iOS: Generate FBReactNativeSpec ObjC++ files at build time

Summary:
Removes the generated FBReactNativeSpec files from source control.

## Generating FBReactNativeSpec files

The files will be generated automatically by CocoaPods when the `RNTesterPods` Xcode workspace is generated:

```
cd packages/rn-tester
pod install
```

The spec files can be re-generated by invoking the script directly:
```
./scripts/generate-native-modules-specs.sh
```

Changelog: [Internal]

Reviewed By: RSNara

Differential Revision: D24261167

fbshipit-source-id: acb7ac856e5e519932e4f587f79e24f49cd84a91

.gitignore

@@ -100,6 +100,7 @@ package-lock.json
 !/packages/rn-tester/Pods/__offline_mirrors__
 
 # react-native-codegen
+/Libraries/FBReactNativeSpec/FBReactNativeSpec
 /packages/react-native-codegen/lib
 /ReactCommon/fabric/components/rncore/
 /schema-native-modules.json

Libraries/FBReactNativeSpec/BUCK

@@ -1,25 +0,0 @@
-load("//tools/build_defs/oss:rn_defs.bzl", "fb_apple_library", "react_native_xplat_target_apple", "subdir_glob")
-
-fb_apple_library(
-    name = "FBReactNativeSpecApple",
-    srcs = glob(["FBReactNativeSpec/**/*.mm"]),
-    exported_headers = subdir_glob(
-        [
-            ("FBReactNativeSpec", "*.h"),
-        ],
-        prefix = "FBReactNativeSpec",
-    ),
-    contacts = ["oncall+react_native@xmail.facebook.com"],
-    extension_api_only = True,
-    frameworks = [
-        "Foundation",
-        "UIKit",
-    ],
-    labels = ["supermodule:xplat/default/public.react_native.infra"],
-    reexport_all_header_dependencies = True,
-    deps = [
-        "//xplat/js/react-native-github:RCTTypeSafety",
-        "//xplat/js/react-native-github/Libraries/RCTRequired:RCTRequired",
-        react_native_xplat_target_apple("react/nativemodule/core:core"),
-    ],
-)

React/CoreModules/BUCK

@@ -130,7 +130,7 @@ rn_apple_library(
     exported_deps = [
         "//xplat/js:RCTLinkingApple",
         "//xplat/js:RCTPushNotificationApple",
+        "//xplat/js:generated_objcpp_modules-react-nativeApple",
         "//xplat/js/react-native-github:ReactInternalApple",
-        "//xplat/js/react-native-github/Libraries/FBReactNativeSpec:FBReactNativeSpecApple",
     ],
 )

packages/react-native-codegen/DEFS.bzl

@@ -8,6 +8,7 @@ load(
     "IOS",
     "MACOSX",
     "YOGA_CXX_TARGET",
+    "fb_apple_library",
     "fb_xplat_cxx_test",
     "get_apple_compiler_flags",
     "get_apple_inspector_flags",
@@ -15,6 +16,7 @@ load(
     "react_native_dep",
     "react_native_target",
     "react_native_xplat_target",
+    "react_native_xplat_target_apple",
     "rn_android_library",
     "rn_xplat_cxx_library",
 )
@@ -139,36 +141,29 @@ def rn_codegen_modules(
         labels = ["codegen_rule"],
     )
 
-    rn_xplat_cxx_library(
-        name = "generated_objcpp_modules-{}".format(name),
+    fb_apple_library(
+        name = "generated_objcpp_modules-{}Apple".format(name),
+        extension_api_only = True,
         header_namespace = "",
-        apple_sdks = (IOS),
+        sdks = (IOS),
         compiler_flags = [
-            "-fexceptions",
-            "-frtti",
-            "-std=c++14",
-            "-Wall",
+            "-Wno-unused-private-field",
         ],
-        fbobjc_compiler_flags = get_apple_compiler_flags(),
-        fbobjc_preprocessor_flags = get_preprocessor_flags_for_build_mode() + get_apple_inspector_flags(),
-        ios_exported_headers = {
+        exported_headers = {
             "{}/{}.h".format(native_module_spec_name, native_module_spec_name): ":{}".format(generate_module_hobjcpp_name),
         },
-        ios_headers = [
+        headers = [
             ":{}".format(generate_module_hobjcpp_name),
         ],
-        ios_srcs = [
+        srcs = [
             ":{}".format(generate_module_mm_name),
         ],
         labels = ["codegen_rule"],
-        platforms = (APPLE),
-        preprocessor_flags = [
-            "-DLOG_TAG=\"ReactNative\"",
-            "-DWITH_FBSYSTRACE=1",
-        ],
         visibility = ["PUBLIC"],
-        deps = [
-            "//xplat/js:React",
+        exported_deps = [
+            "//xplat/js/react-native-github:RCTTypeSafety",
+            "//xplat/js/react-native-github/Libraries/RCTRequired:RCTRequired",
+            react_native_xplat_target_apple("react/nativemodule/core:core"),
         ],
     )