#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 bgamari): George, it would be great if you could have a quick look at D1009 and confirm that the proposed language it addresses your concerns (suggestions for improvement would also be appreciated). Sven, I think we agree that the left-to-right parsing is standard and expected. The problem here is the fact that there is no sign to the user that `-f` and `-O` should interact. This spooky action at a distance has the very real potential to trip up users and has already masked the effectiveness of a workaround to a known bug. However, I can also see that it's not always possible to ensure that `-O` is placed first in the command line and making users endure a warning in this case is unfortunate. However, I think this is outweighed by the danger of a user not knowing which optimizations the compiler is actually performing. Trusting that they we see and remember a note in the documentation does not seem like a strong enough measure here. If the warning really is a problem we could issue it only if the last flag to set a given option was `-O`. This would allow the user to silence the warning by adding an additional `-f`, reaffirming the value set by `-O`. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10560#comment:13 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler