Summary

The module in the code snippet below compiles in about 2.4s on my machine with GHC 8.8.2 and in about 481.76s with GHC 8.10.1. However, if you remove either -Weverything or StrictData from it the compile time will get back to normal. I spent some time bisecting and identified that the following commit causes the issue: c5d888d4 (@sgraf812)

Steps to reproduce

1. Compile this code snippet with GHC 8.10.1.
2. Measure the compilation time.

Expected behavior

The code should not take 8 minutes to compile.

Environment

• GHC version used: 8.10.1

Optional:

• Operating System: NixOS 20.03
• System Architecture: x64_86