GHC 8.4 compatibility.

.travis.yml

@@ -44,7 +44,7 @@ matrix:
           packages:
             - ghc-8.2.1
             - cabal-install-1.24
-    - env: GHCVER=8.4.1 CABALVER=head GHCHEAD=true
+    - env: GHCVER=8.4.1 CABALVER=head
       addons:
         apt:
           sources:
@@ -53,20 +53,16 @@ matrix:
             - ghc-8.4.1
             - cabal-install-head
   allow_failures:
-    - env: GHCVER=8.4.1 CABALVER=head GHCHEAD=true
+    - env: GHCVER=8.4.1 CABALVER=head
 
 before_install:
   - export PATH=/opt/ghc/$GHCVER/bin:/opt/cabal/$CABALVER/bin:$PATH
   - ghc --version
   - cabal --version
   - travis_retry cabal update
   - sed -i 's/^jobs:/-- jobs:/' ${HOME}/.cabal/config
-  - ALLOW_NEWER=''
-  - if ${GHCHEAD-false} ; then ALLOW_NEWER='--allow-newer' ; fi
-  - cabal install --enable-tests --only-dep $ALLOW_NEWER
+  - cabal install --enable-tests --only-dep
 
 script:
-  - WERROR='--ghc-options=-Werror'
-  - if ${GHCHEAD-false} ; then WERROR='' ; fi
-  - (cd ghci-wrapper && cabal configure --enable-tests $WERROR $ALLOW_NEWER && cabal build && cabal test)
-  - cabal configure --enable-tests $WERROR $ALLOW_NEWER && cabal build && cabal test
+  - (cd ghci-wrapper && cabal configure --enable-tests --ghc-options=-Werror && cabal build && cabal test)
+  - cabal configure --enable-tests --ghc-options=-Werror && cabal build && cabal test

CHANGES

@@ -1,3 +1,6 @@
+Changes in NEXT
+  - GHC 8.4 compatibility.
+
 Changes in 0.13.0
   - Add `--preserve-it` for allowing the `it` variable to be preserved between examples
 

doctest.cabal

@@ -2,7 +2,7 @@
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: 69dd6d1ecadc8f87149ce07099560f936552a152651e21b775a0e513aaaaf79a
+-- hash: 963cf1ec79ce30b2c464e5e64a64f5b9f0cba107029eb8fdc5333229775060c9
 
 name:           doctest
 version:        0.14.0
@@ -63,7 +63,7 @@ library
     , deepseq
     , directory
     , filepath
-    , ghc >=7.0 && <8.4
+    , ghc >=7.0 && <8.6
     , ghc-paths >=0.1.0.9
     , process
     , syb >=0.3
@@ -85,7 +85,7 @@ executable doctest
     , directory
     , doctest
     , filepath
-    , ghc >=7.0 && <8.4
+    , ghc >=7.0 && <8.6
     , ghc-paths >=0.1.0.9
     , process
     , syb >=0.3
@@ -106,7 +106,7 @@ test-suite doctests
     , directory
     , doctest
     , filepath
-    , ghc >=7.0 && <8.4
+    , ghc >=7.0 && <8.6
     , ghc-paths >=0.1.0.9
     , process
     , syb >=0.3
@@ -164,7 +164,7 @@ test-suite spec
     , deepseq
     , directory
     , filepath
-    , ghc >=7.0 && <8.4
+    , ghc >=7.0 && <8.6
     , ghc-paths >=0.1.0.9
     , hspec >=1.5.1
     , mockery

package.yaml

@@ -27,7 +27,7 @@ ghc-options: -Wall
 dependencies:
 - base == 4.*
 - base-compat >= 0.7.0
-- ghc >= 7.0 && < 8.4
+- ghc >= 7.0 && < 8.6
 - syb >= 0.3
 - code-page >= 0.1
 - deepseq

src/Extract.hs

@@ -76,6 +76,16 @@ data Module a = Module {
 instance NFData a => NFData (Module a) where
   rnf (Module name setup content) = name `deepseq` setup `deepseq` content `deepseq` ()
 
