fix(ios): keep the podspec's build attributes out of the OpenCV branch

.cspell-wordlist.txt

@@ -385,3 +385,5 @@ pretokenizer
 repoint
 repoints
 basenames
+xcconfig
+toggleable

packages/react-native-executorch/__tests__/api/podspecAttributes.test.ts

@@ -0,0 +1,171 @@
+/**
+ * The attributes the iOS podspec actually assigns, per build config.
+ *
+ * `react-native-executorch.podspec` is Ruby, and `pod install` is the only
+ * thing that ever runs it. Nothing in JS CI evaluates it, so a misplaced `end`
+ * type-checks, lints, spell-checks and reviews clean, then reaches users as a
+ * link error in an app we never built ourselves. That is exactly what happened
+ * in #1450: the `if enable_opencv` guard around the OpenCV pod selection was
+ * left open until the bottom of the spec, so an app that turned OpenCV off got
+ * a pod with no `HEADER_SEARCH_PATHS`, no `static_framework` and no
+ * `ExecutorchLib.xcframework`.
+ *
+ * The config matrix is the part that rots: `rne-build-config.json` is written
+ * by the postinstall hook from the consumer's `package.json` config block, and
+ * our own example apps all take one row of it. Every other row only exists on
+ * a user's machine.
+ *
+ * So this suite evaluates the real podspec under a stubbed `Pod::Spec` and
+ * asserts on what it assigned. The stub records attribute names rather than
+ * modelling CocoaPods: what breaks is an attribute going missing, not its
+ * value being subtly wrong.
+ */
+import { execFileSync } from 'child_process';
+import { join } from 'path';
+
+const PACKAGE_ROOT = join(__dirname, '..', '..');
+
+/**
+ * Evaluates the podspec with `rne-build-config.json` faked to `config`, or
+ * absent when `config` is `null`.
+ *
+ * `File.exist?` and `File.read` are intercepted for that one path instead of
+ * writing the file: a developer's real config sits there, and a test suite
+ * must not overwrite it. The vendored-artifact guard is satisfied the same
+ * way, through `File.directory?`, so the suite runs on a checkout that never
+ * downloaded the native libs (which CI is).
+ */
+function assignedAttributes(config: Record<string, boolean> | null): string[] {
+  // Ruby 2.6 syntax throughout: that is the system Ruby on macOS, and the one
+  // a contributor who has never installed a newer one runs CocoaPods with.
+  const harness = `
+    require "json"
+
+    $assigned = []
+    # nil stands for "the postinstall hook never wrote one".
+    $config_json = ARGV[0] == "" ? nil : ARGV[0]
+
+    module StubbedPaths
+      CONFIG_FILE = "rne-build-config.json".freeze
+
+      def exist?(path)
+        path.to_s.end_with?(CONFIG_FILE) ? !$config_json.nil? : super
+      end
+
+      def read(path, *args)
+        path.to_s.end_with?(CONFIG_FILE) ? $config_json : super
+      end
+
+      # Stands in for the artifacts the postinstall hook downloads; their
+      # absence is a separate check, covered by nativeLibsConfig.test.ts.
+      def directory?(path)
+        path.to_s.include?("third-party/ios") ? true : super
+      end
+    end
+    File.singleton_class.prepend(StubbedPaths)
+
+    module Pod
+      Informative = Class.new(StandardError)
+
+      class Spec
+        def self.new
+          spec = allocate
+          yield spec
+          spec
+        end
+
+        # Attribute writers arrive here as :name=. The platform proxies
+        # (s.ios.vendored_frameworks = ...) return self, so the chained
+        # assignment is recorded under its own name too.
+        def method_missing(name, *args)
+          $assigned << name.to_s.sub(/=$/, "")
+          self
+        end
+
+        def respond_to_missing?(*)
+          true
+        end
+
+        def ios
+          self
+        end
+      end
+    end
+
+    # Provided by react_native_pods.rb, a CocoaPods-time dependency.
+    def install_modules_dependencies(spec); end
+
+    Dir.chdir(${JSON.stringify(PACKAGE_ROOT)}) do
+      eval(File.read("react-native-executorch.podspec"), TOPLEVEL_BINDING, "podspec")
+    end
+    puts JSON.dump($assigned.uniq)
+  `;
+
+  let output: string;
+  try {
+    output = execFileSync('ruby', ['-e', harness, config === null ? '' : JSON.stringify(config)], {
+      encoding: 'utf8',
+      stdio: ['ignore', 'pipe', 'pipe'],
+    });
+  } catch (error) {
+    const details = error instanceof Error ? (error as { stderr?: string }).stderr : undefined;
+    throw new Error(
+      `evaluating the podspec with ${JSON.stringify(config)} failed.\n` +
+        `A Ruby error here is a real podspec defect: this is what \`pod install\` runs.\n` +
+        `${details ?? String(error)}`
+    );
+  }
+  return JSON.parse(output.trim()) as string[];
+}
+
+/**
+ * Attributes that decide whether the pod compiles and links at all, so none of
+ * them may depend on a feature flag. `pod_target_xcconfig` carries every
+ * `HEADER_SEARCH_PATHS` entry, and `vendored_frameworks` carries ExecuTorch
+ * itself.
+ */
+const UNCONDITIONAL_ATTRIBUTES = [
+  'source_files',
+  'public_header_files',
+  'pod_target_xcconfig',
+  'static_framework',
+  'vendored_frameworks',
+  'libraries',
+  'frameworks',
+];
+
+/**
+ * One row per independently toggleable native library, plus the two shapes a
+ * default install takes. `enableOpencv: false` is the row #1450 broke, and
+ * `null` is the branch where it left `rne_build_config` unassigned, so reading
+ * `opencvPod` from it raised `NoMethodError` for nil.
+ */
+const CONFIGS: Record<string, Record<string, boolean> | null> = {
+  'no config file (manual provisioning)': null,
+  'empty config (every feature on)': {},
+  'opencv off': { enableOpencv: false },
+  'phonemis off': { enablePhonemis: false },
+  'xnnpack off': { enableXnnpack: false },
+  'coreml off': { enableCoreml: false },
+  'mlx off': { enableMlx: false },
+  'every optional library off': {
+    enableOpencv: false,
+    enablePhonemis: false,
+    enableXnnpack: false,
+    enableCoreml: false,
+    enableMlx: false,
+  },
+};
+
+describe('podspec attributes', () => {
+  describe.each(Object.entries(CONFIGS))('with %s', (_label, config) => {
+    it('evaluates and assigns every attribute the build depends on', () => {
+      const assigned = assignedAttributes(config);
+      const missing = UNCONDITIONAL_ATTRIBUTES.filter((name) => !assigned.includes(name));
+
+      // A name here means the attribute sits inside a conditional it does not
+      // belong in. The pod still installs; the app fails to compile or link.
+      expect(missing).toEqual([]);
+    });
+  });
+});

