Don't allow orphan COMPLETE pragmas (#13349)

We might support them properly in the future, but for now it's simpler
to disallow them.

Test Plan: validate

Reviewers: mpickering, austin, bgamari, simonpj

Reviewed By: mpickering, simonpj

Subscribers: simonpj, thomie

Differential Revision: https://phabricator.haskell.org/D3243

1 files changed, 5 insertions, 0 deletions

diff --git a/testsuite/tests/patsyn/should_fail/T13349.hs b/testsuite/tests/patsyn/should_fail/T13349.hs
new file mode 100644
index 0000000000..45bdc23ace
--- /dev/null
+++ b/testsuite/tests/patsyn/should_fail/T13349.hs
@@ -0,0 +1,5 @@
+{-# LANGUAGE PatternSynonyms #-}
+
+module T13349 where
+
+{-# COMPLETE False #-}