Print constraints in quotes (#21167)

This patch improves the uniformity of error message formatting by
printing constraints in quotes, as we do for types.

Fix #21167

4 files changed, 12 insertions, 12 deletions

diff --git a/testsuite/tests/ghci/scripts/Defer02.stderr b/testsuite/tests/ghci/scripts/Defer02.stderr
index 3477f47b17..bb787b30c1 100644
--- a/testsuite/tests/ghci/scripts/Defer02.stderr
+++ b/testsuite/tests/ghci/scripts/Defer02.stderr
@@ -80,7 +80,7 @@ Defer01.hs:50:5: warning: [-Wdeferred-type-errors (in -Wdefault)]
       In an equation for ‘a’: a = 'p'
 (deferred type error)
 *** Exception: Defer01.hs:18:9: error:
-    • No instance for (Eq B) arising from a use of ‘==’
+    • No instance for ‘Eq B’ arising from a use of ‘==’
     • In the expression: x == x
       In an equation for ‘b’: b x = x == x
 (deferred type error)
@@ -93,7 +93,7 @@ Defer01.hs:50:5: warning: [-Wdeferred-type-errors (in -Wdefault)]
       In the first argument of ‘print’, namely ‘(c (C2 True))’
       In the expression: print (c (C2 True))
 *** Exception: Defer01.hs:28:5: error:
-    • No instance for (Num (a -> a)) arising from the literal ‘1’
+    • No instance for ‘Num (a -> a)’ arising from the literal ‘1’
         (maybe you haven't applied a function to enough arguments?)
     • In the expression: 1
       In an equation for ‘d’: d = 1
@@ -129,7 +129,7 @@ Defer01.hs:50:5: warning: [-Wdeferred-type-errors (in -Wdefault)]
         i :: a -> () (bound at Defer01.hs:39:1)
 (deferred type error)
 *** Exception: Defer01.hs:43:5: error:
-    • No instance for (MyClass a1) arising from a use of ‘myOp’
+    • No instance for ‘MyClass a1’ arising from a use of ‘myOp’
     • In the expression: myOp 23
       In an equation for ‘j’: j = myOp 23
 (deferred type error)
diff --git a/testsuite/tests/ghci/scripts/T15325.stderr b/testsuite/tests/ghci/scripts/T15325.stderr
index cd473af4dc..e7c6c8fc67 100644
--- a/testsuite/tests/ghci/scripts/T15325.stderr
+++ b/testsuite/tests/ghci/scripts/T15325.stderr
@@ -1,6 +1,6 @@
 
 T15325.hs:11:7: warning: [-Wdeferred-type-errors (in -Wdefault)]
-    • No instance for (PolyList e0) arising from a use of ‘f’
+    • No instance for ‘PolyList e0’ arising from a use of ‘f’
     • In the expression: f 0
       In an equation for ‘plh’: plh = f 0
 
@@ -18,7 +18,7 @@ T15325.hs:11:9: warning: [-Wdeferred-type-errors (in -Wdefault)]
       In the expression: f 0
       In an equation for ‘plh’: plh = f 0
 *** Exception: T15325.hs:11:7: error:
-    • No instance for (PolyList e0) arising from a use of ‘f’
+    • No instance for ‘PolyList e0’ arising from a use of ‘f’
     • In the expression: f 0
       In an equation for ‘plh’: plh = f 0
 (deferred type error)
diff --git a/testsuite/tests/ghci/scripts/T2182ghci.stderr b/testsuite/tests/ghci/scripts/T2182ghci.stderr
index 5f601942ca..5d28baef74 100644
--- a/testsuite/tests/ghci/scripts/T2182ghci.stderr
+++ b/testsuite/tests/ghci/scripts/T2182ghci.stderr
@@ -1,25 +1,25 @@
 
 <interactive>:2:1: error:
-    • No instance for (Show (p0 -> p0)) arising from a use of ‘print’
+    • No instance for ‘Show (p0 -> p0)’ arising from a use of ‘print’
         (maybe you haven't applied a function to enough arguments?)
     • In a stmt of an interactive GHCi command: print it
 
 <interactive>:10:1: error:
-    • No instance for (Show (p0 -> p0)) arising from a use of ‘print’
+    • No instance for ‘Show (p0 -> p0)’ arising from a use of ‘print’
         (maybe you haven't applied a function to enough arguments?)
     • In a stmt of an interactive GHCi command: print it
 
 <interactive>:19:1: error:
-    • No instance for (Show (p0 -> p0)) arising from a use of ‘print’
+    • No instance for ‘Show (p0 -> p0)’ arising from a use of ‘print’
         (maybe you haven't applied a function to enough arguments?)
     • In a stmt of an interactive GHCi command: print it
 
 <interactive>:28:1: error:
-    • No instance for (Show (p0 -> p0)) arising from a use of ‘print’
+    • No instance for ‘Show (p0 -> p0)’ arising from a use of ‘print’
         (maybe you haven't applied a function to enough arguments?)
     • In a stmt of an interactive GHCi command: print it
 
 <interactive>:49:1: error:
-    • No instance for (Show (p0 -> p0)) arising from a use of ‘print’
+    • No instance for ‘Show (p0 -> p0)’ arising from a use of ‘print’
         (maybe you haven't applied a function to enough arguments?)
     • In a stmt of an interactive GHCi command: print it
diff --git a/testsuite/tests/ghci/scripts/T2182ghci2.stderr b/testsuite/tests/ghci/scripts/T2182ghci2.stderr
index 5ebe106bfa..8087c00af9 100644
--- a/testsuite/tests/ghci/scripts/T2182ghci2.stderr
+++ b/testsuite/tests/ghci/scripts/T2182ghci2.stderr
@@ -1,10 +1,10 @@
 
 <interactive>:7:1: error:
-    • No instance for (GHC.Show.Show Float)
+    • No instance for ‘GHC.Show.Show Float’
         arising from a use of ‘System.IO.print’
     • In a stmt of an interactive GHCi command: System.IO.print it
 
 <interactive>:15:1: error:
-    • No instance for (GHC.Show.Show Float)
+    • No instance for ‘GHC.Show.Show Float’
         arising from a use of ‘System.IO.print’
     • In a stmt of an interactive GHCi command: System.IO.print it