From effbdfe8e66b8d171c2b8ccd68fe727660993491 Mon Sep 17 00:00:00 2001
From: Jose Pedro Magalhaes <jpm@cs.ox.ac.uk>
Date: Fri, 7 Dec 2012 16:24:06 +0000
Subject: [PATCH] Fix #7487
Signed-off-by: Jose Pedro Magalhaes <jpm@cs.ox.ac.uk>
---
compiler/typecheck/TcGenGenerics.lhs | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)
diff --git a/compiler/typecheck/TcGenGenerics.lhs b/compiler/typecheck/TcGenGenerics.lhs
index 8745f8e612aa..28dc1aa2edd4 100644
--- a/compiler/typecheck/TcGenGenerics.lhs
+++ b/compiler/typecheck/TcGenGenerics.lhs
@@ -324,17 +324,15 @@ canDoGenerics1_w rep_tc
representable ty = case tcSplitTyConApp_maybe ty of
Nothing -> return Nothing
-- if it's a type constructor, it has to be representable
- Just (tc, tc_args) -> do
+ Just (tc, _) -> do
let n = tyConName tc
s <- S.get
-- internally assume that recursive occurrences are OK
if n `elem` s then return Nothing else do
S.put (n : s)
- fmap {-maybe-} (\_ -> bad_app tc) -- don't give the message, just name what wasn't representable
- `fmap` {-state-} case canDoGenerics tc tc_args of
- j@(Just _) -> return j
- -- only check Generic1 if it passes Generic
- Nothing -> canDoGenerics1_w tc
+ fmap {-maybe-} (\_ -> bad_app tc) -- don't give the message, just
+ -- name what wasn't representable
+ `fmap` {-state-} canDoGenerics1_w tc
existential = (ptext . sLit) "must not have existential arguments"
covariant = (ptext . sLit) "must not use the last type parameter in a function argument"
--
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