#13838: -Wdeferred-type-errors; ghc: panic!; VoidRep; ((() -> ()) :: *) ~# (IO Any :: *) -------------------------------------+------------------------------------- Reporter: harry | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: #13292 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by harry): Although my distro ships version 8.0.2 now I still get a "ghc: panic! (the 'impossible' happened)" with this slightly more complex code but within ghci only: With "ghci -fdefer-type-errors" and this code: {{{#!hs bad1 :: [()] bad1 = num bad2 :: () bad2 = num num = 9 }}} the output: {{{ GHCi, version 8.0.2: http://www.haskell.org/ghc/ :? for help Prelude> :l ghc_bug_2.hs [1 of 1] Compiling Main ( ghc_bug_2.hs, interpreted ) ghc_bug_2.hs:2:8: warning: [-Wdeferred-type-errors] * Couldn't match expected type `[()]' with actual type `()' * In the expression: num In an equation for `bad1': bad1 = num ghc: panic! (the 'impossible' happened) (GHC version 8.0.2 for x86_64-unknown-linux): corePrepPgm [False] cobox_r196 = typeError @ 'VoidRep @ (() :: *) ~# ([()] :: *) "ghc_bug_2.hs:2:8: error:\n\ \ * Couldn't match expected type `[()]' with actual type `()'\n\ \ * In the expression: num\n\ \ In an equation for `bad1': bad1 = num\n\ \(deferred type error)"# Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
}}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13838#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler