#14649: ghc panic: mergeSATInfo -------------------------------------+------------------------------------- Reporter: tianxiaogu | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- ghc panic with option `-O` and `-fstatic-argument-transformation`. Affected versions include 8.2.2 and HEAD (8.5.20180108) {{{#!hs {-# LANGUAGE DataKinds #-} {-# LANGUAGE PartialTypeSignatures #-} {-# LANGUAGE PolyKinds #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE TypeOperators #-} module T12844 where barWraper :: ('(r,r') ~ Head rngs, Foo rngs) => FooData rngs barWraper = bar bar :: (_) => FooData rngs bar = barWraper data FooData rngs class Foo xs where foo :: (Head xs ~ '(r,r')) => FooData xs type family Head (xs :: [k]) where Head (x ': xs) = x }}} Log: {{{ ghc: panic! (the 'impossible' happened) (GHC version 8.5.20180108 for x86_64-unknown-linux): mergeSATInfo Left:STSTSTSTSTSVSV, Right:STSTSTSTSTSVSC Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable pprPanic, called at compiler/simplCore/SAT.hs:152:20 in ghc:SAT Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14649 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler