[commit: ghc] master: Overlapable pragmas for individual instances (#9242) (6290eea)

[Herbert Valerio Riedel]

Hi,

Fyi, this changeset seems to have broken ./validate:

  utils/haddock/src/Haddock/Interface/Rename.hs:449:11: Warning:
      Fields of ‘ClsInstDecl’ not initialised: cid_overlap_mode
      In the first argument of ‘return’, namely
        ‘(ClsInstDecl
            {cid_poly_ty = ltype', cid_binds = emptyBag, cid_sigs = [],
             cid_tyfam_insts = lATs', cid_datafam_insts = lADTs'})’
      In a stmt of a 'do' block:
        return
          (ClsInstDecl
             {cid_poly_ty = ltype', cid_binds = emptyBag, cid_sigs = [],
              cid_tyfam_insts = lATs', cid_datafam_insts = lADTs'})
      In the expression:
        do { ltype' <- renameLType ltype;
             lATs' <- mapM (mapM renameTyFamInstD) lATs;
             lADTs' <- mapM (mapM renameDataFamInstD) lADTs;
             return
               (ClsInstDecl
                  {cid_poly_ty = ltype', cid_binds = emptyBag, cid_sigs = [],
                   cid_tyfam_insts = lATs', cid_datafam_insts = lADTs'}) }
  
  <no location info>: 
  Failing due to -Werror.
  make[1]: *** [utils/haddock/dist/build/Haddock/Interface/Rename.dyn_o] Error 1
  make: *** [all] Error 2
  

On 2014-06-30 at 02:37:52 +0200, git-4Dsf34iY/NkouOHNgZ69ag at public.gmane.org wrote:
> Repository : ssh://git@git.haskell.org/ghc
>
> On branch  : master
> Link       : http://ghc.haskell.org/trac/ghc/changeset/6290eeadf61a40f2eb08d0fd7ef1f3b7f9804178/ghc
>
>>---------------------------------------------------------------
>
> commit 6290eeadf61a40f2eb08d0fd7ef1f3b7f9804178
> Author: Iavor S. Diatchki <iavor.diatchki at gmail.com>
> Date:   Sun Jun 29 17:22:16 2014 -0700
>
>     Overlapable pragmas for individual instances (#9242)
>     
>     Programmers may provide a pragma immediately after the `instance` keyword
>     to control the overlap/incoherence behavior for individual instances.
>     For example:
>     
>         instance {-# OVERLAP #-} C a where ...
>     
>     I chose this notation, rather than the other two outlined in the ticket
>     for these reasons:
>     
>        1. Having the pragma after the type looks odd, I think.
>        2. Having the pragma after there `where` does not work for
>            stand-alone derived instances
>     
>     I have implemented 3 pragams:
>     
>        1. NO_OVERLAP
>        2. OVERLAP
>        3. INCOHERENT
>     
>     These correspond directly to the internal modes currently supported by
>     GHC.  If a pragma is specified, it will be used no matter what flags are
>     turned on.   For example, putting `NO_OVERLAP` on an instance will mark
>     it as non-overlapping, even if `OVERLAPPIN_INSTANCES` is turned on for the
>     module.
>
>
>>---------------------------------------------------------------
>
> 6290eeadf61a40f2eb08d0fd7ef1f3b7f9804178
>  compiler/hsSyn/Convert.lhs        |  2 +-
>  compiler/hsSyn/HsDecls.lhs        | 24 ++++++++++++++++----
>  compiler/parser/Lexer.x           |  6 +++++
>  compiler/parser/Parser.y.pp       | 21 +++++++++++++-----
>  compiler/rename/RnSource.lhs      |  7 ++++--
>  compiler/typecheck/TcDeriv.lhs    | 46 +++++++++++++++++++++++++--------------
>  compiler/typecheck/TcInstDcls.lhs |  5 ++++-
>  7 files changed, 82 insertions(+), 29 deletions(-)
>
> Diff suppressed because of size. To see it, use:
>
>     git diff-tree --root --patch-with-stat --no-color --find-copies-harder --ignore-space-at-eol --cc 6290eeadf61a40f2eb08d0fd7ef1f3b7f9804178

-- 
"Elegance is not optional" -- Richard O'Keefe