From 820d2d503fde7b29634262fd07db2a4744cf813d Mon Sep 17 00:00:00 2001
From: Thomas Hallgren <th-github@altocumulus.org>
Date: Wed, 18 Apr 2018 19:18:10 +0200
Subject: Fixes for GHC 8.4.1 compatibility

* In GHC 8.4.1, the operator <> has become a method of the Semigroup class
  and is exported from the Prelude. This is unfortunate, since <> is also
  exported from the standard library module Text.PrettyPrint, so in any
  module that defines a pretty printer, there is likely to be an ambiguity.

  This affects ~18 modules in GF. Solution:

    import Prelude hiding (<>)

  This works also in older versions of GHC, since GHC does't complain if
  you hide something that doesn't exists.

* In GHC 8.4.1, Semigroup has become a superclass of Monoid. This means
  that anywhere you define an instance of the Monoid class you also have to
  define an instance in the Semigroup class.

  This affects Data.Binary.Builder in GF. Solution: conditionally define
  a Semigroup instance if compiling with base>=4.11 (ghc>=8.4.1)
---
 src/runtime/haskell-bind/PGF2.hsc          | 2 +-
 src/runtime/haskell/Data/Binary/Builder.hs | 5 +++++
 src/runtime/haskell/PGF/ByteCode.hs        | 2 +-
 src/runtime/haskell/PGF/Macros.hs          | 1 +
 src/runtime/haskell/PGF/Printer.hs         | 1 +
 src/runtime/haskell/PGF/VisualizeTree.hs   | 1 +
 6 files changed, 10 insertions(+), 2 deletions(-)

(limited to 'src/runtime')

diff --git a/src/runtime/haskell-bind/PGF2.hsc b/src/runtime/haskell-bind/PGF2.hsc
index fb3672c0f..895d13ca4 100644
--- a/src/runtime/haskell-bind/PGF2.hsc
+++ b/src/runtime/haskell-bind/PGF2.hsc
@@ -82,7 +82,7 @@ module PGF2 (-- * PGF
              LiteralCallback,literalCallbacks
             ) where
 
-import Prelude hiding (fromEnum)
+import Prelude hiding (fromEnum,(<>)) -- GHC 8.4.1 clash with Text.PrettyPrint
 import Control.Exception(Exception,throwIO)
 import Control.Monad(forM_)
 import System.IO.Unsafe(unsafePerformIO,unsafeInterleaveIO)
diff --git a/src/runtime/haskell/Data/Binary/Builder.hs b/src/runtime/haskell/Data/Binary/Builder.hs
index 03531daa7..b69371f0e 100644
--- a/src/runtime/haskell/Data/Binary/Builder.hs
+++ b/src/runtime/haskell/Data/Binary/Builder.hs
@@ -100,6 +100,11 @@ newtype Builder = Builder {
         runBuilder :: (Buffer -> [S.ByteString]) -> Buffer -> [S.ByteString]
     }
 
+#if MIN_VERSION_base(4,11,0)
+instance Semigroup Builder where
+  (<>) = append
+#endif
+
 instance Monoid Builder where
     mempty  = empty
     {-# INLINE mempty #-}
diff --git a/src/runtime/haskell/PGF/ByteCode.hs b/src/runtime/haskell/PGF/ByteCode.hs
index 579d6b3bb..ef21ab229 100644
--- a/src/runtime/haskell/PGF/ByteCode.hs
+++ b/src/runtime/haskell/PGF/ByteCode.hs
@@ -2,7 +2,7 @@ module PGF.ByteCode(Literal(..),
                     CodeLabel, Instr(..), IVal(..), TailInfo(..),
                     ppLit, ppCode, ppInstr
                    ) where
-
+import Prelude hiding ((<>)) -- GHC 8.4.1 clash with Text.PrettyPrint
 import PGF.CId
 import Text.PrettyPrint
 
diff --git a/src/runtime/haskell/PGF/Macros.hs b/src/runtime/haskell/PGF/Macros.hs
index de175616c..3fc7a5804 100644
--- a/src/runtime/haskell/PGF/Macros.hs
+++ b/src/runtime/haskell/PGF/Macros.hs
@@ -1,4 +1,5 @@
 module PGF.Macros where
+import Prelude hiding ((<>)) -- GHC 8.4.1 clash with Text.PrettyPrint
 
 import PGF.CId
 import PGF.Data
diff --git a/src/runtime/haskell/PGF/Printer.hs b/src/runtime/haskell/PGF/Printer.hs
index 43c270b13..07e94f866 100644
--- a/src/runtime/haskell/PGF/Printer.hs
+++ b/src/runtime/haskell/PGF/Printer.hs
@@ -1,5 +1,6 @@
 {-# LANGUAGE FlexibleContexts #-}
 module PGF.Printer (ppPGF,ppCat,ppFId,ppFunId,ppSeqId,ppSeq,ppFun) where
+import Prelude hiding ((<>)) -- GHC 8.4.1 clash with Text.PrettyPrint
 
 import PGF.CId
 import PGF.Data
diff --git a/src/runtime/haskell/PGF/VisualizeTree.hs b/src/runtime/haskell/PGF/VisualizeTree.hs
index 5d884fafe..520eb59c3 100644
--- a/src/runtime/haskell/PGF/VisualizeTree.hs
+++ b/src/runtime/haskell/PGF/VisualizeTree.hs
@@ -23,6 +23,7 @@ module PGF.VisualizeTree
              , gizaAlignment
              , conlls2latexDoc
              ) where
+import Prelude hiding ((<>)) -- GHC 8.4.1 clash with Text.PrettyPrint
 
 import PGF.CId (wildCId,showCId,ppCId,mkCId) --CId,pCId,
 import PGF.Data
-- 
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