Re: [GHC] #10689: compiling singletons-1.1.2.1 as -O1 -fspec-constr fails as 'Template variable unbound in rewrite rule'

#10689: compiling singletons-1.1.2.1 as -O1 -fspec-constr fails as 'Template variable unbound in rewrite rule' -------------------------------------+------------------------------------- Reporter: slyfox | Owner: Type: bug | Status: new Priority: high | Milestone: 7.10.3 Component: Compiler | Version: 7.10.2-rc2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by Simon Peyton Jones ): In [changeset:"4e8d74d2362fbb025614ddeedfa3a9202bb6f2bb/ghc" 4e8d74d/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="4e8d74d2362fbb025614ddeedfa3a9202bb6f2bb" Deal with phantom type variables in rules See Note [Unbound template type variables] in Rules.hs This fixes Trac #10689. The problem was a rule LHS that mentioned a type variable in a phantom argument to a type synonym. Then matching the LHS didn't bind the type variable, and the rule matcher complained. This patch fixes the problem, as described by the Note. I also went back to not-cloning the template varaibles during rule matching. I'm convinced that it's not necessary now (if it ever was), and cloning makes the fix for #10689 much more fiddly. }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10689#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler