Firestore Swift Cpp Experiment

FirebaseCore/Sources/Public/FirebaseCore/FIRVersion.h

@@ -19,7 +19,16 @@
 NS_ASSUME_NONNULL_BEGIN
 
 /** Returns the current version of Firebase. */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 NS_SWIFT_NAME(FirebaseVersion())
 NSString* FIRFirebaseVersion(void);
 
+#ifdef __cplusplus
+}
+#endif
+
 NS_ASSUME_NONNULL_END

FirebaseFirestore.podspec

@@ -31,13 +31,20 @@ Google Cloud Firestore is a NoSQL document database built for automatic scaling,
     'FirebaseFirestoreInternal/**/*.[mh]',
     'Firestore/Swift/Source/**/*.swift',
   ]
+
+  s.pod_target_xcconfig = {
+    # Enables C++ <-> Swift interop (by default it's only C)
+    "SWIFT_OBJC_INTEROP_MODE" => "objcxx",
+  }
+
   s.resource_bundles = {
     "#{s.module_name}_Privacy" => 'Firestore/Swift/Source/Resources/PrivacyInfo.xcprivacy'
   }
 
   s.dependency 'FirebaseCore', '11.5'
   s.dependency 'FirebaseCoreExtension', '11.5'
   s.dependency 'FirebaseFirestoreInternal', '11.5.0'
+  s.dependency 'FirebaseFirestoreCpp', '11.5.0'
   s.dependency 'FirebaseSharedSwift', '~> 11.0'
 
 end

FirebaseFirestoreCpp.podspec

@@ -0,0 +1,65 @@
+Pod::Spec.new do |s|
+  s.name             = 'FirebaseFirestoreCpp'
+  s.version          = '11.5.0'
+  s.summary          = 'Google Cloud Firestore'
+
+  s.description      = <<-DESC
+Google Cloud Firestore is a NoSQL document database built for automatic scaling, high performance, and ease of application development.
+                       DESC
+
+  s.homepage         = 'https://developers.google.com/'
+  s.license          = { :type => 'Apache-2.0', :file => 'Firestore/LICENSE' }
+  s.authors          = 'Google, Inc.'
+
+  s.source           = {
+    :git => 'https://github.com/firebase/firebase-ios-sdk.git',
+    :tag => 'CocoaPods-' + s.version.to_s
+  }
+
+  s.ios.deployment_target = '13.0'
+  s.osx.deployment_target = '10.15'
+  s.tvos.deployment_target = '13.0'
+
+  s.swift_version = '5.9'
+
+  s.cocoapods_version = '>= 1.12.0'
+  s.prefix_header_file = false
+
+  s.public_header_files = 'Firestore/core/swift/include/*.h'
+
+  s.source_files = [
+    'Firestore/core/swift/**/*.{cc,h}'
+  ]
+
+  abseil_version = '~> 1.20240116.1'
+  s.dependency 'abseil/algorithm', abseil_version
+  s.dependency 'abseil/base', abseil_version
+  s.dependency 'abseil/container/flat_hash_map', abseil_version
+  s.dependency 'abseil/memory', abseil_version
+  s.dependency 'abseil/meta', abseil_version
+  s.dependency 'abseil/strings/strings', abseil_version
+  s.dependency 'abseil/time', abseil_version
+  s.dependency 'abseil/types', abseil_version
+
+  s.ios.frameworks = 'SystemConfiguration', 'UIKit'
+  s.osx.frameworks = 'SystemConfiguration'
+  s.tvos.frameworks = 'SystemConfiguration', 'UIKit'
+
+  s.library = 'c++'
+  s.pod_target_xcconfig = {
+    'CLANG_CXX_LANGUAGE_STANDARD' => 'c++14',
+    'CLANG_CXX_LIBRARY' => 'libc++',
+    'GCC_C_LANGUAGE_STANDARD' => 'c99',
+    'GCC_PREPROCESSOR_DEFINITIONS' =>
+      "FIRFirestore_VERSION=#{s.version} " +
+      # The nanopb pod sets these defs, so we must too. (We *do* require 16bit
+      # (or larger) fields, so we'd have to set at least PB_FIELD_16BIT
+      # anyways.)
+      'PB_FIELD_32BIT=1 PB_NO_PACKED_STRUCTS=1 PB_ENABLE_MALLOC=1',
+    'HEADER_SEARCH_PATHS' =>
+      '"${PODS_TARGET_SRCROOT}" ' +
+      '"${PODS_TARGET_SRCROOT}/Firestore/core/swift" '
+  }
+
+  s.compiler_flags = '$(inherited) -Wreorder -Werror=reorder -Wno-comma'
+end

Firestore/Swift/Source/SwiftAPI/SwiftCppAPI.swift

@@ -0,0 +1,23 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import FirebaseFirestoreCpp
+
+public class SwiftCppWrapper {
+  public init(_ value: String) {
+    _ = UsedBySwift(std.string(value))
+  }
+}

