Smarter HsType pretty-print for promoted datacons

Fix Trac #15898, by being smarter about when to print
a space before a promoted data constructor, in a HsType.
I had to implement a mildly tiresome function
    HsType.lhsTypeHasLeadingPromotionQuote
It has multiple cases, of course, but it's very simple.

The patch improves the error-message output in a bunch of
cases, and (to my surprise) actually fixes a bug in the
output of T14343 (Trac #14343), thus

  -  In the expression: _ :: Proxy '('( 'True,  'False),  'False)
  +  In the expression: _ :: Proxy '( '( 'True, 'False), 'False)

I discovered that there were two copies of the PromotionFlag
type (a boolean, with helpfully named data cons), one in
IfaceType and one in HsType.  So I combined into one,
PromotionFlag, and moved it to BasicTypes.  That's why
quite a few files are touched, but it's all routine.

15 files changed, 42 insertions, 34 deletions

diff --git a/testsuite/tests/dependent/should_fail/PromotedClass.stderr b/testsuite/tests/dependent/should_fail/PromotedClass.stderr
index 4da1a32fca..9f8d84a410 100644
--- a/testsuite/tests/dependent/should_fail/PromotedClass.stderr
+++ b/testsuite/tests/dependent/should_fail/PromotedClass.stderr
@@ -2,5 +2,5 @@
 PromotedClass.hs:10:15: error:
     • Data constructor ‘MkX’ cannot be used here
         (it has an unpromotable context ‘Show a’)
-    • In the first argument of ‘Proxy’, namely ‘( 'MkX  'True)’
-      In the type signature: foo :: Proxy ( 'MkX  'True)
+    • In the first argument of ‘Proxy’, namely ‘('MkX 'True)’
+      In the type signature: foo :: Proxy ('MkX 'True)
diff --git a/testsuite/tests/dependent/should_fail/T15245.stderr b/testsuite/tests/dependent/should_fail/T15245.stderr
index b41076636f..859fafda8b 100644
--- a/testsuite/tests/dependent/should_fail/T15245.stderr
+++ b/testsuite/tests/dependent/should_fail/T15245.stderr
@@ -2,6 +2,6 @@
 T15245.hs:10:24: error:
     • Data constructor ‘MkK’ cannot be used here
         (it comes from a data family instance)
-    • In the type ‘ 'MkK’
-      In the first argument of ‘print’, namely ‘(typeRep @ 'MkK)’
-      In the expression: print (typeRep @ 'MkK)
+    • In the type ‘'MkK’
+      In the first argument of ‘print’, namely ‘(typeRep @'MkK)’
+      In the expression: print (typeRep @'MkK)
diff --git a/testsuite/tests/ghci/scripts/T15898.script b/testsuite/tests/ghci/scripts/T15898.script
new file mode 100644
index 0000000000..930b319124
--- /dev/null
+++ b/testsuite/tests/ghci/scripts/T15898.script
@@ -0,0 +1,6 @@
+:set -XDataKinds
+import Data.Proxy
+undefined :: '()
+undefined :: Proxy '() Int
+undefined :: [(), ()]
+undefined :: '( '[], '[] )
diff --git a/testsuite/tests/ghci/scripts/T15898.stdout b/testsuite/tests/ghci/scripts/T15898.stdout
new file mode 100644
index 0000000000..0519ecba6e
--- /dev/null
+++ b/testsuite/tests/ghci/scripts/T15898.stdout
@@ -0,0 +1 @@
+ 
\ No newline at end of file
diff --git a/testsuite/tests/ghci/scripts/all.T b/testsuite/tests/ghci/scripts/all.T
index 97ae8bb26f..493daa4412 100755
--- a/testsuite/tests/ghci/scripts/all.T
+++ b/testsuite/tests/ghci/scripts/all.T
@@ -288,3 +288,4 @@ test('T15568', normal, ghci_script, ['T15568.script'])
 test('T15325', normal, ghci_script, ['T15325.script'])
 test('T15591', normal, ghci_script, ['T15591.script'])
 test('T15743b', normal, ghci_script, ['T15743b.script'])
+test('T15898', normal, ghci_script, ['T15898.script'])
diff --git a/testsuite/tests/parser/should_compile/DumpParsedAst.stderr b/testsuite/tests/parser/should_compile/DumpParsedAst.stderr
index 4648baa1f1..408f28b4f7 100644
--- a/testsuite/tests/parser/should_compile/DumpParsedAst.stderr
+++ b/testsuite/tests/parser/should_compile/DumpParsedAst.stderr
@@ -145,7 +145,7 @@
              [({ DumpParsedAst.hs:9:10-12 }
                (HsExplicitListTy
                 (NoExt)
-                (Promoted)
+                (IsPromoted)
                 []))]
              (Prefix)
              ({ DumpParsedAst.hs:9:21-24 }
diff --git a/testsuite/tests/parser/should_compile/DumpRenamedAst.stderr b/testsuite/tests/parser/should_compile/DumpRenamedAst.stderr
index 5c1a03e091..5a35b0037c 100644
--- a/testsuite/tests/parser/should_compile/DumpRenamedAst.stderr
+++ b/testsuite/tests/parser/should_compile/DumpRenamedAst.stderr
@@ -191,7 +191,7 @@
                [({ DumpRenamedAst.hs:12:10-12 }
                  (HsExplicitListTy
                   (NoExt)
-                  (Promoted)
+                  (IsPromoted)
                   []))]
                (Prefix)
                ({ DumpRenamedAst.hs:12:21-24 }
diff --git a/testsuite/tests/parser/should_compile/KindSigs.stderr b/testsuite/tests/parser/should_compile/KindSigs.stderr
index 71a54b085a..ebbec08ad5 100644
--- a/testsuite/tests/parser/should_compile/KindSigs.stderr
+++ b/testsuite/tests/parser/should_compile/KindSigs.stderr
@@ -377,7 +377,7 @@
       ({ KindSigs.hs:26:13-29 }
        (HsExplicitListTy
         (NoExt)
-        (Promoted)
+        (IsPromoted)
         [({ KindSigs.hs:26:16-27 }
           (HsKindSig
            (NoExt)
diff --git a/testsuite/tests/polykinds/PolyKinds07.stderr b/testsuite/tests/polykinds/PolyKinds07.stderr
index ce70e7d07a..596cae306e 100644
--- a/testsuite/tests/polykinds/PolyKinds07.stderr
+++ b/testsuite/tests/polykinds/PolyKinds07.stderr
@@ -1,7 +1,7 @@
 
