The QuickCheck library swapped the order of the arguments of the 'cover'
function in version 2.12.  Version 0.3.4 of the Diff library still uses
the old argument order.  Swapping the argument order makes Diff work
with newer versions of QuickCheck.

See <https://github.com/commercialhaskell/stackage/issues/4289> for the
upstream bug report.

diff -ruN a/test/Test.hs b/test/Test.hs
--- a/test/Test.hs	2016-04-23 01:21:45.000000000 -0400
+++ b/test/Test.hs	2019-11-01 19:13:04.590770903 -0400
@@ -134,7 +134,7 @@
 prop_ppDiffR (DiffInput le ri) =
     let haskDiff=ppDiff $ getGroupedDiff le ri
         utilDiff= unsafePerformIO (runDiff (unlines le) (unlines ri))
-    in  cover (haskDiff == utilDiff) 90 "exact match" $
+    in  cover 90 (haskDiff == utilDiff) "exact match" $
                 classify (haskDiff == utilDiff) "exact match"
                         (div ((length haskDiff)*100) (length utilDiff) < 110) -- less than 10% bigger
     where
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<div class='path'>path: <a href='/guix/log/?id=554120687687a022e4604ae8a9e33ea5dffeb15c'>root</a>/<a href='/guix/log/gnu?id=554120687687a022e4604ae8a9e33ea5dffeb15c'>gnu</a>/<a href='/guix/log/gnu/packages?id=554120687687a022e4604ae8a9e33ea5dffeb15c'>packages</a>/<a href='/guix/log/gnu/packages/lsof.scm?id=554120687687a022e4604ae8a9e33ea5dffeb15c'>lsof.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/packages/lsof.scm?id=554120687687a022e4604ae8a9e33ea5dffeb15c&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-11-23 05:44:11 +0100'>2020-11-23</span></td><td><a href='/guix/commit/gnu/packages/lsof.scm?id=f942c09b663c3a48a1ae22ae96b69aabc323fd31'>gnu: lsof: Cross-compile.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/lsof.scm (lsof)[arguments]: Use CC-FOR-TARGET.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2020-11-23 05:44:10 +0100'>2020-11-23</span></td><td><a href='/guix/commit/gnu/packages/lsof.scm?id=2bf502138c9c8cad945866061772fe0e1f4b7175'>gnu: lsof: Make test failures fatal.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/lsof.scm (lsof)[source]: Add patch to make test suite
failures stop the build.
* gnu/packages/patches/lsof-fatal-test-failures.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2020-11-23 05:44:10 +0100'>2020-11-23</span></td><td><a href='/guix/commit/gnu/packages/lsof.scm?id=70303d073a4f9e9d9fdfa309c6fc350e80b63a60'>gnu: lsof: Respect #:tests?.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/lsof.scm (lsof)[arguments]: The 'check phase takes and
respects a TESTS? keyword.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2020-11-23 05:44:10 +0100'>2020-11-23</span></td><td><a href='/guix/commit/gnu/packages/lsof.scm?id=518b21e058f9ccf23257a2afe1bbace280c5fe1d'>gnu: lsof: Update to 4.94.0.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/lsof.scm (lsof): Update to 4.94.0.
[source]: Switch to new git upstream.
[native-inputs]: Add groff.
[arguments]: Remove custom 'unpack phase.  Add a 'build-man-page phase.
Remove the upstreamed glibc@2.28 test fix.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2020-07-16 20:12:05 +0200'>2020-07-16</span></td><td><a href='/guix/commit/gnu/packages/lsof.scm?id=3720a6f847d5c4bcbbb14953dd19462cad894b8e'>gnu: lsof: Use HTTPS home page.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/lsof.scm (lsof)[home-page]: Use HTTPS.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>