1 files changed, 22 insertions, 0 deletions
diff --git a/testsuite/tests/tcplugins/TcPlugin_EmitWanted.hs b/testsuite/tests/tcplugins/TcPlugin_EmitWanted.hs
new file mode 100644
index 0000000000..1b9af19902
--- /dev/null
+++ b/testsuite/tests/tcplugins/TcPlugin_EmitWanted.hs
@@ -0,0 +1,22 @@
+{-# OPTIONS_GHC -dcore-lint #-}
+{-# OPTIONS_GHC -fplugin EmitWantedPlugin #-}
+
+module TcPlugin_EmitWanted where
+
+import Definitions
+  ( MyClass(methC) )
+
+foo :: MyClass a => a
+foo = methC
+
+bar :: Bool
+bar = foo
+  -- We need to solve [W] MyClass a.
+  -- The plugin emits [W] a ~# (), and solves [W] MyClass a
+  -- using the coercion hole.
+  -- We then report an error for the unsolved a ~# () constraint,
+  -- where we get to see whether the source location of the newly
+  -- emitted Wanted constraint is as expected.
+  --
+  -- The crucial thing is that the error message should have
+  -- the correct SrcSpan, in this case line 13 column 7.