From a77b9ec2a6153065565bca7bb154fff35b830b82 Mon Sep 17 00:00:00 2001
From: Krzysztof Gogolewski <krzysztof.gogolewski@tweag.io>
Date: Sun, 23 Aug 2020 20:35:52 +0200
Subject: Add a test for #18397

The bug was fixed by !3421.
---
 testsuite/tests/codeGen/should_compile/T18397.hs | 20 ++++++++++++++++++++
 testsuite/tests/codeGen/should_compile/all.T     |  4 ++++
 2 files changed, 24 insertions(+)
 create mode 100644 testsuite/tests/codeGen/should_compile/T18397.hs

(limited to 'testsuite')

diff --git a/testsuite/tests/codeGen/should_compile/T18397.hs b/testsuite/tests/codeGen/should_compile/T18397.hs
new file mode 100644
index 0000000000..6941b811ba
--- /dev/null
+++ b/testsuite/tests/codeGen/should_compile/T18397.hs
@@ -0,0 +1,20 @@
+{-# LANGUAGE MagicHash #-}
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE UnboxedTuples #-}
+module T18397 where
+
+import GHC.Exts
+import GHC.ST
+
+data MutableArray s a = MutableArray (MutableArray# s a)
+
+runArray#
+  :: (forall s. ST s (MutableArray s a))
+  -> Array# a
+runArray# m = case runRW# $ \s ->
+  case unST m s of { (# s', MutableArray mary# #) ->
+  unsafeFreezeArray# mary# s'} of (# _, ary# #) -> ary#
+
+unST :: ST s a -> State# s -> (# State# s, a #)
+unST (ST f) = f
+
diff --git a/testsuite/tests/codeGen/should_compile/all.T b/testsuite/tests/codeGen/should_compile/all.T
index 4e0a25b7d5..cb61b2b44c 100644
--- a/testsuite/tests/codeGen/should_compile/all.T
+++ b/testsuite/tests/codeGen/should_compile/all.T
@@ -91,7 +91,11 @@ test('T17648', normal, makefile_test, [])
 test('T17904', normal, compile, ['-O'])
 test('T18227A', normal, compile, [''])
 test('T18227B', normal, compile, [''])
+
+# runRW#-related
 test('T18291', normal, compile, ['-O0'])
+test('T18397', normal, compile, ['-O0'])
+
 test('T15570',
    when(unregisterised(), skip),
    compile, ['-Wno-overflowed-literals'])
-- 
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