-PolyKinds07.hs:10:11:
-    Data constructor ‘A1’ cannot be used here
-      (it is defined and used in the same recursive group)
-    In the first argument of ‘B’, namely ‘ 'A1’
-    In the type ‘B  'A1’
-    In the definition of data constructor ‘B1’
+PolyKinds07.hs:10:11: error:
+    • Data constructor ‘A1’ cannot be used here
+        (it is defined and used in the same recursive group)
+    • In the first argument of ‘B’, namely ‘'A1’
+      In the type ‘B 'A1’
+      In the definition of data constructor ‘B1’
diff --git a/testsuite/tests/polykinds/T10503.stderr b/testsuite/tests/polykinds/T10503.stderr
index 2309cdaaae..9fb87e9be7 100644
--- a/testsuite/tests/polykinds/T10503.stderr
+++ b/testsuite/tests/polykinds/T10503.stderr
@@ -13,5 +13,5 @@ T10503.hs:8:6: error:
       To defer the ambiguity check to use sites, enable AllowAmbiguousTypes
       In the type signature:
         h :: forall r.
-             (Proxy ( 'KProxy :: KProxy k) ~ Proxy ( 'KProxy :: KProxy *) => r)
+             (Proxy ('KProxy :: KProxy k) ~ Proxy ('KProxy :: KProxy *) => r)
              -> r
diff --git a/testsuite/tests/polykinds/T15116a.stderr b/testsuite/tests/polykinds/T15116a.stderr
index 7e4788f5b8..148432f5ca 100644
--- a/testsuite/tests/polykinds/T15116a.stderr
+++ b/testsuite/tests/polykinds/T15116a.stderr
@@ -2,6 +2,6 @@
 T15116a.hs:6:21: error:
     • Data constructor ‘MkB’ cannot be used here
         (it is defined and used in the same recursive group)
-    • In the first argument of ‘Proxy’, namely ‘ 'MkB’
-      In the type ‘(Proxy  'MkB)’
+    • In the first argument of ‘Proxy’, namely ‘'MkB’
+      In the type ‘(Proxy 'MkB)’
       In the definition of data constructor ‘MkB’
diff --git a/testsuite/tests/polykinds/T7433.stderr b/testsuite/tests/polykinds/T7433.stderr
index 4dce12a653..317a9a4595 100644
--- a/testsuite/tests/polykinds/T7433.stderr
+++ b/testsuite/tests/polykinds/T7433.stderr
@@ -2,5 +2,5 @@
 T7433.hs:2:10: error:
     • Data constructor ‘Z’ cannot be used here
         (perhaps you intended to use DataKinds)
-    • In the type ‘ 'Z’
+    • In the type ‘'Z’
       In the type declaration for ‘T’
diff --git a/testsuite/tests/printer/T14343.stderr b/testsuite/tests/printer/T14343.stderr
index 1bceb67403..5865669302 100644
--- a/testsuite/tests/printer/T14343.stderr
+++ b/testsuite/tests/printer/T14343.stderr
@@ -13,8 +13,8 @@ T14343.hs:10:9: error:
 
