[GHC] #10549: floatExpr tick break<2>

[GHC]

#10549: floatExpr tick break<2>
-------------------------------------+-------------------------------------
        Reporter:  NeilMitchell      |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  high              |               Milestone:  7.10.3
       Component:  Compiler          |                 Version:  7.10.2
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
-------------------------------------+-------------------------------------
Changes (by thomie):

 * priority:  normal => high
 * version:  7.11 => 7.10.2
 * milestone:   => 7.10.3


Comment:

 Here is a test to reproduce the problem with ghci.

 {{{
 {-# OPTIONS_GHC -O2 #-}
 module T10549 where

 import qualified Data.ByteString.Internal as Internal
 import System.IO.Unsafe (unsafePerformIO)
 import Data.Word (Word8)
 import Foreign.Ptr (Ptr)
 import Foreign.Storable (peek)

 type S = Ptr Word8

 chr :: S -> Char
 chr x = Internal.w2c $ unsafePerformIO $ peek x
 }}}

 Running `ghc-7.10.1 --interactive T10549.hs` results in:
 {{{
 GHCi, version 7.10.1: http://www.haskell.org/ghc/  :? for help

 T10549.hs:1:16: Warning:
     -O conflicts with --interactive; -O ignored
 [1 of 1] Compiling T10549           ( T10549.hs, interpreted )
 Ok, modules loaded: T10549.
 }}}

 Running `ghc-7.10.2 --interactive T10549.hs` results in:
 {{{
 GHCi, version 7.10.2: http://www.haskell.org/ghc/  :? for help
 [1 of 1] Compiling T10549           ( T10549.hs, interpreted )
 ghc: panic! (the 'impossible' happened)
   (GHC version 7.10.2 for x86_64-unknown-linux):
         floatExpr tick break<3>()
 }}}

 So somehow the `OPTIONS_GHC -O2` in the file doesn't get ignored (it does
 when given on the command line).

 To reproduce the problem with the Shake sources (version 0.15.4), run
 `ghci src/Development/Ninja/Lexer.hs -isrc`.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10549#comment:5>
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