Looking at one of the regressions, T9010, I set up a trap to catch only
#15019: Fix performance regressions from #14737 -------------------------------------+------------------------------------- Reporter: tdammers | Owner: tdammers Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: #14737 | Differential Rev(s): phab:D4568 Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): those coercions that are found to be equal by eqType, but don't match on isReflCo. And they're all the same: ... Eh? The code you give doesn't look like a coercion. It looks like a type, or a pair of types. I must be misunderstanding. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15019#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler