[GHC] #2678: hLookAhead + hSetBuffering = unsupported operation (Illegal seek)

[GHC]

#2678: hLookAhead + hSetBuffering = unsupported operation (Illegal seek)
------------------------------+---------------------------------------------
 Reporter:  igloo             |          Owner:                  
     Type:  bug               |         Status:  new             
 Priority:  normal            |      Milestone:  6.10.2          
Component:  libraries/base    |        Version:  6.8.3           
 Severity:  normal            |     Resolution:                  
 Keywords:                    |     Difficulty:  Unknown         
 Testcase:                    |   Architecture:  Unknown/Multiple
       Os:  Unknown/Multiple  |  
------------------------------+---------------------------------------------
Changes (by simonmar):

  * milestone:  => 6.10.2

Comment:

 Yes, we could support this.  Changing buffering mode is currently done by
 just flushing the buffer first, which in the case of a ReadMode handle
 means seeking backwards so we read the same data again, but of course that
 fails on a non-seekable Handle.  But of course it's possible to change to
 "more buffering" without flushing the current buffer, so we should do
 that.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2678#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler