[GHC] #10560: -f and -O options interact in non-obvious, order dependent ways

[GHC]

#10560: -f and -O options interact in non-obvious, order dependent ways
-------------------------------------+-------------------------------------
        Reporter:  bgamari           |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Compiler          |                 Version:  7.10.1
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  Incorrect         |  Unknown/Multiple
  warning at compile-time            |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
-------------------------------------+-------------------------------------

Comment (by gidyn):

 It's "completely surprising, unnatural and ad hoc" that a warning should
 be issued when a flag silently undoes the effect of an earlier flag?

 Additionally, we don't even know if any actual build system will be broken
 by this. Only if somebody's using a script which breaks if unexpected
 compiler warnings are encountered, and they're calling GHC with
 "conflicting" flags in a problematic order.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10560#comment:12>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler