[GHC] #437: Recompilation check should include flags

[GHC]

#437: Recompilation check should include flags
-----------------------+----------------------------------------------------
  Reporter:  simonpj   |          Owner:  dterei          
      Type:  bug       |         Status:  new             
  Priority:  low       |      Milestone:  7.2.1           
 Component:  Compiler  |        Version:  6.4.1           
Resolution:  None      |       Keywords:                  
  Testcase:  mod175    |      Blockedby:                  
Difficulty:  Unknown   |             Os:  Unknown/Multiple
  Blocking:            |   Architecture:  Unknown/Multiple
   Failure:  Other     |  
-----------------------+----------------------------------------------------

Comment(by simonmar):

 Replying to [comment:20 igloo]:
 > Flag ordering is important (e.g. `-O0 -O` is not the same as `-O -O0`).
 Also, some flags are equivalent to others.

 You're right, literally sorting the flags would be wrong.  I had in mind
 serialising DynFlags, but making sure that the DynFlag list is sorted to
 normalise it, and omitting things that don't affect the compilation
 result, plus throwing in a few things that aren't in DynFlags (static
 flags).

 > Rather than storing the set of flags (`-O` etc), it might be better to
 use the set of enabled `DynFlag`s (`Opt_Specialise` etc) and
 `ExtensionFlag`s.

 Right.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/437#comment:21>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler