fix(spm): detect install_modules_dependencies as an implicit React-core dep

rn-tester's test libraries (TestLibraryApple / TestLibraryCommon) failed to
build under SwiftPM with `RCTDeprecation/RCTDeprecation.h file not found`: the
scaffolded Package.swift carried no React products because the scaffolder's
`coreReactNative` detection missed them.

Both are plain ObjC modules that wire React core ONLY through the
`install_modules_dependencies(s)` podspec helper and ship no `codegenConfig`.
The scaffolder's two detection paths both fall through for that shape:

  1. Explicit `s.dependency "React-Core"` — but the helper is stripped before
     `pod ipc spec` (and its `min_supported_versions` call makes pod-ipc fail
     outright, falling back to the regex parser, which can't expand the helper
     either), so React-Core never surfaces in the parsed dependencies.
  2. package.json `codegenConfig` — only marks Fabric / New-Arch libraries,
     not plain ObjC modules.

Record whether the podspec source calls `install_modules_dependencies` (visible
even though the helper is stripped for pod-ipc) and treat its presence as an
authoritative React-core signal alongside codegenConfig — injecting that
family is the helper's entire job.

- read-podspec.js: set `usesInstallModulesDependencies` from the podspec source
- scaffold-package-swift.js: OR it into the coreReactNative fallback
- spm-types.js: add the field to PodspecModel

Verified: TestLibraryApple/Common now scaffold with the full React product set
(ReactNative, ReactNativeHeaders, ReactNativeDependenciesHeaders,
ReactAppHeaders); rn-tester BUILD SUCCEEDED. New focused unit test covers the
plain-ObjC-module-with-install_modules_dependencies shape.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: chrfalch

packages/react-native/scripts/spm/__tests__/scaffold-package-swift-test.js

@@ -46,6 +46,7 @@ function podspec(overrides /*: Object */ = {}) {
     requiresArc: true,
     warnings: [],
     partial: false,
+    usesInstallModulesDependencies: false,
     ...overrides,
   };
 }
@@ -341,6 +342,31 @@ describe('translatePodspecToSpmTarget', () => {
     }
   });
 
+  it('treats install_modules_dependencies (no codegenConfig) as an implicit React-core dep (rn-tester TestLibrary shape)', () => {
+    // A plain ObjC module (rn-tester's TestLibraryApple/Common) wires React
+    // core ONLY via install_modules_dependencies(s) and has NO codegenConfig.
+    // The stripped helper leaves model.dependencies without React-Core, so the
+    // usesInstallModulesDependencies marker is what keeps coreReactNative true.
+    const root = fs.mkdtempSync(path.join(os.tmpdir(), 'imd-dep-'));
+    try {
+      fs.writeFileSync(
+        path.join(root, 'package.json'),
+        JSON.stringify({name: 'TestLibraryApple'}), // no codegenConfig
+      );
+      const model = podspec({
+        dependencies: [],
+        usesInstallModulesDependencies: true,
+      });
+      const spec = translatePodspecToSpmTarget(
+        model,
+        autolinkedDep({name: 'TestLibraryApple', root}),
+      );
+      expect(spec.coreReactNative).toBe(true);
+    } finally {
+      fs.rmSync(root, {recursive: true, force: true});
+    }
+  });
+
   it('does NOT force coreReactNative for a non-codegen dep with no React deps', () => {
     const root = fs.mkdtempSync(path.join(os.tmpdir(), 'no-codegen-dep-'));
     try {

packages/react-native/scripts/spm/read-podspec.js

@@ -631,6 +631,8 @@ function flattenSubspecs(rawSpec /*: RawSpec */) /*: PodspecModel */ {
     requiresArc,
     warnings,
     partial,
+    // Default: overridden in readPodspec, which can see the podspec source.
+    usesInstallModulesDependencies: false,
   };
 }
 
@@ -654,7 +656,20 @@ function readPodspec(podspecPath /*: string */) /*: PodspecModel */ {
   }
   const podIpc = runPodIpcSpec(podspecPath);
   const raw = podIpc != null ? podIpc : regexPodspec(podspecPath);
-  return flattenSubspecs(raw);
+  const model = flattenSubspecs(raw);
+  // Record whether the podspec calls `install_modules_dependencies(s)`. We
+  // strip that helper before `pod ipc` and the regex parser can't expand it,
+  // so the React-Core family it injects never lands in `model.dependencies`.
+  // The scaffolder uses this as an implicit React-core marker (plain ObjC
+  // modules using the helper have no `codegenConfig` to detect instead).
+  try {
+    const src = fs.readFileSync(podspecPath, 'utf8');
+    model.usesInstallModulesDependencies =
+      /\binstall_modules_dependencies\b/.test(src);
+  } catch {
+    // best-effort; leave the flattenSubspecs default (false)
+  }
+  return model;
 }
 
 module.exports = {

packages/react-native/scripts/spm/scaffold-package-swift.js

@@ -360,7 +360,16 @@ function translatePodspecToSpmTarget(
   // headers live in the per-app React-GeneratedCode package, so the lib must
   // depend on it (and, transitively, on React core). Treat codegenConfig as
   // an implicit React-core dependency.
-  if (!coreReactNative && depHasCodegenConfig(dep.root)) {
+  // `codegenConfig` only marks Fabric/New-Arch libraries. A plain ObjC module
+  // (e.g. rn-tester's TestLibrary*) that wires React core solely through
+  // `install_modules_dependencies(s)` has no codegenConfig — but the helper's
+  // presence is itself an authoritative "depends on React core" signal, so
+  // treat it the same way.
+  if (
+    !coreReactNative &&
+    (depHasCodegenConfig(dep.root) ||
+      model.usesInstallModulesDependencies === true)
+  ) {
     coreReactNative = true;
   }
 

packages/react-native/scripts/spm/spm-types.js

@@ -299,6 +299,13 @@ export type PodspecModel = {
   // emit a louder banner in the scaffold summary explaining that dependency
   // wiring may be incomplete.
   partial: boolean,
+  // True when the podspec source calls `install_modules_dependencies(s)` —
+  // RN's Podfile-side helper that injects the React-Core family. We strip that
+  // helper before evaluating the spec (and the regex parser can't expand it),
+  // so React-Core never surfaces in `dependencies`. The scaffolder treats this
+  // flag as an implicit React-core dependency (a plain ObjC module using the
+  // helper has no `codegenConfig` to key off).
+  usesInstallModulesDependencies: boolean,
 };
 
 // Intermediate translation result — concrete data the Swift emitter consumes.