Use U+2018 instead of U+201B quote mark in compiler messages

This matches GCC's choice of Unicode quotation marks (i.e. U+2018 and U+2019)
and therefore looks more familiar on the console. This addresses #2507.
Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>

compiler/main/DynFlags.hs

@@ -1281,7 +1281,7 @@ initDynFlags dflags = do
  refRtccInfo <- newIORef Nothing
  wrapperNum <- newIORef emptyModuleEnv
  canUseUnicodeQuotes <- do let enc = localeEncoding
-                               str = "‛’"
+                               str = "‘’"
                            (withCString enc str $ \cstr ->
                                 do str' <- peekCString enc cstr
                                    return (str == str'))

compiler/rename/RnEnv.lhs

@@ -830,7 +830,7 @@ as if there was an "import qualified M" declaration for every
 module.
 
 If we fail we just return Nothing, rather than bleating
-about "attempting to use module ‛D’ (./D.hs) which is not loaded"
+about "attempting to use module ‘D’ (./D.hs) which is not loaded"
 which is what loadSrcInterface does.
 
 Note [Safe Haskell and GHCi]

compiler/utils/Outputable.lhs

@@ -460,7 +460,7 @@ cparen b d     = SDoc $ Pretty.cparen b . runSDoc d
 quotes d =
       sdocWithDynFlags $ \dflags ->
       if useUnicodeQuotes dflags
-      then char '‛' <> d <> char '’'
+      then char '‘' <> d <> char '’'
       else SDoc $ \sty ->
            let pp_d = runSDoc d sty
                str  = show pp_d

testsuite/tests/annotations/should_fail/annfail01.stderr

 
 annfail01.hs:4:1:
-    Not in scope: type constructor or class ‛Foo’
+    Not in scope: type constructor or class ‘Foo’
     In the annotation: {-# ANN type Foo (1 :: Int) #-}
 
 annfail01.hs:5:1:
-    Not in scope: ‛f’
+    Not in scope: ‘f’
     In the annotation: {-# ANN f (1 :: Int) #-}

testsuite/tests/annotations/should_fail/annfail02.stderr

 
 annfail02.hs:6:1:
-    Not in scope: data constructor ‛Foo’
+    Not in scope: data constructor ‘Foo’
     In the annotation: {-# ANN Foo (1 :: Int) #-}
 
 annfail02.hs:7:1:
-    Not in scope: type constructor or class ‛Bar’
+    Not in scope: type constructor or class ‘Bar’
     In the annotation: {-# ANN type Bar (2 :: Int) #-}

testsuite/tests/annotations/should_fail/annfail03.stderr

 
 annfail03.hs:17:11:
     GHC stage restriction:
-      ‛InModule’ is used in a top-level splice or annotation,
+      ‘InModule’ is used in a top-level splice or annotation,
       and must be imported, not defined locally
     In the annotation: {-# ANN f InModule #-}

testsuite/tests/annotations/should_fail/annfail04.stderr

 
 annfail04.hs:14:12:
     GHC stage restriction:
-      instance for ‛Thing
+      instance for ‘Thing
                       Int’ is used in a top-level splice or annotation,
       and must be imported, not defined locally
     In the annotation: {-# ANN f (thing :: Int) #-}

testsuite/tests/annotations/should_fail/annfail06.stderr

 
 annfail06.hs:22:1:
     GHC stage restriction:
-      instance for ‛Data
+      instance for ‘Data
                       InstancesInWrongModule’ is used in a top-level splice or annotation,
       and must be imported, not defined locally
     In the annotation: {-# ANN f InstancesInWrongModule #-}

testsuite/tests/annotations/should_fail/annfail07.stderr

 
 annfail07.hs:9:17:
-    Couldn't match expected type ‛[a0]’ with actual type ‛Bool’
-    In the first argument of ‛head’, namely ‛True’
+    Couldn't match expected type ‘[a0]’ with actual type ‘Bool’
+    In the first argument of ‘head’, namely ‘True’
     In the annotation: {-# ANN f (head True) #-}

testsuite/tests/annotations/should_fail/annfail08.stderr

@@ -5,5 +5,5 @@ annfail08.hs:9:1:
     In the annotation: {-# ANN f (id + 1) #-}
 
 annfail08.hs:9:15:
-    No instance for (Num (a0 -> a0)) arising from a use of ‛+’
+    No instance for (Num (a0 -> a0)) arising from a use of ‘+’
     In the annotation: {-# ANN f (id + 1) #-}

testsuite/tests/annotations/should_fail/annfail09.stderr

 
 annfail09.hs:11:11:
     GHC stage restriction:
-      ‛g’ is used in a top-level splice or annotation,
+      ‘g’ is used in a top-level splice or annotation,
       and must be imported, not defined locally
     In the annotation: {-# ANN f g #-}

testsuite/tests/annotations/should_fail/annfail10.stderr

 
 annfail10.hs:9:1:
     No instance for (Data.Data.Data a0) arising from an annotation
-    The type variable ‛a0’ is ambiguous
+    The type variable ‘a0’ is ambiguous
     Note: there are several potential instances:
-      instance Data.Data.Data () -- Defined in ‛Data.Data’
+      instance Data.Data.Data () -- Defined in ‘Data.Data’
       instance (Data.Data.Data a, Data.Data.Data b) =>
                Data.Data.Data (a, b)
-        -- Defined in ‛Data.Data’
+        -- Defined in ‘Data.Data’
       instance (Data.Data.Data a, Data.Data.Data b, Data.Data.Data c) =>
                Data.Data.Data (a, b, c)
-        -- Defined in ‛Data.Data’
+        -- Defined in ‘Data.Data’
       ...plus 31 others
     In the annotation: {-# ANN f 1 #-}
 
