llvm 20.1.1

[carlocab]

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---

• llvm 20.1.0-rc1
• flang 20.1.0-rc1
• lld 20.1.0-rc1
• unstable_allowlist: add llvm

Closes #217306

[lukeshingles]

LLVM 20.1 final got released a week early. https://github.com/llvm/llvm-project/releases/tag/llvmorg-20.1.0

The CI was last run on rc2, so rc3/final might fix some things automatically, but a couple of notes from the logs:

• afl++ and ldc builds are somehow still linking against libLLVM v20.1, which leads to a missing z3 library (dep of llvm but not llvm@19).

brew install --only-dependencies --verbose --formula --build-bottle afl++
dyld[34548]: Library not loaded: /opt/homebrew/opt/z3/lib/libz3.4.13.dylib
  Referenced from: <397F4426-1635-31E0-978B-ED0A3B7B0957> /opt/homebrew/Cellar/llvm/20.1.0-rc2/lib/libLLVM.dylib
  Reason: tried: '/opt/homebrew/opt/z3/lib/libz3.4.13.dylib' (no such file), '/System/Volumes/Preboot/Cryptexes/OS/opt/homebrew/opt/z3/lib/libz3.4.13.dylib' (no such file), '/opt/homebrew/opt/z3/lib/libz3.4.13.dylib' (no such file), '/usr/local/lib/libz3.4.13.dylib' (no such file), '/usr/lib/libz3.4.13.dylib' (no such file, not in dyld cache)

• wasi-runtimes might need to have the dep reverted from llvm to llvm@19
• halide and wasmedge errors like they might need a legacy lld@19 added so that the CMake finds the correct version of llvm (searching for 20.1 and found 19.1 from llvm@19)

 CMake Error at /opt/homebrew/lib/cmake/lld/LLDConfig.cmake:10 (find_package):
    Could not find a configuration file for package "LLVM" that exactly matches
    requested version "20.1.0".
  
    The following configuration files were considered but not accepted:
  
      /opt/homebrew/opt/llvm@19/lib/cmake/llvm/LLVMConfig.cmake, version: 19.1.7
      /opt/homebrew/opt/llvm@19/lib/cmake/llvm/llvm-config.cmake, version: unknown

[FabioFracassi]

This issue #196905 is probably relevant here again. Only now brew install llvm --HEAD should be labeled llvm@21 otherwise users can not install latest head and latest stable side by side.

[michaelaeriksen]

Any plans to release this? 20.1.2 is just around the corner April 1st

[MikeMcQuaid]

@michaelaeriksen CI is failing here. If you can help move it along: we'd welcome that. Otherwise: it can't be merged until it's working.

[MikeMcQuaid]

Going to merge this and follow up on the remaining 2 formulae:

@cho-m sounds good, thanks!

For split, there has been previous discussion but just that no one has tried it out yet

I'd be 👎🏻 on split before we've tried versioning.

For versioning, will need to make sure the compiler selection and special brew handling of LLVM works correctly. Mainly checking that the alias will be used correctly everywhere. Also may need to decide on what to do with HEAD

Yup, thanks for spelling that out. Think it's worthwhile, though.

At this point: anything that takes >= 1 week to deal with dependency revision bumps is probably worth moving to being a versioned formula.