MacBook-Air:~ mikkunn$ brew doctor

Warning: You have Xcode 4.2.1, which is outdated.

Please install Xcode 4.3.

Warning: /usr/bin occurs before /usr/local/bin

This means that system-provided programs will be used instead of those

provided by Homebrew. The following tools exist at both paths:

    git

    git-cvsserver

    git-receive-pack

    git-shell

    git-upload-archive

    git-upload-pack

    gitk

Consider ammending your PATH so that /usr/local/bin

is ahead of /usr/bin in your PATH.

MacBook-Air:~ mikkunn$ 

Last login: Fri Mar  9 08:48:10 on ttys000

MacBook-Air:~ mikkunn$ brew doctor

Warning: You have Xcode 4.2, which is outdated.

Please install Xcode 4.3.

Warning: /usr/bin occurs before /usr/local/bin

This means that system-provided programs will be used instead of those

provided by Homebrew. The following tools exist at both paths:

    git

    git-cvsserver

    git-receive-pack

    git-shell

    git-upload-archive

    git-upload-pack

    gitk

Consider ammending your PATH so that /usr/local/bin

is ahead of /usr/bin in your PATH.

Warning: Your Xcode is configured with an invalid path.

You should change it to the correct path. Please note that there is no correct

path at this time if you have *only* installed the Command Line Tools for Xcode.

If your Xcode is pre-4.3 or you installed the whole of Xcode 4.3 then one of

these is (probably) what you want:

    sudo xcode-select -switch /Developer

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