 annfail10.hs:9:11:
-    No instance for (Num a0) arising from the literal ‛1’
-    The type variable ‛a0’ is ambiguous
+    No instance for (Num a0) arising from the literal ‘1’
+    The type variable ‘a0’ is ambiguous
     Note: there are several potential instances:
-      instance Num Double -- Defined in ‛GHC.Float’
-      instance Num Float -- Defined in ‛GHC.Float’
+      instance Num Double -- Defined in ‘GHC.Float’
+      instance Num Float -- Defined in ‘GHC.Float’
       instance Integral a => Num (GHC.Real.Ratio a)
-        -- Defined in ‛GHC.Real’
+        -- Defined in ‘GHC.Real’
       ...plus 11 others
     In the annotation: {-# ANN f 1 #-}

testsuite/tests/annotations/should_fail/annfail11.stderr

 
 annfail11.hs:3:1:
-    Not in scope: ‛length’
+    Not in scope: ‘length’
     In the annotation:
       {-# ANN length "Cannot annotate other modules yet" #-}
 
 annfail11.hs:4:1:
-    Not in scope: type constructor or class ‛Integer’
+    Not in scope: type constructor or class ‘Integer’
     In the annotation:
       {-# ANN type Integer "Cannot annotate other modules yet" #-}

testsuite/tests/annotations/should_fail/annfail13.stderr

 
-annfail13.hs:4:14: parse error on input ‛1’
+annfail13.hs:4:14: parse error on input ‘1’

testsuite/tests/arrows/should_fail/T5380.stderr

 
 T5380.hs:7:27:
-    Couldn't match expected type ‛Bool’ with actual type ‛not_bool’
-      ‛not_bool’ is a rigid type variable bound by
+    Couldn't match expected type ‘Bool’ with actual type ‘not_bool’
+      ‘not_bool’ is a rigid type variable bound by
                  the type signature for
                    testB :: not_bool -> (() -> ()) -> () -> not_unit
                  at T5380.hs:6:10
@@ -13,8 +13,8 @@ T5380.hs:7:27:
     In the expression: proc () -> if b then f -< () else f -< ()
 
 T5380.hs:7:34:
-    Couldn't match type ‛not_unit’ with ‛()’
-      ‛not_unit’ is a rigid type variable bound by
+    Couldn't match type ‘not_unit’ with ‘()’
+      ‘not_unit’ is a rigid type variable bound by
                  the type signature for
                    testB :: not_bool -> (() -> ()) -> () -> not_unit
                  at T5380.hs:6:10

testsuite/tests/arrows/should_fail/arrowfail001.stderr

 
 arrowfail001.hs:16:36:
-    No instance for (Foo a) arising from a use of ‛foo’
+    No instance for (Foo a) arising from a use of ‘foo’
     In the expression: foo
     In the expression: proc x -> case x of { Bar a -> foo -< a }
-    In an equation for ‛get’:
+    In an equation for ‘get’:
         get = proc x -> case x of { Bar a -> foo -< a }

testsuite/tests/arrows/should_fail/arrowfail002.stderr

 
-arrowfail002.hs:6:17: Not in scope: ‛x’
+arrowfail002.hs:6:17: Not in scope: ‘x’

testsuite/tests/arrows/should_fail/arrowfail004.stderr

@@ -3,5 +3,5 @@ arrowfail004.hs:12:15:
     Proc patterns cannot use existential or GADT data constructors
     In the pattern: T x
     In the expression: proc (T x) -> do { returnA -< T x }
-    In an equation for ‛panic’:
+    In an equation for ‘panic’:
         panic = proc (T x) -> do { returnA -< T x }

testsuite/tests/deSugar/should_compile/GadtOverlap.stderr

 
 GadtOverlap.hs:19:1: Warning:
     Pattern match(es) are non-exhaustive
-    In an equation for ‛h’: Patterns not matched: T3
+    In an equation for ‘h’: Patterns not matched: T3

testsuite/tests/deSugar/should_compile/T2395.stderr

 
 T2395.hs:12:1: Warning:
     Pattern match(es) are overlapped
-    In an equation for ‛bar’: bar _ = ...
+    In an equation for ‘bar’: bar _ = ...

testsuite/tests/deSugar/should_compile/T3263-1.stderr

 
 T3263-1.hs:25:3: Warning:
-    A do-notation statement discarded a result of type ‛Int’
-    Suppress this warning by saying ‛_ <- nonNullM’
+    A do-notation statement discarded a result of type ‘Int’
+    Suppress this warning by saying ‘_ <- nonNullM’
     or by using the flag -fno-warn-unused-do-bind
 
 T3263-1.hs:35:3: Warning:
-    A do-notation statement discarded a result of type ‛Int’
-    Suppress this warning by saying ‛_ <- nonNullM’
+    A do-notation statement discarded a result of type ‘Int’
+    Suppress this warning by saying ‘_ <- nonNullM’
     or by using the flag -fno-warn-unused-do-bind

testsuite/tests/deSugar/should_compile/T3263-2.stderr

 
 T3263-2.hs:25:3: Warning:
-    A do-notation statement discarded a result of type ‛m Int’
-    Suppress this warning by saying ‛_ <- return (return 10 :: m Int)’
+    A do-notation statement discarded a result of type ‘m Int’
+    Suppress this warning by saying ‘_ <- return (return 10 :: m Int)’
     or by using the flag -fno-warn-wrong-do-bind
 
 T3263-2.hs:37:3: Warning:
-    A do-notation statement discarded a result of type ‛m Int’
-    Suppress this warning by saying ‛_ <- return (return 10 :: m Int)’
+    A do-notation statement discarded a result of type ‘m Int’
+    Suppress this warning by saying ‘_ <- return (return 10 :: m Int)’
     or by using the flag -fno-warn-wrong-do-bind