Mac OS X Lion and Xcode upgraded: missing headers and libs

After upgrading to Lion, and upgrading开发者_JAVA技巧 Xcode, make can't seem to locate headers and libs. I looked in /usr/include. The only thing in there was 'parallels-server'. So, I renamed /usr/include to /usr/include.old, and made a symlink to:

/Developer/SDKs/MacOSX10.6.sdk/usr/include/

This is pretty evil. But, make can now find headers. Still can't locate libs (e.g., lcrt1.10.6.o).

What is the correct way to solve both the include and lib problems?

Thanks!

---

After downloading Xcode 4 from the App Store, try running "/Applications/Install Xcode.app".

---

From me, just downloading the Xcode Command line tools did the trick. (For that, of course, I had first to install Xcode itself, which I installed trough App Store.

1. Start Xcode
2. Open Xcode→Preferences...
3. Select the Downloads tab
4. Install the Command line tools

That installs a few packages, see /var/db/receipts. The package that contains /usr/include is com.apple.pkg.DevSDKLeo.

I don't think xcode-select is needed, but I had run that command before I downloaded the Command line tools, so I don't know for sure.

---

To get Xcode to populate the /usr/include directory, run the following command:

sudo xcode-select -switch /Applications/Xcode.app/Contents/Developer/

You may need to install the Xcode Command Line Tools within Xcode for this to work. Open the Preferences menu, then under Downloads install Command Line Tools.

---

The above answer by njamesp also addresses the following error:

configure: error: C compiler cannot create executables

I received this error when trying to compile code on my 10.7 system after setting it up from a 10.5 time machine, so I assume the wrong version of xcode was installed on my system.