feat: Add definition to check if generated CMake is building the code

packages/nitrogen/src/autolinking/android/createCMakeExtension.ts

@@ -1,5 +1,5 @@
 import { NitroConfig } from '../../config/NitroConfig.js'
-import { indent, toUnixPath } from '../../utils.js'
+import { indent, toLowerCamelCase, toUnixPath } from '../../utils.js'
 import {
   createFileMetadataString,
   getRelativeDirectory,
@@ -13,6 +13,12 @@ export interface CMakeFile extends Omit<SourceFile, 'language'> {
   language: 'cmake'
 }
 
+export function getBuildingWithGeneratedCmakeDefinition(): string {
+  const moduleName = NitroConfig.getAndroidCxxLibName()
+  const upper = toLowerCamelCase(moduleName).toUpperCase()
+  return `BUILDING_${upper}_WITH_GENERATED_CMAKE_PROJECT`
+}
+
 export function createCMakeExtension(files: SourceFile[]): CMakeFile {
   const name = NitroConfig.getAndroidCxxLibName()
   const sharedFiles = files
@@ -30,6 +36,7 @@ export function createCMakeExtension(files: SourceFile[]): CMakeFile {
     `${name}OnLoad.cpp`
   )
   const autolinkingFile = toUnixPath(autolinkingFilePath)
+  const buildingWithDefinition = getBuildingWithGeneratedCmakeDefinition()
 
   const code = `
 ${createFileMetadataString(`${name}+autolinking.cmake`, '#')}
@@ -61,6 +68,9 @@ target_sources(
   ${indent(androidFiles.join('\n'), '  ')}
 )
 
+# Define a flag to check if we are building properly
+add_definitions(-D${buildingWithDefinition})
+
 # Add all libraries required by the generated specs
 find_package(fbjni REQUIRED) # <-- Used for communication between Java <-> C++
 find_package(ReactAndroid REQUIRED) # <-- Used to set up React Native bindings (e.g. CallInvoker/TurboModule)

packages/nitrogen/src/autolinking/android/createHybridObjectInitializer.ts

@@ -9,6 +9,7 @@ import { getJNINativeRegistrations } from '../../syntax/kotlin/JNINativeRegistra
 import { createJNIHybridObjectRegistration } from '../../syntax/kotlin/KotlinHybridObjectRegistration.js'
 import type { SourceFile, SourceImport } from '../../syntax/SourceFile.js'
 import { indent } from '../../utils.js'
+import { getBuildingWithGeneratedCmakeDefinition } from './createCMakeExtension.js'
 
 export function createHybridObjectIntializer(): SourceFile[] {
   const cxxNamespace = NitroConfig.getCxxNamespace('c++')
@@ -45,6 +46,8 @@ export function createHybridObjectIntializer(): SourceFile[] {
     }
   }
 
+  const buildingWithDefinition = getBuildingWithGeneratedCmakeDefinition()
+
   const includes = [
     ...getJNINativeRegistrations().map((r) => includeHeader(r.import)),
     ...cppHybridObjectImports.map((i) => includeHeader(i)),
@@ -78,6 +81,10 @@ namespace ${cxxNamespace} {
   const cppCode = `
 ${createFileMetadataString(`${autolinkingClassName}.cpp`)}
 
+#ifndef ${buildingWithDefinition}
+#error ${autolinkingClassName}.cpp is not being built with the autogenerated CMakeLists.txt project. Is a different CMakeLists.txt building this?
+#endif
+
 #include "${autolinkingClassName}.hpp"
 
 #include <jni.h>

packages/react-native-nitro-image/nitrogen/generated/android/NitroImage+autolinking.cmake

@@ -41,6 +41,9 @@ target_sources(
   ../nitrogen/generated/android/c++/JHybridChildSpec.cpp
 )
 
+# Define a flag to check if we are building properly
+add_definitions(-DBUILDING_NITROIMAGE_WITH_GENERATED_CMAKE_PROJECT)
+
 # Add all libraries required by the generated specs
 find_package(fbjni REQUIRED) # <-- Used for communication between Java <-> C++
 find_package(ReactAndroid REQUIRED) # <-- Used to set up React Native bindings (e.g. CallInvoker/TurboModule)

packages/react-native-nitro-image/nitrogen/generated/android/NitroImageOnLoad.cpp

@@ -5,6 +5,10 @@
 /// Copyright © 2025 Marc Rousavy @ Margelo
 ///
 
+#ifndef BUILDING_NITROIMAGE_WITH_GENERATED_CMAKE_PROJECT
+#error NitroImageOnLoad.cpp is not being built with the autogenerated CMakeLists.txt project. Is a different CMakeLists.txt building this?
+#endif
+
 #include "NitroImageOnLoad.hpp"
 
 #include <jni.h>