llvm@3.9 (new formula)

[tmcdonell]

• Have you followed the guidelines for contributing?
• Have you checked that there aren't other open pull requests for the same formula update/change?
• Have you built your formula locally with brew install --build-from-source <formula>, where <formula> is the name of the formula you're submitting?
• Does your build pass brew audit --strict <formula> (after doing brew install <formula>)?

---

Versioned install of LLVM-3.9. Useful for people who need to install multiple versions of LLVM simultaneously (like me), or who need to install a specific version (also useful in documentation).

LLVM-4.0 is currently in RC and scheduled to be released in a few days. Once that is out we can bump the llvm.rb formula and LLVM-3.9 will still be available via this formula.

I included the fix to llvm@3.8 in this PR, since that was causing problems installing multiple versions simultaneously, but I could probably split that out. I currently have llvm@3.7, llvm@3.8, and llvm@3.9 formula installed and they seem to be working together nicely.

[ilovezfs]

The current formula is already 3.9.x, so at most we'd consider adding an alias.

[tmcdonell]

@ilovezfs As I mentioned in the comment, LLVM is about to land 4.0, so this is still necessary. At worst I am a few days early with the PR.

Additionally, for my own use can, LLVM is one of the dependencies of my software and it requires a specific version to be installed. It is much easier to write in the documentation/installation instructions brew install llvm@3.9; rather than brew install llvm; brew link --force llvm and hope for the best. I think this is a valid use case.

[ilovezfs]

which is why I said we'd accept a PR for an alias

[ilovezfs]

See #8945.

[MikeMcQuaid]

I included the fix to llvm@3.8 in this PR, since that was causing problems installing multiple versions simultaneously, but I could probably split that out.

Yeh, a separate PR would be best for this, thanks.

As I mentioned in the comment, LLVM is about to land 4.0, so this is still necessary. At worst I am a few days early with the PR.

I'd recommend creating a PR for both LLVM 4.0 and LLVM@3.9 in the same one.

[tmcdonell]

@MikeMcQuaid sure, I'll create a separate PR for that.

I appreciate your courtesy to actually read the commit message. Thanks.

[ilovezfs]

Cute.

[MikeMcQuaid]

I appreciate your courtesy to actually read the commit message. Thanks.

GitHub's UI is PR-focused rather than commit-focused and Homebrew's maintainers are busy people so it's best to put information you need to be read in the PR message as well as the commit message.