+  buildFeatures { prefab = true }
 
   dependencies {
     implementation(libs.fbjni)
@@ -365,13 +361,6 @@ android {
     jniLibs.excludes.add("**/libfbjni.so")
   }
 
-  publishing {
-    multipleVariants {
-      withSourcesJar()
-      allVariants()
-    }
-  }
-
   prefab { create("hermesvm") { headers = prefabHeadersDir.absolutePath } }
 }
 

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

@@ -28,6 +28,14 @@ else
   version = versionProperties['HERMES_VERSION_NAME']
 end
 
+# Local monorepo build
+if package['version'] == "1000.0.0" then
+  hermesCompilerVersion = package['dependencies']['hermes-compiler']
+  if hermesCompilerVersion != "0.0.0" then
+    version = hermesCompilerVersion
+  end
+end
+
 source_type = hermes_source_type(version, react_native_path)
 source = podspec_source(source_type, version, react_native_path)
 

packages/rn-tester/android/app/build.gradle.kts

@@ -61,7 +61,14 @@ react {
 
   /* Hermes Commands */
   //   The hermes compiler command to run. By default it is 'hermesc'
-  hermesCommand = "$reactNativeDirPath/ReactAndroid/hermes-engine/build/hermes/bin/hermesc"
+  hermesCommand =
+      if (
+          project.findProperty("react.internal.useHermesStable")?.toString()?.toBoolean() == true ||
+              project.findProperty("react.internal.useHermesNightly")?.toString()?.toBoolean() ==
+                  true
+      )
+          "$rootDir/node_modules/hermes-compiler/hermesc/%OS-BIN%/hermesc"
+      else "$reactNativeDirPath/ReactAndroid/hermes-engine/build/hermes/bin/hermesc"
 
   autolinkLibrariesWithApp()
 }
@@ -179,8 +186,10 @@ tasks.withType<KotlinCompile>().configureEach {
 
 afterEvaluate {
   if (
-      project.findProperty("react.internal.useHermesNightly") == null ||
-          project.findProperty("react.internal.useHermesNightly").toString() == "false"
+      (project.findProperty("react.internal.useHermesNightly") == null ||
+          project.findProperty("react.internal.useHermesNightly").toString() == "false") &&
+          (project.findProperty("react.internal.useHermesStable") == null ||
+              project.findProperty("react.internal.useHermesStable").toString() == "false")
   ) {
     // As we're consuming Hermes from source, we want to make sure
     // `hermesc` is built before we actually invoke the `emit*HermesResource` task

private/react-native-fantom/build.gradle.kts

@@ -139,9 +139,17 @@ val prepareRNCodegen by
       into(codegenOutDir)
     }
 
+val enableHermesBuild by
+    tasks.registering {
+      project(":packages:react-native:ReactAndroid:hermes-engine") {
+        tasks.configureEach { enabled = true }
+      }
+    }
+
 val prepareHermesDependencies by
     tasks.registering {
       dependsOn(
+          enableHermesBuild,
           ":packages:react-native:ReactAndroid:hermes-engine:buildHermesLib",
           ":packages:react-native:ReactAndroid:hermes-engine:prepareHeadersForPrefab",
       )

scripts/try-set-nightly-hermes-compiler.js

@@ -0,0 +1,26 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+// @flow
+const { execSync } = require('child_process');
+const fs = require('fs');
+const path = require('path');
+
+function main() {
+ const packageJsonPath = path.join(__dirname, '../packages/react-native/package.json');
+ const packageJson = JSON.parse(fs.readFileSync(packageJsonPath, 'utf8'));
+ const hermesCompilerVersion = packageJson.dependencies['hermes-compiler'];
+
+ if (hermesCompilerVersion === '0.0.0') {
+   console.log(`Hermes compiler version not set. Updating to the latest nightly release.`);
+   execSync('yarn workspace react-native add hermes-compiler@nightly --exact', { stdio: 'inherit' });
+ } else {
+   console.log(`Hermes compiler version set to ${hermesCompilerVersion}. Not setting nightly hermes.`);
+ }
+}
+
+main();