Initialise cec_suppress properly

In TcErrors, cec_suppress is used to suppress low-priority
errors in favour of truly insoluble ones.

But I was failing to initialise it correcly at top level, which
resulted in Trac #15539.  Easy to fix.

A few regression tests have fewer errors reported, but that seems to
be an improvement.

1 files changed, 0 insertions, 30 deletions

diff --git a/testsuite/tests/typecheck/should_compile/valid_hole_fits.stderr b/testsuite/tests/typecheck/should_compile/valid_hole_fits.stderr
index 6dde6ea5cf..93de053f54 100644
--- a/testsuite/tests/typecheck/should_compile/valid_hole_fits.stderr
+++ b/testsuite/tests/typecheck/should_compile/valid_hole_fits.stderr
@@ -88,21 +88,6 @@ valid_hole_fits.hs:27:5: warning: [-Wtyped-holes (in -Wdefault)]
           (imported from ‘Prelude’ at valid_hole_fits.hs:3:1-40
            (and originally defined in ‘GHC.Base’))
 
-valid_hole_fits.hs:30:5: warning: [-Wdeferred-type-errors (in -Wdefault)]
-    • Ambiguous type variable ‘a1’ arising from a use of ‘show’
-      prevents the constraint ‘(Show a1)’ from being solved.
-      Probable fix: use a type annotation to specify what ‘a1’ should be.
-      These potential instances exist:
-        instance (Show a, Show b) => Show (Either a b)
-          -- Defined in ‘Data.Either’
-        instance Show Ordering -- Defined in ‘GHC.Show’
-        instance Show Integer -- Defined in ‘GHC.Show’
-        ...plus 23 others
-        ...plus 70 instances involving out-of-scope types
-        (use -fprint-potential-instances to see them all)
-    • In the expression: show _
-      In an equation for ‘f’: f = show _
-
 valid_hole_fits.hs:30:10: warning: [-Wtyped-holes (in -Wdefault)]
     • Found hole: _ :: a1
       Where: ‘a1’ is an ambiguous type variable
@@ -138,21 +123,6 @@ valid_hole_fits.hs:30:10: warning: [-Wtyped-holes (in -Wdefault)]
           (imported from ‘Prelude’ at valid_hole_fits.hs:3:1-40
            (and originally defined in ‘GHC.Float’))
 
-valid_hole_fits.hs:34:5: warning: [-Wdeferred-type-errors (in -Wdefault)]
-    • Ambiguous type variable ‘a0’ arising from a use of ‘show’
-      prevents the constraint ‘(Show a0)’ from being solved.
-      Probable fix: use a type annotation to specify what ‘a0’ should be.
-      These potential instances exist:
-        instance (Show a, Show b) => Show (Either a b)
-          -- Defined in ‘Data.Either’
-        instance Show Ordering -- Defined in ‘GHC.Show’
-        instance Show Integer -- Defined in ‘GHC.Show’
-        ...plus 23 others
-        ...plus 70 instances involving out-of-scope types
-        (use -fprint-potential-instances to see them all)
-    • In the expression: show (_ (_ :: Bool))
-      In an equation for ‘h’: h = show (_ (_ :: Bool))
-
 valid_hole_fits.hs:34:11: warning: [-Wtyped-holes (in -Wdefault)]
     • Found hole: _ :: Bool -> a0
       Where: ‘a0’ is an ambiguous type variable