Firestore/core/CMakeLists.txt

@@ -218,6 +218,8 @@ firebase_ios_glob(
   src/objc/*.h
   src/remote/*.cc
   src/remote/*.h
+  swift/include/*.h
+  swift/src/*.cc
   EXCLUDE ${nanopb_sources}
 )
 

Firestore/core/swift/include/FirebaseFirestoreCpp.h

@@ -0,0 +1,22 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef FIREBASE_FIREBASEFIRESTORECPP_H
+#define FIREBASE_FIREBASEFIRESTORECPP_H
+
+#import "used_by_swift.h"
+
+#endif  // FIREBASE_FIREBASEFIRESTORECPP_H

Firestore/core/swift/include/used_by_swift.h

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef FIREBASE_USED_BY_SWIFT_H
+#define FIREBASE_USED_BY_SWIFT_H
+
+#include <string>
+
+class UsedBySwift {
+ public:
+  explicit UsedBySwift(std::string content);
+};
+
+#endif  // FIREBASE_USED_BY_SWIFT_H

Firestore/core/swift/src/used_by_swift.cc

@@ -0,0 +1,22 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "../include/used_by_swift.h"
+#include <iostream>
+
+UsedBySwift::UsedBySwift(std::string content) {
+  std::cout << "ctor runs with value: " << content << std::endl;
+}

Package.swift

@@ -476,7 +476,10 @@ let package = Package(
       dependencies: [
         "FirebaseFirestoreTarget",
       ],
-      path: "FirebaseCombineSwift/Sources/Firestore"
+      path: "FirebaseCombineSwift/Sources/Firestore",
+      swiftSettings: [
+        .interoperabilityMode(.Cxx), // C++ interoperability setting
+      ]
     ),
     .target(
       name: "FirebaseStorageCombineSwift",
@@ -1171,7 +1174,10 @@ let package = Package(
         "FirebaseStorage",
         .product(name: "nanopb", package: "nanopb"),
       ],
-      path: "SwiftPMTests/swift-test"
+      path: "SwiftPMTests/swift-test",
+      swiftSettings: [
+        .interoperabilityMode(.Cxx), // C++ interoperability setting
+      ]
     ),
     .testTarget(
       name: "analytics-import-test",
@@ -1399,6 +1405,17 @@ func firestoreWrapperTarget() -> Target {
   )
 }
 
+func firebaseFirestoreCppTarget() -> Target {
+  return .target(
+    name: "FirebaseFirestoreCpp",
+    path: "Firestore/core/swift",
+    publicHeadersPath: "include", // Path to the public headers
+    cxxSettings: [
+      .headerSearchPath("include"), // Ensure the header search path is correct
+    ]
+  )
+}
+
 func firestoreTargets() -> [Target] {
   if ProcessInfo.processInfo.environment["FIREBASE_SOURCE_FIRESTORE"] != nil {
     return [
@@ -1469,13 +1486,15 @@ func firestoreTargets() -> [Target] {
           .linkedLibrary("c++"),
         ]
       ),
+      firebaseFirestoreCppTarget(),
       .target(
         name: "FirebaseFirestore",
         dependencies: [
           "FirebaseCore",
           "FirebaseCoreExtension",
           "FirebaseFirestoreInternalWrapper",
           "FirebaseSharedSwift",
+          "FirebaseFirestoreCpp",
         ],
         path: "Firestore",
         exclude: [
@@ -1496,7 +1515,10 @@ func firestoreTargets() -> [Target] {
         sources: [
           "Swift/Source/",
         ],
-        resources: [.process("Source/Resources/PrivacyInfo.xcprivacy")]
+        resources: [.process("Source/Resources/PrivacyInfo.xcprivacy")],
+        swiftSettings: [
+          .interoperabilityMode(.Cxx), // C++ interoperability setting
+        ]
       ),
     ]
   }
@@ -1542,9 +1564,13 @@ func firestoreTargets() -> [Target] {
         "FirebaseCoreExtension",
         "leveldb",
         "FirebaseSharedSwift",
+        "FirebaseFirestoreCpp",
       ],
       path: "Firestore/Swift/Source",
       resources: [.process("Resources/PrivacyInfo.xcprivacy")],
+      swiftSettings: [
+        .interoperabilityMode(.Cxx), // C++ interoperability setting
+      ],
       linkerSettings: [
         .linkedFramework("SystemConfiguration", .when(platforms: [.iOS, .macOS, .tvOS])),
         .linkedFramework("UIKit", .when(platforms: [.iOS, .tvOS])),
@@ -1561,5 +1587,6 @@ func firestoreTargets() -> [Target] {
       publicHeadersPath: "."
     ),
     firestoreInternalTarget,
+    firebaseFirestoreCppTarget(),
   ]
 }