Turn on Hermes builds in our test matrix

.ado/jobs/build-test-rntester.yml

@@ -50,6 +50,54 @@ parameters:
         packager_platform: 'ios'
         new_arch_enabled: '1'
         use_hermes: '0'
+      - name: macos_debug_oldarch_hermes
+        friendly_name: 'macOS, Old Arch, Hermes'
+        sdk: macosx
+        configuration: Debug
+        scheme: RNTester-macOS
+        packager_platform: 'macos'
+        new_arch_enabled: '0'
+        use_hermes: '1'
+      - name: macos_debug_newarch_hermes
+        friendly_name: 'macOS, New Arch, Hermes'
+        sdk: macosx
+        configuration: Debug
+        scheme: RNTester-macOS
+        packager_platform: 'macos'
+        new_arch_enabled: '1'
+        use_hermes: '1'
+      - name: ios_debug_oldarch_hermes
+        friendly_name: 'iOS, Old Arch, Hermes'
+        sdk: iphonesimulator
+        configuration: Debug
+        scheme: RNTester
+        packager_platform: 'ios'
+        new_arch_enabled: '0'
+        use_hermes: '1'
+      - name: ios_debug_newarch_hermes
+        friendly_name: 'iOS, New Arch, Hermes'
+        sdk: iphonesimulator
+        configuration: Debug
+        scheme: RNTester
+        packager_platform: 'ios'
+        new_arch_enabled: '1'
+        use_hermes: '1'
+      - name: xros_debug_oldarch_hermes
+        friendly_name: 'xrOS, Old Arch, Hermes'
+        sdk: xrsimulator
+        configuration: Debug
+        scheme: RNTester-visionOS
+        packager_platform: 'ios'
+        new_arch_enabled: '0'
+        use_hermes: '1'
+      - name: xros_debug_newarch_hermes
+        friendly_name: 'xrOS, New Arch, Hermes'
+        sdk: xrsimulator
+        configuration: Debug
+        scheme: RNTester-visionOS
+        packager_platform: 'ios'
+        new_arch_enabled: '1'
+        use_hermes: '1'
 
 jobs:
   - ${{ each slice in parameters.appleBuildMatrix }}:

packages/react-native/scripts/cocoapods/utils.rb

@@ -195,16 +195,22 @@ def self.apply_xcode_15_patch(installer, xcodebuild_manager: Xcodebuild)
     private
 
     def self.add_build_settings_to_pod(installer, settings_name, settings_value, target_pod_name, configuration_type)
+        # [macOS
+        # Since some RN projects might combine multiple platforms into the same Xcode project,
+        # we'll be much more forgiving with the pod name matching in react-native-macos.
+        # Could be upstreamed as part of https://github.com/microsoft/react-native-macos/issues/2526.
+        valid_suffixes = ["", "-iOS", "-macOS", "-visionOS"]
+        # macOS]
         installer.target_installation_results.pod_target_installation_results.each do |pod_name, target_installation_result|
-            if pod_name.to_s == target_pod_name
+            if valid_suffixes.any? { |suffix| pod_name.to_s == "#{target_pod_name}#{suffix}" } # [macOS]
                 target_installation_result.native_target.build_configurations.each do |config|
-                        if configuration_type == nil || (configuration_type != nil && config.type == configuration_type)
-                            config.build_settings[settings_name] ||= '$(inherited) '
-                            config.build_settings[settings_name] << settings_value
-                        end
+                    if configuration_type == nil || (configuration_type != nil && config.type == configuration_type)
+                        config.build_settings[settings_name] ||= '$(inherited) '
+                        config.build_settings[settings_name] << settings_value
                     end
                 end
             end
+        end
     end
 
     def self.fix_library_search_path(config)

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

@@ -23,7 +23,7 @@ end
 package = JSON.parse(File.read(File.join(react_native_path, "package.json")))
 # [macOS
 rn_version = package['version']
-version = findLastestVersionWithArtifact(rn_version) || rn_version
+version = findLatestVersionWithArtifact(rn_version) || rn_version
 # macOS]
 
 source_type = hermes_source_type(version, react_native_path)

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

@@ -7,6 +7,7 @@
 require 'rexml/document'
 require 'open3' # [macOS]
 require 'json' # [macOS]
+require 'tmpdir' # [macOS]
 