packages/react-native-executorch/react-native-executorch.podspec

@@ -7,20 +7,17 @@ package = JSON.parse(File.read(File.join(__dir__, "package.json")))
 # Falls back to all features enabled if the file doesn't exist (e.g. a fresh
 # checkout where the native libs were provisioned manually).
 rne_build_config_path = File.join(__dir__, "rne-build-config.json")
-if File.exist?(rne_build_config_path)
-  rne_build_config = JSON.parse(File.read(rne_build_config_path))
-  enable_opencv   = rne_build_config["enableOpencv"]   != false
-  enable_phonemis = rne_build_config["enablePhonemis"] != false
-  enable_xnnpack  = rne_build_config["enableXnnpack"]  != false
-  enable_coreml   = rne_build_config["enableCoreml"]   != false
-  enable_mlx      = rne_build_config["enableMlx"]      != false
-else
-  enable_opencv   = true
-  enable_phonemis = true
-  enable_xnnpack  = true
-  enable_coreml   = true
-  enable_mlx      = true
-end
+rne_build_config =
+  File.exist?(rne_build_config_path) ? JSON.parse(File.read(rne_build_config_path)) : {}
+
+# Every flag reads `!= false`, so an absent file and an absent key both mean
+# enabled. Keep the hash rather than branching on the file: `opencvPod` below
+# is read from it too, and a nil `rne_build_config` there is a NoMethodError.
+enable_opencv   = rne_build_config["enableOpencv"]   != false
+enable_phonemis = rne_build_config["enablePhonemis"] != false
+enable_xnnpack  = rne_build_config["enableXnnpack"]  != false
+enable_coreml   = rne_build_config["enableCoreml"]   != false
+enable_mlx      = rne_build_config["enableMlx"]      != false
 
 # The native artifacts are not in the npm tarball - `package.json` excludes
 # them and `scripts/download-libs.js` fetches them from the matching GitHub
@@ -249,6 +246,7 @@ Pod::Spec.new do |s|
       s.dependency opencv_pod
       external_opencv = true
     end
+  end
 
   # Our own OpenCV headers ship under third-party/include and are newer than
   # what another OpenCV pod vendors: react-native-fast-opencv carries 4.9, and
@@ -336,7 +334,5 @@ Pod::Spec.new do |s|
   # ExecutorchLib goes in vendored_frameworks to avoid duplicate symbol errors.
   s.ios.vendored_frameworks = ["third-party/ios/ExecutorchLib.xcframework"]
 
-  end
-
   install_modules_dependencies(s)
 end