hSetBinaryMode fails after some input has been read

For the following program (BadSeek.hs), type a couple characters of input and press return. With ghc-6.10.3, it works fine; with ghc-6.11 it throws an error.

module Main where

import System.IO

main = do   
    getChar >>= print
    hSetBinaryMode stdin True
    getChar >>= print

With ghc-6.10:

$ ./BadSeek 
ab
'a'
'b'

With ghc-6.11:

$ ./BadSeek
ab
'a'
BadSeek: <stdin>: hSetBinaryMode: illegal operation (cannot flush the read buffer of a text-mode handle)

The error goes away if the first 'getChar' is commented out.

For libraries which are not yet using the Unicode I/O layer, having a way to temporarily set stdin to BinaryMode would be useful.

Trac metadata

Trac field	Value
Version	6.11
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	libraries/base
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