[GHC] #9242: Implement {-# OVERLAPPABLE #-} and {-# INCOHERENT #-} pragmas

[GHC]

#9242: Implement {-# OVERLAPPABLE #-} and {-# INCOHERENT #-} pragmas
-------------------------------------+-------------------------------------
              Reporter:  simonpj     |            Owner:  diatchki
                  Type:  feature     |           Status:  new
  request                            |        Milestone:
              Priority:  normal      |          Version:  7.8.2
             Component:  Compiler    |         Keywords:
            Resolution:              |     Architecture:  Unknown/Multiple
      Operating System:              |       Difficulty:  Unknown
  Unknown/Multiple                   |       Blocked By:
       Type of failure:              |  Related Tickets:
  None/Unknown                       |
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
-------------------------------------+-------------------------------------

Comment (by jrp):

 The ghc build system itself still uses -XOverlappingInstances and so
 presumably needs to be updated too.


 {{{
 "rm" -f libraries/haskeline/dist-
 install/build/.depend-v-dyn-p-dyn.haskell.tmp
 "inplace/bin/ghc-stage1" -M -static  -O -H64m    -package-name
 haskeline-0.7.1.2 -hide-all-packages -i -ilibraries/haskeline/.
 -ilibraries/haskeline/dist-install/build -ilibraries/haskeline/dist-
 install/build/autogen -Ilibraries/haskeline/dist-install/build
 -Ilibraries/haskeline/dist-install/build/autogen
 -Ilibraries/haskeline/includes   -optP-DUSE_GHC_ENCODINGS -optP-DTERMINFO
 -optP-include -optPlibraries/haskeline/dist-
 install/build/autogen/cabal_macros.h -package base-4.7.1.0 -package
 bytestring-0.10.4.0 -package containers-0.5.5.1 -package directory-1.2.1.0
 -package filepath-1.3.0.2 -package terminfo-0.4.0.0 -package
 transformers-0.4.1.0 -package unix-2.7.0.2 -Wall -XHaskell98
 -XForeignFunctionInterface -XRank2Types -XFlexibleInstances
 -XTypeSynonymInstances -XFlexibleContexts -XExistentialQuantification
 -XScopedTypeVariables -XGeneralizedNewtypeDeriving -XMultiParamTypeClasses
 -XOverlappingInstances -XUndecidableInstances -XCPP -XDeriveDataTypeable
 -XPatternGuards -O2  -no-user-package-db -rtsopts      -odir
 libraries/haskeline/dist-install/build -hidir libraries/haskeline/dist-
 install/build -stubdir libraries/haskeline/dist-install/build -dep-
 makefile libraries/haskeline/dist-
 install/build/.depend-v-dyn-p-dyn.haskell.tmp -dep-suffix "" -dep-suffix
 "dyn_" -dep-suffix "p_" -dep-suffix "dyn_" -include-pkg-deps
 libraries/haskeline/./System/Console/Haskeline.hs
 libraries/haskeline/./System/Console/Haskeline/Completion.hs
 libraries/haskeline/./System/Console/Haskeline/MonadException.hs
 libraries/haskeline/./System/Console/Haskeline/History.hs
 libraries/haskeline/./System/Console/Haskeline/IO.hs
 libraries/haskeline/./System/Console/Haskeline/Backend.hs
 libraries/haskeline/./System/Console/Haskeline/Backend/WCWidth.hs
 libraries/haskeline/./System/Console/Haskeline/Command.hs
 libraries/haskeline/./System/Console/Haskeline/Command/Completion.hs
 libraries/haskeline/./System/Console/Haskeline/Command/History.hs
 libraries/haskeline/./System/Console/Haskeline/Command/KillRing.hs
 libraries/haskeline/dist-
 install/build/System/Console/Haskeline/Directory.hs
 libraries/haskeline/./System/Console/Haskeline/Emacs.hs
 libraries/haskeline/./System/Console/Haskeline/InputT.hs
 libraries/haskeline/./System/Console/Haskeline/Key.hs
 libraries/haskeline/./System/Console/Haskeline/LineState.hs
 libraries/haskeline/./System/Console/Haskeline/Monads.hs
 libraries/haskeline/./System/Console/Haskeline/Prefs.hs
 libraries/haskeline/./System/Console/Haskeline/RunCommand.hs
 libraries/haskeline/./System/Console/Haskeline/Term.hs
 libraries/haskeline/./System/Console/Haskeline/Command/Undo.hs
 libraries/haskeline/./System/Console/Haskeline/Vi.hs
 libraries/haskeline/./System/Console/Haskeline/Recover.hs
 libraries/haskeline/dist-
 install/build/System/Console/Haskeline/Backend/Posix.hs
 libraries/haskeline/./System/Console/Haskeline/Backend/Posix/Encoder.hs
 libraries/haskeline/./System/Console/Haskeline/Backend/DumbTerm.hs
 libraries/haskeline/./System/Console/Haskeline/Backend/Terminfo.hs

 on the commandline: Warning:
     -XOverlappingInstances is deprecated: instead use per-instance pragmas
 OVERLAPPING/OVERLAPPABLE/OVERLAPS

 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9242#comment:31>
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