(Originally reported here.)

Here's a module:

module Main where

main :: IO ()
main = return ()

On GHC 8.6.5, compiling this with both -prof and -optP-traditional works just fine:

$ /opt/ghc/8.6.5/bin/ghc Main.hs -prof -optP-traditional
[1 of 1] Compiling Main             ( Main.hs, Main.o )
Linking Main ...

But on GHC 8.8.1, it errors:

$ /opt/ghc/8.8.1/bin/ghc Main.hs -prof -optP-traditional
Loaded package environment from /home/rgscott/.ghc/x86_64-linux-8.8.1/environments/default
[1 of 1] Compiling Main             ( Main.hs, Main.o )
cc1: error: command line option ‘-traditional’ is valid for the driver but not for C
`gcc' failed in phase `C Compiler'. (Exit code: 1)

This prevents the lens-4.18 library from being built in profiled mode on 8.8.1.