It would be good to know how to fix this.  It’s blocking my builds.

For some reason it doesn’t seem to kill CI

Simon

From: Simon Peyton Jones
Sent: 25 January 2020 20:26
To: ghc-devs <ghc-devs@haskell.org>
Subject: stage2 build fails

I’m getting this with “sh validate –legacy”

compiler/main/DynFlags.hs:1344:15: error: [-Woverlapping-patterns, -Werror=overlapping-patterns]

    Pattern match is redundant

    In an equation for ‘settings’: settings s | otherwise = ...

     |

1344 |             | otherwise = panic $ "Invalid cfg parameters." ++ exampleString

     |               ^^^^^^^^^

This is when compiling the stage-2 compiler.  There’s an ifdef in DynFlags thus

#if __GLASGOW_HASKELL__ <= 810

            | otherwise = panic $ "Invalid cfg parameters." ++ exampleString

#endif

but somehow it’s not triggering for the stage2 compiler.

Any ideas?  It’s blocking a full build.  

This #ifdef was added in 8038cbd96f4, when GHC became better at reporting redundant code.

Simon