#13410: GHC HEAD regression: Template variable unbound in rewrite rule -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: highest | Milestone: 8.2.1 Component: Compiler | Version: 8.0.1 Resolution: | Keywords: JoinPoints 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: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * version: 8.1 => 8.0.1 Comment: Oh dear, there's actually a distinction between the attached program and the program in comment:4. The attached program compiles without issue on GHC 8.0.2 and earlier, but panics on GHC HEAD (post–join points). The program in comment:4, however, compiles without issue on GHC 7.10.3 and earlier, but panics on GHC 8.0.1, 8.0.2, //and// HEAD. This isn't terribly surprising, as [https://github.com/ekmett/hybrid- vectors/issues/7#issue-133619382 others have reported] seeing this error on earlier versions of GHC, but AFAICT, no one was able to minimize the panic down to a single file until now. So the issue likely predates join points, but join points have made it easier to trigger in GHC HEAD. I'll see if I can figure out what commit lead to the panic surfacing in the program in comment:4. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13410#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler