I tried to build HEAD to verify this, but got a linker error. IIRC when I filed this bug I provided a test case which did compile, but you had to uncomment signatures to see an error. I did not see those sigs uncommented in your repro checkin.

So it might be too early for a party...

   Gabor

Em segunda-feira, 1 de dezembro de 2014, Simon Peyton Jones <simonpj@microsoft.com> escreveu:
Good point, thank you!

| -----Original Message-----
| From: ghc-devs [mailto:ghc-devs-bounces@haskell.org] On Behalf Of Gabor
| Greif
| Sent: 01 December 2014 16:01
| To: ghc-devs@haskell.org
| Subject: Re: [commit: ghc] master: Fix the handling of instance
| signatures (Trac #9582, #9833) (e6a2050)
|
| Maybe this (https://ghc.haskell.org/trac/ghc/ticket/7908) is fixed too?
|
| Cheers,
|
|     Gabor
|
| On 12/1/14, git@git.haskell.org <git@git.haskell.org> wrote:
| > Repository : ssh://git@git.haskell.org/ghc
| >
| > On branch  : master
| > Link       :
| >
| http://ghc.haskell.org/trac/ghc/changeset/e6a2050ebb6da316aecec66a6795715
| fbab355ca/ghc
| >
| >>---------------------------------------------------------------
| >
| > commit e6a2050ebb6da316aecec66a6795715fbab355ca
| > Author: Simon Peyton Jones <simonpj@microsoft.com>
| > Date:   Mon Dec 1 11:43:20 2014 +0000
| >
| >     Fix the handling of instance signatures (Trac #9582, #9833)
| >
| >     This finally solves the issue of instance-method signatures that
| are
| >     more polymorphic than the instanted class method.
| >
| >     See Note [Instance method signatures] in TcInstDcls.
| >
| >     A very nice fix for the two Trac tickets above.
| >
| >
| >>---------------------------------------------------------------
| >
| > e6a2050ebb6da316aecec66a6795715fbab355ca
| >  compiler/typecheck/TcBinds.lhs                     |  18 ++-
| >  compiler/typecheck/TcClassDcl.lhs                  |  16 +--
| >  compiler/typecheck/TcInstDcls.lhs                  | 121
| > ++++++++++++---------
| >  docs/users_guide/glasgow_exts.xml                  |  29 ++++-
| >  .../tests/indexed-types/should_compile/T9582.hs    |  14 +++
| >  testsuite/tests/indexed-types/should_compile/all.T |   1 +
| >  testsuite/tests/polykinds/T9833.hs                 |  18 +++
| >  testsuite/tests/polykinds/all.T                    |   2 +
| >  testsuite/tests/typecheck/should_fail/T6001.stderr |   9 +-
| >  testsuite/tests/typecheck/should_fail/T7545.hs     |   1 +
| >  testsuite/tests/typecheck/should_fail/T7545.stderr |   5 -
| >  testsuite/tests/typecheck/should_fail/all.T        |   2 +-
| >  12 files changed, 157 insertions(+), 79 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 e6a2050ebb6da316aecec66a6795715fbab355ca
| > _______________________________________________
| > ghc-commits mailing list
| > ghc-commits@haskell.org
| > http://www.haskell.org/mailman/listinfo/ghc-commits
| >
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