Add a type signature to hsConDeclsBinders’s gowip/T9156

1 files changed, 5 insertions, 2 deletions

diff --git a/compiler/hsSyn/HsUtils.lhs b/compiler/hsSyn/HsUtils.lhs
index 38d340c359..e12daf45cc 100644
--- a/compiler/hsSyn/HsUtils.lhs
+++ b/compiler/hsSyn/HsUtils.lhs
@@ -1,3 +1,5 @@
+> {-# LANGUAGE ScopedTypeVariables #-}
+
 %
 % (c) The University of Glasgow, 1992-2006
 %
@@ -746,12 +748,13 @@ hsDataDefnBinders (HsDataDefn { dd_cons = cons }) = hsConDeclsBinders cons
   -- See Note [Binders in family instances]
 
 -------------------
-hsConDeclsBinders :: (Eq name) => [LConDecl name] -> [Located name]
+hsConDeclsBinders :: forall name. (Eq name) => [LConDecl name] -> [Located name]
   -- See hsLTyClDeclBinders for what this does
   -- The function is boringly complicated because of the records
   -- And since we only have equality, we have to be a little careful
 hsConDeclsBinders cons = go id cons
-  where go _ [] = []
+  where go :: ([Located name] -> [Located name]) -> [LConDecl name] -> [Located name]
+        go _ [] = []
         go remSeen (r:rs) =
           -- don't re-mangle the location of field names, because we don't
           -- have a record of the full location of the field declaration anyway