[GHC] #8710: Overlapping patterns warning misplaced

[GHC]

#8710: Overlapping patterns warning misplaced
-------------------------------------+-------------------------------------
        Reporter:  goldfire          |                Owner:
            Type:  bug               |               Status:  new
        Priority:  low               |            Milestone:
       Component:  Compiler          |              Version:  7.7
      Resolution:                    |             Keywords:
                                     |  PatternMatchWarnings
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):  Phab:D1910,
       Wiki Page:                    |  Phab:D1920
-------------------------------------+-------------------------------------

Comment (by bgamari):

 So to be clear, I believe that given a function with redundant patterns,
 {{{#!hs
 module Bug where

 hello _ = "world"
 hello 1 = "turtle"
 hello 2 = "frog"
 }}}

 Phab:D1910 will provide a warning like,
 {{{
 Bug.hs:3:1: Warning:
     Pattern match(es) are overlapped
     In an equation for ‘hello’:
         hello 1 = ...
         hello 2 = ...
 }}}

 whereas Phab:D1920 will provide,
 {{{
 Bug.hs:3:1: Warning:
     Pattern match is overlapped
     In an equation for ‘hello’:
         hello 1 = ...

 Bug.hs:4:1: Warning:
     Pattern match is overlapped
     In an equation for ‘hello’:
         hello 2 = ...
 }}}

 Is this right George?

 The former seems more user friendly to me

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8710#comment:13>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler