[commit: ghc] master: Comments only (2c7b183)

[git at git.haskell.org]

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

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/2c7b18309cab95636d4d520c60b880dacc45497b/ghc

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

commit 2c7b18309cab95636d4d520c60b880dacc45497b
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Fri Dec 22 17:49:41 2017 +0000

    Comments only


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

2c7b18309cab95636d4d520c60b880dacc45497b
 compiler/typecheck/TcSimplify.hs | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/compiler/typecheck/TcSimplify.hs b/compiler/typecheck/TcSimplify.hs
index 56d6c78..f1d7e9a 100644
--- a/compiler/typecheck/TcSimplify.hs
+++ b/compiler/typecheck/TcSimplify.hs
@@ -1086,6 +1086,11 @@ decideQuantifiedTyVars mono_tvs name_taus psigs candidates
 
        ; qtvs <- quantifyTyVars mono_tvs dvs_plus
        ; return (qtvs, co_vars) }
+         -- Return all the CoVars that (transitively) might be mentioned
+         -- in the tau_tys etc.  We don't need to do a closeOverKinds on
+         -- co_vars to get the transitive ones, becuase the grown_tvs
+         -- are already closed over kinds, and hence contain all such
+         -- co_vars
 
 ------------------
 growThetaTyVars :: ThetaType -> TyCoVarSet -> TyCoVarSet