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)

13 files changed, 13 insertions, 3 deletions

diff --git a/src/compiler/GF/Command/Commands.hs b/src/compiler/GF/Command/Commands.hs
index 3ca2ab962..a8a175f7c 100644
--- a/src/compiler/GF/Command/Commands.hs
+++ b/src/compiler/GF/Command/Commands.hs
@@ -3,7 +3,7 @@ module GF.Command.Commands (
   PGFEnv,HasPGFEnv(..),pgf,mos,pgfEnv,pgfCommands,
   options,flags,
   ) where
-import Prelude hiding (putStrLn)
+import Prelude hiding (putStrLn,(<>)) -- GHC 8.4.1 clash with Text.PrettyPrint
 
 import PGF
 
diff --git a/src/compiler/GF/Command/Commands2.hs b/src/compiler/GF/Command/Commands2.hs
index 0cc5d7d23..b5335479c 100644
--- a/src/compiler/GF/Command/Commands2.hs
+++ b/src/compiler/GF/Command/Commands2.hs
@@ -3,7 +3,7 @@ module GF.Command.Commands2 (
   PGFEnv,HasPGFEnv(..),pgf,concs,pgfEnv,emptyPGFEnv,pgfCommands,
   options, flags,
   ) where
-import Prelude hiding (putStrLn)
+import Prelude hiding (putStrLn,(<>)) -- GHC 8.4.1 clash with Text.PrettyPrint
 
 import PGF2
 import qualified PGF as H
diff --git a/src/compiler/GF/Compile/CheckGrammar.hs b/src/compiler/GF/Compile/CheckGrammar.hs
index 5c1743b74..1348d8e41 100644
--- a/src/compiler/GF/Compile/CheckGrammar.hs
+++ b/src/compiler/GF/Compile/CheckGrammar.hs
@@ -21,6 +21,7 @@
 -----------------------------------------------------------------------------
 
 module GF.Compile.CheckGrammar(checkModule) where
+import Prelude hiding ((<>)) -- GHC 8.4.1 clash with Text.PrettyPrint
 
 import GF.Infra.Ident
 import GF.Infra.Option
diff --git a/src/compiler/GF/Compile/Compute/ConcreteNew.hs b/src/compiler/GF/Compile/Compute/ConcreteNew.hs
index a77da88bf..f9edc931c 100644
--- a/src/compiler/GF/Compile/Compute/ConcreteNew.hs
+++ b/src/compiler/GF/Compile/Compute/ConcreteNew.hs
@@ -5,6 +5,7 @@ module GF.Compile.Compute.ConcreteNew
             normalForm,
             Value(..), Bind(..), Env, value2term, eval, vapply
            ) where
+import Prelude hiding ((<>)) -- GHC 8.4.1 clash with Text.PrettyPrint
 
 import GF.Grammar hiding (Env, VGen, VApp, VRecType)
 import GF.Grammar.Lookup(lookupResDefLoc,allParamValues)
diff --git a/src/compiler/GF/Compile/TypeCheck/RConcrete.hs b/src/compiler/GF/Compile/TypeCheck/RConcrete.hs
index 2fe08b256..88e324ff3 100644
--- a/src/compiler/GF/Compile/TypeCheck/RConcrete.hs
+++ b/src/compiler/GF/Compile/TypeCheck/RConcrete.hs
@@ -1,5 +1,6 @@
 {-# LANGUAGE PatternGuards #-}
 module GF.Compile.TypeCheck.RConcrete( checkLType, inferLType, computeLType, ppType ) where
+import Prelude hiding ((<>)) -- GHC 8.4.1 clash with Text.PrettyPrint
 
 import GF.Infra.CheckM
 import GF.Data.Operations
diff --git a/src/compiler/GF/CompileInParallel.hs b/src/compiler/GF/CompileInParallel.hs
index 7986656ec..8420b1771 100644
--- a/src/compiler/GF/CompileInParallel.hs
+++ b/src/compiler/GF/CompileInParallel.hs
@@ -1,6 +1,6 @@
 -- | Parallel grammar compilation
 module GF.CompileInParallel(parallelBatchCompile) where
-import Prelude hiding (catch)
+import Prelude hiding (catch,(<>)) -- GHC 8.4.1 clash with Text.PrettyPrint
 import Control.Monad(join,ap,when,unless)
 import Control.Applicative
 import GF.Infra.Concurrency
diff --git a/src/compiler/GF/Grammar/Printer.hs b/src/compiler/GF/Grammar/Printer.hs
index dcd419c42..4b19d215b 100644
--- a/src/compiler/GF/Grammar/Printer.hs
+++ b/src/compiler/GF/Grammar/Printer.hs
@@ -22,6 +22,7 @@ module GF.Grammar.Printer
            , ppMeta

