From f99f13d8005146b53b3c31dc96ea4d5d5db6ffb4 Mon Sep 17 00:00:00 2001 From: Dan Bonachea Date: Wed, 7 Jan 2026 20:01:36 -0800 Subject: [PATCH] README: Add clarifications about LLVM use on macOS/Homebrew --- README.md | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/README.md b/README.md index eacdf91c..949c86ce 100644 --- a/README.md +++ b/README.md @@ -104,6 +104,14 @@ of a given compiler suite installation. The C++ compiler is optional for single-node deployments (and can be disabled using command-line option `--without-cxx`), but C++ is required for some network backends. +*Note for macOS/Homebrew users*: Homebrew may be used to install +[LLVM flang](https://formulae.brew.sh/formula/flang) for use with Caffeine, however +by default Homebrew will not replace the incompatible Apple-provided `clang` in your `PATH`. +Such users are recommended to use Homebrew's version-suffixed compiler variants, +for example setting `FC=flang-21 CC=clang-21 CXX=clang++-21` in the command above, +to ensure that a matching set of LLVM compilers are used. +See also [issue #228](https://github.com/BerkeleyLab/caffeine/issues/228). + The `install.sh` recognizes a number of command-line options and environment variables to customize behavior for your system. See the output of `./install.sh --help` for full documentation, including options for how to build for a distributed-memory platform.