LLVM 16.0.0.rc4

[h-vetinari]

I might just succeed for once to build the whole compiler stack during the rc phase 🙃

Blockers for merging this PR and thus enabling the compilers in conda-forge (indentation denotes dependency; c.f. list from 15.x):

• llvmdev 16.0.0.rc4 llvmdev-feedstock#201
  • bump to 16.0.0.rc4 clangdev-feedstock#204
    • Rebuild for LLVM 16 cctools-and-ld64-feedstock#58
    • compiler-rt 16.0.0.rc4 compiler-rt-feedstock#62
      • https://github.com/conda-forge/clang-win-activation-feedstock **
      • WIP: LLVM flang 16.0.x flang-feedstock#27 **
    • bump to 16.0.0.rc4 libcxx-feedstock#112
  • bump to 16.0.0.rc4 lld-feedstock#55
  • bump to 16.0.0.rc4 mlir-feedstock#39 **
  • bump to 16.0.0.rc4 openmp-feedstock#80

The PRs marked ** are not strictly speaking necessary for merging this PR, but for LLVM 16.x support in conda-forge.

[h-vetinari]

@conda-forge/core
I managed to build the LLVM 16.0.0.rc stack under conda-forge/label/llvm_rc; however, I've hit one last snag that I haven't seen before - upon merging this PR to the rc branch, the upload step says "The branch rc is not configured to be uploaded", e.g.:

▶︎ Validating outputs
▼ Uploading packages
  + [[ True != \F\a\l\s\e ]]
  + [[ False == \F\a\l\s\e ]]
  + upload_package --validate --feedstock-name=clang-compiler-activation-feedstock /home/conda/feedstock_root /home/conda/recipe_root /home/conda/feedstock_root/.ci_support/linux_64_channel_targetsconda-forge_maincross_target_platformosx-arm64macos_machinearm64-apple-darwin20.0.0version15.0.7.yaml
  The branch rc is not configured to be uploaded
▶︎ Final checks
   Finishing: Run docker build

[mikemhenry]

from https://github.com/conda-forge/clang-compiler-activation-feedstock/pull/95/files#diff-ff61408cdc05bc9667deeadb55e4aaceb1371972076b6bf6934f9008920f2bd2R24

I think the branch name needs to be llvm_rc as the target

[h-vetinari]

Thanks, but that's not it. It's as Billy mentioned on matrix, we need to remove upload_on_branch: main. I didn't know this setting, but it's documented.