guix/gnu/packages/patches/idris-build-with-megaparsec-9.patch

From 6ea9bc913877d765048d7cdb7fc5aec60b196fac Mon Sep 17 00:00:00 2001
From: Felix Yan <felixonmars@archlinux.org>
Date: Wed, 16 Dec 2020 21:48:32 +0800
Subject: [PATCH] Fix compatibility with megaparsec 9

---
Taken from <https://github.com/idris-lang/Idris-dev/pull/4892>

 src/Idris/Parser/Stack.hs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/Idris/Parser/Stack.hs b/src/Idris/Parser/Stack.hs
index fb7b611440..879786f4d2 100644
--- a/src/Idris/Parser/Stack.hs
+++ b/src/Idris/Parser/Stack.hs
@@ -84,7 +84,11 @@ instance Message ParseError where
       (pos, _) = P.reachOffsetNoLine (parseErrorOffset err) (parseErrorPosState err)
 #endif
   messageText = PP.text . init . P.parseErrorTextPretty . parseError
+#if MIN_VERSION_megaparsec(9,0,0)
+  messageSource err = sline
+#else
   messageSource err = Just sline
+#endif
     where
 #if MIN_VERSION_megaparsec(8,0,0)
       (sline, _) = P.reachOffset (parseErrorOffset err) (parseErrorPosState err)