From e5ba5791b231e4d1066318dcc110956355d992da Mon Sep 17 00:00:00 2001
From: Pieter De Baets <pieterdb@meta.com>
Date: Mon, 3 Feb 2025 06:29:28 -0800
Subject: [PATCH] Enable -Wundef for react-native targets (#49041)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/49041

Prevent the class of issues seen in D68797482 by making `#if FOO` where `FOO` is not defined an error.

Changelog: [Internal]

Reviewed By: NickGerleman, sammy-SC

Differential Revision: D68824244

fbshipit-source-id: 1291c5f2f84ecb023ba76a015716cc7c9ae0f89e
---
 packages/react-native/Libraries/Required/RCTRequired.h        | 2 +-
 packages/react-native/React/Base/RCTAssert.h                  | 2 +-
 packages/react-native/React/Base/RCTDefines.h                 | 4 ++--
 .../ReactCommon/react/renderer/graphics/Transform.h           | 2 ++
 4 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/packages/react-native/Libraries/Required/RCTRequired.h b/packages/react-native/Libraries/Required/RCTRequired.h
index abcff0e47ee..169cf00fb2d 100644
--- a/packages/react-native/Libraries/Required/RCTRequired.h
+++ b/packages/react-native/Libraries/Required/RCTRequired.h
@@ -12,7 +12,7 @@
 // the inlining decisions to avoid unnecessary code bloat. In effect RCTRequired
 // is a cost-free abstraction in non-DEBUG mode. In DEBUG mode we don't force
 // inlining for ease of debugging.
-#if DEBUG
+#ifdef DEBUG
 #define RCTREQUIRED_INLINE inline
 #else
 #define RCTREQUIRED_INLINE __attribute__((always_inline)) inline
diff --git a/packages/react-native/React/Base/RCTAssert.h b/packages/react-native/React/Base/RCTAssert.h
index e088fa9582b..47d4409f6e2 100644
--- a/packages/react-native/React/Base/RCTAssert.h
+++ b/packages/react-native/React/Base/RCTAssert.h
@@ -157,7 +157,7 @@ RCT_EXTERN NSString *RCTFormatStackTrace(NSArray<NSDictionary<NSString *, id> *>
 /**
  * Convenience macro to assert which thread is currently running (DEBUG mode only)
  */
-#if DEBUG
+#ifdef DEBUG
 
 #define RCTAssertThread(thread, ...)                                                                                  \
   _Pragma("clang diagnostic push") _Pragma("clang diagnostic ignored \"-Wdeprecated-declarations\"") RCTAssert(       \
diff --git a/packages/react-native/React/Base/RCTDefines.h b/packages/react-native/React/Base/RCTDefines.h
index ed038680a41..2332681c721 100644
--- a/packages/react-native/React/Base/RCTDefines.h
+++ b/packages/react-native/React/Base/RCTDefines.h
@@ -27,7 +27,7 @@
  * from release builds to improve performance and reduce binary size.
  */
 #ifndef RCT_DEBUG
-#if DEBUG
+#ifdef DEBUG
 #define RCT_DEBUG 1
 #else
 #define RCT_DEBUG 0
@@ -39,7 +39,7 @@
  * such as the debug executors, dev menu, red box, etc.
  */
 #ifndef RCT_DEV
-#if DEBUG
+#ifdef DEBUG
 #define RCT_DEV 1
 #else
 #define RCT_DEV 0
diff --git a/packages/react-native/ReactCommon/react/renderer/graphics/Transform.h b/packages/react-native/ReactCommon/react/renderer/graphics/Transform.h
index 9977807244f..911774d35df 100644
--- a/packages/react-native/ReactCommon/react/renderer/graphics/Transform.h
+++ b/packages/react-native/ReactCommon/react/renderer/graphics/Transform.h
@@ -8,8 +8,10 @@
 #pragma once
 
 #include <array>
+#include <string>
 #include <vector>
 
+#include <react/renderer/debug/flags.h>
 #include <react/renderer/graphics/Float.h>
 #include <react/renderer/graphics/Point.h>
 #include <react/renderer/graphics/RectangleEdges.h>