From d3d73db15317ad8a68abf38ef0e74d840f5d5af2 Mon Sep 17 00:00:00 2001
From: Bodigrim <andrew.lelechenko@gmail.com>
Date: Wed, 8 Sep 2021 19:04:49 +0100
Subject: [PATCH] Work around when getFileSystemEncoding is ASCII

---
 tests/Properties/ByteString.hs | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/tests/Properties/ByteString.hs b/tests/Properties/ByteString.hs
index c014cb02a..b7189ca1d 100644
--- a/tests/Properties/ByteString.hs
+++ b/tests/Properties/ByteString.hs
@@ -23,6 +23,7 @@
 #ifndef BYTESTRING_LAZY
 module Properties.ByteString (tests) where
 import qualified Data.ByteString as B
+import GHC.IO.Encoding
 #else
 module Properties.ByteStringLazy (tests) where
 import qualified Data.ByteString.Lazy as B
@@ -83,10 +84,16 @@ tests =
     \x -> ioProperty $ do
       r <- B.toFilePath x >>= B.fromFilePath
       pure (r === x)
-  , testProperty "fromFilePath >>= toFilePath" $
-    \x -> ioProperty $ do
-      r <- B.fromFilePath x >>= B.toFilePath
-      pure (r === x)
+  , testProperty "fromFilePath >>= toFilePath" $ ioProperty $ do
+    let prop x = ioProperty $ do
+          r <- B.fromFilePath x >>= B.toFilePath
+          pure (r === x)
+    -- Normally getFileSystemEncoding returns one of Unicode encodings,
+    -- but if it is ASCII, we should not generate Unicode filenames.
+    enc <- getFileSystemEncoding
+    pure $ case textEncodingName enc of
+      "ASCII" -> property (prop . getASCIIString)
+      _       -> property prop
 #endif
 #endif