#10602: ghc panic: Template variable unbound in rewrite rule when compiling with -O2 -------------------------------------+------------------------------------- Reporter: pacak | Owner: bgamari Type: bug | Status: infoneeded Priority: highest | Milestone: 7.10.2 Component: Compiler | Version: 7.10.2-rc2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by thomie): I attached an alternative test that also fails with a devel2 build. `-fno- spec-constr` makes the problem go away, as do a few other things (see `T10602.hs`). Maybe this debug message is of help to someone: {{{ $ ./ghc-devel2/inplace/bin/ghc-stage2 T10602.hs [2 of 2] Compiling T10602 ( T10602.hs, T10602.o ) SpecConstr Function ‘$wgo_s13x’ has one call pattern, but the limit is 0 Use -fspec-constr-count=n to set the bound Use -dppr-debug to see specialisations ghc-stage2: panic! (the 'impossible' happened) }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10602#comment:16 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler