--- /dev/null	2018-12-22 16:25:47.047680317 +0000
+++ ffi/should_run/ffi018_ghci.run/ffi018_ghci.run.stderr.normalised	2018-12-22 17:31:34.178826693 +0000
@@ -0,0 +1,4 @@
+
+ffi018_ghci:6:30:
+    Not in scope: ‘Main.main’
+    No module named ‘Main’ is imported.

I suspect the testsuite driver is hiding the interesting part of the failure.