 T14343.hs:11:9: error:
     • Found hole: _ :: Proxy '[ '[1]]
-    • In the expression: _ :: Proxy '['[1]]
-      In an equation for ‘test2’: test2 = _ :: Proxy '['[1]]
+    • In the expression: _ :: Proxy '[ '[1]]
+      In an equation for ‘test2’: test2 = _ :: Proxy '[ '[1]]
     • Relevant bindings include
         test2 :: Proxy '[ '[1]] (bound at T14343.hs:11:1)
       Valid hole fits include
@@ -25,8 +25,8 @@ T14343.hs:11:9: error:
 
 T14343.hs:12:9: error:
     • Found hole: _ :: Proxy '[ '("Symbol", 1)]
-    • In the expression: _ :: Proxy '['("Symbol", 1)]
-      In an equation for ‘test3’: test3 = _ :: Proxy '['("Symbol", 1)]
+    • In the expression: _ :: Proxy '[ '("Symbol", 1)]
+      In an equation for ‘test3’: test3 = _ :: Proxy '[ '("Symbol", 1)]
     • Relevant bindings include
         test3 :: Proxy '[ '("Symbol", 1)] (bound at T14343.hs:12:1)
       Valid hole fits include
diff --git a/testsuite/tests/printer/T14343b.stderr b/testsuite/tests/printer/T14343b.stderr
index 1954f9465a..7573169414 100644
--- a/testsuite/tests/printer/T14343b.stderr
+++ b/testsuite/tests/printer/T14343b.stderr
@@ -1,8 +1,8 @@
 
 T14343b.hs:10:9: error:
     • Found hole: _ :: Proxy '( 'True, 'False)
-    • In the expression: _ :: Proxy '( 'True,  'False)
-      In an equation for ‘test1’: test1 = _ :: Proxy '( 'True,  'False)
+    • In the expression: _ :: Proxy '( 'True, 'False)
+      In an equation for ‘test1’: test1 = _ :: Proxy '( 'True, 'False)
     • Relevant bindings include
         test1 :: Proxy '( 'True, 'False) (bound at T14343b.hs:10:1)
       Valid hole fits include
@@ -13,9 +13,9 @@ T14343b.hs:10:9: error:
 
 T14343b.hs:11:9: error:
     • Found hole: _ :: Proxy '( '( 'True, 'False), 'False)
-    • In the expression: _ :: Proxy '('( 'True,  'False),  'False)
+    • In the expression: _ :: Proxy '( '( 'True, 'False), 'False)
       In an equation for ‘test2’:
-          test2 = _ :: Proxy '('( 'True,  'False),  'False)
+          test2 = _ :: Proxy '( '( 'True, 'False), 'False)
     • Relevant bindings include
         test2 :: Proxy '( '( 'True, 'False), 'False)
           (bound at T14343b.hs:11:1)
@@ -28,8 +28,8 @@ T14343b.hs:11:9: error:
 
 T14343b.hs:12:9: error:
     • Found hole: _ :: Proxy '( '[1], 'False)
-    • In the expression: _ :: Proxy '('[1],  'False)
-      In an equation for ‘test3’: test3 = _ :: Proxy '('[1],  'False)
+    • In the expression: _ :: Proxy '( '[1], 'False)
+      In an equation for ‘test3’: test3 = _ :: Proxy '( '[1], 'False)
     • Relevant bindings include
         test3 :: Proxy '( '[1], 'False) (bound at T14343b.hs:12:1)
       Valid hole fits include
diff --git a/testsuite/tests/typecheck/should_fail/T14607.stderr b/testsuite/tests/typecheck/should_fail/T14607.stderr
index 740f89a0d4..5e0b66a340 100644
--- a/testsuite/tests/typecheck/should_fail/T14607.stderr
+++ b/testsuite/tests/typecheck/should_fail/T14607.stderr
@@ -1,14 +1,14 @@
 
 T14607.hs:22:9: warning: [-Wdeferred-type-errors (in -Wdefault)]
-    • Expecting one more argument to ‘LamCons a  '()’
-      Expected a type, but ‘LamCons a  '()’ has kind ‘() -> *’
-    • In the type signature: mk :: LamCons a  '()
+    • Expecting one more argument to ‘LamCons a '()’
+      Expected a type, but ‘LamCons a '()’ has kind ‘() -> *’
+    • In the type signature: mk :: LamCons a '()
       In the instance declaration for ‘Mk a’
 
 T14607.hs:22:19: warning: [-Wdeferred-type-errors (in -Wdefault)]
-    • Expected a type, but ‘ '()’ has kind ‘()’
-    • In the second argument of ‘LamCons’, namely ‘ '()’
-      In the type signature: mk :: LamCons a  '()
+    • Expected a type, but ‘'()’ has kind ‘()’
+    • In the second argument of ‘LamCons’, namely ‘'()’
+      In the type signature: mk :: LamCons a '()
       In the instance declaration for ‘Mk a’
 
 T14607.hs:23:8: warning: [-Wdeferred-type-errors (in -Wdefault)]