Add test for T11122

Test Plan: validate

Reviewers: austin

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D1655

GHC Trac Issues: #11122

3 files changed, 36 insertions, 1 deletions

diff --git a/testsuite/tests/partial-sigs/should_fail/T11122.hs b/testsuite/tests/partial-sigs/should_fail/T11122.hs
new file mode 100644
index 0000000000..5cf104d872
--- /dev/null
+++ b/testsuite/tests/partial-sigs/should_fail/T11122.hs
@@ -0,0 +1,28 @@
+{-# LANGUAGE NoMonomorphismRestriction #-}
+{-# LANGUAGE PartialTypeSignatures #-}
+
+module T11122 where
+
+data Parser a
+
+instance Functor Parser where
+  fmap = undefined
+
+many p = undefined
+
+digit = undefined
+
+parseTest = undefined
+
+--------------------------------------------
+
+parser :: Parser _
+--parser :: Parser Int
+parser = read <$> many digit
+
+data Wrapper = Wrapper Int deriving Show
+
+wrapperParser = Wrapper <$> parser
+
+main :: IO ()
+main = parseTest wrapperParser "0"
diff --git a/testsuite/tests/partial-sigs/should_fail/T11122.stderr b/testsuite/tests/partial-sigs/should_fail/T11122.stderr
new file mode 100644
index 0000000000..57a74f9e58
--- /dev/null
+++ b/testsuite/tests/partial-sigs/should_fail/T11122.stderr
@@ -0,0 +1,7 @@
+
+T11122.hs:19:18: warning:
+    • Found type wildcard ‘_’ standing for ‘Int’
+    • In the type signature:
+        parser :: Parser _
+    • Relevant bindings include
+        parser :: Parser Int (bound at T11122.hs:21:1)
diff --git a/testsuite/tests/partial-sigs/should_fail/all.T b/testsuite/tests/partial-sigs/should_fail/all.T
index dbbe9462db..2cb65f000b 100644
--- a/testsuite/tests/partial-sigs/should_fail/all.T
+++ b/testsuite/tests/partial-sigs/should_fail/all.T
@@ -60,4 +60,4 @@ test('WildcardInTypeSynonymRHS', normal, compile_fail, [''])
 test('T10615', normal, compile_fail, [''])
 test('T10045', normal, compile_fail, [''])
 test('T10999', normal, compile_fail, [''])
-
+test('T11122', normal, compile, [''])
\ No newline at end of file