[GHC] #3262: Identifiers beginning with _ should not be considered for shadowing

[GHC]

#3262: Identifiers beginning with _ should not be considered for shadowing
-----------------------------+----------------------------------------------
Reporter:  batterseapower    |          Owner:                  
    Type:  proposal          |         Status:  new             
Priority:  normal            |      Component:  Compiler        
 Version:  6.10.2            |       Severity:  trivial         
Keywords:                    |       Testcase:                  
      Os:  Unknown/Multiple  |   Architecture:  Unknown/Multiple
-----------------------------+----------------------------------------------
 The following program:

 {{{
 main = do
   let _ignored = 10
   let _ignored = 20
   return ()
 }}}

 Prints this warning (when compiled with, for example, -Wall):

 {{{
 temp.hs:3:6:
     Warning: This binding for `_ignored' shadows the existing binding
                bound at temp.hs:2:6
              In the binding group for: _ignored
 }}}

 In my opinion identifiers prefixed with _ should be ignored for the
 purposes of determining shadowing in the same way as they are ignored for
 the purposes of checking if something is bound but not used. So in
 particular, this warning would not be generated.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3262>
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