[commit: ghc] wip/rwbarton-dep-finsts: WIP: FamInst: Don't need to check imports against their dep_finsts (12d1c70)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : wip/rwbarton-dep-finsts
Link       : http://ghc.haskell.org/trac/ghc/changeset/12d1c70c8c40dd0f40a3cbe036073a3fc15348fc/ghc

>---------------------------------------------------------------

commit 12d1c70c8c40dd0f40a3cbe036073a3fc15348fc
Author: Reid Barton <rwbarton at gmail.com>
Date:   Mon Jan 9 13:43:36 2017 -0500

    WIP: FamInst: Don't need to check imports against their dep_finsts
    
    Test Plan: harbormaster
    
    Reviewers: austin, bgamari
    
    Subscribers: thomie
    
    Differential Revision: https://phabricator.haskell.org/D2947


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12d1c70c8c40dd0f40a3cbe036073a3fc15348fc
 compiler/typecheck/FamInst.hs             | 5 ++++-
 testsuite/tests/ghci/scripts/T4175.stdout | 2 +-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/compiler/typecheck/FamInst.hs b/compiler/typecheck/FamInst.hs
index 0c1bdef..0dd385d 100644
--- a/compiler/typecheck/FamInst.hs
+++ b/compiler/typecheck/FamInst.hs
@@ -120,6 +120,9 @@ modules where both modules occur in the `HscTypes.dep_finsts' set (of the
 already been checked.  Everything else, we check now.  (So that we can be
 certain that the modules in our `HscTypes.dep_finsts' are consistent.)
 
+XXX Presumably, each of our imports has itself already been checked against
+its dep_finsts, as well.
+
 There is some fancy footwork regarding hs-boot module loops, see
 Note [Don't check hs-boot type family instances too early]
 -}
@@ -211,7 +214,7 @@ checkFamInstConsistency famInstMods directlyImpMods
                                . md_fam_insts . hm_details
              ; hpt_fam_insts = mkModuleEnv [ (hmiModule hmi, hmiFamInstEnv hmi)
                                            | hmi <- eltsHpt hpt]
-             ; groups        = map (dep_finsts . mi_deps . modIface)
+             ; groups        = map (\mod -> mod : (dep_finsts . mi_deps . modIface $ mod))
                                    directlyImpMods
              ; okPairs       = listToSet $ concatMap allPairs groups
                  -- instances of okPairs are consistent
diff --git a/testsuite/tests/ghci/scripts/T4175.stdout b/testsuite/tests/ghci/scripts/T4175.stdout
index d96a2ef..994886c 100644
--- a/testsuite/tests/ghci/scripts/T4175.stdout
+++ b/testsuite/tests/ghci/scripts/T4175.stdout
@@ -28,9 +28,9 @@ instance Show () -- Defined in ‘GHC.Show’
 type instance D () a = Bool 	-- Defined at T4175.hs:22:10
 data instance B () = MkB 	-- Defined at T4175.hs:13:15
 data Maybe a = Nothing | Just a 	-- Defined in ‘GHC.Base’
-instance Foldable Maybe -- Defined in ‘Data.Foldable’
 instance Traversable Maybe -- Defined in ‘Data.Traversable’
 instance Monoid a => Monoid (Maybe a) -- Defined in ‘GHC.Base’
+instance Foldable Maybe -- Defined in ‘Data.Foldable’
 instance Read a => Read (Maybe a) -- Defined in ‘GHC.Read’
 instance Applicative Maybe -- Defined in ‘GHC.Base’
 instance Functor Maybe -- Defined in ‘GHC.Base’