feat: Support autolinking C++ only TurboModules on Android (#2387)

* feat(android): add cxxOnly config property

* feat(android-autolinking): Dont search for java related properties if cxxOnly is true

* feat(android-autolinking): Don't autolink cxxOnly modules using the Java packagelist

This also ignores them from getting included with gradle dependencies

* chore: remove unnecessary newline from dependencies

* chore: remove the cxxOnly property

* feat: derive if a dependency is pure cxx from other properties

* docs: document pure cxx linking

Author: atlj

docs/autolinking.md

@@ -70,6 +70,26 @@ You’re already using Gradle, so Android support will work by default.
 
 On the iOS side, you will need to ensure you have a Podspec to the root of your repo. The `react-native-webview` Podspec is a good example of a [`package.json`](https://github.com/react-native-community/react-native-webview/blob/master/react-native-webview.podspec)-driven Podspec. Note that CocoaPods does not support having `/`s in the name of a dependency, so if you are using scoped packages - you may need to change the name for the Podspec.
 
+### Pure C++ libraries
+
+Alternatively, if you have a pure C++ library and don't want to use Gradle, you can still use autolinking. You need to update your `react-native.config.js` to include the following:
+
+```js
+// react-native.config.js
+module.exports = {
+  dependency: {
+    platforms: {
+      android: {
+        sourceDir: 'path/to/your/c++/code',
+        cxxModuleCMakeListsPath: `relative/path/to/CMakeLists.txt`, // This is relative to the sourceDir.
+        cxxModuleCMakeListsModuleName: 'MyModule', // This is the name of the CMake target.
+        cxxModuleHeaderName: 'MyHeader', // CLI will include this header while linking.
+      },
+    },
+  },
+};
+```
+
 ## How can I customize how autolinking works for my package?
 
 A library can add a `react-native.config.js` configuration file, which will customize the defaults, example:

packages/cli-platform-android/native_modules.gradle

@@ -186,6 +186,11 @@ class ReactNativeModules {
     reactNativeModules.forEach { reactNativeModule ->
       def nameCleansed = reactNativeModule["nameCleansed"]
       def dependencyConfiguration = reactNativeModule["dependencyConfiguration"]
+      def isPureCxxDependency = reactNativeModule["isPureCxxDependency"]
+      if (isPureCxxDependency) {
+        return
+      }
+
       appProject.dependencies {
         if (reactNativeModulesBuildVariants.containsKey(nameCleansed)) {
           reactNativeModulesBuildVariants
@@ -248,10 +253,14 @@ class ReactNativeModules {
                     "${prefix}${packageName}.${className}${suffix}"
                 })
       }
-      packageImports = packages.collect {
+      packageImports = packages
+      .findAll { !it.isPureCxxDependency }
+      .collect {
         "// ${it.name}\n${interpolateDynamicValues(it.packageImportPath)}"
       }.join('\n')
-      packageClassInstances = ",\n      " + packages.collect {
+      packageClassInstances = ",\n      " + packages
+      .findAll { !it.isPureCxxDependency }
+      .collect {
         interpolateDynamicValues(it.packageInstance)
       }.join(",\n      ")
     }
@@ -481,6 +490,7 @@ class ReactNativeModules {
         reactNativeModuleConfig.put("cxxModuleCMakeListsModuleName", androidConfig["cxxModuleCMakeListsModuleName"])
         reactNativeModuleConfig.put("cxxModuleCMakeListsPath", androidConfig["cxxModuleCMakeListsPath"])
         reactNativeModuleConfig.put("cxxModuleHeaderName", androidConfig["cxxModuleHeaderName"])
+        reactNativeModuleConfig.put("isPureCxxDependency", androidConfig["isPureCxxDependency"])
 
         if (androidConfig["buildTypes"] && !androidConfig["buildTypes"].isEmpty()) {
           reactNativeModulesBuildVariants.put(nameCleansed, androidConfig["buildTypes"])

packages/cli-platform-android/src/config/index.ts

@@ -135,28 +135,38 @@ export function dependencyConfig(
     ? path.join(sourceDir, userConfig.manifestPath)
     : findManifest(sourceDir);
   const buildGradlePath = findBuildGradle(sourceDir, true);
-
-  if (!manifestPath && !buildGradlePath) {
+  const isPureCxxDependency =
+    userConfig.cxxModuleCMakeListsModuleName != null &&
+    userConfig.cxxModuleCMakeListsPath != null &&
+    userConfig.cxxModuleHeaderName != null &&
+    !manifestPath &&
+    !buildGradlePath;
+
+  if (!manifestPath && !buildGradlePath && !isPureCxxDependency) {
     return null;
   }
 
-  const packageName =
-    userConfig.packageName || getPackageName(manifestPath, buildGradlePath);
-  const packageClassName = findPackageClassName(sourceDir);
+  let packageImportPath = null,
+    packageInstance = null;
 
-  /**
-   * This module has no package to export
-   */
-  if (!packageClassName) {
-    return null;
-  }
+  if (!isPureCxxDependency) {
+    const packageName =
+      userConfig.packageName || getPackageName(manifestPath, buildGradlePath);
+    const packageClassName = findPackageClassName(sourceDir);
+
+    /**
+     * This module has no package to export
+     */
+    if (!packageClassName) {
+      return null;
+    }
 
-  const packageImportPath =
-    userConfig.packageImportPath ||
-    `import ${packageName}.${packageClassName};`;
+    packageImportPath =
+      userConfig.packageImportPath ||
+      `import ${packageName}.${packageClassName};`;
 
-  const packageInstance =
-    userConfig.packageInstance || `new ${packageClassName}()`;
+    packageInstance = userConfig.packageInstance || `new ${packageClassName}()`;
+  }
 
   const buildTypes = userConfig.buildTypes || [];
   const dependencyConfiguration = userConfig.dependencyConfiguration;
@@ -193,5 +203,6 @@ export function dependencyConfig(
     cxxModuleCMakeListsModuleName,
     cxxModuleCMakeListsPath,
     cxxModuleHeaderName,
+    isPureCxxDependency,
   };
 }

packages/cli-types/src/android.ts

@@ -25,8 +25,8 @@ export type AndroidProjectParams = {
 
 export type AndroidDependencyConfig = {
   sourceDir: string;
-  packageImportPath: string;
-  packageInstance: string;
+  packageImportPath: string | null;
+  packageInstance: string | null;
   dependencyConfiguration?: string;
   buildTypes: string[];
   libraryName?: string | null;
@@ -35,6 +35,7 @@ export type AndroidDependencyConfig = {
   cxxModuleCMakeListsModuleName?: string | null;
   cxxModuleCMakeListsPath?: string | null;
   cxxModuleHeaderName?: string | null;
+  isPureCxxDependency?: boolean;
 };
 
 export type AndroidDependencyParams = {