 HERMES_GITHUB_URL = "https://github.com/facebook/hermes.git"
 ENV_BUILD_FROM_SOURCE = "RCT_BUILD_HERMES_FROM_SOURCE"
@@ -177,8 +178,18 @@ def podspec_source_build_from_github_tag(react_native_path)
 end
 
 def podspec_source_build_from_github_main()
-    hermes_log("Using the latest commit from main.")
-    return {:git => HERMES_GITHUB_URL, :commit => `git ls-remote #{HERMES_GITHUB_URL} main | cut -f 1`.strip}
+    # hermes_log("Using the latest commit from main.")
+    # return {:git => HERMES_GITHUB_URL, :commit => `git ls-remote #{HERMES_GITHUB_URL} main | cut -f 1`.strip}
+
+    # [macOS
+    # The logic for this is a bit different on macOS.
+    # Since react-native-macos lags slightly behind facebook/react-native, we can't always use
+    # the latest Hermes commit because Hermes and JSI don't always guarantee backwards compatibility.
+    # Instead, we take the commit hash of Hermes at the time of the merge base with facebook/react-native.
+    commit = hermes_commit_at_merge_base()
+    hermes_log("Using Hermes commit from the merge base with facebook/react-native: #{commit}")
+    return {:git => HERMES_GITHUB_URL, :commit => commit}
+    # macOS]
 end
 
 def podspec_source_download_prebuild_release_tarball(react_native_path, version)
@@ -201,6 +212,51 @@ def artifacts_dir()
     return File.join(Pod::Config.instance.project_pods_root, "hermes-engine-artifacts")
 end
 
+# [macOS
+def hermes_commit_at_merge_base()
+    # We don't need ls-remote because react-native-macos is a fork of facebook/react-native
+    fetch_result = `git fetch -q https://github.com/facebook/react-native.git`
+    if $?.exitstatus != 0
+        abort <<-EOS
+        [Hermes] Failed to fetch facebook/react-native into the local repository.
+        EOS
+    end
+
+    merge_base = `git merge-base FETCH_HEAD HEAD`.strip
+    if merge_base.empty?
+        abort <<-EOS
+        [Hermes] Unable to find the merge base between our HEAD and upstream's HEAD.
+        EOS
+    end
+
+    timestamp = `git show -s --format=%ci #{merge_base}`.strip
+    if timestamp.empty?
+        abort <<-EOS
+        [Hermes] Unable to extract the timestamp for the merge base (#{merge_base}).
+        EOS
+    end
+
+    commit = nil
+    Dir.mktmpdir do |tmpdir|
+        hermes_git_dir = File.join(tmpdir, "hermes.git")
+        # Unfortunately we can't use git rev-list on HERMES_GITHUB_URL directly since we're not in that repo.
+        # Instead, we create a shallow clone to avoid downloading the entire history.
+        `git clone -q --bare --shallow-since="#{timestamp}" #{HERMES_GITHUB_URL} "#{hermes_git_dir}"`
+        `git --git-dir="#{hermes_git_dir}" fetch -q --deepen=1`
+
+        # If all goes well, this will be the commit hash of Hermes at the time of the merge base
+        commit = `git --git-dir="#{hermes_git_dir}" rev-list -1 --before="#{timestamp}" HEAD`.strip
+        if commit.empty?
+            abort <<-EOS
+            [Hermes] Unable to find the Hermes commit hash at time #{timestamp}.
+            EOS
+        end
+    end
+
+    return commit
+end
+# macOS]
+
 def hermestag_file(react_native_path)
     return File.join(react_native_path, "sdks", ".hermesversion")
 end
@@ -242,7 +298,12 @@ def resolve_url_redirects(url)
 
 # [macOS react-native-macos does not publish macos specific hermes artifacts
 # so we attempt to find the latest patch version of the iOS artifacts and use that
-def findLastestVersionWithArtifact(version)
+def findLatestVersionWithArtifact(version)
+    if version == "1000.0.0"
+        # The main branch builds from source, so skip the artifact check
+        return nil
+    end
+
     # See https://central.sonatype.org/search/rest-api-guide/ for details on query params
     versionWithoutPatch = "#{version.match(/^(\d+\.\d+)/)}"
     res, = Open3.capture3("curl -s https://search.maven.org/solrsearch/select?q=g:com.facebook.react+AND+a:react-native-artifacts+AND+v:#{versionWithoutPatch}.*&core=gav&rows=1&wt=json")

packages/rn-tester/Podfile

@@ -107,5 +107,6 @@ end
 # visionOS]
 
 post_install do |installer|
+  $RN_PLATFORMS = %w[iOS macOS visionOS] # [macOS]
   react_native_post_install(installer, @prefix_path, :mac_catalyst_enabled => false)
 end