9.4.1-rc1 flaky build failure using the make build system

Summary

Here's a build failure I've observed only once for GHC 9.4. Likely that it's easier to trigger with a high number of jobs (-j24 in my case) and/or on busy machines. Log is attached below.

5949h833j9rp8h5ypzn86x5cbq80j94w-ghc-9.4.0.20220721.drv.log.txt

Steps to reproduce

Check out 721c6659bd388120a6b136bc32ab2393607597a9 of nixpkgs, run nix-build -A haskell.compiler.ghc941 (with --check on subsequent calls) until you trigger the failure. The Nix cores option had value 24 in my case.

Expected behavior

GHC 9.4.1-rc1 builds fine every time.

Environment

• GHC version used: 9.4.1-rc1, 9.0.2 for bootstrapping

Optional:

• Operating System: NixOS
• System Architecture: x86_64-pc-linux-gnu