Highlight mappend invariant for DepError

Related: https://github.com/commercialhaskell/stack/issues/2078
2016-05-05 03:10:19 +02:00 · 2016-05-05 03:10:19 +02:00 · 63feb972ae
commit 63feb972ae
parent 6f108a10a4
1 changed files with 1 additions and 1 deletions
--- a/src/Stack/BuildPlan.hs
+++ b/src/Stack/BuildPlan.hs
@ -625,7 +625,7 @@ data DepError = DepError
 instance Monoid DepError where
    mempty = DepError Nothing Map.empty
    mappend (DepError a x) (DepError b y) = DepError
-        (maybe a Just b)
+        (assert (a == b) a)
        (Map.unionWith C.intersectVersionRanges x y)

 -- | Given a bundle of packages (a list of @GenericPackageDescriptions@'s) to