Performance of pattern checker on OptCoercions

Thomas Miedema thomasmiedema at
Sun Dec 20 12:23:17 UTC 2015

> I have a small question though: do we need the opposites too (I mean
> `-fno-full-guard-reasoning` and ` -Wtoo-many-guards`)? I cannot think of
> a scenario where we do or am I missing something?

A scenario where `-fno-full-guard-reasoning` could be useful: you add
`-ffull-guard-reasoning` to ghc-options in your .cabal file, but switch it
off in an OPTIONS_GHC pragma in a specific file.

But `-f` and `-W` flags always come in pairs, so that is easy. You would
add `-Wtoo-many-guards` to `standardWarnings` in compiler/main/DynFlags.hs.

Others? If I get the green light, this is a matter of minutes to change :)

If it is not too much trouble, please submit your patch to Phabricator.
Then others can review, and harbormaster can validate it.
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