#8710: Overlapping patterns warning misplaced -------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: low | Milestone: Component: Compiler | Version: 7.7 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect | Unknown/Multiple warning at compile-time | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by gkaracha): Replying to [comment:1 thomie]:
George, how hard would it be to do this?
Not very if we agree how we want the messages to look like. At the moment function `dsPmWarn` in `deSugar/Check.hs` takes the location **of the whole match**, so that it can say that "the following clauses of this match are redundant..". Every clause is an `LMatch` so we have location information available if we want to use this instead of the location of the match. My question is, do we want a separate warning for every redundant clause, or we want the 1 warning/match (what we currently have), just with more information in it? E.g. something like the following: {{{ Bug.hs:22:3: Warning: Pattern match(es) are overlapped In an equation for ‘show’: Bug.hs:24:3: len _ = ... Bug.hs:25:3: len _ = ... }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8710#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler