#15886: Spurious warning about incomplete pattern with PatternSynonyms -------------------------------------+------------------------------------- Reporter: selinger | Owner: (none) Type: bug | Status: closed Priority: normal | Milestone: 8.6.3 Component: Compiler | Version: 8.6.1 Resolution: invalid | Keywords: | PatternSynonyms, | PatternMatchWarnings Operating System: Linux | Architecture: x86_64 Type of failure: Incorrect | (amd64) error/warning at compile-time | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by selinger): Interesting. Thanks for pointing this out. I assumed (wrongly, it turns out) that since pattern synonyms are just syntactic sugar, the checker could desugar it for the purposes of coverage checking. Are there good reasons for "the checker is very naive"? For sure, there are good uses cases for COMPLETE pragmas, because there are cases (even without using pattern synonyms) that's aren't readily decidable. I'm just surprised that the checker can't solve obvious cases. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15886#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler