#15523: GHC Panic on malformed newtype and StrictData -------------------------------------+------------------------------------- Reporter: rdnetto | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.4.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D5070 Wiki Page: | -------------------------------------+------------------------------------- Changes (by monoidal): * differential: => Phab:D5070 Comment: Fortunately, the bug is not present in master. I put a regression test on Phab. {{{ $ ghc -O T15523 [1 of 1] Compiling Main ( T15523.hs, T15523.o ) ghc: panic! (the 'impossible' happened) (GHC version 8.4.3 for x86_64-unknown-linux): mkNewTyConRhs Foo [] Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable pprPanic, called at compiler/iface/BuildTyCl.hs:77:27 in ghc:BuildTyCl Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug $ head/inplace/bin/ghc-stage2 T15523 [1 of 1] Compiling Main ( T15523.hs, T15523.o ) T15523.hs:5:20: error: • The constructor of a newtype must have exactly one field but ‘Foo’ has none • In the definition of data constructor ‘Foo’ In the newtype declaration for ‘Duration’ | 5 | newtype Duration = Foo | ^^^ }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15523#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler