3 files changed, 45 insertions, 0 deletions
diff --git a/testsuite/tests/stranal/sigs/T18086.hs b/testsuite/tests/stranal/sigs/T18086.hs
new file mode 100644
index 0000000000..639409adce
--- /dev/null
+++ b/testsuite/tests/stranal/sigs/T18086.hs
@@ -0,0 +1,23 @@
+{-# OPTIONS_GHC -O2 -fforce-recomp #-}
+module T18086 where
+
+import GHC.Stack
+import GHC.Utils.Panic.Plain
+import Control.Exception
+import System.IO.Unsafe
+
+-- Should have strictness signature <L,U>x, emphasis on the exceptional
+-- divergence result.
+m :: IO ()
+m = do
+  putStrLn "foo"
+  error "bar"
+
+-- Dito, just in a more complex scenario (the original reproducer of #18086)
+panic :: String -> a
+panic x = unsafeDupablePerformIO $ do
+  stack <- ccsToStrings =<< getCurrentCCS x
+  if null stack
+  then throw (PlainPanic x)
+  else throw (PlainPanic (x ++ '\n' : renderStack stack))
+
diff --git a/testsuite/tests/stranal/sigs/T18086.stderr b/testsuite/tests/stranal/sigs/T18086.stderr
new file mode 100644
index 0000000000..6941e233f8
--- /dev/null
+++ b/testsuite/tests/stranal/sigs/T18086.stderr
@@ -0,0 +1,21 @@
+
+==================== Strictness signatures ====================
+T18086.$trModule:
+T18086.m: <L,U>x
+T18086.panic: <L,U>x
+
+
+
+==================== Cpr signatures ====================
+T18086.$trModule:
+T18086.m: b
+T18086.panic:
+
+
+
+==================== Strictness signatures ====================
+T18086.$trModule:
+T18086.m: <L,U>x
+T18086.panic: <L,U>x
+
+
diff --git a/testsuite/tests/stranal/sigs/all.T b/testsuite/tests/stranal/sigs/all.T
index 8802389cb4..387a1a7f7d 100644
--- a/testsuite/tests/stranal/sigs/all.T
+++ b/testsuite/tests/stranal/sigs/all.T
@@ -22,3 +22,4 @@ test('T5075', normal, compile, [''])
 test('T17932', normal, compile, [''])
 test('T13380c', expect_broken('!3014'), compile, [''])
 test('T13380f', normal, compile, [''])
+test('T18086', normal, compile, ['-package ghc'])