It's still useful to do a basic test even if requirements cannot be
satisfied.

Raise an error when attempting to create universal binaries with a GCC
that can't do so.

Closes Homebrew/homebrew#46630.

Signed-off-by: Baptiste Fontaine <batifon@yahoo.fr>

Refs caskroom/homebrew-cask#15381

Closes Homebrew/homebrew#46845.

So we can remove the formula installation from `brew.rb`.

Closes Homebrew/homebrew#46843.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

`Formula-Cookbook.md` contains leftover git conflict markers introduced
in 15f291ddaa05cc010456a733b799382175c29dd4.

This commit removes the conflict makers and a duplicated paragraph.

Closes Homebrew/homebrew#46836.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

Closes Homebrew/homebrew#46794.

Signed-off-by: Baptiste Fontaine <batifon@yahoo.fr>

A blocker for https://github.com/caskroom/homebrew-cask/pull/15381
being merged.

Closes Homebrew/homebrew#46795.

Closes Homebrew/homebrew#46735.

Signed-off-by: Xu Cheng <xucheng@me.com>

It's now handled by Tap.fetch

Closes Homebrew/homebrew#39167.
Closes Homebrew/homebrew#46727.

Signed-off-by: Dominyk Tiller <dominyktiller@gmail.com>

Fixes a couple issues left behind by Homebrew/homebrew#46676.

Closes Homebrew/homebrew#46706.

Signed-off-by: Andrew Janke <andrew@apjanke.net>

Otherwise it would assume if `cask` was tapped it was also installed.

This matches similar caveats messages.

`MacOS.sdk` and `.sdk_path` will now return the newest installed SDK
instead of nil if called on a system that doesn’t have an SDK for the
currently-installed OS. For example, Xcode 7 on OS X 10.10 does not
include the 10.10 SDK, only the 10.11 SDK; software can be built by
specifying both SDKROOT and MACOSX_DEPLOYMENT_TARGET.

* Pull SDK lookup code into a new `locator` class, which caches its
  results
* SDKLocator only queries one SDK location, not all SDK locations
* Build a map of all installed SDKs inside that location, instead of
  just the requested SDK
* Ask xcrun for --show-sdk-platform-path first so that all SDKs can be
  found, instead of asking xcodebuild for a specific SDK
* Add a new `SDK` class, which tracks the version and the prefix; add a
  new `MacOS.sdk` method which returns an `SDK` instance instead of a
  bare path; MacOS.sdk_path still returns a bare path

Sometimes the linkage means the recursive dependencies also link to
libraries and need bumped.