            , getAbs

            ) where

+import Prelude hiding ((<>)) -- GHC 8.4.1 clash with Text.PrettyPrint

 

 import GF.Infra.Ident

 import GF.Infra.Option

diff --git a/src/compiler/GF/Haskell.hs b/src/compiler/GF/Haskell.hs
index e2156ac5d..57601c1d5 100644
--- a/src/compiler/GF/Haskell.hs
+++ b/src/compiler/GF/Haskell.hs
@@ -1,6 +1,7 @@
 -- | Abstract syntax and a pretty printer for a subset of Haskell
 {-# LANGUAGE DeriveFunctor #-}
 module GF.Haskell where
+import Prelude hiding ((<>)) -- GHC 8.4.1 clash with Text.PrettyPrint
 import GF.Infra.Ident(Ident,identS)
 import GF.Text.Pretty
 
diff --git a/src/compiler/GF/Infra/CheckM.hs b/src/compiler/GF/Infra/CheckM.hs
index 3b6833f0f..c5f9ba255 100644
--- a/src/compiler/GF/Infra/CheckM.hs
+++ b/src/compiler/GF/Infra/CheckM.hs
@@ -18,6 +18,7 @@ module GF.Infra.CheckM
 	   checkIn, checkInModule, checkMap, checkMapRecover,
            parallelCheck, accumulateError, commitCheck,
 	  ) where
+import Prelude hiding ((<>)) -- GHC 8.4.1 clash with Text.PrettyPrint
 
 import GF.Data.Operations
 --import GF.Infra.Ident
diff --git a/src/compiler/GF/Infra/Location.hs b/src/compiler/GF/Infra/Location.hs
index 0bf85b37f..8447a297c 100644
--- a/src/compiler/GF/Infra/Location.hs
+++ b/src/compiler/GF/Infra/Location.hs
@@ -1,5 +1,6 @@
 -- | Source locations
 module GF.Infra.Location where
+import Prelude hiding ((<>)) -- GHC 8.4.1 clash with Text.PrettyPrint
 import GF.Text.Pretty
 
 -- ** Source locations
diff --git a/src/compiler/GF/Speech/GSL.hs b/src/compiler/GF/Speech/GSL.hs
index d9d6af0cc..a898a4bb5 100644
--- a/src/compiler/GF/Speech/GSL.hs
+++ b/src/compiler/GF/Speech/GSL.hs
@@ -7,6 +7,7 @@
 -----------------------------------------------------------------------------
 
 module GF.Speech.GSL (gslPrinter) where
+import Prelude hiding ((<>)) -- GHC 8.4.1 clash with Text.PrettyPrint
 
 --import GF.Data.Utilities
 import GF.Grammar.CFG
diff --git a/src/compiler/GF/Speech/JSGF.hs b/src/compiler/GF/Speech/JSGF.hs
index 25168dbc8..15f5ff69d 100644
--- a/src/compiler/GF/Speech/JSGF.hs
+++ b/src/compiler/GF/Speech/JSGF.hs
@@ -11,6 +11,7 @@
 -----------------------------------------------------------------------------
 
 module GF.Speech.JSGF (jsgfPrinter) where
+import Prelude hiding ((<>)) -- GHC 8.4.1 clash with Text.PrettyPrint
 
 --import GF.Data.Utilities
 import GF.Infra.Option
diff --git a/src/compiler/GF/Speech/SRGS_ABNF.hs b/src/compiler/GF/Speech/SRGS_ABNF.hs
index 75d206a0c..dc5c7bbd3 100644
--- a/src/compiler/GF/Speech/SRGS_ABNF.hs
+++ b/src/compiler/GF/Speech/SRGS_ABNF.hs
@@ -18,6 +18,7 @@
 -----------------------------------------------------------------------------
 
 module GF.Speech.SRGS_ABNF (srgsAbnfPrinter, srgsAbnfNonRecursivePrinter) where
+import Prelude hiding ((<>)) -- GHC 8.4.1 clash with Text.PrettyPrint
 
 --import GF.Data.Utilities
 import GF.Infra.Option