Use #if TARGET_OS_IOS instead of #ifdef TARGET_OS_IOS.

runtime/platform/globals.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef PLATFORM_GLOBALS_H_
 #define PLATFORM_GLOBALS_H_
 
 // __STDC_FORMAT_MACROS has to be defined before including <inttypes.h> to
 // enable platform independent printf format specifiers.
 #ifndef __STDC_FORMAT_MACROS
@@ skipping 77 matching lines @@
 #define TARGET_OS_ANDROID 1
 #elif defined(__linux__) || defined(__FreeBSD__)
 #define TARGET_OS_LINUX 1
 #elif defined(__APPLE__)
 // Define the flavor of Mac OS we are running on.
 #include <TargetConditionals.h>
 // TODO(iposva): Rename TARGET_OS_MACOS to TARGET_OS_MAC to inherit
 // the value defined in TargetConditionals.h
 #define TARGET_OS_MACOS 1
 #if TARGET_OS_IPHONE
-#define TARGET_OS_IOS
+#define TARGET_OS_IOS 1

[Ivan Posva, 2015/10/12 09:23:56]

Should we check whether TARGET_OS_IOS has been defined before blindly overriding
it here?

[Bill Hesse, 2015/10/12 10:38:48]

I'm not sure what we want to do if it is defined as 0, or even why this is
necessary.  Adding a guard so it gets defined only if it was previously
undefined.

 #endif
 
 #elif defined(_WIN32)
 #define TARGET_OS_WINDOWS 1
 #else
 #error Automatic target os detection failed.
 #endif
 
 namespace dart {
 
@@ skipping 163 matching lines @@
 #error Mismatched Host/Target architectures.
 #endif
 #endif
 
 // Determine whether we will be using the simulator.
 #if defined(TARGET_ARCH_IA32)
   // No simulator used.
 #elif defined(TARGET_ARCH_X64)
   // No simulator used.
 #elif defined(TARGET_ARCH_ARM)
-#if !defined(HOST_ARCH_ARM) || defined(TARGET_OS_IOS)
+#if !defined(HOST_ARCH_ARM) || TARGET_OS_IOS
 #define USING_SIMULATOR 1
 #endif
 
 #elif defined(TARGET_ARCH_ARM64)
-#if !defined(HOST_ARCH_ARM64) || defined(TARGET_OS_IOS)
+#if !defined(HOST_ARCH_ARM64) || TARGET_OS_IOS
 #define USING_SIMULATOR 1
 #endif
 
 #elif defined(TARGET_ARCH_MIPS)
-#if !defined(HOST_ARCH_MIPS) || defined(TARGET_OS_IOS)
+#if !defined(HOST_ARCH_MIPS) || TARGET_OS_IOS
 #define USING_SIMULATOR 1
 #endif
 
 #else
 #error Unknown architecture.
 #endif
 
 
 // Short form printf format specifiers
 #define Pd PRIdPTR
@@ skipping 299 matching lines @@
 
 #if defined(_WIN32)
 #define STDIN_FILENO 0
 #define STDOUT_FILENO 1
 #define STDERR_FILENO 2
 #endif
 
 }  // namespace dart
 
 #endif  // PLATFORM_GLOBALS_H_