After I upgrade to Xcode 5, some projects failed with the following error:

fatal error: 'tr1/functional' file not found
#include <tr1/functional>

Then I checked the iOS SDK 7.0 that was shipped with the Xcode 5 and I found that there’s actually the tr1 folder in the header directory:

/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS7.0.sdk/usr/include/c++/4.2.1/tr1

Issue the same command which failed in Xcode, but plus -v to let clang show the verbose output:

$ clang -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS7.0.sdk -v -arch armv7 -miphoneos-version-min=7.0 ...
Apple LLVM version 5.0 (clang-500.2.76) (based on LLVM 3.3svn)
Target: arm-apple-darwin13.0.0
Thread model: posix
	...
clang -cc1 version 5.0 based upon LLVM 3.3svn default target x86_64-apple-darwin13.0.0
ignoring nonexistent directory "/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS7.0.sdk/usr/include/c++/v1"
ignoring nonexistent directory "/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS7.0.sdk/usr/local/include"
ignoring nonexistent directory "/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS7.0.sdk/Library/Frameworks"
#include "..." search starts here:
#include <...> search starts here:
	...
	/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/c++/v1
	/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/clang/5.0/include
	/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include
	/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS7.0.sdk/usr/include
	/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS7.0.sdk/System/Library/Frameworks (framework directory)
End of search list.
…

We can see the iPhoneOS7.0.sdk/usr/include/c++/4.2.1 hasn’t been searched. After several attempts I found it’s the -miphoneos-version-min=7.0 makes the difference. When I changed it to 4.3, the c++ header directory has been searched and it builds okay.

$ clang -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS7.0.sdk -v -arch armv7 -miphoneos-version-min=4.3 ...
...
#include "..." search starts here:
#include <...> search starts here:
	/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS7.0.sdk/usr/include/c++/4.2.1
	/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS7.0.sdk/usr/include/c++/4.2.1/backward
	/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/clang/5.0/include
	/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include
	/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS7.0.sdk/usr/include
	/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS7.0.sdk/System/Library/Frameworks (framework directory)
End of search list.
...