macos-10.15 missing LLVM 13

[strager]

Description

The documentation for macos-10.15 says that LLVM 13 is installed in /usr/local/opt/llvm:

Clang/LLVM 13.0.1 is available on '$(brew --prefix llvm)/bin/clang'

I have relied on this tool at this location for many months.

Today (or yesterday), my CI scripts stopped working correctly. It looks like /usr/local/opt/llvm no longer exists on macos-10.15 workers.

According to brew, llvm@13 is installed. However, $(brew --prefix llvm)/bin/clang doesn't exist:

$ brew list llvm@13 
/usr/local/Cellar/llvm@13/13.0.1/bin/FileCheck
/usr/local/Cellar/llvm@13/13.0.1/bin/analyze-build
/usr/local/Cellar/llvm@13/13.0.1/bin/bugpoint
/usr/local/Cellar/llvm@13/13.0.1/bin/c-index-test
/usr/local/Cellar/llvm@13/13.0.1/bin/clang
/usr/local/Cellar/llvm@13/13.0.1/bin/clang++
/usr/local/Cellar/llvm@13/13.0.1/bin/clang-13

$ brew --prefix llvm
/usr/local/opt/llvm
$ ls /usr/local/opt/llvm
ls: /usr/local/opt/llvm: No such file or directory

$ sw_vers
ProductName:    Mac OS X
ProductVersion: 10.15.7
BuildVersion:   19H1922

Platforms affected

• Azure DevOps
• GitHub Actions

Virtual environments affected

• Ubuntu 18.04
• Ubuntu 20.04
• Ubuntu 22.04
• macOS 10.15
• macOS 11
• macOS 12
• Windows Server 2019
• Windows Server 2022

Image version and build link

Environment: macos-10.15
Version: 20220627.1
Included Software: https://github.com/actions/virtual-environments/blob/macOS-10.15/20220627.1/images/macos/macos-10.15-Readme.md
Image Release: https://github.com/actions/virtual-environments/releases/tag/macOS-10.15%2F20220627.1

https://github.com/quick-lint/quick-lint-js/runs/7123423723?check_suite_focus=true

Is it regression?

yes; 20220622.2; https://github.com/quick-lint/quick-lint-js/runs/7105900086?check_suite_focus=true

Expected behavior

$(brew --prefix llvm)/bin/clang exists and is executable

Actual behavior

$(brew --prefix llvm)/bin/clang does not exist

Repro steps

Run ls /usr/local/opt/llvm in a job

[al-cheb]

Hello @strager.
It's expected that the path /usr/local/opt/llvm doesn't exist - #5819 (comment)

If you're explicitly installing llvm@13, then it will only be found through /usr/local/opt/llvm@13. /usr/local/opt/llvm will only exist if you've installed llvm, and it will point to LLVM 14. So if anything was previously hardcoded to /usr/local/opt/llvm, it will have to be changed to /usr/local/opt/llvm@13 or LLVM 14 will have to be used instead.

[strager]

It's expected that the path /usr/local/opt/llvm doesn't exist

Then the documentation should be updated.

[al-cheb]

#5837 is in progress.