gcc: add caveats about broken openmp multilib

Closes #29670.

1 files changed, 10 insertions, 0 deletions

diff --git a/Library/Formula/gcc.rb b/Library/Formula/gcc.rb
index 7bb827261..d2568d0ac 100644
--- a/Library/Formula/gcc.rb
+++ b/Library/Formula/gcc.rb
@@ -181,6 +181,16 @@ class Gcc < Formula
     File.rename file, "#{dir}/#{base}-#{suffix}#{ext}"
   end
 
+  def caveats
+    if build.with?("multilib") then <<-EOS.undent
+      GCC has been built with multilib support. Notably, OpenMP may not work:
+        https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60670
+      If you need OpenMP support you may want to
+        brew reinstall gcc --without-multilib
+      EOS
+    end
+  end
+
   test do
     if build.with?("fortran") || build.with?("all-languages")
       fixture = <<-EOS.undent