Re: [GHC] #12165: Multiple pattern type signatures accepted

#12165: Multiple pattern type signatures accepted -------------------------------------+------------------------------------- Reporter: goldfire | Owner: seraphime Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Resolution: | Keywords: | PatternSynonyms, newcomer Operating System: Unknown/Multiple | Architecture: Type of failure: GHC accepts | Unknown/Multiple invalid program | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D2361 Wiki Page: | -------------------------------------+------------------------------------- Comment (by Ben Gamari ): In [changeset:"2a3af15270d1c04745b1c42e61bf4d5f6dbc8ad5/ghc" 2a3af152/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="2a3af15270d1c04745b1c42e61bf4d5f6dbc8ad5" Treat duplicate pattern synonym signatures as an error Fixes issue T12165 by banning duplicate pattern synonyms signatures. This seems to me the best solution because: 1) it is coherent with the way we treat other duplicate signatures 2) the typechecker currently doesn't try to apply a second signature to a pattern to see if it matches, probably because it assumes there is no more than one signature per object. Test Plan: ./validate Reviewers: goldfire, austin, mpickering, bgamari Reviewed By: mpickering, bgamari Subscribers: mpickering, thomie Differential Revision: https://phabricator.haskell.org/D2361 GHC Trac Issues: #12165 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12165#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler