Find out the path location to Command Line Tools for Xcode

This worked for me: sudo xcode-select --reset

Short version: the answer to my problem is to install the full Xcode, not only the Command Line Tools.

Long version:

Based on this I found out, that the location of the tools is /usr/bin . So I ran sudo xcode-select -switch /usr/bin. After that however, I got this error:

Error: failed to exec real xcrun. (No such file or directory)

So based on this I install the full Xcode app, ran sudo xcode-select -switch /Applications/Xcode.app/Contents/Developer and this solved my problem.

The entries in /usr/bin are just a front for whatever you choose with xcode-select:

$> /usr/bin/clang --version
Apple LLVM version 8.0.0 (clang-800.0.38)
Target: x86_64-apple-darwin15.6.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin

The standalone command line tools are installed in /Library/Developer/CommandLineTools:

$> sudo xcode-select -s /Library/Developer/CommandLineTools
$> /usr/bin/clang --version
Apple LLVM version 7.3.0 (clang-703.0.31)
Target: x86_64-apple-darwin15.6.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin