[commit: ghc] master: Add a comment explaining CompleteMatchSig in HsBinds (00c0120)

[git at git.haskell.org]

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

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/00c01200cd1653b63ce77a57bc7e3a76f8ded26b/ghc

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

commit 00c01200cd1653b63ce77a57bc7e3a76f8ded26b
Author: Matthew Pickering <matthewtpickering at gmail.com>
Date:   Fri Feb 24 17:37:19 2017 +0000

    Add a comment explaining CompleteMatchSig in HsBinds
    
    [skip ci]


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

00c01200cd1653b63ce77a57bc7e3a76f8ded26b
 compiler/hsSyn/HsBinds.hs | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/compiler/hsSyn/HsBinds.hs b/compiler/hsSyn/HsBinds.hs
index d985082..b39e25a 100644
--- a/compiler/hsSyn/HsBinds.hs
+++ b/compiler/hsSyn/HsBinds.hs
@@ -853,6 +853,13 @@ data Sig name
   | SCCFunSig  SourceText      -- Note [Pragma source text] in BasicTypes
                (Located name)  -- Function name
                (Maybe (Located StringLiteral))
+       -- | A complete match pragma
+       --
+       -- > {-# COMPLETE C, D [:: T] #-}
+       --
+       -- Used to inform the pattern match checker about additional
+       -- complete matchings which, for example, arise from pattern
+       -- synonym definitions.
   | CompleteMatchSig SourceText (Located [Located name]) (Maybe (Located name))
 
 deriving instance (DataId name) => Data (Sig name)