semigroup monoid change fallout; drop ghc 7 support

Fix build with ghc 8.4, which broke due to the Semigroup Monoid change.
See https://prime.haskell.org/wiki/Libraries/Proposals/SemigroupMonoid

Dropped support for building propellor with ghc 7 (as in debian
oldstable), to avoid needing to depend on the semigroups transitional
package, but also because it's just too old to be worth supporting.

If we indeed drop ghc 7 support entirely, some code to support "jessie"
can be removed; concurrent-output can be de-embedded, and the Singletons
code can be simplified.

This commit was sponsored by Jack Hill on Patreon.

1 files changed, 4 insertions, 2 deletions

diff --git a/src/Propellor/Property/FreeBSD/Pkg.hs b/src/Propellor/Property/FreeBSD/Pkg.hs
index 77bf5768..56ac55fb 100644
--- a/src/Propellor/Property/FreeBSD/Pkg.hs
+++ b/src/Propellor/Property/FreeBSD/Pkg.hs
@@ -9,6 +9,8 @@ module Propellor.Property.FreeBSD.Pkg where
 import Propellor.Base
 import Propellor.Types.Info
 
+import qualified Data.Semigroup as Sem
+
 noninteractiveEnv :: [([Char], [Char])]
 noninteractiveEnv = [("ASSUME_ALWAYS_YES", "yes")]
 
@@ -37,7 +39,7 @@ pkgCmd cmd args =
 		lines <$> readProcessEnv p a (Just noninteractiveEnv)
 
 newtype PkgUpdate = PkgUpdate String
-	deriving (Typeable, Monoid, Show)
+	deriving (Typeable, Sem.Semigroup, Monoid, Show)
 instance IsInfo PkgUpdate where
 	propagateInfo _ = PropagateInfo False
 
@@ -54,7 +56,7 @@ update =
 			`setInfoProperty` (toInfo (PkgUpdate ""))
 
 newtype PkgUpgrade = PkgUpgrade String
-	deriving (Typeable, Monoid, Show)
+	deriving (Typeable, Sem.Semigroup, Monoid, Show)
 
 instance IsInfo PkgUpgrade where
 	propagateInfo _ = PropagateInfo False