So I went to get updates from the App Store today and saw that Xcode 8 was available for my mid-2007 aluminum iMac running OS X v10.11.6 'El Capitan.' I had a little trouble getting it to finish downloading and installing (probably since it's such a big download — I've had problmes like this before,) but I did finally manage to get it do that! In any case, once I was done doing that, I expected to find myself able to download and install the corresponding command line tools package update even though it didn't appear when I first checked for updates. And, yet, for some strange reason, the expected update in question still hasn't appeared! I also checked Apple Developer Connection's manual 'Downloads for Apple Developers' page, but the El Capitan command-line tools installer wasn't listed there, either! To make matters even more confusing, I did see the macOS Sierra (10.12) command-line tools installer listed there! What in the heck is going on here?!? I need the command-line tools to continue using Homebrew in --build-from-source mode!
There is no Command Line Tools (OS X 10.11) for Xcode 8 package. Xcode 8 contains SDKs that are incompatible with earlier toolchains. Developers who want to make use of the Xcode 8 SDKs from the command line must choose the SDK with xcode-select. Developers on OS X El Capitan who have installed versions of the Command Line Tools (OS X 10.11) for Xcode 8 Beta should install Command Line Tools (OS X 10.11) for Xcode 7.3.1.