Important: New toolchain requirements to build LLVM will (most likely) be landing within a week. Prepare your buildbots

Hi,

After discussions in https://discourse.llvm.org/t/rfc-increasing-the-gcc-and-clang-requirements-to-support-c-17-in-llvm

And also review comments in: :gear: D122976 Bump minimum toolchain version (llvm.org)

Update: Commit has landed: Bump minimum toolchain version · llvm/llvm-project@4c72deb (github.com)

It seems likely that we will raise the toolchain version requirements later this week or beginning of next one. This message is a heads up for the buildbot owners and other people that build LLVM directly from main to make preparations for this migration.

The new requirements are as follows:

  • Clang 5.0
  • Apple Clang 9.3
  • GCC 7.1
  • Visual Studio 2019 16.7 (This is already the requirement in main)

The current time-plan looks like this:

  • Let the diff be reviewed and discussed during this week 4/4 - 8/4
  • The soft error will land in main after this.
  • This soft error will then live in main until LLVM 15 has been branched
  • Hard error will be landed in main after the branch
  • CXX_VERSION will be changed to C+17 and developers are allowed to use C++17 in main.
  • LLVM 16.x will be the first version hard requiring these changes.

Please keep comments about this change to the phabricator review or the first forum post. This one is mainly used as an announcement thread where I will update the status as we go along.

Thanks,
Tobias

6 Likes

AFAICT the Visual Studio minimum has not changed?

1 Like

Yeah that’s correct, it was already raised earlier. I will edit the post and note that it hasn’t changed.

Update: The commit for soft errors when using an older toolchain has now landed.

Nothing more will happen here until LLVM 15 has been branched, then the soft error will transform into a hard error on main and CXX_STANDARD will be bumped to 17.

Thanks everyone providing input and helping me push this forward.