In hole fits, don't show VTA for inferred variables (#16456)

We fetch the ArgFlag for every argument by using splitForAllVarBndrs
instead of splitForAllTys in unwrapTypeVars.

5 files changed, 25 insertions, 6 deletions

diff --git a/testsuite/tests/printer/T14343.stderr b/testsuite/tests/printer/T14343.stderr
index 5865669302..7ffb689a7d 100644
--- a/testsuite/tests/printer/T14343.stderr
+++ b/testsuite/tests/printer/T14343.stderr
@@ -8,7 +8,7 @@ T14343.hs:10:9: error:
       Valid hole fits include
         test1 :: Proxy '[ 'True] (defined at T14343.hs:10:1)
         Proxy :: forall k1 (k2 :: k1). Proxy k2
-          with Proxy @[Bool] @'[ 'True]
+          with Proxy @'[ 'True]
           (defined at T14343.hs:8:16)
 
 T14343.hs:11:9: error:
@@ -20,7 +20,7 @@ T14343.hs:11:9: error:
       Valid hole fits include
         test2 :: Proxy '[ '[1]] (defined at T14343.hs:11:1)
         Proxy :: forall k1 (k2 :: k1). Proxy k2
-          with Proxy @[[GHC.Types.Nat]] @'[ '[1]]
+          with Proxy @'[ '[1]]
           (defined at T14343.hs:8:16)
 
 T14343.hs:12:9: error:
@@ -32,5 +32,5 @@ T14343.hs:12:9: error:
       Valid hole fits include
         test3 :: Proxy '[ '("Symbol", 1)] (defined at T14343.hs:12:1)
         Proxy :: forall k1 (k2 :: k1). Proxy k2
-          with Proxy @[(GHC.Types.Symbol, GHC.Types.Nat)] @'[ '("Symbol", 1)]
+          with Proxy @'[ '("Symbol", 1)]
           (defined at T14343.hs:8:16)
diff --git a/testsuite/tests/printer/T14343b.stderr b/testsuite/tests/printer/T14343b.stderr
index 7573169414..94e540c79e 100644
--- a/testsuite/tests/printer/T14343b.stderr
+++ b/testsuite/tests/printer/T14343b.stderr
@@ -8,7 +8,7 @@ T14343b.hs:10:9: error:
       Valid hole fits include
         test1 :: Proxy '( 'True, 'False) (defined at T14343b.hs:10:1)
         Proxy :: forall k1 (k2 :: k1). Proxy k2
-          with Proxy @(Bool, Bool) @'( 'True, 'False)
+          with Proxy @'( 'True, 'False)
           (defined at T14343b.hs:8:16)
 
 T14343b.hs:11:9: error:
@@ -23,7 +23,7 @@ T14343b.hs:11:9: error:
         test2 :: Proxy '( '( 'True, 'False), 'False)
           (defined at T14343b.hs:11:1)
         Proxy :: forall k1 (k2 :: k1). Proxy k2
-          with Proxy @((Bool, Bool), Bool) @'( '( 'True, 'False), 'False)
+          with Proxy @'( '( 'True, 'False), 'False)
           (defined at T14343b.hs:8:16)
 
 T14343b.hs:12:9: error:
@@ -35,5 +35,5 @@ T14343b.hs:12:9: error:
       Valid hole fits include
         test3 :: Proxy '( '[1], 'False) (defined at T14343b.hs:12:1)
         Proxy :: forall k1 (k2 :: k1). Proxy k2
-          with Proxy @([GHC.Types.Nat], Bool) @'( '[1], 'False)
+          with Proxy @'( '[1], 'False)
           (defined at T14343b.hs:8:16)
diff --git a/testsuite/tests/typecheck/should_fail/T16456.hs b/testsuite/tests/typecheck/should_fail/T16456.hs
new file mode 100644
index 0000000000..4257483c75
--- /dev/null
+++ b/testsuite/tests/typecheck/should_fail/T16456.hs
@@ -0,0 +1,7 @@
+{-# LANGUAGE PolyKinds #-}
+module T16456 where
+
+data T p = MkT
+
+foo :: T Int
+foo = _
diff --git a/testsuite/tests/typecheck/should_fail/T16456.stderr b/testsuite/tests/typecheck/should_fail/T16456.stderr
new file mode 100644
index 0000000000..fbc0cc6ed5
--- /dev/null
+++ b/testsuite/tests/typecheck/should_fail/T16456.stderr
@@ -0,0 +1,11 @@
+
+T16456.hs:7:7: error:
+    • Found hole: _ :: T Int
+    • In the expression: _
+      In an equation for ‘foo’: foo = _
+    • Relevant bindings include foo :: T Int (bound at T16456.hs:7:1)
+      Valid hole fits include
+        foo :: T Int (bound at T16456.hs:7:1)
+        MkT :: forall {k} (p :: k). T p
+          with MkT @Int
+          (defined at T16456.hs:4:12)
diff --git a/testsuite/tests/typecheck/should_fail/all.T b/testsuite/tests/typecheck/should_fail/all.T
index 962febd640..9e0ba2e455 100644
--- a/testsuite/tests/typecheck/should_fail/all.T
+++ b/testsuite/tests/typecheck/should_fail/all.T
@@ -514,5 +514,6 @@ test('T16255', normal, compile_fail, [''])
 test('T16204c', normal, compile_fail, [''])
 test('T16394', normal, compile_fail, [''])
 test('T16414', normal, compile_fail, [''])
+test('T16456', normal, compile_fail, ['-fprint-explicit-foralls'])
 test('T16627', normal, compile_fail, [''])
 test('T502', normal, compile_fail, [''])