[commit: ghc] master: Extra docs on exports_from_avail. (71dadd7)

[git at git.haskell.org]

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

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/71dadd71e7bb397a05b45c45d679139b08f76598/ghc

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

commit 71dadd71e7bb397a05b45c45d679139b08f76598
Author: Edward Z. Yang <ezyang at cs.stanford.edu>
Date:   Tue Mar 28 10:20:19 2017 -0700

    Extra docs on exports_from_avail.
    
    Signed-off-by: Edward Z. Yang <ezyang at cs.stanford.edu>


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

71dadd71e7bb397a05b45c45d679139b08f76598
 compiler/typecheck/TcRnExports.hs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/compiler/typecheck/TcRnExports.hs b/compiler/typecheck/TcRnExports.hs
index 35e30a7..3c0b8d3 100644
--- a/compiler/typecheck/TcRnExports.hs
+++ b/compiler/typecheck/TcRnExports.hs
@@ -164,6 +164,9 @@ exports_from_avail :: Maybe (Located [LIE RdrName])
                          -- Nothing => no explicit export list
                    -> GlobalRdrEnv
                    -> ImportAvails
+                         -- Imported modules; this is used to test if a
+                         -- 'module Foo' export is valid (it's not valid
+                         -- if we didn't import Foo!)
                    -> Module
                    -> RnM (Maybe [LIE Name], [AvailInfo])