#14773: MultiWayIf makes it easy to write partial programs that are not catched by -Wall -------------------------------------+------------------------------------- Reporter: SimonHengel | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Resolution: | Keywords: | PatternMatchWarnings Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by RyanGlScott): Sigh. I don't see an easy way to fix this. The issue is that the entry- point into the pattern match coverage checker, `checkMatches`, requires a list of `LPat`s as its arguments. However, the AST for multi-way-`if` (`HsMultiIf`) has `GRHS`es, not `LPat`s. That's the same reason why this program doesn't emit any warnings under `-Wall`: {{{#!hs b :: Bool Just b | False = Nothing }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14773#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler