"lookup_final_id" panic (out of scope type application + deferred type errors)
The following program panics GHCi 8.10-rc1 (ghc-8.10.0.20200123):
{-# LANGUAGE TypeApplications #-}
{-# OPTIONS_GHC -fdefer-type-errors #-}
module Bug where
class C a where
m :: a
instance C Bool where
m = notInScope @Word
Bug.hs:10:7: warning: [-Wdeferred-out-of-scope-variables]
Variable not in scope: notInScope
|
10 | m = notInScope @Word
| ^^^^^^^^^^
ghc.exe: panic! (the 'impossible' happened)
(GHC version 8.10.0.20200123:
lookup_final_id
$fCBool
Call stack:
CallStack (from HasCallStack):
callStackDoc, called at compiler\utils\Outputable.hs:1179:37 in ghc:Outputable
pprPanic, called at compiler\\main\\TidyPgm.hs:201:12 in ghc:TidyPgm