+#if __GLASGOW_HASKELL__ < 803
+type GhcPs = RdrName
+
+needsTemplateHaskellOrQQ :: ModuleGraph -> Bool
+needsTemplateHaskellOrQQ = needsTemplateHaskell
+
+mapMG :: (ModSummary -> ModSummary) -> ModuleGraph -> ModuleGraph
+mapMG = map
+#endif
+
 -- | Parse a list of modules.
 parse :: [String] -> IO [TypecheckedModule]
 parse args = withGhc args $ \modules_ -> withTempOutputDir $ do
@@ -86,7 +96,7 @@ parse args = withGhc args $ \modules_ -> withTempOutputDir $ do
   mapM (`guessTarget` Nothing) modules >>= setTargets
   mods <- depanal [] False
 
-  mods' <- if needsTemplateHaskell mods then enableCompilation mods else return mods
+  mods' <- if needsTemplateHaskellOrQQ mods then enableCompilation mods else return mods
 
   let sortedMods = flattenSCCs (topSortModuleGraph False mods' Nothing)
   reverse <$> mapM (parseModule >=> typecheckModule >=> loadModule) sortedMods
@@ -103,7 +113,7 @@ parse args = withGhc args $ \modules_ -> withTempOutputDir $ do
       modifySessionDynFlags enableComp
       -- We need to update the DynFlags of the ModSummaries as well.
       let upd m = m { ms_hspp_opts = enableComp (ms_hspp_opts m) }
-      let modGraph' = map upd modGraph
+      let modGraph' = mapMG upd modGraph
       return modGraph'
 
     -- copied from Haddock/GhcUtils.hs
@@ -236,7 +246,7 @@ extractDocStrings = everythingBut (++) (([], False) `mkQ` fromLHsDecl
 #endif
   )
   where
-    fromLHsDecl :: Selector (LHsDecl RdrName)
+    fromLHsDecl :: Selector (LHsDecl GhcPs)
     fromLHsDecl (L loc decl) = case decl of
 
       -- Top-level documentation has to be treated separately, because it has

src/Runner.hs

@@ -14,9 +14,12 @@ module Runner (
 import           Prelude hiding (putStr, putStrLn, error)
 
 #if __GLASGOW_HASKELL__ < 710
-import           Data.Monoid
+import           Data.Monoid hiding ((<>))
 import           Control.Applicative
 #endif
+#if MIN_VERSION_base(4,9,0) && !MIN_VERSION_base(4,11,0)
+import           Data.Semigroup
+#endif
 
 import           Control.Monad hiding (forM_)
 import           Text.Printf (printf)
@@ -46,10 +49,21 @@ instance Show Summary where
   show (Summary examples tried errors failures) =
     printf "Examples: %d  Tried: %d  Errors: %d  Failures: %d" examples tried errors failures
 
+appendSummary :: Summary -> Summary -> Summary
+appendSummary (Summary x1 x2 x3 x4) (Summary y1 y2 y3 y4) = Summary (x1 + y1) (x2 + y2) (x3 + y3) (x4 + y4)
+
 -- | Sum up summaries.
 instance Monoid Summary where
   mempty = Summary 0 0 0 0
-  (Summary x1 x2 x3 x4) `mappend` (Summary y1 y2 y3 y4) = Summary (x1 + y1) (x2 + y2) (x3 + y3) (x4 + y4)
+#if MIN_VERSION_base(4,9,0)
+  mappend = (<>)
+
+-- | Sum up summaries.
+instance Semigroup Summary where
+  (<>) = appendSummary
+#else
+  mappend = appendSummary
+#endif
 
 -- | Run all examples from a list of modules.
 runModules :: Bool -> Bool -> Interpreter -> [Module [Located DocTest]] -> IO Summary