The flag `Werror=unrecognised-warning-flags` does not turn unrecognised warnings on fatal errors

By running on GHC 9.2.3

ghc -Werror -Wunrecognised-warning-flags -Wfoo Main.hs

I got a compilation error as expected due to the unrecognised warning Wfoo. However, by running

ghc -Werror=unrecognised-warning-flags -Werror=foo Main.hs

I only got a warning instead of a compilation error.

added needs triage label

changed title from The flag Werror=unrecognised-warning-flags does not turn unrecognised warnings on a fatal errors to The flag Werror=unrecognised-warning-flags does not turn unrecognised warnings on fatal errors

changed the description

What about

ghc -Werror=unrecognised-warning-flags -Wfoo Main.hs

then also not fatal

on the commandline: warning: unrecognised warning flag: -Wfoo
[1 of 1] Compiling Main             ( Main.hs, Main.o )
Linking Main ...

Yep. The behaviour of ghc -Werror=unrecognised-warning-flags -Wfoo Main.hs describes the issue better.

assigned to @mpickering

I tried with HEAD again today and I get the correct error:

[matt@nixos:~/ghc-vanessa]$ _build/stage1/bin/ghc -Werror=unrecognised-warning-flags -Wfoo Main.hs

on the commandline: error: [-Wunrecognised-warning-flags, -Werror=unrecognised-warning-flags]
    unrecognised warning flag: -Wfoo

Also works fine with 9.4.1 but fails with 9.2.2.

mentioned in commit 4fc2dac0

mentioned in commit 6b952e32

mentioned in commit 2810e751

mentioned in commit 69e6e7a2

mentioned in merge request !8420 (closed)

added Pnormal Tbug driver error messages labels and removed needs triage label

changed milestone to %9.2.4

mentioned in commit f1d5aaa8

mentioned in commit 6a7f8e4c

mentioned in commit 8b3197ee

mentioned in commit cbd13e2c

mentioned in commit 08999f97

mentioned in commit bbdc667e

mentioned in commit 0b82ea3e