#15450: Inconsistency w.r.t. coverage checking warnings for EmptyCase under unsatisfiable constraints -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: patch Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.4.3 Resolution: | Keywords: | PatternMatchWarnings Operating System: Unknown/Multiple | Architecture: Type of failure: Poor/confusing | Unknown/Multiple error message | Test Case: Blocked By: | Blocking: Related Tickets: #12957 | Differential Rev(s): Phab:D5017 Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj):
This is all explained in the commentary in https://phabricator.haskell.org/D3064 (which I've attempted to turn into Note form in this patch).
Thank you for turning it into a Note. Yes, I am questioning the principle. It seems bizarrely discontinuous to fling the door wide open when (but only when) it completely closes. Indeed I see that on Phab:D3064 George did suggest "The patch as is just drops information, we can instead issue no warnings if we are already in a dead-code branch." -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15450#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler