#14063: Compiling with --backpack with undefined dependency results in "the 'impossible' happened" -------------------------------------+------------------------------------- Reporter: rcook | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 Keywords: Backpack | 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: -------------------------------------+------------------------------------- Using GHC 8.2.1: {{{

ghc --version The Glorious Glasgow Haskell Compilation System, version 8.2.1 }}}

And compiling with `--backpack` as follows: {{{

ghc --backpack foo.bkp [1 of 4] Processing foo-indef [1 of 2] Compiling Str[sig] ( foo-indef\Str.hsig, nothing ) [2 of 2] Compiling Foo ( foo-indef\Foo.hs, nothing ) [2 of 4] Processing foo-string Instantiating foo-string [1 of 1] Compiling Str ( foo-string\Str.hs, foo- string\Str.o ) [3 of 4] Processing foo-int Instantiating foo-int [1 of 1] Compiling Str ( foo-int\Str.hs, foo-int\Str.o ) [4 of 4] Processing main ghc.EXE: panic! (the 'impossible' happened) (GHC version 8.2.1 for x86_64-unknown-mingw32): no package name CallStack (from HasCallStack): error, called at compiler\backpack\DriverBkp.hs:573:32 in ghc:DriverBkp

Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug make: *** [foo-indef/Foo.hi] Error 1 }}} See attached `foo.bkp` file. While the Backpack file ''is'' invalid, in that the `main` unit mentions the `foo` dependency, which does not exist, this shouldn't lead to a GHC panic. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14063 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler